JP2013210589A - Diffraction grating and method for manufacturing the same, and optical waveguide - Google Patents

Diffraction grating and method for manufacturing the same, and optical waveguide Download PDF

Info

Publication number
JP2013210589A
JP2013210589A JP2012082527A JP2012082527A JP2013210589A JP 2013210589 A JP2013210589 A JP 2013210589A JP 2012082527 A JP2012082527 A JP 2012082527A JP 2012082527 A JP2012082527 A JP 2012082527A JP 2013210589 A JP2013210589 A JP 2013210589A
Authority
JP
Japan
Prior art keywords
polarized light
refractive index
cos
diffraction grating
diffraction
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
JP2012082527A
Other languages
Japanese (ja)
Other versions
JP6168642B2 (en
Inventor
Noboru Ebizuka
昇 海老塚
Masaru Hori
勝 堀
Masafumi Ito
昌文 伊藤
Yasuhiro Tojima
康裕 東島
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
NU SYSTEM KK
Nagoya University NUC
Original Assignee
NU SYSTEM KK
Nagoya University NUC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by NU SYSTEM KK, Nagoya University NUC filed Critical NU SYSTEM KK
Priority to JP2012082527A priority Critical patent/JP6168642B2/en
Publication of JP2013210589A publication Critical patent/JP2013210589A/en
Application granted granted Critical
Publication of JP6168642B2 publication Critical patent/JP6168642B2/en
Expired - Fee Related legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Landscapes

  • Liquid Crystal (AREA)
  • Diffracting Gratings Or Hologram Optical Elements (AREA)
  • Optical Head (AREA)

Abstract

PROBLEM TO BE SOLVED: To solve the problem that diffraction efficiency to natural polarization or the like is deteriorated since diffraction efficiency characteristics between S polarization and P polarization are deviated in accordance with a fact that a Bragg angle becomes larger in a transmission type VPH (volume Phase Holographic) diffraction grating and a thick transmission type rectangular diffraction grating.SOLUTION: It becomes possible to set diffraction efficiency of S polarization and P polarization to desired spectral characteristics in arbitrary wavelength and an arbitrary Bragg angle by making two values: difference between the maximum refractive index and the minimum refractive index to the S polarization; and difference between the maximum refractive index and the minimum refractive index to the P polarization to different predetermined values, by using an optical anisotropic medium as a material of a transmission type VPH diffraction grating and a thick transmission type rectangular diffraction grating.

Description

本発明は、各種光学計測機器および、自動車や航空機の計器類等のヘッドアップディスプレイ、３次元映像用ディスプレイ、省エネオフィスや省エネ住宅の外光導入等に利用される効率が高い回折格子、あるいは偏光分離機能を有する回折格子、さらには光情報処理や光コンピューティング等に利用される能動的な回折光学素子に関するものである。   The present invention relates to various optical measuring instruments, head-up displays such as automobile and aircraft instruments, three-dimensional video displays, high-efficiency diffraction gratings used for introducing external light into energy-saving offices and energy-saving houses, or polarized light The present invention relates to a diffraction grating having a separation function, and further to an active diffractive optical element used for optical information processing, optical computing, and the like.

［透過型ＶＰＨ回折格子］
二光束のレーザ干渉露光によって製作され、屈折率が正弦波状に変化する厚い回折格子は、ＶＰＨ（Volume Phase Holographic）と呼ばれる。ここで、波長をλ、格子の厚さをｔ、格子周期をΛ、平均屈折率をｎ＝（ｎmax＋ｎmin）／２としたときに
Q＝2πλt /(nΛ2) ・・・(１)
で定義される回折格子のＱ値がＱ＜１である場合に薄い回折格子、Ｑ＞１０である場合に厚い回折格子に分類される。なお、ｎmaxとｎminはそれぞれ回折格子の最大屈折率と最小屈折率である。 [Transmission type VPH diffraction grating]
A thick diffraction grating manufactured by two-beam laser interference exposure and having a refractive index changing in a sinusoidal shape is called VPH (Volume Phase Holographic). Here, when the wavelength is λ, the thickness of the grating is t, the grating period is Λ, and the average refractive index is n = (n max + n min ) / 2.
Q = 2πλt / (nΛ 2 ) (1)
When the Q value of the diffraction grating defined by (1) is Q <1, the diffraction grating is classified as a thin diffraction grating, and when Q> 10, the diffraction grating is classified as a thick diffraction grating. Note that n max and n min are the maximum refractive index and the minimum refractive index of the diffraction grating, respectively.

図１のように透過型ＶＰＨ回折格子１は、格子の厚さｔや屈折率変調：Δｎ＝（ｎmax−ｎmin）／２を調整して下記ブラッグの回折条件を満足させるとＳ偏光（電界ベクトルが格子方向に対して水平に振動する偏光成分）あるいはＰ偏光（電界ベクトルが格子方向に対して垂直に振動する偏光成分）のいずれかについて最大１００％の回折効率を達成することが可能である。ブラッグの回折条件は、
mλ＝2nΛ sin(θ) ・・・(２)
によって与えられる。ここで、ｍは回折次数である。また、光束が透過型ＶＰＨ回折格子１に入射する面および出射する面に対して格子が垂直である場合にはブラッグ角θ＝入射角＝回折角、また、格子が角度α傾斜している場合には、入射角＝θ＋α、回折角＝θ−αである。 As shown in FIG. 1, the transmission type VPH diffraction grating 1 is adjusted to S-polarized light when the grating thickness t and refractive index modulation: Δn = (n max −n min ) / 2 are adjusted to satisfy the following Bragg diffraction conditions. A diffraction efficiency of up to 100% can be achieved for either the polarization component whose electric field vector oscillates horizontally with respect to the grating direction) or P-polarized light (the polarization component whose electric field vector oscillates perpendicular to the grating direction). It is. Bragg's diffraction conditions are
mλ = 2nΛ sin (θ) (2)
Given by. Here, m is the diffraction order. Further, when the grating is perpendicular to the surface on which the light beam enters and exits the transmission type VPH diffraction grating 1, the Bragg angle θ = incidence angle = diffraction angle, and the grating is inclined at an angle α. Are incident angle = θ + α and diffraction angle = θ−α.

ＶＰＨ回折格子等の屈折率が正弦波状に変化する厚い回折格子は、０次回折光と1次回折光の結合のみを扱う２波結合解析法により、０次回折光と1次回折光の偏光回折効率特性の相対値（Ｓ偏光およびＰ偏光の極大値が常に１００％になる）を見積ることができる。非特許文献１や非特許文献２によれば、格子が入射する面および出射する面に対して垂直な透過型ＶＰＨ回折格子１に入射した光束が上記ブラッグの回折条件を満足する場合に式（２）に格子周期Λと波長λ、平均屈折率ｎを代入してブラッグ角θを求め、最大屈折率ｎmaxと最小屈折率ｎmin、格子の厚さｔが与えられると、１次回折光のＳ偏光に対する回折効率ηＳおよび、Ｐ偏光に対する回折効率ηＰはそれぞれ、 A thick diffraction grating such as a VPH diffraction grating whose refractive index changes in a sinusoidal shape is obtained by using a two-wave coupling analysis method that handles only the combination of the 0th-order diffracted light and the 1st-order diffracted light. The relative value (the maximum value of S-polarized light and P-polarized light is always 100%) can be estimated. According to Non-Patent Document 1 and Non-Patent Document 2, when the light beam incident on the transmission type VPH diffraction grating 1 perpendicular to the surface on which the grating enters and the surface on which the light exits satisfies the Bragg diffraction condition, The Bragg angle θ is obtained by substituting the grating period Λ, wavelength λ, and average refractive index n into 2), and given the maximum refractive index n max , minimum refractive index n min , and grating thickness t, the first-order diffracted light The diffraction efficiency η S for S-polarized light and the diffraction efficiency η P for P-polarized light are respectively

Figure 2013210589
Figure 2013210589

Figure 2013210589
によって求めることができる。
Figure 2013210589
 Can be obtained.

透過型ＶＰＨ回折格子１は、たとえば日本ペイント製のホログラム樹脂２０によって作製される。日本ペイント製のホログラム樹脂２０は可視光および紫外線によって重合する屈折率が高い樹脂のモノマー（ＲＰＭ: Radically polymerized monomer）と紫外線によって重合する屈折率が低い樹脂のモノマー（ＣＰＭ: Cationically polymerized monomer）、色素、光開始剤、溶剤等が含まれており、図１のように基板３０と基板４０との間に厚さｔを調整するためのスペーサとしてガラスビーズ（図示しない）等を混入したホログラム樹脂２０を挟み、可視光レーザの干渉露光によって干渉縞の明部のＲＰＭが重合すると明部と暗部との間でＣＰＭとＲＰＭの濃度勾配が生じるため、それを解消するように明部から暗部にＣＰＭが移動し、暗部から明部にＲＰＭが移動する。その後、均質な紫外線照射を行うことによって残ったＲＰＭとＣＰＭが重合して屈折率変調が定着される。すなわち、このホログラム樹脂２０の現像と定着は乾式工程である。厚いホログラムの記録材料として他にも重クロム酸ゼラチン等が利用される。重クロム酸ゼラチンの現像と定着（漂白）は湿式工程である。   The transmissive VPH diffraction grating 1 is made of, for example, a hologram resin 20 made by Nippon Paint. Nippon Paint's hologram resin 20 is a resin monomer (RPM) that is highly refractive index polymerized by visible light and ultraviolet light, a monomer monomer (CPM: Cationically polymerized monomer) that is polymerized by UV light and a low refractive index. , A photoinitiator, a solvent, and the like, and a hologram resin 20 in which glass beads (not shown) or the like are mixed as a spacer for adjusting the thickness t between the substrate 30 and the substrate 40 as shown in FIG. When the RPM of the bright part of the interference fringe is overlapped by the interference exposure of the visible light laser, a CPM and RPM density gradient is generated between the bright part and the dark part. And the RPM moves from the dark part to the bright part. Thereafter, the remaining RPM and CPM are polymerized by performing uniform ultraviolet irradiation, and the refractive index modulation is fixed. That is, development and fixing of the hologram resin 20 are dry processes. In addition, dichromated gelatin or the like is used as a thick hologram recording material. Development and fixing (bleaching) of dichromated gelatin is a wet process.

図２は上記ホログラム樹脂２０によって製作された、格子周期Λ＝０．９８４μｍ、平均屈折率ｎ＝１．５３の透過型ＶＰＨ回折格子１の波長λ＝０．９６、１．０２、１．１１μｍ、すなわち式（２）よりブラッグ角がそれぞれ、θ＝１８．６°、１９．８°、２１．６°における偏光回折効率の波長特性の実測値である。格子の厚さがｔ＝２０μｍであることから、図２の３波長のブラッグ角における偏光回折効率特性から式（３）と式（４）を満足するような、もっともらしい屈折率変調量：Δｎ＝（ｎmax−ｎmin）／２＝０．０１７が求められた。図３は、図２の透過型ＶＰＨ回折格子１のλ＝１．０２μｍ（θ＝１９．８°）における厚さに対する偏光回折効率の数値計算を示した図である。図３に示すように、この透過型ＶＰＨ回折格子１は式（３）よりｔ＝２３．８μｍにおいてＳ偏光の回折効率が最大であり、式（４）よりｔ＝３１．４μｍにおいてＰ偏光の回折効率が最大であり、Ｓ偏光の回折効率とＰ偏光の回折効率の平均がｔ＝２６．６μｍにおいて最大値の９６％であることがわかる。 FIG. 2 shows the wavelength λ = 0.96, 1.02, 1.11 μm of the transmissive VPH diffraction grating 1 manufactured using the hologram resin 20 and having a grating period Λ = 0.984 μm and an average refractive index n = 1.53. That is, from equation (2), the Bragg angles are measured values of the wavelength characteristics of the polarization diffraction efficiency at θ = 18.6 °, 19.8 °, and 21.6 °, respectively. Since the thickness of the grating is t = 20 μm, a plausible refractive index modulation amount Δn that satisfies the expressions (3) and (4) from the polarization diffraction efficiency characteristics at the Bragg angles of three wavelengths in FIG. = (N max -n min ) /2=0.17 was obtained. FIG. 3 is a diagram showing numerical calculation of polarization diffraction efficiency with respect to the thickness of the transmission type VPH diffraction grating 1 of FIG. 2 at λ = 1.02 μm (θ = 19.8 °). As shown in FIG. 3, this transmission type VPH diffraction grating 1 has the maximum diffraction efficiency of S-polarized light at t = 23.8 μm from the equation (3), and P-polarized light at t = 31.4 μm from the equation (4). It can be seen that the diffraction efficiency is maximum, and the average of the diffraction efficiency of S polarization and that of P polarization is 96% of the maximum value at t = 26.6 μm.

非特許文献３によれば、透過型ＶＰＨ回折格子１の内部におけるブラッグ角がθ＝３０°である場合には、式（３）と式（４）より、図４のようにＰ偏光の回折効率が最初に極大になる厚さにおいてＳ偏光の回折効率が０％になるような条件（ディクソンの条件１）、すなわち、偏光分離素子であることが示されている。図４の透過型ＶＰＨ回折格子１は格子周期：Λ＝０．４μｍ、波長：λ＝０．６μｍ、平均屈折率：ｎ＝１．５、屈折率変調量：Δｎ＝０．０７、θ＝３０°である。スネルの屈折式：ｎ×ｓｉｎθ＝ｓｉｎθ０より、真空中におけるブラッグ角はθ０＝４８．６°である。なお、図４においてＳ偏光の第一極大近傍に見られるＳ偏光とＰ偏光の回折効率の平均値の極大は７９％である。さらに、θ＝３５．３°の場合には、式（３）と式（４）より、図５のようにＰ偏光の回折効率が最初の極大の厚さにおいてＳ偏光の回折効率が第二極大となるために、Ｓ偏光とＰ偏光いずれも最大１００％の高い回折効率を達成できる条件（ディクソンの条件２）であることが示されている。ただし、透過型ＶＰＨ回折格子１は厚さが厚くなるのに従って波長帯域幅が狭くなってしまうために、Ｓ偏光の第二極大の厚さにおける波長帯域幅はＳ偏光の第一極大の厚さの波長帯域幅の１／３である。図５の透過型ＶＰＨ回折格子１はΛ＝０．３４６μｍ、λ＝０．６μｍ、ｎ＝１．５、Δｎ＝０．０７、θ＝３５．３°（θ０＝６０°）である。なお、図５においてＳ偏光の第一極大近傍に見られるＳ偏光とＰ偏光の回折効率の平均値の極大は６３．５％である。 According to Non-Patent Document 3, when the Bragg angle inside the transmissive VPH diffraction grating 1 is θ = 30 °, the diffraction of P-polarized light as shown in FIG. 4 from the equations (3) and (4). It is shown that the polarization separation element is a condition (Dixon's condition 1) in which the diffraction efficiency of S-polarized light becomes 0% at the thickness where the efficiency is first maximized. The transmission type VPH diffraction grating 1 of FIG. 4 has a grating period: Λ = 0.4 μm, wavelength: λ = 0.6 μm, average refractive index: n = 1.5, refractive index modulation amount: Δn = 0.07, θ = 30 °. From Snell's refraction formula: n × sin θ = sin θ 0 , the Bragg angle in vacuum is θ 0 = 48.6 °. In FIG. 4, the maximum of the average value of the diffraction efficiencies of S-polarized light and P-polarized light seen in the vicinity of the first maximum of S-polarized light is 79%. Further, in the case of θ = 35.3 °, from the equations (3) and (4), the diffraction efficiency of the S-polarized light is the second maximum when the diffraction efficiency of the P-polarized light is the first maximum thickness as shown in FIG. In order to maximize, it is shown that both S-polarized light and P-polarized light are conditions (Dixon condition 2) that can achieve a high diffraction efficiency of 100% at the maximum. However, since the wavelength bandwidth becomes narrower as the thickness of the transmission type VPH diffraction grating 1 increases, the wavelength bandwidth at the second maximum thickness of S-polarized light is the thickness of the first maximum of S-polarized light. 1/3 of the wavelength bandwidth. The transmission type VPH diffraction grating 1 in FIG. 5 has Λ = 0.346 μm, λ = 0.6 μm, n = 1.5, Δn = 0.07, and θ = 35.3 ° (θ 0 = 60 °). In FIG. 5, the maximum of the average value of the diffraction efficiency of S-polarized light and P-polarized light seen in the vicinity of the first maximum of S-polarized light is 63.5%.

［厚い透過型矩形回折格子］
厚い透過型矩形回折格子２は図６のように屈折率がｎ１の光学等方性媒質の基板３０と、屈折率がｎ３の光学等方性媒質の基板４０の間に断面が長方形あるいは平行四辺形である屈折率がｎ２ａの光学等方性媒質２１と屈折率がｎ２ｂ（ｎ２ａ≠ｎ２ｂ）の光学等方性媒質２２が交互に設置された厚い位相型回折格子である。 [Thick transmission type rectangular diffraction grating]
As shown in FIG. 6, the thick transmissive rectangular diffraction grating 2 has a rectangular cross section between a substrate 30 of an optical isotropic medium having a refractive index n 1 and a substrate 40 of an optical isotropic medium having a refractive index n 3. A thick phase type diffraction grating in which an optical isotropic medium 21 having a refractive index of n 2a and an optical isotropic medium 22 having a refractive index of n 2b (n 2a ≠ n 2b ), which are parallelograms, are alternately installed. .

厚い透過型矩形回折格子２は多くの場合に光学等方性媒質の基板３０上に付与された光学等方性媒質の層あるいは、基板３０自体をフォトリソグラフィ技術等によって光学等方性媒質２１の矩形格子の畝：Ridgeが形成され、矩形格子の溝：Grooveに光学等方性媒質２２が充填される。すなわち、光学等方性媒質２１は基板３０と同じ材質であってもよい。さらには格子の上に光学等方性媒質の基板４０が設置される場合がある。なお、光学等方性媒質の基板４０は光学等方性媒質２２と同じ材質であってもよい。また、矩形格子の溝および基板４０が空気等の気体や真空である場合には表面刻線型回折格子とも呼ばれる。   In many cases, the thick transmission type rectangular diffraction grating 2 is formed of an optically isotropic medium layer formed on the optically isotropic medium substrate 30 or the substrate 30 itself by a photolithography technique or the like. A rectangular lattice of ridges: Ridge is formed, and a groove: Groove of the rectangular lattice is filled with the optical isotropic medium 22. In other words, the optical isotropic medium 21 may be the same material as the substrate 30. Furthermore, an optically isotropic medium substrate 40 may be provided on the grating. The substrate 40 of the optical isotropic medium may be the same material as the optical isotropic medium 22. Also, when the grooves of the rectangular grating and the substrate 40 are a gas such as air or a vacuum, it is also called a surface engraved diffraction grating.

厚い透過型矩形回折格子２の回折効率を求める場合には、２波結合解析による数値計算では精度が不十分であり、０次回折光と1次回折光について正確な偏光回折効率を見積るためには、非特許文献４によれば厳密結合波解析法（Rigorous Coupled Wave Analysis：ＲＣＷＡ）等を用いた、例えば−３次回折光から４次回折光までの８波程度の数値計算が必要である。ただし、格子周期Λと格子の畝あるいは溝の幅の比（デューティ比）が２：１、すなわち光学等方性媒質２１と光学等方性媒質２２の幅が等しい厚い透過型矩形回折格子２と透過型ＶＰＨ回折格子１の偏光回折効率特性は類似しており、いずれの回折格子も図３〜５のように厚さに対してＳ偏光とＰ偏光の回折効率が極大と極小を周期的に繰り返す。非特許文献５によれば、厚い透過型矩形回折格子２は使用波長λと格子周期Λが与えられた場合に、光学等方性媒質２１の屈折率ｎ２ａと光学等方性媒質２２の屈折率ｎ２ｂおよび格子の厚さｔを調整して、上記ブラッグの回折条件を満足させることによってＳ偏光あるいはＰ偏光のいずれかについて最大１００％の回折効率を達成することが可能である。ただし、デューティ比が２：１の厚い透過型矩形回折格子２の格子の厚さｔに対する回折効率の周期と使用波長λや格子周期Λ、最大屈折率、最小屈折率が等しい透過型ＶＰＨ回折格子１の上記回折効率の周期とは、ブラッグ角θが大きくなるほど乖離する。 When calculating the diffraction efficiency of the thick transmissive rectangular diffraction grating 2, the numerical calculation by the two-wave coupling analysis is insufficient in accuracy, and in order to estimate the accurate polarization diffraction efficiency for the 0th-order diffracted light and the 1st-order diffracted light, According to Non-Patent Document 4, numerical calculation of, for example, about 8 waves from -3rd order diffracted light to 4th order diffracted light using a strictly coupled wave analysis (RCWA) or the like is necessary. However, the ratio of the grating period Λ to the width of the groove or groove (duty ratio) is 2: 1, that is, the thick transmission type rectangular diffraction grating 2 in which the optical isotropic medium 21 and the optical isotropic medium 22 are equal in width. The polarization diffraction efficiency characteristics of the transmissive VPH diffraction grating 1 are similar. As shown in FIGS. 3 to 5, the diffraction efficiency of the S-polarized light and the P-polarized light is periodically maximized and minimized with respect to the thickness. repeat. According to Non-Patent Document 5, the thick transmissive rectangular diffraction grating 2 is provided with the refractive index n 2a of the optical isotropic medium 21 and the refraction of the optical isotropic medium 22 when the use wavelength λ and the grating period Λ are given. It is possible to achieve a diffraction efficiency of up to 100% for either S-polarized light or P-polarized light by adjusting the rate n 2b and the grating thickness t to satisfy the Bragg diffraction conditions. However, the transmission type VPH diffraction grating in which the period of diffraction efficiency with respect to the grating thickness t of the thick transmission type rectangular diffraction grating 2 having a duty ratio of 2: 1 and the operating wavelength λ, the grating period Λ, the maximum refractive index, and the minimum refractive index are equal. The period of the diffraction efficiency of 1 becomes more dissimilar as the Bragg angle θ increases.

光学等方性媒質２１の屈折率：ｎ２ａ＝１．７であり、光学等方性媒質２２の屈折率：ｎ２ｂ＝１．５であり、デューティ比が２：１の厚い透過型矩形回折格子２について、波長λと格子周期Λが等しい、すなわち式（２）より真空中におけるブラッグ角がθ０＝３０°の場合に、１次回折光の回折効率が最初に最大になる格子周期で規格化された厚さ：ｔ／Λを上記ＲＣＷＡ法によって求めた場合にはＳ偏光がｔ／Λ＝１．８０、Ｐ偏光がｔ／Λ＝２．３０である。一方、最大屈折率：ｎmax＝１．７であり、最小屈折率：ｎmin＝１．５である透過型ＶＰＨ回折格子１（つまり、透過型矩形回折格子１の最大屈折率は、透過型矩形回折格子２の光学等方性媒質２１、２２の屈折率のうち大きい方で、最小屈折率は光学等方性媒質２１、２２の屈折率のうち小さい方）についてθ０＝３０°の場合に式（３）および式（４）によって１次回折光の回折効率を求めると、Ｓ偏光がｔ／Λ＝２．３８であり、Ｐ偏光がｔ／Λ＝２．９５である。従って、厚い透過型矩形回折格子２と透過型ＶＰＨ回折格子１の厚さの比はＳ偏光とＰ偏光について、それぞれ１：１．３２と１：１．２８である。 Refractive index of the optical isotropic medium 21: n 2a = 1.7, Refractive index of the optical isotropic medium 22: n 2b = 1.5, and a thick transmissive rectangular diffraction with a duty ratio of 2: 1 For the grating 2, when the wavelength λ is equal to the grating period Λ, that is, when the Bragg angle in vacuum is θ 0 = 30 °, the standard is the grating period that maximizes the diffraction efficiency of the first-order diffracted light first. When t / Λ is determined by the above RCWA method, t / Λ = 1.80 for S-polarized light and t / Λ = 2.30 for P-polarized light. On the other hand, the transmissive VPH diffraction grating 1 having a maximum refractive index: n max = 1.7 and a minimum refractive index: n min = 1.5 (that is, the maximum refractive index of the transmissive rectangular diffraction grating 1 is transmissive). In the case of θ 0 = 30 ° with respect to the larger one of the refractive indexes of the optical isotropic media 21 and 22 of the rectangular diffraction grating 2 and the smallest refractive index being the smaller of the refractive indexes of the optical isotropic media 21 and 22 When the diffraction efficiencies of the first-order diffracted light are obtained by the equations (3) and (4), the S-polarized light is t / Λ = 2.38 and the P-polarized light is t / Λ = 2.95. Therefore, the ratio of the thicknesses of the thick transmissive rectangular diffraction grating 2 and the transmissive VPH diffraction grating 1 is 1: 1.32 and 1: 1.28 for S-polarized light and P-polarized light, respectively.

特許文献１によれば、表面刻線型の厚い透過型矩形回折格子２についてデューティ比と格子の畝の屈折率を調整することによって、任意のブラッグ角θに対して、一方の偏光の回折効率が極大になる厚さにおいて、もう一方の偏光の回折効率が０％になる条件が数値計算によって示されている。また、非特許文献６によれば、表面刻線型の厚い透過型矩形回折格子２についてデューティ比と格子の畝の屈折率を調整することによって、任意の入射角および回折角に対して、Ｓ偏光とＰ偏光の効率の波長特性を近づけてＳ偏光とＰ偏光を同時、すなわち自然偏光や円偏光、４５°直線偏光等に対して１００％に近い高い回折効率を達成できることが数値計算によって示されている。厚い透過型矩形回折格子２の光学等方性媒質２１の屈折率：ｎ２ａ＝１．４であり、光学等方性媒質２２の屈折率：ｎ２ｂ＝１．０である表面刻線型の厚い透過型矩形回折格子２について、非特許文献６によると、使用波長λと格子周期Λが等しい、すなわち式（２）より真空中におけるブラッグ角がθ０＝３０°の場合に、（２２）のデューティ比が概ね１０：３であり、ｔ／Λ＝３．１である条件において自然偏光等に対して９７％程度の高い回折効率を達成できると見積られている。この時、厚さｔと光学等方性媒質２２の幅ｗ２のアスペクト比は１０．３：１である。 According to Patent Document 1, by adjusting the duty ratio and the refractive index of the grating ridge for a thick surface-transmitted rectangular diffraction grating 2, the diffraction efficiency of one polarized light can be obtained for an arbitrary Bragg angle θ. The numerical calculation shows the condition that the diffraction efficiency of the other polarized light becomes 0% at the maximum thickness. Further, according to Non-Patent Document 6, by adjusting the duty ratio and the refractive index of the grating ridge in the surface-transmitted thick transmission rectangular diffraction grating 2, the S-polarized light can be obtained for any incident angle and diffraction angle. Numerical calculations show that high wavelength efficiency close to 100% can be achieved for S polarization and P polarization simultaneously, that is, natural polarization, circular polarization, 45 ° linear polarization, etc. ing. The refractive index of the optical isotropic medium 21 of the thick transmission type rectangular diffraction grating 2 is n 2a = 1.4, and the refractive index of the optical isotropic medium 22 is n 2b = 1.0. Regarding the transmission type rectangular diffraction grating 2, according to Non-Patent Document 6, when the used wavelength λ is equal to the grating period Λ, that is, when the Bragg angle in the vacuum is θ 0 = 30 ° from Equation (2), (22) It is estimated that a high diffraction efficiency of about 97% can be achieved with respect to natural polarization or the like under the condition where the duty ratio is approximately 10: 3 and t / Λ = 3.1. In this case, the aspect ratio of the width w 2 of the thickness t and the optically isotropic medium 22 is 10.3: 1.

特許文献２および特許文献３によれば、偏光分離素子は厚い透過型矩形回折格子２の光学等方性媒質２１の代わりに光学異方性媒質を使用して、入射光束に対してＳ偏光あるいはＰ偏光の屈折率を格子の溝に充填される光学等方性材質２２の屈折率ｎ２ｂと一致させ、もう一方の偏光が光学等方性媒質２２の屈折率ｎ２ｂと異なるようにすることによって、０次以外の回折光についてＳ偏光あるいはＰ偏光のみを利用する回折光学素子について記述されている。 According to Patent Document 2 and Patent Document 3, the polarization separating element uses an optically anisotropic medium instead of the optically isotropic medium 21 of the thick transmission type rectangular diffraction grating 2, so The refractive index of P-polarized light is matched with the refractive index n 2b of the optical isotropic material 22 filled in the grooves of the grating, and the other polarized light is different from the refractive index n 2b of the optical isotropic medium 22. Describes a diffractive optical element that uses only S-polarized light or P-polarized light for diffracted light other than the 0th order.

非特許文献７によれば、図６のような厚い矩形回折格子の溝に液晶を充填して、無電界において入射光束に対して光学等方性媒質２１の屈折率ｎ２ａと光学異方性媒質である液晶の屈折率とを一致させておく。厚い矩形回折格子の光束が入射する面と出射する面に配置された透明電極によって格子に電圧を印可して液晶の屈折率を変化させることによって、素通しの窓から回折格子に切り替える機能性回折光学素子について記述されている。ただし、無電界でも電圧を印可した場合であってもＳ偏光とＰ偏光に対する屈折率や回折効率の異方性についての記述は見当たらない。 According to Non-Patent Document 7, a groove of a thick rectangular diffraction grating as shown in FIG. 6 is filled with liquid crystal, and the refractive index n 2a of the optical isotropic medium 21 and the optical anisotropy with respect to the incident light beam without an electric field. The refractive index of the liquid crystal that is the medium is matched. Functional diffractive optics that switches from a transparent window to a diffraction grating by applying a voltage to the grating and changing the refractive index of the liquid crystal by means of transparent electrodes placed on the light incident and exit surfaces of a thick rectangular diffraction grating The device is described. However, there is no description about the refractive index and diffraction efficiency anisotropy for S-polarized light and P-polarized light even when no voltage is applied.

特開２００４−１９８６４１号公報JP 2004-198641 A 特開２０００−７５１３０号公報JP 2000-75130 A 特開２００５−５５７７３号公報JP 2005-55773 A 特開２００６−２０１３８８号公報JP 2006-201388 A

H. Kogelnik, “Coupled Wave Theory for Thick Hologram Grating”, Bell System Technical Journal, 48, 2909-2946, 1969.H. Kogelnik, “Coupled Wave Theory for Thick Hologram Grating”, Bell System Technical Journal, 48, 2909-2946, 1969. I. K. Baldry, J. Bland-Hawthorn, J. G. Robertson, “Volume Phase Holographic gratings: Polarization properties and Diffraction Efficiency”, Publ. Astron. Soc. Pacific 116, 403-414, 2004.I. K. Baldry, J. Bland-Hawthorn, J. G. Robertson, “Volume Phase Holographic gratings: Polarization properties and Diffraction Efficiency”, Publ. Astron. Soc. Pacific 116, 403-414, 2004. L. D. Dickson, R. D. Rallison, B. H. Yung, “Holographic polarization-separation elements”, Appl. Opt. 33, 5378-5385, 1994.L. D. Dickson, R. D. Rallison, B. H. Yung, “Holographic polarization-separation elements”, Appl. Opt. 33, 5378-5385, 1994. N. Chateau, J. Hugonin, “Algorithm for the rigorous coupled-wave analysis of grating diffraction”, J. Opt. Soc. Am. A, 11, 1321-1331, 1994.N. Chateau, J. Hugonin, “Algorithm for the rigorous coupled-wave analysis of grating diffraction”, J. Opt. Soc. Am. A, 11, 1321-1331, 1994. M. C. Gupta, S. T. Peng,“Diffraction characteristics of surface-relief gratings”,Appl. Opt., 32, 2911-2917, 1993.M. C. Gupta, S. T. Peng, “Diffraction characteristics of surface-relief gratings”, Appl. Opt., 32, 2911-2917, 1993. H. J. Gerritsen, M. L. Jepsen, “Rectangular Surface-Relief Transmission Gratings with a Very Large First-Order Diffraction Efficiency (95%) for Unpolarized Light”, Appl. Opt., 37, 5823-5829, 1998.H. J. Gerritsen, M. L. Jepsen, “Rectangular Surface-Relief Transmission Gratings with a Very Large First-Order Diffraction Efficiency (95%) for Unpolarized Light”, Appl. Opt., 37, 5823-5829, 1998. M. L. Jepsen, H. J. Gerritsen, “Liquide-crystal-filled gratings with high diffraction efficiency”, Opt. L., 21, 1081-1083, 1996.M. L. Jepsen, H. J. Gerritsen, “Liquide-crystal-filled gratings with high diffraction efficiency”, Opt. L., 21, 1081-1083, 1996. N. Ebizuka, M. Iye, T. Sasaki, “Optically Anisotropic Crystalline Grisms or Astronomical Spectrographs”, Appl. Opt., 37, 1236-1242, 1998.N. Ebizuka, M. Iye, T. Sasaki, “Optically Anisotropic Crystalline Grisms or Astronomical Spectrographs”, Appl. Opt., 37, 1236-1242, 1998.

解決しようとする問題点は、透過型ＶＰＨ回折格子１はブラッグ角θが大きくなるのに従いＳ偏光とＰ偏光の回折効率特性が乖離することである。透過型ＶＰＨ回折格子１の真空中のブラッグ角がθ０＝４５°、すなわち光軸を直角に折曲げる場合に、格子の平均屈折率がｎ＝１．４１において図４のような上記ディクソンの条件１の偏光回折効率特性であるために自然偏光等に対する回折効率は最大７９％程度である。格子の平均屈折率ｎをより大きくすることにより自然偏光等に対する回折効率を向上できるが、現状で入手可能なホログラム記録材料の平均屈折率ｎは最大１．５５程度であるために、自然偏光等に対する回折効率が最大８５％程度であることが問題である。また、透過型ＶＰＨ回折格子１は上記ディクソンの条件２において自然偏光等に対して最大１００％の高い回折効率を達成することが可能であるが、平均屈折率ｎによってθ０が限定されてしまう上に、格子の厚さｔが厚くなることにより回折効率特性の半値幅が狭くなることが問題である。 The problem to be solved is that the diffractive efficiency characteristics of the S-polarized light and the P-polarized light deviate as the Bragg angle θ increases in the transmissive VPH diffraction grating 1. When the Bragg angle in the vacuum of the transmission type VPH diffraction grating 1 is θ 0 = 45 °, that is, when the optical axis is bent at a right angle, the average refractive index of the grating is n = 1.41 and the above-mentioned Dixon as shown in FIG. Because of the polarization diffraction efficiency characteristics of condition 1, the diffraction efficiency for natural polarization or the like is about 79% at maximum. Although the diffraction efficiency for natural polarized light and the like can be improved by increasing the average refractive index n of the grating, the average refractive index n of the currently available hologram recording material is about 1.55 at the maximum, so The problem is that the diffraction efficiency with respect to the maximum is about 85%. In addition, the transmission type VPH diffraction grating 1 can achieve a high diffraction efficiency of up to 100% with respect to natural polarization or the like in the above-mentioned Dixon condition 2, but θ 0 is limited by the average refractive index n. Another problem is that the full width at half maximum of the diffraction efficiency characteristic becomes narrow as the thickness t of the grating increases.

厚い透過型矩形回折格子２は前述のように光学等方性媒質２１と光学等方性媒質２２の屈折率の比と幅を調整することにより、Ｓ偏光とＰ偏光の回折効率特性を近づけることができる。しかし、ＲＣＷＡの数値計算によると、光学等方性媒質２１の屈折率ｎ２ａと光学等方性媒質２２の屈折率ｎ２ｂの比が小さくなるほど、あるいはブラッグ角θが大きくなるほど、屈折率が低い媒質の幅が狭くなり、格子の厚さｔが厚くなるために、屈折率が低い媒質の幅と厚さｔのアスペクト比が大きくなり、屈折率が低い媒質を注入する溝の加工が困難になってしまうことが問題である。非特許文献６によると、光学等方性媒質２１の屈折率：ｎ２ａ＝１．４であり、光学等方性媒質２２の屈折率：ｎ２ｂ＝１．０である表面刻線型の厚い透過型矩形回折格子２は真空中のブラッグ角がθ０＝４５°の場合に、格子周期Λと光学等方性媒質２２の幅ｗ２のデューティ比がΛ：ｗ２＝２０：３程度であり、ｔ／Λ＝４．２である条件において自然偏光等に対して約９８％の高い回折効率を達成できると見積られている。しかし、光学等方性媒質２２の溝のアスペクト比がｔ：ｗ２＝２８：１であるため、ドライエッチング等による光学等方性媒質２２の溝の加工が困難である。 The thick transmission type rectangular diffraction grating 2 adjusts the refractive index ratio and the width of the optical isotropic medium 21 and the optical isotropic medium 22 as described above, thereby bringing the diffraction efficiency characteristics of S-polarized light and P-polarized light closer to each other. Can do. However, according to numerical calculation of RCWA, the larger the ratio of the refractive index n 2b of the refractive index n 2a and optically isotropic medium 22 optically isotropic medium 21 is reduced, or the Bragg angle θ increases, the refractive index is low Since the width of the medium is reduced and the thickness t of the grating is increased, the aspect ratio between the width of the medium having a low refractive index and the thickness t is increased, making it difficult to process a groove for injecting a medium having a low refractive index. The problem is that it becomes. According to Non-Patent Document 6, the refractive index of the optical isotropic medium 21 is n 2a = 1.4, and the refractive index of the optical isotropic medium 22 is n 2b = 1.0. When the Bragg angle in vacuum is θ 0 = 45 °, the type rectangular diffraction grating 2 has a duty ratio of the grating period Λ and the width w 2 of the optical isotropic medium 22 of about Λ: w 2 = 20: 3. It is estimated that a high diffraction efficiency of about 98% can be achieved for natural polarized light and the like under the condition of t / Λ = 4.2. However, since the aspect ratio of the groove of the optical isotropic medium 22 is t: w 2 = 28: 1, it is difficult to process the groove of the optical isotropic medium 22 by dry etching or the like.

請求項１に記載の回折格子は、屈折率が正弦波状に変調された格子構造である透過型ＶＰＨ回折格子であって、光学異方性媒質を用い、その光学異方性媒質のＳ偏光に対する最大屈折率と最少屈折率との差と、Ｐ偏光に対する最大屈折率と最少屈折率との差を、異なる所定値とすることで、Ｓ偏光の回折効率とＰ偏光の回折効率とを所望の特性（回折効率の格子厚さ依存性）に制御したことを特徴とする。つまり、光学異方性媒質のＳ偏光に対する最大屈折率と最少屈折率との差、およびＰ偏光に対する最大屈折率と最少屈折率との差、および格子の厚さtの３つの制御によって、任意の波長λおよび任意の格子周期Λ、すなわち任意のブラッグ角θにおいてＳ偏光とＰ偏光の回折効率を所望の分光特性に制御したことを主要な特徴とする。上記差に替えて、Ｓ偏光に対する屈折率変調量（最大屈折率と最少屈折率との差の二分の一）、およびＰ偏光に対する屈折率変調量、および格子の厚さtの３つを制御するのも、同様である。   The diffraction grating according to claim 1 is a transmissive VPH diffraction grating having a grating structure in which a refractive index is modulated in a sinusoidal shape, and uses an optically anisotropic medium, and the optically anisotropic medium has S-polarized light. By setting the difference between the maximum refractive index and the minimum refractive index and the difference between the maximum refractive index and the minimum refractive index for P-polarized light to different predetermined values, the diffraction efficiency of S-polarized light and the diffraction efficiency of P-polarized light can be set as desired. It is characterized by being controlled to characteristics (dependence of diffraction efficiency on the grating thickness). In other words, any control is possible by controlling the difference between the maximum refractive index and the minimum refractive index for the S-polarized light of the optically anisotropic medium, the difference between the maximum refractive index and the minimum refractive index for the P-polarized light, and the thickness t of the grating. The main characteristic is that the diffraction efficiencies of the S-polarized light and the P-polarized light are controlled to the desired spectral characteristics at the wavelength λ and the arbitrary grating period Λ, that is, the arbitrary Bragg angle θ. In place of the above difference, the refractive index modulation amount for S-polarized light (one half of the difference between the maximum refractive index and the minimum refractive index), the refractive index modulation amount for P-polarized light, and the grating thickness t are controlled. The same applies to the above.

つまり、本発明の回折格子は、請求項１に記載の回折格子において、Ｓ偏光に対する最大屈折率をｎＳｍａx、最少屈折率をｎＳｍｉｎ、Ｐ偏光に対する最大屈折率をｎＰｍａx、最少屈折率をｎＰｍｉｎとして、ｎＳｍａx、ｎＳｍｉｎ、ｎＰｍａx、およびｎＰｍｉｎは、
（ｎＳｍａx−ｎＳｍｉｎ）／ｃｏｓθＳ＝（ｎＰｍａx−ｎＰｍｉｎ）＊ｃｏｓ２θＰ／ｃｏｓθＰ
を満たす値とすることで、Ｓ偏光の回折効率およびＰ偏光の回折効率の平均を、所望の波長、入射角において９０％以上としたことを特徴とする。さらには９５％以上、あるいは９９％以上とすることも可能である。
ただし、上記式においてθＳはＳ偏光に対するブラッグ角、θＰはＰ偏光に対するブラッグ角である。 That is, the diffraction grating of the present invention is the diffraction grating according to claim 1, wherein the maximum refractive index for S-polarized light is n Smax , the minimum refractive index is n Smin , the maximum refractive index for P-polarized light is n Pmax , and the minimum refractive index is As n Pmin , n Smax , n Smin , n Pmax , and n Pmin are
(N Smax −n Smin ) / cos θ S = (n Pmax −n Pmin ) * cos 2θ P / cos θ P
By satisfying the above condition, the average of the diffraction efficiency of S-polarized light and the diffraction efficiency of P-polarized light is set to 90% or more at a desired wavelength and incident angle. Further, it can be 95% or more, or 99% or more.
In the above equation, θ S is the Bragg angle for S-polarized light, and θ P is the Bragg angle for P-polarized light.

また、本発明の回折格子は、請求項１に記載の回折格子において、Ｓ偏光に対する最大屈折率をｎＳｍａx、最少屈折率をｎＳｍｉｎ、Ｐ偏光に対する最大屈折率をｎＰｍａx、最少屈折率をｎＰｍｉｎとして、ｎＳｍａx、ｎＳｍｉｎ、ｎＰｍａx、およびｎＰｍｉｎは、
（ｎＳｍａx−ｎＳｍｉｎ）／ｃｏｓθＳ＝２（ｎＰｍａx−ｎＰｍｉｎ）＊ｃｏｓ２θＰ／ｃｏｓθＰ
または、
２（ｎＳｍａx−ｎＳｍｉｎ）／ｃｏｓθＳ＝（ｎＰｍａx−ｎＰｍｉｎ）＊ｃｏｓ２θＰ／ｃｏｓθＰ
を満たす値とすることで、Ｓ偏光およびＰ偏光の回折効率のうち、一方を９０％以上、他方を１％以下としたことを特徴とする。一方の回折効率を９５％以上、あるいは９９％以上とすることも可能である。
ただし、上記式においてθＳはＳ偏光に対するブラッグ角、θＰはＰ偏光に対するブラッグ角である。 The diffraction grating of the present invention is the diffraction grating according to claim 1, wherein the maximum refractive index for S-polarized light is n Smax , the minimum refractive index is n Smin , the maximum refractive index for P-polarized light is n Pmax , and the minimum refractive index is As n Pmin , n Smax , n Smin , n Pmax , and n Pmin are
(N Smax −n Smin ) / cos θ S = 2 (n Pmax −n Pmin ) * cos 2θ P / cos θ P
Or
2 (n Smax −n Smin ) / cos θ S = (n Pmax −n Pmin ) * cos 2θ P / cos θ P
By satisfying the above, one of the diffraction efficiencies of S-polarized light and P-polarized light is set to 90% or more and the other is set to 1% or less. One diffraction efficiency can be 95% or more, or 99% or more.
In the above equation, θ S is the Bragg angle for S-polarized light, and θ P is the Bragg angle for P-polarized light.

また、請求項１に記載の回折格子は、以下のような構成とすることができる。
１つは、光学等方性の樹脂に、所定の方向に配向した一軸性あるいは二軸性光学異方性の液晶が混合された樹脂であり、樹脂中の液晶の濃度によって屈折率が正弦波状に変調され、液晶の濃度および液晶分子の配向方向によって、Ｓ偏光に対する最大屈折率と最少屈折率との差と、Ｐ偏光に対する最大屈折率と最少屈折率との差とを、異なる所定値としたことを特徴とする回折格子である。
他の１つは、二軸性光学異方性の液晶と、液晶を挟んでその液晶に接し、液晶を所定の方向に配向させる液晶配向膜と、液晶を挟む１対の電極が周期的に配置された電極部と、を有し、電極部への電圧の印加によって液晶分子の配向方向を制御することにより、液晶の屈折率を正弦波状に変調し、かつ、Ｓ偏光に対する最大屈折率と最少屈折率との差と、Ｐ偏光に対する最大屈折率と最少屈折率との差とを異なる所定値とし、電極部への印加電圧値を変えることで、Ｓ偏光の回折効率とＰ偏光の回折効率とを可変としたことを特徴とする回折格子である。 Moreover, the diffraction grating of Claim 1 can be set as the following structures.
One is a resin in which uniaxial or biaxial optically anisotropic liquid crystal oriented in a predetermined direction is mixed with an optically isotropic resin, and the refractive index is sinusoidal depending on the concentration of the liquid crystal in the resin. The difference between the maximum refractive index and the minimum refractive index for S-polarized light and the difference between the maximum refractive index and the minimum refractive index for P-polarized light are different from each other according to the concentration of liquid crystal and the orientation direction of liquid crystal molecules. This is a diffraction grating characterized by the above.
The other is that a biaxial optically anisotropic liquid crystal, a liquid crystal alignment film that contacts the liquid crystal with the liquid crystal sandwiched therebetween, and aligns the liquid crystal in a predetermined direction, and a pair of electrodes that sandwich the liquid crystal periodically And controlling the orientation direction of the liquid crystal molecules by applying a voltage to the electrode portion, thereby modulating the refractive index of the liquid crystal in a sine wave shape, and the maximum refractive index for S-polarized light By making the difference between the minimum refractive index and the difference between the maximum refractive index and the minimum refractive index for P-polarized light different from each other and changing the voltage applied to the electrode section, the diffraction efficiency of S-polarized light and the diffraction of P-polarized light The diffraction grating is characterized in that the efficiency is variable.

請求項１に記載の回折格子は、透過型ＶＰＨ回折格子において、液晶等の光学異方性媒質を使用した場合に、光学異方性媒質はＳ偏光に対する最大屈折率がｎＳｍａx、最小屈折率がｎＳｍｉｎ、Ｐ偏光に対する最大屈折率がｎＰｍａx、最小屈折率がｎＰｍｉｎ、Ｓ偏光とＰ偏光に対するブラッグ角がそれぞれ、θＳおよびθＰであるとすると、ｎＳｍａx、ｎＳｍｉｎ、ｎＰｍａx、およびｎＰｍｉｎを調整することによって、 The diffraction grating according to claim 1 is a transmission type VPH diffraction grating, and when an optical anisotropic medium such as liquid crystal is used, the optical anisotropic medium has a maximum refractive index of n Smax and a minimum refractive index for S-polarized light. Is n Smin , the maximum refractive index for P-polarized light is n Pmax , the minimum refractive index is n Pmin , and the Bragg angles for S-polarized light and P-polarized light are θ S and θ P , respectively, n Smax , n Smin , n Pmax And by adjusting n Pmin

Figure 2013210589
Figure 2013210589

Figure 2013210589
Figure 2013210589

スネルの屈折の式より
(nSmax+nSmin) sinθS = (nPmax+nPmin) sinθP
であるから、 From Snell's equation of refraction
(n Smax + n Smin ) sinθ S = (n Pmax + n Pmin ) sinθ P
Because

Figure 2013210589
Figure 2013210589

を満足するようなθＳとθＰにおいて、式（３）と式（４）が等しくなるために、図７のようにＳ偏光およびＰ偏光の１次回折光の回折効率特性が一致する。そして、その一致した極大値において９０％以上の回折効率となる。つまり、所望のブラッグ角（言い換えれば所望の格子周期Λ、波長λ）において、式（５）を満たすようＳ偏光に対する最大屈折率と最大屈折率との差、およびＰ偏光に対する最大屈折率と最少屈折率との差を制御すれば、Ｓ偏光の回折効率の特性とＰ偏光の回折効率の特性を一致させて、その一致した極大値においてＳ偏光とＰ偏光の回折効率の平均を９０％以上とすることができる。式（５）の左辺と右辺が近似等号によって結ばれているのは、左辺と右辺が厳密に等しくなくても、多くの場合に実用上問題なく利用できるからである。左辺と右辺が１０％以内の違いであれば、実用上問題ない。 In θ S and θ P that satisfy the above, Equations (3) and (4) are equal, so that the diffraction efficiency characteristics of the first-order diffracted light of S-polarized light and P-polarized light coincide as shown in FIG. The diffraction efficiency is 90% or more at the matched maximum value. That is, at a desired Bragg angle (in other words, a desired grating period Λ, wavelength λ), the difference between the maximum refractive index and the maximum refractive index for S-polarized light and the maximum refractive index and minimum for P-polarized light so as to satisfy Equation (5). If the difference from the refractive index is controlled, the characteristics of the diffraction efficiency of S-polarized light and the characteristics of diffraction efficiency of P-polarized light are matched, and the average of the diffraction efficiency of S-polarized light and P-polarized light is 90% or more at the matched maximum value. It can be. The reason why the left side and the right side of Equation (5) are connected by an approximate equal sign is that in many cases, the left side and the right side can be used without any problem even if they are not exactly equal. If the difference between the left side and the right side is within 10%, there is no practical problem.

請求項１に記載の回折格子は、透過型ＶＰＨ回折格子において、液晶等の光学異方性媒質を使用した場合に、光学異方性媒質はＳ偏光に対する最大屈折率がｎＳｍａx、最小屈折率がｎＳｍｉｎ、Ｐ偏光に対する最大屈折率がｎＰｍａx、最小屈折率がｎＰｍｉｎ、Ｓ偏光とＰ偏光に対するブラッグ角がそれぞれ、θＳおよびθＰであるとすると、ｎＳｍａx、ｎＳｍｉｎ、ｎＰｍａxおよびｎＰｍｉｎを調整することによって、 The diffraction grating according to claim 1 is a transmission type VPH diffraction grating, and when an optical anisotropic medium such as liquid crystal is used, the optical anisotropic medium has a maximum refractive index of n Smax and a minimum refractive index for S-polarized light. Is n Smin , the maximum refractive index for P-polarized light is n Pmax , the minimum refractive index is n Pmin , and the Bragg angles for S-polarized light and P-polarized light are θ S and θ P , respectively, n Smax , n Smin , n Pmax And by adjusting n Pmin

Figure 2013210589
あるいは、
Figure 2013210589
Figure 2013210589
 Or
Figure 2013210589

を満足するような任意のθＳとθＰにおいて、式（３）の格子の厚さｔに対する周期が式（４）の格子の厚さｔに対する周期の２倍あるいは１／２になり、図４に示す上記ディクソンの条件１のように、Ｓ偏光あるいはＰ偏光の１次回折光の効率が最初の極大になる格子の厚さｔにおいて、Ｐ偏光あるいはＳ偏光の１次回折光の効率が０％になる偏光特性になる。つまり、所望のブラッグ角において、式（６）あるいは式（７）を満たすようＳ偏光に対する最大屈折率と最少屈折率との差、およびＰ偏光に対する最大屈折率と最少屈折率との差を制御すれば、Ｓ偏光とＰ偏光のうち、一方を９０％以上の回折効率とし、他方を１％以下の回折効率とすることができ、偏光分離素子として機能させることができる。式（６）および式（７）の左辺と右辺が近似等号によって結ばれているのは、左辺と右辺が厳密に等しくなくても、多くの場合に実用上問題なく利用できるからである。
以上のことから、所望のブラッグ角において、Ｓ偏光に対する最大屈折率と最少屈折率との差、およびＰ偏光に対する最大屈折率と最少屈折率との差を制御すれば、Ｓ偏光の回折効率と、Ｐ偏光の回折効率を所望の特性とすることができることがわかる。 For any θ S and θ P that satisfy the above, the period for the grating thickness t in equation (3) is twice or ½ of the period for the grating thickness t in equation (4). As in the above-mentioned Dixon condition 1 shown in FIG. 4, the efficiency of the first-order diffracted light of P-polarized light or S-polarized light is 0% at the thickness t of the grating where the efficiency of the first-order diffracted light of S-polarized light or P-polarized light reaches the first maximum. The polarization characteristic becomes. That is, at the desired Bragg angle, the difference between the maximum refractive index and the minimum refractive index for S-polarized light and the difference between the maximum refractive index and the minimum refractive index for P-polarized light are controlled so as to satisfy Equation (6) or Equation (7). If so, one of the S-polarized light and the P-polarized light can have a diffraction efficiency of 90% or more, and the other can have a diffraction efficiency of 1% or less, and can function as a polarization separation element. The reason why the left side and the right side of the equations (6) and (7) are connected by the approximate equal sign is that even if the left side and the right side are not exactly equal, in many cases, they can be used without any practical problem.
From the above, by controlling the difference between the maximum refractive index and the minimum refractive index for S-polarized light and the difference between the maximum refractive index and the minimum refractive index for P-polarized light at the desired Bragg angle, It can be seen that the diffraction efficiency of P-polarized light can be set to a desired characteristic.

請求項６に記載の回折格子は、２種類の屈折率が異なる材料が交互に周期的に配置された格子構造である透過型の回折格子であって、２種類の材料のうち少なくとも一方が光学異方性媒質であり、その光学異方性媒質のＳ偏光に対する屈折率と他方の材料の屈折率との差と、光学異方性媒質のＰ偏光に対する屈折率と他方の材料の屈折率との差を、異なる所定値とすることで、Ｓ偏光の回折効率とＰ偏光の回折効率とを所望の特性に制御したことを特徴とする。
また、本発明の回折格子は、請求項６に記載の回折格子において、光学異方性媒質のＳ偏光に対する最大屈折率をｎ２ｃＳ、Ｐ偏光に対する最大屈折率をｎ２ｃＰとし、２種類の材料のうち他方の屈折率をｎ２ａとして、ｎ２ａ、ｎ２ｃＳ、およびｎ２ｃＰは、
ｎ２ｃＰ＞ｎ２ｃＳ＞ｎ２ａまたはｎ２ｃＰ＜ｎ２ｃＳ＜ｎ２ａの場合には、Ａ１＊（ｎ２ｃＳ−ｎ２ａ）／ｃｏｓθＳ＝Ｂ１＊（ｎ２ｃＰ−ｎ２ａ）＊ｃｏｓ２θＰ／ｃｏｓθＰ
ｎ２ｃＰ＞ｎ２ａ＞ｎ２ｃＳまたはｎ２ｃＰ＜ｎ２ａ＜ｎ２ｃＳの場合には、Ａ２＊（ｎ２ｃＳ−ｎ２ａ）／ｃｏｓθＳ＝−Ｂ２＊（ｎ２ｃＰ−ｎ２ａ）＊ｃｏｓ２θＰ／ｃｏｓθＰ
を満たす値とすることで、Ｓ偏光の回折効率およびＰ偏光の回折効率の平均を、所望の波長、入射角において９０％以上としたことを特徴とする。さらには９５％以上、あるいは９９％以上とすることも可能である。
ただし、上記式においてθＳはＳ偏光に対するブラッグ角、θＰはＰ偏光に対するブラッグ角である。また、Ａ１、Ａ２はＲＣＷＡ法によって求めた上記回折格子のＳ偏光の回折効率の格子の厚さに対する周期を、２波結合解析法によって求めた透過型ＶＰＨ回折格子のＳ偏光の回折効率の厚さに対する周期で割った値である。また、Ｂ１とＢ２はＲＣＷＡ法によって求めた上記回折格子のＰ偏光の回折効率の厚さに対する周期を、２波結合解析法によって求めた透過型ＶＰＨ回折格子のＰ偏光の回折効率の厚さに対する周期で割った値である。また、上記２波結合解析法によって求めた透過型ＶＰＨ回折格子とは、Ｓ偏光に対する最大屈折率をｎ２ｃＳ、ｎ２ａのうち大きい方、最小屈折率をｎ２ｃＳ、ｎ２ａのうち小さい方とし、Ｐ偏光に対する最大屈折率をｎ２ｃＰ、ｎ２ａのうち大きい方、最小屈折率をｎ２ｃＰ、ｎ２ａのうち小さい方とした透過型ＶＰＨ回折格子である。
また、本発明の回折格子は、請求項６に記載の回折格子において、光学異方性媒質のＳ偏光に対する最大屈折率をｎ２ｃＳ、Ｐ偏光に対する最大屈折率をｎ２ｃＰとし、２種類の材料のうち他方の材料の屈折率をｎ２ａとして、ｎ２ａ、ｎ２ｃＳ、およびｎ２ｃＰは、
ｎ２ｃＰ＞ｎ２ｃＳ＞ｎ２ａまたはｎ２ｃＰ＜ｎ２ｃＳ＜ｎ２ａの場合には、２Ａ１＊（ｎ２ｃＳ−ｎ２ａ）／ｃｏｓθＳ＝Ｂ１＊（ｎ２ｃＰ−ｎ２ａ）＊ｃｏｓ２θＰ／ｃｏｓθＰ、あるいは、Ａ１＊（ｎ２ｃＳ−ｎ２ａ）／ｃｏｓθＳ＝２Ｂ１＊（ｎ２ｃＰ−ｎ２ａ）＊ｃｏｓ２θＰ／ｃｏｓθＰ
ｎ２ｃＰ＞ｎ２ａ＞ｎ２ｃＳまたはｎ２ｃＰ＜ｎ２ａ＜ｎ２ｃＳの場合には、２Ａ２＊（ｎ２ｃＳ−ｎ２ａ）／ｃｏｓθＳ＝−Ｂ２＊（ｎ２ｃＰ−ｎ２ａ）＊ｃｏｓ２θＰ／ｃｏｓθＰ、あるいは、Ａ２＊（ｎ２ｃＳ−ｎ２ａ）／ｃｏｓθＳ＝−２Ｂ２＊（ｎ２ｃＰ−ｎ２ａ）＊ｃｏｓ２θＰ／ｃｏｓθＰを満たす値とすることで、Ｓ偏光およびＰ偏光の回折効率のうち、一方を９０％以上、他方を１％以下としたことを特徴とする。一方の回折効率を９５％以上、あるいは９９％以上とすることも可能である。
なお、上記式におけるθＳ、θＰ、Ａ１、Ａ２、Ｂ１、Ｂ２は、前述と同様である。
請求項６に記載の回折格子は、２種類の屈折率が異なる材料が交互に周期的に配置された格子構造である透過型の回折格子において、一方の材料として光学異方性媒質を用い、その光学異方性媒質のＳ偏光に対する屈折率がｎ２ｃＳ、Ｐ偏光に対する屈折率がｎ２ｃＰ、Ｓ偏光とＰ偏光に対するブラッグ角がそれぞれθＳおよびθＰであるとすると式５と同様にｎ２ａ、ｎ２ｃＳ、およびｎ２ｃＰを選ぶことによって、 The diffraction grating according to claim 6 is a transmission type diffraction grating having a grating structure in which two kinds of materials having different refractive indexes are alternately and periodically arranged, at least one of the two kinds of materials being optical. The difference between the refractive index of the optically anisotropic medium for S-polarized light and the refractive index of the other material, the refractive index of the optically anisotropic medium for P-polarized light and the refractive index of the other material By making the difference between the two different predetermined values, the diffraction efficiency of the S-polarized light and the diffraction efficiency of the P-polarized light are controlled to have desired characteristics.
The diffraction grating of the present invention is the diffraction grating according to claim 6, wherein the optically anisotropic medium has a maximum refractive index for S-polarized light of n 2cS and a maximum refractive index for P-polarized light of n 2cP. N 2a , n 2cS , and n 2cP , where n 2a is the other refractive index,
In the case of n 2cP > n 2cS > n 2a or n 2cP <n 2cS <n 2a , A 1 * (n 2cS −n 2a ) / cos θ S = B 1 * (n 2cP −n 2a ) * cos 2θ P / cosθ P
In the case of n 2cP > n 2a > n 2cS or n 2cP <n 2a <n 2cS , A 2 * (n 2cS −n 2a ) / cos θ S = −B 2 * (n 2cP −n 2a ) * cos 2θ P / Cosθ P
By satisfying the above condition, the average of the diffraction efficiency of S-polarized light and the diffraction efficiency of P-polarized light is set to 90% or more at a desired wavelength and incident angle. Further, it can be 95% or more, or 99% or more.
In the above equation, θ S is the Bragg angle for S-polarized light, and θ P is the Bragg angle for P-polarized light. A 1 and A 2 are the diffraction efficiency of the S-polarized light of the transmission type VPH diffraction grating obtained by the two-wave coupling analysis method, and the period of the diffraction efficiency of the S-polarized light of the diffraction grating obtained by the RCWA method with respect to the thickness of the grating. It is the value divided by the period for the thickness. B 1 and B 2 are the periods of the diffraction efficiency of the P-polarized light of the diffraction grating obtained by the RCWA method with respect to the thickness of the diffraction efficiency of the P-polarized light of the transmission VPH diffraction grating obtained by the two-wave coupling analysis method. It is the value divided by the period for the length. The transmission type VPH diffraction grating obtained by the above two-wave coupling analysis method has a maximum refractive index for S-polarized light of n 2cS and n 2a which is larger and a minimum refractive index which is smaller of n 2cS and n 2a. , A transmission type VPH diffraction grating having a maximum refractive index for P-polarized light of n 2cP and n 2a , and a minimum refractive index of n 2cP and n 2a , whichever is smaller.
The diffraction grating of the present invention is the diffraction grating according to claim 6, wherein the optically anisotropic medium has a maximum refractive index for S-polarized light of n 2cS and a maximum refractive index for P-polarized light of n 2cP. Where n 2a is the refractive index of the other material, n 2a , n 2cS , and n 2cP are
In the case of n 2cP > n 2cS > n 2a or n 2cP <n 2cS <n 2a , 2A 1 * (n 2cS −n 2a ) / cos θ S = B 1 * (n 2cP −n 2a ) * cos 2θ P / cos θ P or A 1 * (n 2cS −n 2a ) / cos θ S = 2B 1 * (n 2cP −n 2a ) * cos 2θ P / cos θ P
In the case of n 2cP > n 2a > n 2cS or n 2cP <n 2a <n 2cS , 2A 2 * (n 2cS −n 2a ) / cos θ S = −B 2 * (n 2cP −n 2a ) * cos 2θ P / Cos θ P or A 2 * (n 2cS −n 2a ) / cos θ S = −2B 2 * (n 2cP −n 2a ) * cos 2θ P / cos θ P Of these diffraction efficiencies, one is 90% or more and the other is 1% or less. One diffraction efficiency can be 95% or more, or 99% or more.
Note that θ S , θ P , A 1 , A 2 , B 1 , and B 2 in the above formula are the same as described above.
The diffraction grating according to claim 6 is a transmissive diffraction grating having a grating structure in which two kinds of materials having different refractive indexes are alternately and periodically arranged. If the refractive index of the optically anisotropic medium for S-polarized light is n 2cS , the refractive index for P-polarized light is n 2cP , and the Bragg angles for S-polarized light and P-polarized light are θ S and θ P , respectively, By choosing 2a , n 2cS and n 2cP ,

Figure 2013210589
Figure 2013210589

（ｎ２ｃＰ＞ｎ２ｃＳ＞ｎ２ａまたはｎ２ｃＰ＜ｎ２ｃＳ＜ｎ２ａの場合）、 (When n 2cP > n 2cS > n 2a or n 2cP <n 2cS <n 2a ),

Figure 2013210589
Figure 2013210589

（ｎ２ｃＰ＞ｎ２ａ＞ｎ２ｃＳまたはｎ２ｃＰ＜ｎ２ａ＜ｎ２ｃＳの場合）
のいずれかを満足するような任意のθＳとθＰにおいて、式（３）と式（４）が等しくなるために、図７のようにＳ偏光およびＰ偏光の１次回折光の回折効率特性が一致する。そして、その一致した極大値において９０％以上の回折効率となる。つまり、所望のブラッグ角（言い換えれば所望の格子周期Λ、波長λ）において、式（８）、（９）を満たすよう光学異方性媒質のＳ偏光に対する屈折率と他の材料の屈折率との差、および光学異方性媒質のＰ偏光に対する屈折率と他の材料の屈折率との差、の２つを制御すれば、Ｓ偏光の回折効率の特性とＰ偏光の回折効率の特性を一致させて、その一致した極大値となる格子の厚さにおいてＳ偏光とＰ偏光の回折効率の平均を９０％以上とすることができる。ここでＡ１とＡ２は上記ＲＣＷＡ法によって求めた厚い透過型矩形回折格子のＳ偏光の回折効率の格子の厚さｔに対する周期ＰＲＳを上記２波結合解析法によって求めた厚い透過型ＶＰＨ回折格子のＳ偏光の回折効率の格子の厚さｔに対する周期Ｐ２Ｓで割った値である。また、Ｂ１とＢ２は上記ＲＣＷＡ法によって求めた厚い透過型矩形回折格子のＰ偏光の回折効率の格子の厚さｔに対する周期ＰＲＰを上記２波結合解析法によって求めた透過型ＶＰＨ回折格子１のＰ偏光の回折効率の格子の厚さｔに対する周期Ｐ２Ｐで割った値である。なお、式（８）および式（９）の左辺と右辺が近似等号によって結ばれているのは、左辺と右辺が厳密に等しくなくても、多くの場合に実用上問題なく利用できるからである。 (When n 2cP > n 2a > n 2cS or n 2cP <n 2a <n 2cS )
Since the equations (3) and (4) are equal at any θ S and θ P that satisfy any of the above, the diffraction efficiency characteristics of the first-order diffracted light of S-polarized light and P-polarized light as shown in FIG. Match. The diffraction efficiency is 90% or more at the matched maximum value. That is, at the desired Bragg angle (in other words, the desired grating period Λ, wavelength λ), the refractive index of the optically anisotropic medium with respect to the S-polarized light and the refractive index of other materials so as to satisfy the expressions (8) and (9) And the difference between the refractive index of the optically anisotropic medium for the P-polarized light and the refractive index of the other material, the characteristics of the diffraction efficiency of the S-polarized light and the characteristics of the diffraction efficiency of the P-polarized light can be controlled. By matching, the average of the diffraction efficiencies of S-polarized light and P-polarized light can be 90% or more at the thickness of the grating having the matched maximum value. Here, A 1 and A 2 are thick transmission type VPH obtained by calculating the period P RS with respect to the grating thickness t of the diffraction efficiency of S polarization of the thick transmission type rectangular diffraction grating obtained by the RCWA method by the two-wave coupling analysis method. This is a value obtained by dividing the diffraction efficiency of S-polarized light of the diffraction grating by the period P 2S with respect to the thickness t of the grating. B 1 and B 2 are transmission type VPH diffractions obtained by calculating the period P RP of the diffraction efficiency of P-polarized light with respect to the grating thickness t of the thick transmission type rectangular diffraction grating obtained by the RCWA method by the two-wave coupling analysis method. This is a value obtained by dividing the diffraction efficiency of the P-polarized light of the grating 1 by the period P2P with respect to the grating thickness t. Note that the reason why the left and right sides of Equations (8) and (9) are connected by an approximate equal sign is that they can be used without practical problems in many cases even if the left and right sides are not exactly equal. is there.

一方、式（６）や式（７）と同様にｎ２ａとｎ２ｃＳとｎ２ｃＰを選ぶことによって、つまり式（８）、（９）の右辺または左辺の一方を２倍とした等式を満たすようｎ２ａとｎ２ｃＳとｎ２ｃＰを選ぶことによって、任意のθＳとθＰにおいて、式（３）の格子の厚さｔに対する周期が式（４）の格子の厚さｔに対する周期の２倍あるいは１／２になり、図４に示す上記ディクソンの条件１のように、Ｓ偏光あるいはＰ偏光の１次回折光の効率が最初の極大になる格子の厚さｔにおいて、Ｐ偏光あるいはＳ偏光の１次回折光の効率が０％になる偏光特性を実現できる。つまり、ｎ２ｃＰ＞ｎ２ｃＳ＞ｎ２ａまたはｎ２ｃＰ＜ｎ２ｃＳ＜ｎ２ａの場合に、

Figure 2013210589
または、
Figure 2013210589
 あるいは、ｎ２ｃＰ＞ｎ２ｃＳ＞ｎ２ａまたはｎ２ｃＰ＜ｎ２ｃＳ＜ｎ２ａの場合に、
Figure 2013210589
 または、
Figure 2013210589
 のように、所望のブラッグ角において、式（８）、（９）の右辺または左辺の一方を２倍とした等式を満たすよう一方の材料である光学異方性媒質のＳ偏光に対する屈折率と他の材料の屈折率との差、および光学異方性媒質のＰ偏光に対する屈折率と他の材料の屈折率との差、および格子の厚さtの３つを制御すれば、Ｓ偏光とＰ偏光のうち、一方を９０％以上の回折効率とし、他方を１％以下の回折効率とすることができ、偏光分離素子として機能させることができる。なお、式（１０）〜（１３）の左辺と右辺が近似等号によって結ばれているのは、左辺と右辺が厳密に等しくなくても、多くの場合に実用上問題なく利用できるからである。
以上のことから、所望のブラッグ角において、一方の材料である光学異方性媒質のＳ偏光に対する屈折率と他の材料の屈折率との差、および光学異方性媒質のＰ偏光に対する屈折率と他の材料の屈折率との差、および格子の厚さtを制御すれば、Ｓ偏光の回折効率と、Ｐ偏光の回折効率を所望の特性とすることができることがわかる。 On the other hand, by selecting n 2a , n 2cS, and n 2cP in the same manner as in formula (6) and formula (7), that is, an equation in which one of the right side or the left side of formulas (8) and (9) is doubled. By selecting n 2a , n 2cS, and n 2cP to satisfy, at any θ S and θ P , the period with respect to the grating thickness t in Expression (3) is equal to the period with respect to the grating thickness t in Expression (4). At the thickness t of the grating where the efficiency of the first-order diffracted light of S-polarized light or P-polarized light reaches the first maximum as in the above-mentioned Dixon condition 1 shown in FIG. It is possible to realize a polarization characteristic in which the efficiency of polarized first-order diffracted light is 0%. That is, if n 2cP > n 2cS > n 2a or n 2cP <n 2cS <n 2a ,
Figure 2013210589
 Or
Figure 2013210589
 Alternatively, if n 2cP > n 2cS > n 2a or n 2cP <n 2cS <n 2a
Figure 2013210589
 Or
Figure 2013210589
 As shown, the refractive index with respect to the S-polarized light of the optically anisotropic medium, which is one of the materials, satisfies the equation where one of the right side or the left side of the formulas (8) and (9) is doubled at the desired Bragg angle. S-polarized light can be controlled by controlling the difference between the refractive index of the other material and the refractive index of the optically anisotropic medium, the difference between the refractive index of the optically anisotropic medium and the refractive index of the other material, and the thickness t of the grating. And P-polarized light, one can have a diffraction efficiency of 90% or more and the other can have a diffraction efficiency of 1% or less, and can function as a polarization separation element. The reason why the left side and the right side of the equations (10) to (13) are connected by an approximate equal sign is that even if the left side and the right side are not exactly equal, they can be used without any practical problems in many cases. .
From the above, at the desired Bragg angle, the difference between the refractive index of the optically anisotropic medium, which is one material, with respect to S-polarized light and the refractive index of the other material, and the refractive index of the optically anisotropic medium with respect to P-polarized light. It can be seen that the diffraction efficiency of S-polarized light and the efficiency of diffraction of P-polarized light can be made to have desired characteristics by controlling the difference between the refractive index of the other material and the refractive index of other materials and the thickness t of the grating.

本発明の回折格子の光学異方性媒質として、液晶、光配向性樹脂、延伸された樹脂、一軸性結晶や二軸性結晶、ホトニッククリスタル、メタマテリアル等が利用できる。
本発明の回折格子を格子周期方向に伸びる直線状または曲線状とし、それをコア材およびクラッド材により埋め込むことで、平面型の光導波路としてもよい。光導波路においては、本明細書中のＳ偏光をＴＥ波、Ｐ偏光をＴＭ波と置き替えて読めばよい。 As the optically anisotropic medium of the diffraction grating of the present invention, liquid crystal, photo-alignment resin, stretched resin, uniaxial crystal, biaxial crystal, photonic crystal, metamaterial, and the like can be used.
The diffraction grating of the present invention may be a linear or curved shape extending in the grating period direction and embedded with a core material and a clad material to form a planar optical waveguide. In the optical waveguide, the S-polarized light in this specification may be read by replacing it with the TE wave and the P-polarized light with the TM wave.

請求項１、６に記載の回折格子は、任意のブラッグ角θにおいて、Ｓ偏光に対する回折効率とＰ偏光に対する回折効率とを所望の特性とすることができる。
特に、請求項１に記載の回折格子においては式（５）を満たすように光学異方性媒質の屈折率を調整し、請求項６に記載の回折格子においては式（８）あるいは式（９）を満たすように光学異方性媒質の屈折率を調整し、格子の厚さｔを調整することによって、Ｓ偏光とＰ偏光が同時に９０％以上、最大１００％に達する高い回折効率と広い帯域幅を達成することができるという利点がある。 The diffraction gratings according to claims 1 and 6 can achieve desired characteristics of diffraction efficiency for S-polarized light and diffraction efficiency for P-polarized light at an arbitrary Bragg angle θ.
Particularly, in the diffraction grating according to claim 1, the refractive index of the optically anisotropic medium is adjusted so as to satisfy the expression (5), and in the diffraction grating according to claim 6, the expression (8) or the expression (9) ) To adjust the refractive index of the optically anisotropic medium and the thickness t of the grating so that the S-polarized light and the P-polarized light are simultaneously 90% or more, and a high diffraction efficiency and a wide band reaching a maximum of 100%. There is an advantage that the width can be achieved.

また、請求項１に記載の回折格子は、任意のブラッグ角θにおいて、式（６）あるいは式（７）を満足するように光学異方性媒質の屈折率を調整することによって、一方の偏光の回折効率が１％以下（最少０％）、他方の偏光の回折効率が９０％以上（最大１００％）に達するような偏光分離機能が付加された回折格子を高い回折効率で実現できるという利点がある。同様に請求項６に記載の回折格子は、任意のブラッグ角θにおいて、一方の材料である光学異方性媒質の屈折率と他方の材料の屈折率を調整し、格子の厚さｔを調整することによって、一方の偏光の回折効率が１％以下（最少０％）、他方の偏光の回折効率が９０％以上（最大１００％）に達するような偏光分離機能が付加された回折格子を高い回折効率を実現できるという利点がある。   Further, the diffraction grating according to claim 1 is configured to adjust one refractive index of the optically anisotropic medium so as to satisfy Expression (6) or Expression (7) at an arbitrary Bragg angle θ. Advantage of being able to realize a diffraction grating with a polarization separation function with a high diffraction efficiency such that the diffraction efficiency of the other polarization reaches 1% or less (minimum 0%) and the polarization efficiency of the other polarization reaches 90% or more (maximum 100%) There is. Similarly, the diffraction grating according to claim 6 adjusts the refractive index of the optically anisotropic medium, which is one material, and the refractive index of the other material, and adjusts the thickness t of the grating at an arbitrary Bragg angle θ. By doing so, the diffraction grating with the polarization separation function added so that the diffraction efficiency of one polarization reaches 1% or less (minimum 0%) and the diffraction efficiency of the other polarization reaches 90% or more (maximum 100%) is high. There is an advantage that diffraction efficiency can be realized.

請求項６に記載の回折格子は、高次回折光においても適用可能である。   The diffraction grating according to claim 6 can also be applied to higher-order diffracted light.

従来の厚い透過型ＶＰＨ回折格子１や厚い透過型矩形回折格子２は、回折格子内部においてブラッグの条件を満足する次数の回折光と入射光が直交する場合にその回折次数の格子と直交する偏光の電界ベクトル成分が０になってしまうために、Ｐ偏光の回折効率が著しく低下してしまう。請求項１に記載の回折格子は、Ｐ偏光の入射光と回折光が直交しないように光学異方性材料のＰ偏光の平均屈折率や液晶等の配向方向を調整することによって、上記回折次数のＰ偏光の回折効率の低下を防止あるいは軽減することが可能である。また、請求項６に記載の回折格子は、Ｐ偏光において入射光と回折光が直交しないように液晶等の配向方向や、２つの材料のＰ偏光の屈折率の組み合わせを選ぶことによって上記回折次数のＰ偏光の回折効率の低下を防止あるいは軽減することが可能である。   The conventional thick transmission type VPH diffraction grating 1 and thick transmission type rectangular diffraction grating 2 are polarized light orthogonal to the diffraction order grating when the diffraction light of the order satisfying the Bragg condition and the incident light are orthogonal within the diffraction grating. Therefore, the diffraction efficiency of P-polarized light is significantly reduced. The diffraction grating according to claim 1 is characterized in that the diffraction order is adjusted by adjusting an average refractive index of P-polarized light of an optically anisotropic material and an alignment direction of liquid crystal so that incident light of P-polarized light and diffracted light are not orthogonal to each other. It is possible to prevent or reduce the decrease in diffraction efficiency of P-polarized light. In the diffraction grating according to claim 6, the diffraction order is selected by selecting the orientation direction of the liquid crystal or the like and the combination of the refractive indices of the P-polarized light of the two materials so that the incident light and the diffracted light are not orthogonal in the P-polarized light. It is possible to prevent or reduce the decrease in diffraction efficiency of P-polarized light.

請求項１に記載の回折格子や請求項６に記載の回折格子は、光学異方性媒質として硬化型液晶材料を使用し、電界等によって液晶の配向方位を制御することによって製造過程において偏光回折効率特性の調整が容易になる。   The diffraction grating according to claim 1 or the diffraction grating according to claim 6 uses a curable liquid crystal material as an optically anisotropic medium, and polarization diffraction in a manufacturing process by controlling an orientation direction of liquid crystal by an electric field or the like. Adjustment of efficiency characteristics is facilitated.

請求項１に記載の回折格子や請求項６に記載の回折格子は、光学異方性媒質として液晶材料を使用して、電極あるいは透明電極を配置することによって、Ｓ偏光およびＰ偏光に対する回折効率を変動させることが可能な能動的な回折光学素子を実現できる。
なお、本発明の回折格子を用いた請求項１３に記載の光導波路についても、上記と同様の利点を得ることができる。 The diffraction grating according to claim 1 and the diffraction grating according to claim 6 use a liquid crystal material as an optically anisotropic medium and dispose an electrode or a transparent electrode, thereby diffractive efficiency for S-polarized light and P-polarized light. It is possible to realize an active diffractive optical element capable of varying the above.
The same advantages as described above can also be obtained for the optical waveguide according to the thirteenth aspect using the diffraction grating of the present invention.

図１は、ホログラフィック回折格子露光用の二光束干渉計の二光束の偏光方位と振幅および干渉縞の偏光方位と振幅およびＶＰＨ回折格子の概念図である。FIG. 1 is a conceptual diagram of the polarization direction and amplitude of two beams and the polarization direction and amplitude of interference fringes and a VPH diffraction grating of a two-beam interferometer for holographic diffraction grating exposure. 図２は、ＶＰＨ回折格子の回折効率の分光特性の実測値を示した図である。FIG. 2 is a diagram showing measured values of the spectral characteristics of the diffraction efficiency of the VPH diffraction grating. 図３は、図２のＶＰＨ回折格子の厚さに対する回折効率の数値計算の結果を示した図である。FIG. 3 is a diagram showing the results of numerical calculation of diffraction efficiency with respect to the thickness of the VPH diffraction grating of FIG. 図４は、ＶＰＨ回折格子のＰ偏光の最初の極大の厚さにおいてＳ偏光の効率が極小となるような条件（ディクソンの条件１）における厚さに対する回折効率の計算値を示した図である。FIG. 4 is a diagram showing a calculated value of the diffraction efficiency with respect to the thickness under the condition (Dickson's condition 1) in which the efficiency of the S-polarized light becomes minimum at the first maximum thickness of the P-polarized light of the VPH diffraction grating. . 図５はＶＰＨ回折格子のＰ偏光の最初の極大の厚さにおいてＳ偏光の効率が第二極大となるように調整して、いずれの偏光の回折効率も最大１００％に達するような条件（ディクソンの条件２）における厚さに対する回折効率の計算値を示した図である。FIG. 5 shows a condition (Dixon) in which the diffraction efficiency of any polarization reaches a maximum of 100% by adjusting the efficiency of the S polarization at the first maximum thickness of the P polarization of the VPH diffraction grating. It is the figure which showed the calculated value of the diffraction efficiency with respect to the thickness in condition 2). 図６は、厚い透過型矩形回折格子の概念図である。FIG. 6 is a conceptual diagram of a thick transmissive rectangular diffraction grating. 図７は、回折格子３によってＳ偏光とＰ偏光の特性を一致させた場合の厚さに対する回折効率の計算値を示した図である。FIG. 7 is a diagram showing a calculated value of the diffraction efficiency with respect to the thickness when the characteristics of the S-polarized light and the P-polarized light are matched by the diffraction grating 3. 図８は、実施例１の回折格子３の構成を示した図である。FIG. 8 is a diagram illustrating a configuration of the diffraction grating 3 according to the first embodiment. 図９は、実施例２の光導波路４の構成を示した図である。FIG. 9 is a diagram illustrating the configuration of the optical waveguide 4 according to the second embodiment. 図１０は、実施例３の回折格子５の構成を示した図である。FIG. 10 is a diagram illustrating a configuration of the diffraction grating 5 according to the third embodiment. 図１１は、実施例５の光導波路６の構成を示した図である。FIG. 11 is a diagram illustrating the configuration of the optical waveguide 6 according to the fifth embodiment. 図１２は、実施例６の回折格子７の構成を示した図である。FIG. 12 is a diagram illustrating the configuration of the diffraction grating 7 according to the sixth embodiment. 図１３は、二軸性異方性の液晶の座標面内を伝搬する光束について電界が座標面と平行に振動する偏光（実線）および垂直に振動する偏光（破線）の入射方位の屈折率を示した図である。FIG. 13 shows the refractive indexes of incident azimuths of polarized light (solid line) whose electric field oscillates parallel to the coordinate surface (polarized line) and polarized light (broken line) oscillates perpendicularly to the light beam propagating in the coordinate plane of the biaxially anisotropic liquid crystal FIG. 図１４は、実施例７の光導波路８の概念図である。FIG. 14 is a conceptual diagram of the optical waveguide 8 of the seventh embodiment. 図１５は、実施例８の回折格子９の概念図である。FIG. 15 is a conceptual diagram of the diffraction grating 9 according to the eighth embodiment. 図１６は、実施例９の光導波路１０の概念図である。FIG. 16 is a conceptual diagram of the optical waveguide 10 of the ninth embodiment.

図８の正面図（側面図でのＡ−Ａ断面図）および側面図（入射面での断面図）に示すような回折格子３の製作方法を説明する。従来ＶＰＨ回折格子の作製に用いられていたホログラム樹脂に替えて、次のような材料を用いる。その材料は、直線偏光の照射によって近接する2分子の光官能基が偏光の電界振動方向と平行である場合に選択的に二量化するような光学異方性の液晶性有機材料２１０と、屈折率が等方性の熱硬化型樹脂材料２２０と、を主成分とする光学異方性のホログラム樹脂２３０である。二枚のガラス、樹脂、結晶等である基板２００と基板２４０の間に、ガラスビーズ等のスペーサ（図示しない）が混入された上記ホログラム樹脂２３０を挟んでホログラム乾板を作製する。あるいは、このホログラム樹脂２３０をガラス、樹脂、結晶等の基板２００に塗布してもよい。
次に、図８の上部に示した矢印のように、回折格子の周期方向とする方向に偏光させた二光束のレーザ干渉露光によって、干渉縞の明部では、偏光の電界振動方向に長軸が配置されている液晶性有機材料２１０の感光性基が選択的に架橋反応を起こして二量化する。二量化した液晶性有機材料２１０の周囲では、単量体の液晶性有機材料２１０が二量化した液晶性有機材料２１０と同じ方向に配列して、レーザ干渉露光中には近接する単量体の液晶性有機材料２１０と二量化する。その結果、干渉縞の明部においては単量体の液晶性有機材料２１０の濃度が低下するために、干渉縞の暗部から単量体の液晶性有機材料２１０が明部に移動し、一方、明部から熱硬化型樹脂２２０が暗部に移動し、明部に移動した単量体の液晶性有機材料２１０は二量化した液晶性有機材料２１０と同じ方向に配向して近接する単量体の液晶性有機材料と二量化する。
レーザ干渉露光の後に、上記ホログラム乾板を熱硬化性樹脂２２０の硬化温度まで加熱して常温まで冷却することによって、図８の正面図あるいは側面図のような回折格子の周期方向に液晶性有機材料２１０が配向した、本発明の回折格子３を実現できる。
回折格子３は、液晶性有機材料２１０の濃度の違いによって、ホログラム樹脂２３０の屈折率が正弦波状に変化するＶＰＨである。また、液晶性有機材料２１０の配向により、その液晶性有機材料２１０のＳ偏光に対する屈折率とＰ偏光に対する屈折率とは異なっている。
なお、実施例１の回折格子３は、図８の側面図に示すように、ホログラム樹脂２３０の厚さ方向（光の入射面に対して垂直な方向）については液晶性有機材料２１０の濃度を均一として屈折率の変化が内容にしているが、図９の上面図のように、厚さ方向の液晶性有機材料２１０の濃度を変化させることで、厚さ方向の屈折率が角度αの傾斜を有するようにしてもよい。
そして、実施例１の回折格子３は、ホログラム樹脂２３０のＳ偏光に対する最大屈折率ｎＳｍａxと最少屈折率ｎＳｍｉｎとの差：ｎＳｍａx−ｎＳｍｉｎ、およびＰ偏光に対する最大屈折率ｎＰｍａxと最少屈折率ｎＰｍｉｎとの差：ｎＰｍａx−ｎＰｍｉｎを、式（５）を満たす所定の値に制御することにより、Ｓ偏光およびＰ偏光の１次回折光の回折効率特性（回折効率の格子厚さｔ依存性）を一致させることができ、格子の厚さtを調整することによって回折格子３への所望の入射角に対して、Ｓ偏光とＰ偏光の回折効率の平均値を９０％以上とすることができる。もちろん、上記差の二分の一、つまり、Ｓ偏光に対する屈折率変調量：ΔｎＳ＝（ｎＳｍａx−ｎＳｍｉｎ）／２、および、Ｐ偏光に対する屈折率変調量：ΔｎＰ＝（ｎＰｍａx−ｎＰｍｉｎ）／２によって制御してもよい。
また、ホログラム樹脂２３０のＳ偏光に対する最大屈折率ｎＳｍａxと最少屈折率ｎＳｍｉｎとの差、およびＰ偏光に対する最大屈折率ｎＰｍａxと最少屈折率ｎＰｍｉｎとの差を、式（６）または式（７）を満たす所定の値に制御することにより、Ｓ偏光の１次回折光の回折効率特性が極大となるときにＰ偏光の１次回折光の回折効率特性が極小となるように、あるいはその逆に、Ｓ偏光の１次回折光の回折効率特性が極小となるときにＰ偏光の１次回折光の回折効率特性が極大となるようにことができる。そのため、回折格子３への所望の入射角に対して、Ｓ偏光の回折効率が９０％以上でＰ偏光の回折効率が１％以下、またはＳ偏光の回折効率が１％以下でＰ偏光の回折効率が９０％以上とすることができ、回折格子３を偏光分離素子とすることができる。 A manufacturing method of the diffraction grating 3 as shown in the front view (AA cross-sectional view in the side view) and the side view (cross-sectional view in the incident surface) of FIG. 8 will be described. The following materials are used in place of the hologram resin that has been conventionally used for manufacturing the VPH diffraction grating. The material is composed of an optically anisotropic liquid crystalline organic material 210 that selectively dimerizes when two adjacent photofunctional groups are parallel to the direction of electric field vibration of polarized light by irradiation with linearly polarized light, and refraction. An optically anisotropic hologram resin 230 mainly composed of a thermosetting resin material 220 having an isotropic rate. A hologram dry plate is produced by sandwiching the hologram resin 230 in which a spacer (not shown) such as glass beads is mixed between a substrate 200 and a substrate 240, which are two pieces of glass, resin, crystal, or the like. Alternatively, the hologram resin 230 may be applied to a substrate 200 such as glass, resin, or crystal.
Next, as indicated by the arrows shown in the upper part of FIG. 8, the long axis in the direction of the electric field oscillation of the polarized light in the bright part of the interference fringes is obtained by laser interference exposure of two light beams polarized in the direction of the diffraction grating period. The photosensitive group of the liquid crystal organic material 210 in which is placed selectively undergoes a crosslinking reaction to dimerize. Around the dimerized liquid crystal organic material 210, the monomer liquid crystal organic material 210 is aligned in the same direction as the dimerized liquid crystal organic material 210, and during the laser interference exposure, the adjacent monomer liquid crystal organic material 210 is aligned. Dimerizes with the liquid crystalline organic material 210. As a result, since the concentration of the monomer liquid crystalline organic material 210 decreases in the bright part of the interference fringes, the monomer liquid crystalline organic material 210 moves from the dark part of the interference fringes to the bright part, The thermosetting resin 220 moves from the bright part to the dark part, and the liquid crystalline organic material 210 of the monomer that has moved to the bright part is aligned in the same direction as the dimerized liquid crystalline organic material 210 and is close to the monomer. Dimerize with liquid crystalline organic materials.
After the laser interference exposure, the hologram dry plate is heated to the curing temperature of the thermosetting resin 220 and cooled to room temperature, whereby a liquid crystalline organic material is formed in the periodic direction of the diffraction grating as shown in the front view or side view of FIG. The diffraction grating 3 of the present invention in which 210 is oriented can be realized.
The diffraction grating 3 is a VPH in which the refractive index of the hologram resin 230 changes in a sine wave shape due to the difference in concentration of the liquid crystalline organic material 210. Further, the refractive index for S-polarized light and the refractive index for P-polarized light of the liquid-crystalline organic material 210 are different depending on the orientation of the liquid-crystalline organic material 210.
In the diffraction grating 3 of Example 1, as shown in the side view of FIG. 8, the concentration of the liquid crystalline organic material 210 is set in the thickness direction of the hologram resin 230 (direction perpendicular to the light incident surface). The content of the change in the refractive index is uniform, but the refractive index in the thickness direction is inclined at an angle α by changing the concentration of the liquid crystal organic material 210 in the thickness direction as shown in the top view of FIG. You may make it have.
The diffraction grating 3 of Example 1 has a difference between the maximum refractive index n Smax and the minimum refractive index n Smin for the S-polarized light of the hologram resin 230: n Smax −n Smin and the maximum refractive index n Pmax and the minimum for the P-polarized light. Difference from refractive index n Pmin : By controlling n Pmax −n Pmin to a predetermined value satisfying the equation (5), diffraction efficiency characteristics of the first-order diffracted light of S-polarized light and P-polarized light (grating thickness of diffraction efficiency) t dependence), and by adjusting the thickness t of the grating, the average value of the diffraction efficiency of S-polarized light and P-polarized light is 90% or more with respect to a desired incident angle to the diffraction grating 3 can do. Of course, one half of the above difference, that is, refractive index modulation amount for S-polarized light: Δn S = (n Smax −n Smin ) / 2, and refractive index modulation amount for P-polarized light: Δn P = (n Pmax −n Pmin ) / 2 may be used for control.
Further, the difference between the maximum refractive index n Smax and the minimum refractive index n Smin with respect to the S-polarized light of the hologram resin 230 and the difference between the maximum refractive index n Pmax and the minimum refractive index n Pmin with respect to the P-polarized light are expressed by Equation (6) or By controlling to a predetermined value that satisfies (7), when the diffraction efficiency characteristic of the first-order diffracted light of S-polarization becomes maximum, the diffraction efficiency characteristic of the first-order diffracted light of P-polarization becomes minimum, or vice versa. In addition, when the diffraction efficiency characteristic of the S-polarized first-order diffracted light is minimized, the diffraction efficiency characteristic of the P-polarized first-order diffracted light can be maximized. Therefore, with respect to the desired incident angle to the diffraction grating 3, the diffraction efficiency of S-polarized light is 90% or more and the P-polarization diffraction efficiency is 1% or less, or the diffraction efficiency of S-polarization is 1% or less and The efficiency can be 90% or more, and the diffraction grating 3 can be a polarization separation element.

上記偏光配向性の液晶性有機材料２１０が一軸性の液晶であり、常光線屈折率がｎｏ＝１．５、異常光線屈折率がｎｅ＝１．７、熱硬化性樹脂２２０の屈折率が１．５９である場合に、回折格子３はｎＳｍａx＝１．５９、ｎＳｍｉｎ＝１．５、ｎＰｍａx＝１．７、ｎＰｍｉｎ＝１．５９であるとすると、式（５）およびスネルの式（２）より、Ｓ偏光に対するブラッグ角がθＳ＝１８．６°、Ｐ偏光に対するブラッグ角がθＰ＝１７．４°（真空中のブラッグ角：θ０＝２９．４°）のときにＳ偏光とＰ偏光の特性が一致する。図７は波長：λ＝０．６μｍにおいて実施例１の回折格子３によってＳ偏光とＰ偏光の特性を一致させた場合の厚さに対する回折効率の計算値を示した図である。なお、図７は、Ｓ偏光の回折効率の特性とＰ偏光の回折効率の特性とを見易くするために、式（５）が等式になる条件よりブラッグ角が若干小さくなるように格子周期をΛ＝０．６４６μｍとしてあり、Ｓ偏光に対するブラッグ角がθＳ＝１７．５°、Ｐ偏光に対するブラッグ角がθＰ＝１６．４°（真空中のブラッグ角はいずれもθ０＝２７．７°）であり、ホログラム樹脂２３０の厚さｔ＝３．１においてＳ偏光とＰ偏光の回折効率の平均値が９９．９％である。 The polarizing alignment liquid crystalline organic material 210 is a uniaxial liquid crystal, the ordinary ray refractive index is no = 1.5, the extraordinary ray refractive index is ne = 1.7, and the refractive index of the thermosetting resin 220 is 1. .5, the diffraction grating 3 has n Smax = 1.59, n Smin = 1.5, n Pmax = 1.7, and n Pmin = 1.59. From equation (2), when the Bragg angle for S-polarized light is θ S = 18.6 ° and the Bragg angle for P-polarized light is θ P = 17.4 ° (Bragg angle in vacuum: θ 0 = 29.4 °). The characteristics of S-polarized light and P-polarized light coincide with each other. FIG. 7 is a diagram showing a calculated value of diffraction efficiency with respect to thickness when the characteristics of S-polarized light and P-polarized light are matched by the diffraction grating 3 of Example 1 at a wavelength: λ = 0.6 μm. In FIG. 7, in order to make it easier to see the characteristics of S-polarized light and P-polarized light, the grating period is set so that the Bragg angle is slightly smaller than the condition in which Equation (5) becomes an equation. Λ = 0.646 μm, the Bragg angle for S-polarized light is θ S = 17.5 °, the Bragg angle for P-polarized light is θ P = 16.4 ° (the Bragg angles in vacuum are both θ 0 = 27.7) The average value of the diffraction efficiencies of S-polarized light and P-polarized light is 99.9% when the thickness t of the hologram resin 230 is t = 3.1.

図９に示す実施例２の光導波路４の製作方法として、実施例１のような方法で製作された回折格子３のホログラム樹脂２３０を格子と垂直あるいは任意の方位に切断して格子周期方向に伸びる直線状あるいは曲線状の形状に加工し、これをコア層３１０とクラッド層３００に埋設することによって、平面光導波路である光導波路４を実現できる。
この光導波路４は、回折格子３のホログラム樹脂２３０の屈折率を実施例１で示したように制御することにより、ＴＥ波およびＴＭ波の回折効率の特性を所望の特性に制御することが可能である。 As a manufacturing method of the optical waveguide 4 of the second embodiment shown in FIG. 9, the hologram resin 230 of the diffraction grating 3 manufactured by the method as in the first embodiment is cut in a direction perpendicular to the grating or in an arbitrary direction in the grating periodic direction. An optical waveguide 4 that is a planar optical waveguide can be realized by processing into an extending linear or curved shape and embedding it in the core layer 310 and the cladding layer 300.
This optical waveguide 4 can control the diffraction efficiency characteristics of TE wave and TM wave to desired characteristics by controlling the refractive index of the hologram resin 230 of the diffraction grating 3 as shown in the first embodiment. It is.

図１０に示す実施例３の回折格子５の製作方法として、任意の方位に切り出した光学異方性の結晶あるいは延伸によって光学異方性が生じた樹脂等の光学異方性媒質の基板４００にフォトリソグラフィとエッチング技術等によってストライプ状の溝４１０を形成して深い矩形格子４２０を形成し、任意の屈折率を有する樹脂等の光学等方性媒質４５０を充填し、その上に基板４３０を配置して封止することによって回折格子５を実現することができる。図１０のように、光学異方性媒質である基板４００の光学軸は、溝４１０のストライプ方向と同一の方向である。
逆に、光学等方性の基板に断面が矩形のストライプ状の溝を形成し、溝に光学異方性媒質を充填することで回折格子５を形成してもよい。この場合、光学異方性媒質には、電界や配光の照射などによって所定の方向に配向させた状態で硬化させた液晶を用いることができる。
また、光学等方性の基板に光学異方性の膜を形成し、膜をエッチングして断面が矩形のストライプ状の溝を形成し、溝に光学等方性媒質を充填することで回折格子５を形成してもよい。光学異方性の膜には、延伸された樹脂、または配向された状態で硬化した液晶などを用いることができる。 As a method for manufacturing the diffraction grating 5 of Example 3 shown in FIG. 10, an optically anisotropic crystal cut out in an arbitrary orientation or an optically anisotropic medium substrate 400 such as a resin having optical anisotropy caused by stretching is used. Striped grooves 410 are formed by photolithography and etching techniques to form a deep rectangular lattice 420, filled with an optical isotropic medium 450 such as a resin having an arbitrary refractive index, and a substrate 430 is disposed thereon. Then, the diffraction grating 5 can be realized by sealing. As shown in FIG. 10, the optical axis of the substrate 400, which is an optically anisotropic medium, is the same direction as the stripe direction of the groove 410.
Conversely, the diffraction grating 5 may be formed by forming a striped groove having a rectangular cross section on an optically isotropic substrate and filling the groove with an optically anisotropic medium. In this case, the optically anisotropic medium can be a liquid crystal that is cured while being aligned in a predetermined direction by irradiation of an electric field or light distribution.
Further, a diffraction grating is formed by forming an optically anisotropic film on an optically isotropic substrate, etching the film to form a striped groove having a rectangular cross section, and filling the groove with an optically isotropic medium. 5 may be formed. For the optically anisotropic film, a stretched resin, a liquid crystal cured in an aligned state, or the like can be used.

例えば光学異方性の結晶材料として、フッ化イットリウム−リチウム（ＹＬｉＦ４：ＹＬＦ）やβ−メタホウ酸バリウム（β−ＢａＢ２Ｏ４：β−ＢＢＯ）、ニオブ酸リチウム（ＬｉＮｂＯ３）等が挙げられる。また、可視光における樹脂の平均屈折率は１．３５〜１．７４程度である。このうちβ−ＢＢＯは常光線と異常光線の屈折率差が大きく、常光線屈折率：ｎｏ＝１．６６９および異常光線屈折率：ｎｅ＝１．５５１であり、屈折率：ｎ２ａ＝１．３５〜１．５あるいはｎ２ａ＝１．６近傍あるいはｎ２ａ＝１．７〜１．７４の樹脂等と組み合わせることにより、広い回折効率の波長帯域幅を実現できる。なお、非特許文献８によれば、格子以外の部分の基板が光学異方性を有していても平行平面板とみなせる場合には、後置される光学等方性媒質４５０中に出射後のＳ偏光とＰ偏光の回折角は平行平面板部分の光学異方性（複屈折）の影響を受けずに等しいために、溝４１０が基板４００まで貫通しなくても構わない。
この回折格子５は、光学等方性媒質４５０の屈折率ｎ２ａおよび、光学異方性媒質である基板４００のＳ偏光に対する屈折率ｎ２ｃＳとＰ偏光に対する屈折率ｎ２ｃＰとを、式（８）または式（９）を満たす所定の値に制御することにより、図７のようにＳ偏光およびＰ偏光の１次回折光の回折効率特性を一致させることができ、回折格子５への所望の入射角に対して、Ｓ偏光とＰ偏光の回折効率の平均値を９０％以上とすることができる。
また、光学等方性媒質４５０の屈折率ｎ２ａおよび光学異等方性媒質である基板４００のＳ偏光に対する屈折率ｎ２ｃＳ、Ｐ偏光に対する屈折率ｎ２ｃＰを、式（８）、（９）の左辺または右辺の一方を２倍とした等式、つまり、式（１０）、（１１）、（１２）、（１３）のいずれかを満たす所定値に制御することにより、Ｓ偏光の１次回折光の回折効率特性が極大となるときにＰ偏光の１次回折光の回折効率特性が極小となるように、あるいはその逆に、Ｓ偏光の１次回折光の回折効率特性が極小となるときにＰ偏光の１次回折光の回折効率特性が極大となるようにことができる。そのため、回折格子５への所望の入射角に対して、Ｓ偏光の回折効率が９０％以上でＰ偏光の回折効率が１％以下、またはＳ偏光の回折効率が１％以下でＰ偏光の回折効率が９０％以上とすることができ、回折格子５を偏光分離素子とすることができる。
なお、実施例３の回折格子５では、溝４１０を光の入射面に対して垂直なものとしたが、図１１の上面図に示すように、溝４１０を光の入射面に垂直な方向に対して角度α傾斜させ、光学異方性媒質と光学等方性媒質が交互に傾斜して配列された構造としてもよい。 For example, examples of the optically anisotropic crystal material include yttrium fluoride-lithium (YLiF 4 : YLF), β-barium metaborate (β-BaB 2 O 4 : β-BBO), lithium niobate (LiNbO 3 ), and the like. It is done. The average refractive index of the resin in visible light is about 1.35 to 1.74. Among them, β-BBO has a large refractive index difference between ordinary light and extraordinary light, ordinary light refractive index: no = 1.669, extraordinary light refractive index: ne = 1.551, and refractive index: n 2a = 1. A wide wavelength bandwidth with a wide diffraction efficiency can be realized by combining with a resin of 35 to 1.5 or near n 2a = 1.6 or n 2a = 1.7 to 1.74. According to Non-Patent Document 8, when the substrate other than the grating has optical anisotropy and can be regarded as a plane parallel plate, it is emitted into the optically isotropic medium 450 to be placed later. Since the diffraction angles of S-polarized light and P-polarized light are equal without being affected by the optical anisotropy (birefringence) of the plane-parallel plate portion, the groove 410 may not penetrate to the substrate 400.
The diffraction grating 5, the refractive index n 2a and optically isotropic medium 450, and a refractive index n 2 cP to the refractive index n 2CS and P-polarized light with respect to S-polarized light of the substrate 400 is an optically anisotropic medium, the formula (8 ) Or the predetermined value satisfying the expression (9), the diffraction efficiency characteristics of the first-order diffracted light of S-polarized light and P-polarized light can be matched as shown in FIG. The average value of diffraction efficiency of S-polarized light and P-polarized light can be 90% or more with respect to the angle.
Further, the refractive index n 2a of the optically isotropic medium 450 and the refractive index n 2cS for the S-polarized light and the refractive index n 2cP for the P-polarized light of the substrate 400, which is an optically anisotropic medium, are expressed by equations (8) and (9). By controlling to a predetermined value satisfying any one of the equations in which one of the left side or the right side is doubled, that is, the formulas (10), (11), (12), and (13), The diffraction efficiency characteristic of the P-polarized first-order diffracted light is minimized when the diffraction efficiency characteristic of the folded light is maximized, or conversely, the diffraction efficiency characteristic of the S-polarized first-order diffracted light is minimized. It is possible to maximize the diffraction efficiency characteristics of the polarized first-order diffracted light. Therefore, with respect to a desired incident angle to the diffraction grating 5, the diffraction efficiency of S-polarized light is 90% or more and the diffraction efficiency of P-polarized light is 1% or less, or the diffraction efficiency of S-polarized light is 1% or less. The efficiency can be 90% or more, and the diffraction grating 5 can be a polarization separation element.
In the diffraction grating 5 of Example 3, the groove 410 is perpendicular to the light incident surface. However, as shown in the top view of FIG. 11, the groove 410 is oriented in a direction perpendicular to the light incident surface. Alternatively, the structure may be configured such that the optically anisotropic medium and the optically isotropic medium are alternately inclined and arranged at an angle α.

実施例４の回折格子の製作方法として、第１透明基板あるいは第１透明基板に付与された透明媒質の膜をフォトリソグラフィやエッチング技術等によってストライプ状の溝を形成して深い矩形格子を形成し、溝の底部に任意の方位とプレティルト角に液晶を配向される液晶配向膜を配置し、溝に硬化型の液晶を充填し、第２透明基板によって液晶を封止して、紫外線等によって硬化することにより、実施例３の回折格子５とほぼ同一の構成である実施例４の回折格子を実現することができる。なお、第２透明基板の液晶に接する面にも溝の底部と略同じ方位に液晶を配向される液晶配向膜を配置しても良い。   As a method of manufacturing the diffraction grating of Example 4, a deep rectangular grating is formed by forming a stripe-shaped groove on the first transparent substrate or a transparent medium film applied to the first transparent substrate by photolithography or etching technique. The liquid crystal alignment film that aligns the liquid crystal in an arbitrary orientation and pretilt angle is placed at the bottom of the groove, the groove is filled with a curable liquid crystal, the liquid crystal is sealed with a second transparent substrate, and cured by ultraviolet rays or the like By doing so, it is possible to realize the diffraction grating of the fourth embodiment that has substantially the same configuration as the diffraction grating 5 of the third embodiment. Note that a liquid crystal alignment film that aligns the liquid crystal in substantially the same direction as the bottom of the groove may be disposed on the surface of the second transparent substrate that contacts the liquid crystal.

図１１に示す実施例５の光導波路６の製作方法として、実施例３あるいは実施例４のような方法で製作された回折格子５を格子と垂直あるいは任意の方位に切断して格子周期方向に伸びる直線状あるいは曲線状の形状に加工し、これをコア層５１０とクラッド層５００に埋設することによって、平面光導波路である光導波路６を実現できる。光導波路６の埋設された回折格子部分は、図１１のように、光学異方性媒質５３０と光学等方性媒質５２０が傾斜して交互に配列された構造である。   As a method of manufacturing the optical waveguide 6 of Example 5 shown in FIG. 11, the diffraction grating 5 manufactured by the method of Example 3 or Example 4 is cut perpendicularly to the grating or in an arbitrary direction so as to be in the grating period direction. An optical waveguide 6 that is a planar optical waveguide can be realized by processing into an extending linear or curved shape and embedding it in the core layer 510 and the cladding layer 500. As shown in FIG. 11, the diffraction grating portion in which the optical waveguide 6 is embedded has a structure in which the optical anisotropic medium 530 and the optical isotropic medium 520 are alternately arranged in an inclined manner.

図１２に示す実施例６の回折格子７の製作方法を以下に説明する。下基板７００と上基板７３０を任意の厚さの隙間を開けて対向する配置とし、下基板７００および上基板７３０の対向する側の面それぞれには、上下同一格子周期かつ、任意のデューティ比をなす透明電極７１０の格子を配置する。この時、下基板７００側に設けた透明電極７１０と、上基板７３０側に設けた透明電極７１０は対向するように配置する。また、下基板７００と上基板７３０の対向する側の面（液晶に接する面）および透明電極７１０が液晶に接する面に液晶配向膜７２０を配置する。次に、下基板７００と上基板７３０との間の隙間に液晶７４０を充填する。液晶７４０は、強誘電性であるために自発的なキラリティ（Chirality：３次元の図形や物体がその鏡像と重ね合わすことができない性質。掌性。）によって二軸性光学異方性を発現する液晶（バナナ型液晶やディスク型液晶等）であり、任意の方位と下基板７００および上基板７３０に平行あるいは任意のプレティルト角に配向するようにする。また、図１２の側面図のように、液晶７４０の分子７５０の長軸が上下の電極方向（電気力線に平行な方向）に傾き、キラリティが消失して液晶７４０の分子７５０が一軸性光学異性体として振る舞い、透明電極７１０の間に位置する液晶７４０の分子７５０からの距離が離れるに従って、上下の透明電極７１０の間に位置する液晶７４０の分子７５０の傾きから徐々に下基板７００および上基板７３０に平行あるいはプレティルト角に液晶７４０の傾きが変化し、キラリティによって二軸性光学異性体として振る舞うようにする。このようにして実施例６の回折格子７を実現することができる。
この実施例６の回折格子７は、二軸性光学異方性を有する液晶７４０の配向によって、屈折率が正弦波状に変化し、その屈折率を透明電極７１０に印加する電圧によって可変とすることが可能な透過型ＶＰＨ回折格子を実現している。つまり、透明電極７１０の印加電圧の制御によって、Ｓ偏光およびＰ偏光に対する回折効率の特性を制御することができる。 A method for manufacturing the diffraction grating 7 of Example 6 shown in FIG. 12 will be described below. The lower substrate 700 and the upper substrate 730 are arranged to face each other with a gap having an arbitrary thickness, and the opposing surfaces of the lower substrate 700 and the upper substrate 730 have the same upper and lower lattice periods and an arbitrary duty ratio. A grid of transparent electrodes 710 is arranged. At this time, the transparent electrode 710 provided on the lower substrate 700 side and the transparent electrode 710 provided on the upper substrate 730 side are arranged to face each other. In addition, a liquid crystal alignment film 720 is disposed on the opposite surface (the surface in contact with the liquid crystal) of the lower substrate 700 and the upper substrate 730 and the surface in which the transparent electrode 710 is in contact with the liquid crystal. Next, a liquid crystal 740 is filled in a gap between the lower substrate 700 and the upper substrate 730. Since the liquid crystal 740 is ferroelectric, it exhibits biaxial optical anisotropy due to spontaneous chirality (Chirality: a property in which a three-dimensional figure or object cannot be superimposed on its mirror image. Palmarity). It is a liquid crystal (banana-type liquid crystal, disk-type liquid crystal, etc.) and is oriented in an arbitrary direction and parallel to the lower substrate 700 and the upper substrate 730 or at an arbitrary pretilt angle. In addition, as shown in the side view of FIG. 12, the major axis of the molecule 750 of the liquid crystal 740 is inclined in the upper and lower electrode directions (direction parallel to the lines of electric force), the chirality disappears, and the molecule 750 of the liquid crystal 740 becomes uniaxial optical. As the distance from the molecules 750 of the liquid crystal 740 located between the transparent electrodes 710 increases, the lower substrate 700 and the upper substrate gradually move from the inclination of the molecules 750 of the liquid crystals 740 located between the upper and lower transparent electrodes 710. The inclination of the liquid crystal 740 changes parallel to the substrate 730 or at a pretilt angle so that it behaves as a biaxial optical isomer due to chirality. In this way, the diffraction grating 7 of Example 6 can be realized.
In the diffraction grating 7 of Example 6, the refractive index changes sinusoidally depending on the orientation of the liquid crystal 740 having biaxial optical anisotropy, and the refractive index is variable depending on the voltage applied to the transparent electrode 710. A transmissive VPH diffraction grating capable of satisfying the above has been realized. That is, the characteristics of the diffraction efficiency for S-polarized light and P-polarized light can be controlled by controlling the voltage applied to the transparent electrode 710.

図１３は二軸性異方性の液晶の座標面内を伝搬する光束について電界が座標面と平行に振動する偏光（実線）および垂直に振動する偏光（破線）の入射方位の屈折率を示した。図１３の左の図のｘ−ｙ平面においてｘ軸に沿って入射する光束はｚ軸方向に電界が振動する偏光の屈折率がｎ1、ｙ軸方向に電界が振動する偏光の屈折率がｎ２であり、ｙ軸に沿って入射する光束はｚ軸方向に電界が振動する偏光の屈折率がｎ1、ｘ軸方向に電界が振動する偏光の屈折率がｎ３あることがわかる。また、中央あるいは右の図より、ｚ軸に沿って入射する光束はｘ軸方向に電界が振動する偏光の屈折率がｎ３、ｙ軸方向に電界が振動する偏光の屈折率がｎ２であることがわかる。
例えば上記二軸性光学異方性の液晶７４０の分子７５０の長軸がｚ軸であり、ｎ１＝１．７、ｎ２＝１．６６、ｎ３＝１．５である場合に、液晶配向膜７２０によって液晶７４０の分子７５０の長軸が格子と垂直かつ上下の基板と平行に、またｙ軸が格子と平行に配向させると、Ｓ偏光の屈折率が１．６６、Ｐ偏光の屈折率が１．７となる。一方、透明電極７１０の間の液晶７４０の分子７５０は透明電極７１０に電圧を印可すると長軸（ｚ軸）が透明電極７１０の方向に向いて個々の液晶７４０の分子７５０のｘ軸とｙ軸はｚ軸を回転中心にして自由な方向を向いているとすると、Ｓ偏光およびＰ偏光の屈折率はｎ２とｎ３の平均値１．５８である。すなわち、ｎＳｍａx＝１．６６、ｎＳｍｉｎ＝１．５８、ｎＰｍａx＝１．７、ｎＰｍｉｎ＝１．５８である。式（５）およびスネルの式（２）よりＳ偏光に対するブラッグ角がθＳ＝２３．８°、Ｐ偏光に対するブラッグ角がθＰ＝２４．１°（真空中のブラッグ角はともにθ０＝４０．８°）とすると、図７のようにＳ偏光とＰ偏光の特性が一致する。 FIG. 13 shows the refractive indices of incident azimuths of polarized light (solid line) whose electric field oscillates parallel to the coordinate plane (broken line) and polarized light (broken line) oscillates perpendicularly to the light beam propagating in the coordinate plane of the liquid crystal having biaxial anisotropy. It was. In the xy plane in the left diagram of FIG. 13, the light beam incident along the x-axis has a refractive index n1 of polarized light whose electric field oscillates in the z-axis direction and a refractive index n2 of polarized light whose electric field oscillates in the y-axis direction. It can be seen that the light beam incident along the y-axis has a refractive index n1 of polarized light whose electric field oscillates in the z-axis direction and a refractive index n3 of polarized light whose electric field oscillates in the x-axis direction. From the center or right figure, the light beam incident along the z-axis has a refractive index n3 of polarized light whose electric field oscillates in the x-axis direction and n2 of polarized light whose electric field oscillates in the y-axis direction. I understand.
For example, when the major axis of the molecule 750 of the liquid crystal 740 having the biaxial optical anisotropy is the z axis, and n1 = 1.7, n2 = 1.66, and n3 = 1.5, the liquid crystal alignment film 720 If the major axis of the molecules 750 of the liquid crystal 740 is aligned perpendicular to the lattice and parallel to the upper and lower substrates, and the y-axis is aligned parallel to the lattice, the refractive index of S-polarized light is 1.66 and the refractive index of P-polarized light is 1. .7. On the other hand, the molecules 750 of the liquid crystal 740 between the transparent electrodes 710 are such that when a voltage is applied to the transparent electrode 710, the major axis (z-axis) faces the direction of the transparent electrode 710 and the x-axis and y-axis of each molecule 750 of the liquid crystal 740. Is oriented in any direction with the z axis as the rotation center, the refractive index of S-polarized light and P-polarized light is the average value of n2 and n3 of 1.58. That is, n Smax = 1.66, n Smin = 1.58, n Pmax = 1.7, and n Pmin = 1.58. From Equation (5) and Snell's Equation (2), the Bragg angle for S-polarized light is θ S = 23.8 °, and the Bragg angle for P-polarized light is θ P = 24.1 ° (both Bragg angles in vacuum are θ 0 = 40.8 °), the characteristics of S-polarized light and P-polarized light coincide with each other as shown in FIG.

図１４に示す実施例７の光導波路８の製作方法を説明する。コア層８１０の上下をクラッド層８００によって挟まれた平面型の光導波路の、コア層８１０の一部を直線あるいは任意の曲線を描く帯状に除去する。その除去されたコア層８１０の上下のクラッド層８００に上下同一格子周期かつ任意のデューティ比をなす電極８３０の格子を、上記直線あるいは曲線に垂直あるいは任意の角度をなして略同位相で配置する。また、強誘電性であるために自発的なキラリティによって二軸性光学異方性を発現する液晶８４０が、任意の方位と上下のクラッド層８００に平行あるいは任意のプレティルト角に配向するように、上下のクラッド層８００および電極８３０が液晶８４０と接する面に液晶配向膜８２０を配置する。次に、除去されたコア層８１０部分に液晶８４０を充填する。以上により実施例７の平面型の光導波路８を製造する。
この光導波路８は、上下の電極８３０に任意の電圧を印加することによって、図１４の正面図のように上下の電極８３０の間の液晶８４０が上下の電極方向に配向が傾き、キラリティが消失して液晶８４０が一軸性光学異性体として振る舞い、電極８３０の間に位置する液晶８４０からの距離が離れるに従って電極８３０の間に位置する液晶８４０の傾きから徐々にクラッド層８００に平行あるいはプレティルト角に液晶８４０の配向の傾きが変化し、キラリティによって二軸性光学異性体として振る舞う。これにより、屈折率が正弦波状に変調している。つまり、実施例６の回折格子７をコア材とクラッド材により埋め込んだ平面型の構造の光導波路であり、電極８３０の印加電圧によって、ＴＥ波およびＴＭ波の回折効率の特性を制御可能となっている。 A method for manufacturing the optical waveguide 8 of Example 7 shown in FIG. 14 will be described. Part of the core layer 810 of the planar optical waveguide sandwiched between the upper and lower sides of the core layer 810 by the clad layer 800 is removed in a strip shape that draws a straight line or an arbitrary curve. The gratings of the electrodes 830 having the same upper and lower grating periods and an arbitrary duty ratio are arranged on the upper and lower clad layers 800 of the removed core layer 810 in substantially the same phase perpendicular to the straight line or curve or at an arbitrary angle. . In addition, since the liquid crystal 840 that exhibits biaxial optical anisotropy due to spontaneous chirality due to its ferroelectricity is aligned in an arbitrary direction and parallel to the upper and lower cladding layers 800 or in an arbitrary pretilt angle, A liquid crystal alignment film 820 is disposed on the surface where the upper and lower cladding layers 800 and the electrode 830 are in contact with the liquid crystal 840. Next, liquid crystal 840 is filled in the removed core layer 810 portion. As described above, the planar optical waveguide 8 of Example 7 is manufactured.
In this optical waveguide 8, by applying an arbitrary voltage to the upper and lower electrodes 830, the liquid crystal 840 between the upper and lower electrodes 830 is tilted in the upper and lower electrode directions as shown in the front view of FIG. The liquid crystal 840 behaves as a uniaxial optical isomer, and gradually becomes parallel to the cladding layer 800 or pretilt angle from the inclination of the liquid crystal 840 positioned between the electrodes 830 as the distance from the liquid crystal 840 positioned between the electrodes 830 increases. The tilt of the orientation of the liquid crystal 840 changes, and it behaves as a biaxial optical isomer due to chirality. Thereby, the refractive index is modulated in a sine wave shape. That is, the optical waveguide has a planar structure in which the diffraction grating 7 of Example 6 is embedded with a core material and a cladding material, and the diffraction efficiency characteristics of the TE wave and the TM wave can be controlled by the voltage applied to the electrode 830. ing.

図１５に示す実施例８の回折格子９の製作方法を説明する。透明な基板９００上に透明電極９１０を配置する。その上にフォトリソグラフィ技術等によって、樹脂やガラス等の光学等方性媒質の層を形成した後、断面が矩形のストライプ状の溝９４０を形成して、深い矩形格子９３０を形成する。溝９４０の幅はｗ１、矩形格子９３０の幅はｗ２である。溝９４０の底部に任意の方位と透明基板９００に平行あるいは任意のプレティルト角に液晶を配向させる液晶配向膜９２０を配置する。そして、溝９４０に液晶９６０を充填し、透明電極９１０が配置された透明な基板９５０を、その透明電極９１０側を液晶９６０に向けて配置することで、液晶９６０を封止する。以上により、実施例８の回折格子９を製造することができる。
この回折格子９は、実施例３の回折格子５において、光学異方性媒質として液晶を用い、液晶の分子の配向を電圧印加によって制御することで、Ｓ偏光およびＰ偏光の回折効率の特性を可変としたものである。例えば液晶９６０を一軸性の液晶とする場合に、常光線屈折率を光学等方性媒質の屈折率と一致させておき、無電界においては式（８）あるいは式（９）を満足する屈折率になるように所望の方位に液晶を配向させておき、透明電極９１０に電圧を印可した場合においては、液晶９６０の分子の長軸が透明電極９１０の方位に配向することによって、図１１のようにＳ偏光とＰ偏光ともに最大１００％の回折効率を達成する回折格子から、素通しの窓に切り替えることができる。 A method for manufacturing the diffraction grating 9 of Example 8 shown in FIG. 15 will be described. A transparent electrode 910 is disposed on a transparent substrate 900. A layer of an optically isotropic medium such as resin or glass is formed thereon by a photolithography technique or the like, and then a stripe-shaped groove 940 having a rectangular cross section is formed to form a deep rectangular lattice 930. The width of the groove 940 is w 1 , and the width of the rectangular lattice 930 is w 2 . A liquid crystal alignment film 920 that aligns liquid crystal in an arbitrary orientation and parallel to the transparent substrate 900 or in an arbitrary pretilt angle is disposed at the bottom of the groove 940. Then, the liquid crystal 960 is sealed by filling the groove 940 with the liquid crystal 960 and disposing the transparent substrate 950 on which the transparent electrode 910 is disposed with the transparent electrode 910 side facing the liquid crystal 960. Thus, the diffraction grating 9 of Example 8 can be manufactured.
This diffraction grating 9 uses the liquid crystal as the optically anisotropic medium in the diffraction grating 5 of the third embodiment, and controls the orientation of the liquid crystal molecules by applying a voltage, thereby improving the diffraction efficiency characteristics of S-polarized light and P-polarized light. It is variable. For example, when the liquid crystal 960 is a uniaxial liquid crystal, the ordinary ray refractive index is made to coincide with the refractive index of the optical isotropic medium, and the refractive index satisfying the formula (8) or the formula (9) in the absence of an electric field. In the case where the liquid crystal is aligned in a desired direction and a voltage is applied to the transparent electrode 910, the long axes of the molecules of the liquid crystal 960 are aligned in the direction of the transparent electrode 910, as shown in FIG. In addition, it is possible to switch from a diffraction grating that achieves diffraction efficiency up to 100% for both S-polarized light and P-polarized light to a plain window.

図１６に示す実施例９の光導波路１０の製作方法を説明する。まず、クラッド層１０００上に電極１０３０を形成し、さらに電極１０３０上にコア層１０１０を形成する。次に、コア層１０１０の一部を直線あるいは任意の曲線を描く帯状に配列された浅い短冊状の溝１０４０を形成し、矩形格子１０５０を形成する。次に、溝１０４０の底部に液晶が任意の方位とクラッド層に平行あるいは任意のプレティルト角に配向するよう液晶配向膜１０２０を配置する。そして、溝１０４０に液晶１０６０を充填し、電極１０３０と液晶配向膜１０２０が形成されたクラッド層１０１０を、その液晶配向膜１０２０側を液晶１０６０に向けてコア層１０１０に接触させて液晶１０６０を封止する。以上によって実施例９の光導波路１０を製造することができる。
この実施例９の光導波路１０は、電極１０３０に電圧を印加することによって、液晶１０６０が上下の電極方向に任意の角度で傾くので、屈折率を変化させることができ、その結果、ＴＥ波およびＴＭ波の回折効率の特性を制御可能である。 A method for manufacturing the optical waveguide 10 of Example 9 shown in FIG. 16 will be described. First, the electrode 1030 is formed on the cladding layer 1000, and the core layer 1010 is further formed on the electrode 1030. Next, a shallow strip-shaped groove 1040 arranged in a strip shape drawing a straight line or an arbitrary curve is formed on a part of the core layer 1010, and a rectangular lattice 1050 is formed. Next, a liquid crystal alignment film 1020 is disposed at the bottom of the groove 1040 so that the liquid crystal is aligned in an arbitrary orientation and parallel to the cladding layer or in an arbitrary pretilt angle. Then, the liquid crystal 1060 is filled in the groove 1040, and the cladding layer 1010 on which the electrode 1030 and the liquid crystal alignment film 1020 are formed is brought into contact with the core layer 1010 with the liquid crystal alignment film 1020 side facing the liquid crystal 1060, thereby sealing the liquid crystal 1060. Stop. Thus, the optical waveguide 10 of Example 9 can be manufactured.
In the optical waveguide 10 of the ninth embodiment, by applying a voltage to the electrode 1030, the liquid crystal 1060 tilts at an arbitrary angle in the upper and lower electrode directions, so that the refractive index can be changed. The characteristics of TM wave diffraction efficiency can be controlled.

本発明の回折格子３、光導波路４、回折格子７、光導波路８は、式（５）または、式（６）や式（７）が等式である条件から概ね±１０％の偏差であれば多くの場合に実用上問題なく利用できる。   The diffraction grating 3, the optical waveguide 4, the diffraction grating 7, and the optical waveguide 8 according to the present invention should have a deviation of approximately ± 10% from the condition that the equation (5) or the equations (6) and (7) are equal. In many cases, it can be used without any practical problem.

本発明の回折格子５、光導波路６、回折格子９、光導波路１０は、式（８）や式（９）または、式（１０）や式（１１）、式（１２）、式（１３）が等式である条件から概ね±１０％の偏差であれば多くの場合に実用上問題なく利用できる。   The diffraction grating 5, the optical waveguide 6, the diffraction grating 9, and the optical waveguide 10 according to the present invention have the formula (8), the formula (9), the formula (10), the formula (11), the formula (12), and the formula (13). If the deviation is approximately ± 10% from the condition that is an equation, it can be used practically without problems.

本発明の回折格子５、光導波路６、回折格子９、光導波路１０は、それらの素子に用いている光学等方性媒質の代わりに、それらの素子に用いている光学異方性媒質とは異なる特性の光学異方性媒質を組み合せた矩形格子であっても良い。   The diffraction grating 5, the optical waveguide 6, the diffraction grating 9, and the optical waveguide 10 according to the present invention are different from the optically isotropic medium used in these elements, and the optical anisotropic medium used in these elements is A rectangular grating combining optically anisotropic media having different characteristics may be used.

本発明の回折格子５、光導波路６、回折格子９、光導波路１０は、Ｓ偏光（ＴＥ波）の屈折率とＰ偏光（ＴＭ波）の屈折率の調節による偏光回折効率特性の調整の効果と非特許文献６のようなデューティ比の調節によるＳ偏光（ＴＥ波）とＰ偏光（ＴＭ波）の偏光回折効率特性の調整の効果を組み合わせても良い。   The diffraction grating 5, the optical waveguide 6, the diffraction grating 9, and the optical waveguide 10 of the present invention have the effect of adjusting the polarization diffraction efficiency characteristics by adjusting the refractive index of S-polarized light (TE wave) and the refractive index of P-polarized light (TM wave). And the effect of adjusting the polarization diffraction efficiency characteristics of S-polarized light (TE wave) and P-polarized light (TM wave) by adjusting the duty ratio as in Non-Patent Document 6 may be combined.

以上、本発明の実施例について詳細に説明したが、これらは例示に過ぎず、特許請求の範囲を限定するものではない。特許請求の範囲に記載の技術には、以上に例示した具体例を様々に変形、変更したものが含まれる。   As mentioned above, although the Example of this invention was described in detail, these are only illustrations and do not limit a claim. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.

本明細書または図面に説明した技術要素は、単独であるいは各種の組合せによって技術的有用性を発揮するものであり、出願時請求項記載の組合せに限定されるものではない。また、本明細書または図面に例示した技術は複数目的を同時に達成し得るものであり、そのうちの一つの目的を達成すること自体で技術的有用性を持つものである。   The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in this specification or the drawings can achieve a plurality of objects at the same time, and has technical usefulness by achieving one of the objects.

本発明の回折格子および光導波路は、従来の表面刻線型回折格子やＶＰＨ回折格子、厚い透過型矩形回折格子と比べて、高い回折効率と大きな波長分散、広い波長帯域を同時に実現可能であるために、ラマン散乱やトムソン散乱、生体等の蛍光、天文学観測等の微弱光の分光計測装置をはじめ、各種光計測器に利用されることによって測定限界の向上や大幅な計測時間の短縮等が可能になる。   The diffraction grating and optical waveguide of the present invention can simultaneously realize high diffraction efficiency, large wavelength dispersion, and a wide wavelength band, compared to conventional surface-stitched diffraction gratings, VPH diffraction gratings, and thick transmission rectangular diffraction gratings. In addition, it can be used in various optical measuring instruments such as Raman scattering, Thomson scattering, fluorescence of living organisms, and faint light spectroscopic measurement devices such as astronomical observation, etc., which can improve the measurement limit and greatly shorten the measurement time. become.

本発明の回折格子３およびは回折格子５の光学異方性媒質として硬化型の液晶を採用することにより、液晶フラット・ディスプレイ等と同様の製造工程によってメートルクラスのサイズの回折光学素を低価格で製作が可能である。メートルクラスの大面積回折格子が実用化されれば、大型ヘッドアップディスプレイや３次元映像用大型ディスプレイ、外光を天井や部屋の奥に導いて照明として利用する省エネ窓等の応用が可能になる。   By adopting a curable liquid crystal as the optically anisotropic medium of the diffraction grating 3 and the diffraction grating 5 of the present invention, a diffractive optical element of a metric class size can be manufactured at a low cost by the same manufacturing process as a liquid crystal flat display or the like. Can be produced. If a meter-class large-area diffraction grating is put to practical use, it will be possible to apply large head-up displays, large-sized displays for 3D images, energy-saving windows that guide outside light to the ceiling or the back of the room and use it as lighting. .

本発明の回折格子７および回折格子９は、光学異方性媒質として液晶を採用し、格子の両面に透明電極を配置することにより、任意の偏光回折効率特性から任意の偏光回折効率特性に切り換えることが可能な効率が高い能動的な回折光学素子を実現できる。このような光学素子は偏光分光計測装置等の光計測装置や光情報処理、光コンピューティング等に利用可能である。また、上記の大型ヘッドアップディスプレイや３次元映像用大型ディスプレイ、外光導入窓に利用した場合に調光が可能になる。   The diffraction grating 7 and the diffraction grating 9 of the present invention employ a liquid crystal as an optically anisotropic medium, and arrange transparent electrodes on both sides of the grating, thereby switching from an arbitrary polarization diffraction efficiency characteristic to an arbitrary polarization diffraction efficiency characteristic. It is possible to realize an active diffractive optical element with high efficiency. Such an optical element can be used for an optical measuring device such as a polarization spectroscopic measuring device, optical information processing, optical computing, and the like. In addition, dimming is possible when used for the large head-up display, the large display for 3D video, and the external light introduction window.

本発明の光導波路８および光導波路１０は設置された矩形格子の光学異方性媒質として溝に液晶を任意の方位に配向させて充填し、平面光導波路の上下に電極を配置することにより、任意の偏光回折効率特性から任意の偏光回折効率特性に切り換えることが可能な効率が高い能動的な回折光学素子を実現できる。このような光学素子は光通信や光情報処理、光コンピューティング等に利用可能である。   The optical waveguide 8 and the optical waveguide 10 of the present invention are filled with a liquid crystal oriented in an arbitrary direction as an optically anisotropic medium having a rectangular lattice, and electrodes are arranged above and below the planar optical waveguide, An active diffractive optical element with high efficiency that can be switched from an arbitrary polarization diffraction efficiency characteristic to an arbitrary polarization diffraction efficiency characteristic can be realized. Such an optical element can be used for optical communication, optical information processing, optical computing, and the like.

１ 透過型ＶＰＨ回折格子
２ 厚い透過型矩形回折格子
３、５、７、９ 回折格子
４、６、８、１０ 光導波路
２０、２３０ ホログラム樹脂
２１、２２、４５０、５２０ 光学等方性媒質
３０、４０、２００、２４０、４００、４３０、９００、９５０ 基板
７００ 下基板
７３０ 上基板
２１０ 液晶性有機材料
２２０ 熱硬化型樹脂材料
３００、５００、８００、１０００ クラッド層
３１０、５１０、８１０、１０１０ コア層
４１０、９４０、１０４０ 溝
４２０、９３０、１０５０ 矩形格子
５３０ 光学異方性媒質
７１０、９１０ 透明電極
７２０、８２０、９２０、１０２０ 液晶配向膜
７４０、８４０、９６０、１０６０ 液晶
７５０ 液晶の分子
８３０、１０３０ 電極 DESCRIPTION OF SYMBOLS 1 Transmission type VPH diffraction grating 2 Thick transmission type rectangular diffraction grating 3, 5, 7, 9 Diffraction gratings 4, 6, 8, 10 Optical waveguide 20, 230 Hologram resin 21, 22, 450, 520 Optical isotropic medium 30, 40, 200, 240, 400, 430, 900, 950 Substrate 700 Lower substrate 730 Upper substrate 210 Liquid crystalline organic material 220 Thermosetting resin material 300, 500, 800, 1000 Clad layer 310, 510, 810, 1010 Core layer 410 , 940, 1040 Groove 420, 930, 1050 Rectangular grating 530 Optical anisotropic medium 710, 910 Transparent electrode 720, 820, 920, 1020 Liquid crystal alignment film 740, 840, 960, 1060 Liquid crystal 750 Liquid crystal molecule 830, 1030 Electrode

Claims (19)

屈折率が正弦波状に変調された格子構造である透過型ＶＰＨ回折格子であって、
光学異方性媒質を用い、その光学異方性媒質のＳ偏光に対する最大屈折率と最少屈折率との差と、Ｐ偏光に対する最大屈折率と最少屈折率との差を、異なる所定値とすることで、Ｓ偏光の回折効率とＰ偏光の回折効率とを所望の特性に制御したことを特徴とする回折格子。 A transmissive VPH diffraction grating having a grating structure with a refractive index modulated in a sinusoidal shape,
An optically anisotropic medium is used, and the difference between the maximum refractive index and the minimum refractive index for the S-polarized light of the optical anisotropic medium and the difference between the maximum refractive index and the minimum refractive index for the P-polarized light are set to different predetermined values. A diffraction grating characterized in that the diffraction efficiency of S-polarized light and the diffraction efficiency of P-polarized light are controlled to desired characteristics. Ｓ偏光に対する最大屈折率をｎＳｍａx、最少屈折率をｎＳｍｉｎ、Ｐ偏光に対する最大屈折率をｎＰｍａx、最少屈折率をｎＰｍｉｎとして、
ｎＳｍａx、ｎＳｍｉｎ、ｎＰｍａx、およびｎＰｍｉｎは、
（ｎＳｍａx−ｎＳｍｉｎ）／ｃｏｓθＳ＝（ｎＰｍａx−ｎＰｍｉｎ）＊ｃｏｓ２θＰ／ｃｏｓθＰ
を満たす値とすることで、Ｓ偏光の回折効率およびＰ偏光の回折効率の平均を、所望の波長、入射角において９０％以上としたことを特徴とする請求項１に記載の回折格子。
ただし、上記式においてθＳはＳ偏光に対するブラッグ角、θＰはＰ偏光に対するブラッグ角である。 The maximum refractive index for S-polarized light is n Smax , the minimum refractive index is n Smin , the maximum refractive index for P-polarized light is n Pmax , and the minimum refractive index is n Pmin ,
n Smax , n Smin , n Pmax , and n Pmin are
(N Smax −n Smin ) / cos θ S = (n Pmax −n Pmin ) * cos 2θ P / cos θ P
2. The diffraction grating according to claim 1, wherein an average of diffraction efficiency of S-polarized light and diffraction efficiency of P-polarized light is 90% or more at a desired wavelength and an incident angle by setting the value to satisfy the above.
In the above equation, θ S is the Bragg angle for S-polarized light, and θ P is the Bragg angle for P-polarized light. Ｓ偏光に対する最大屈折率をｎＳｍａx、最少屈折率をｎＳｍｉｎ、Ｐ偏光に対する最大屈折率をｎＰｍａx、最少屈折率をｎＰｍｉｎとして、
ｎＳｍａx、ｎＳｍｉｎ、ｎＰｍａx、およびｎＰｍｉｎは、
（ｎＳｍａx−ｎＳｍｉｎ）／ｃｏｓθＳ＝２（ｎＰｍａx−ｎＰｍｉｎ）＊ｃｏｓ２θＰ／ｃｏｓθＰ
または、
２（ｎＳｍａx−ｎＳｍｉｎ）／ｃｏｓθＳ＝（ｎＰｍａx−ｎＰｍｉｎ）＊ｃｏｓ２θＰ／ｃｏｓθＰ
を満たす値とすることで、Ｓ偏光およびＰ偏光の回折効率のうち、一方を９０％以上、他方を１％以下としたことを特徴とする請求項１に記載の回折格子。
ただし、上記式においてθＳはＳ偏光に対するブラッグ角、θＰはＰ偏光に対するブラッグ角である。 The maximum refractive index for S-polarized light is n Smax , the minimum refractive index is n Smin , the maximum refractive index for P-polarized light is n Pmax , and the minimum refractive index is n Pmin ,
n Smax , n Smin , n Pmax , and n Pmin are
(N Smax −n Smin ) / cos θ S = 2 (n Pmax −n Pmin ) * cos 2θ P / cos θ P
Or
2 (n Smax −n Smin ) / cos θ S = (n Pmax −n Pmin ) * cos 2θ P / cos θ P
2. The diffraction grating according to claim 1, wherein one of the diffraction efficiencies of S-polarized light and P-polarized light is set to 90% or more and the other is set to 1% or less by satisfying the above.
In the above equation, θ S is the Bragg angle for S-polarized light, and θ P is the Bragg angle for P-polarized light. 前記回折格子は、光学等方性の樹脂に、所定の方向に配向した光学異方性の液晶が混合された樹脂であり、
前記樹脂中の前記液晶の濃度によって屈折率が正弦波状に変調され、
前記液晶の濃度および液晶分子の配向方向によって、Ｓ偏光に対する最大屈折率と最少屈折率との差と、Ｐ偏光に対する最大屈折率と最少屈折率との差とを、異なる所定値としたことを特徴とする請求項１ないし請求項３のいずれか１項に記載の回折格子。 The diffraction grating is a resin in which an optically isotropic resin is mixed with an optically anisotropic liquid crystal oriented in a predetermined direction,
The refractive index is modulated in a sinusoidal shape by the concentration of the liquid crystal in the resin,
The difference between the maximum refractive index and the minimum refractive index for S-polarized light and the difference between the maximum refractive index and the minimum refractive index for P-polarized light are set to different predetermined values depending on the concentration of the liquid crystal and the orientation direction of the liquid crystal molecules. The diffraction grating according to any one of claims 1 to 3, characterized in that: 前記回折格子は、
二軸性光学異方性の液晶と、
前記液晶を挟んでその液晶に接し、前記液晶を所定の方向に配向させる液晶配向膜と、
前記液晶を挟む１対の電極が周期的に配置された電極部と、
を有し、
前記電極部への電圧の印加によって前記液晶分子の配向方向を制御することにより、前記液晶の屈折率を正弦波状に変調し、かつ、Ｓ偏光に対する最大屈折率と最少屈折率との差と、Ｐ偏光に対する最大屈折率と最少屈折率との差とを異なる所定値とし、
前記電極部への印加電圧値を変えることで、Ｓ偏光の回折効率とＰ偏光の回折効率とを可変としたことを特徴とする請求項１ないし請求項３のいずれか１項に記載の回折格子。 The diffraction grating is
A biaxial optically anisotropic liquid crystal;
A liquid crystal alignment film in contact with the liquid crystal with the liquid crystal sandwiched therebetween, and aligning the liquid crystal in a predetermined direction;
An electrode portion in which a pair of electrodes sandwiching the liquid crystal is periodically arranged;
Have
By controlling the orientation direction of the liquid crystal molecules by applying a voltage to the electrode portion, the refractive index of the liquid crystal is modulated in a sinusoidal shape, and the difference between the maximum refractive index and the minimum refractive index for S-polarized light, The difference between the maximum refractive index and the minimum refractive index for P-polarized light is set to a different predetermined value.
4. The diffraction according to claim 1, wherein the diffraction efficiency of S-polarized light and the diffraction efficiency of P-polarized light are made variable by changing a voltage value applied to the electrode unit. 5. lattice. ２種類の屈折率が異なる材料が交互に周期的に配置された格子構造である透過型の回折格子であって、
２種類の材料のうち少なくとも一方が光学異方性媒質であり、その光学異方性媒質のＳ偏光に対する屈折率と他方の材料の屈折率との差と、前記光学異方性媒質のＰ偏光に対する屈折率と他方の材料の屈折率との差を、異なる所定値とすることで、Ｓ偏光の回折効率とＰ偏光の回折効率とを所望の特性に制御したことを特徴とする回折格子。 A transmission type diffraction grating having a grating structure in which two kinds of materials having different refractive indexes are alternately and periodically arranged,
At least one of the two types of materials is an optically anisotropic medium, the difference between the refractive index of the optically anisotropic medium with respect to S-polarized light and the refractive index of the other material, and the P-polarized light of the optically anisotropic medium. A diffraction grating characterized in that the diffraction efficiency of S-polarized light and the efficiency of diffraction of P-polarized light are controlled to have desired characteristics by setting the difference between the refractive index of the light and the refractive index of the other material to different predetermined values. 前記光学異方性媒質のＳ偏光に対する最大屈折率をｎ２ｃＳ、Ｐ偏光に対する最大屈折率をｎ２ｃＰとし、２種類の材料のうち他方の材料の屈折率をｎ２ａとして、ｎ２ａ、ｎ２ｃＳ、およびｎ２ｃＰは、
ｎ２ｃＰ＞ｎ２ｃＳ＞ｎ２ａまたはｎ２ｃＰ＜ｎ２ｃＳ＜ｎ２ａの場合には、Ａ１＊（ｎ２ｃＳ−ｎ２ａ）／ｃｏｓθＳ＝Ｂ１＊（ｎ２ｃＰ−ｎ２ａ）＊ｃｏｓ２θＰ／ｃｏｓθＰ
ｎ２ｃＰ＞ｎ２ａ＞ｎ２ｃＳまたはｎ２ｃＰ＜ｎ２ａ＜ｎ２ｃＳの場合には、Ａ２＊（ｎ２ｃＳ−ｎ２ａ）／ｃｏｓθＳ＝−Ｂ２＊（ｎ２ｃＰ−ｎ２ａ）＊ｃｏｓ２θＰ／ｃｏｓθＰ
を満たす値とすることで、Ｓ偏光の回折効率およびＰ偏光の回折効率の平均を、所望の波長、入射角において９０％以上としたことを特徴とする請求項６に記載の回折格子。
ただし、上記式においてθＳはＳ偏光に対するブラッグ角、θＰはＰ偏光に対するブラッグ角である。また、Ａ１、Ａ２はＲＣＷＡ法によって求めた前記回折格子のＳ偏光の回折効率の格子の厚さに対する周期を、２波結合解析法によって求めた透過型ＶＰＨ回折格子のＳ偏光の回折効率の厚さに対する周期で割った値である。また、Ｂ１とＢ２はＲＣＷＡ法によって求めた前記回折格子のＰ偏光の回折効率の厚さに対する周期を２波結合解析法によって求めた透過型ＶＰＨ回折格子のＰ偏光の回折効率の厚さに対する周期で割った値である。 The maximum refractive index for S-polarized light of the optically anisotropic medium is n 2cS , the maximum refractive index for P-polarized light is n 2cP, and the refractive index of the other material is n 2a , and n 2a , n 2cS. And n 2cP is
In the case of n 2cP > n 2cS > n 2a or n 2cP <n 2cS <n 2a , A 1 * (n 2cS −n 2a ) / cos θ S = B 1 * (n 2cP −n 2a ) * cos 2θ P / cosθ P
In the case of n 2cP > n 2a > n 2cS or n 2cP <n 2a <n 2cS , A 2 * (n 2cS −n 2a ) / cos θ S = −B 2 * (n 2cP −n 2a ) * cos 2θ P / Cosθ P
The diffraction grating according to claim 6, wherein the average of the diffraction efficiency of S-polarized light and the diffraction efficiency of P-polarized light is 90% or more at a desired wavelength and incident angle by setting the value to satisfy the above.
In the above equation, θ S is the Bragg angle for S-polarized light, and θ P is the Bragg angle for P-polarized light. A 1 and A 2 are the diffraction efficiency of the S-polarized light of the transmission-type VPH diffraction grating obtained by the two-wave coupling analysis method with respect to the grating thickness of the diffraction efficiency of the S-polarized light of the diffraction grating obtained by the RCWA method. It is the value divided by the period for the thickness. B 1 and B 2 are the thicknesses of the P-polarized diffraction efficiency of the transmission type VPH diffraction grating obtained by the two-wave coupling analysis method with respect to the thickness of the diffraction efficiency of the P-polarized light of the diffraction grating obtained by the RCWA method. Divided by the period for. 前記光学異方性媒質のＳ偏光に対する最大屈折率をｎ２ｃＳ、Ｐ偏光に対する最大屈折率をｎ２ｃＰとし、２種類の材料のうち他方の材料の屈折率をｎ２ａとして、ｎ２ａ、ｎ２ｃＳ、およびｎ２ｃＰは、
ｎ２ｃＰ＞ｎ２ｃＳ＞ｎ２ａまたはｎ２ｃＰ＜ｎ２ｃＳ＜ｎ２ａの場合には、２Ａ１＊（ｎ２ｃＳ−ｎ２ａ）／ｃｏｓθＳ＝Ｂ１＊（ｎ２ｃＰ−ｎ２ａ）＊ｃｏｓ２θＰ／ｃｏｓθＰ、あるいは、Ａ１＊（ｎ２ｃＳ−ｎ２ａ）／ｃｏｓθＳ＝２Ｂ１＊（ｎ２ｃＰ−ｎ２ａ）＊ｃｏｓ２θＰ／ｃｏｓθＰ
ｎ２ｃＰ＞ｎ２ａ＞ｎ２ｃＳまたはｎ２ｃＰ＜ｎ２ａ＜ｎ２ｃＳの場合には、２Ａ２＊（ｎ２ｃＳ−ｎ２ａ）／ｃｏｓθＳ＝−Ｂ２＊（ｎ２ｃＰ−ｎ２ａ）＊ｃｏｓ２θＰ／ｃｏｓθＰ、あるいは、Ａ２＊（ｎ２ｃＳ−ｎ２ａ）／ｃｏｓθＳ＝−２Ｂ２＊（ｎ２ｃＰ−ｎ２ａ）＊ｃｏｓ２θＰ／ｃｏｓθＰを満たす値とすることで、Ｓ偏光およびＰ偏光の回折効率のうち、一方を９０％以上、他方を１％以下としたことを特徴とする請求項６に記載の回折格子。
ただし、上記式においてθＳはＳ偏光に対するブラッグ角、θＰはＰ偏光に対するブラッグ角である。また、Ａ１、Ａ２はＲＣＷＡ法によって求めた前記回折格子のＳ偏光の回折効率の格子の厚さに対する周期を、２波結合解析法によって求めた透過型ＶＰＨ回折格子のＳ偏光の回折効率の厚さに対する周期で割った値である。また、Ｂ１とＢ２はＲＣＷＡ法によって求めた前記回折格子のＰ偏光の回折効率の厚さに対する周期を、２波結合解析法によって求めた透過型ＶＰＨ回折格子のＰ偏光の回折効率の厚さに対する周期で割った値である。 The maximum refractive index for S-polarized light of the optically anisotropic medium is n 2cS , the maximum refractive index for P-polarized light is n 2cP, and the refractive index of the other material is n 2a , and n 2a , n 2cS. And n 2cP is
In the case of n 2cP > n 2cS > n 2a or n 2cP <n 2cS <n 2a , 2A 1 * (n 2cS −n 2a ) / cos θ S = B 1 * (n 2cP −n 2a ) * cos 2θ P / cos θ P or A 1 * (n 2cS −n 2a ) / cos θ S = 2B 1 * (n 2cP −n 2a ) * cos 2θ P / cos θ P
In the case of n 2cP > n 2a > n 2cS or n 2cP <n 2a <n 2cS , 2A 2 * (n 2cS −n 2a ) / cos θ S = −B 2 * (n 2cP −n 2a ) * cos 2θ P / Cos θ P or A 2 * (n 2cS −n 2a ) / cos θ S = −2B 2 * (n 2cP −n 2a ) * cos 2θ P / cos θ P 7. The diffraction grating according to claim 6, wherein one of the diffraction efficiencies is 90% or more and the other is 1% or less.
In the above equation, θ S is the Bragg angle for S-polarized light, and θ P is the Bragg angle for P-polarized light. A 1 and A 2 are the diffraction efficiency of the S-polarized light of the transmission-type VPH diffraction grating obtained by the two-wave coupling analysis method with respect to the grating thickness of the diffraction efficiency of the S-polarized light of the diffraction grating obtained by the RCWA method. It is the value divided by the period for the thickness. B 1 and B 2 are the periods of the diffraction efficiency of the P-polarized light of the diffraction grating obtained by the RCWA method with respect to the thickness of the diffraction efficiency of the P-polarized light of the transmission type VPH diffraction grating obtained by the two-wave coupling analysis method. It is the value divided by the period for the length. 格子状の溝が設けられた光学異方性材料からなる基板と、前記基板の前記溝を埋める光学等方性材料と、によって構成されていることを特徴とする請求項６ないし請求項８のいずれか１項に記載の回折格子。   9. The substrate according to claim 6, wherein the substrate is made of an optically anisotropic material provided with a lattice-like groove, and an optically isotropic material filling the groove of the substrate. A diffraction grating given in any 1 paragraph. 前記基板は、β−メタホウ酸バリウム（β−ＢａＢ２Ｏ４：β−ＢＢＯ）、フッ化イットリウム−リチウム（ＹＬｉＦ４：ＹＬＦ）、またはニオブ酸リチウム（ＬｉＮｂＯ３）からなる結晶、ないしは、延伸された樹脂、または配向された状態で硬化した液晶である、ことを特徴とする請求項９に記載の回折格子。 The substrate is a crystal or stretched of β-barium metaborate (β-BaB 2 O 4 : β-BBO), yttrium fluoride-lithium (YLiF 4 : YLF), or lithium niobate (LiNbO 3 ). The diffraction grating according to claim 9, wherein the diffraction grating is a liquid crystal cured in an aligned state. 格子状の溝が設けられた光学等方性材料からなる基板と、前記溝を埋める所定の方向に配光した状態で硬化された液晶と、によって構成されていることを特徴とする請求項６ないし請求項８のいずれか１項に記載の回折格子。   7. A substrate made of an optically isotropic material provided with a lattice-like groove, and a liquid crystal cured in a light distribution state in a predetermined direction filling the groove. The diffraction grating according to any one of claims 8 to 9. 格子状の溝が設けられた光学等方性材料からなる第１基板と、
前記第１基板の溝に充填された液晶と、
前記第１基板上に配置され、前記液晶に接し、前記液晶を所定の方向に配向させる液晶配向膜が設けられた第２基板と、
前記第１基板の各前記溝の底面と、前記第２基板の前記第１基板側表面であって前記溝に対向する位置と、に設けられた電極部と、
を有し、
前記電極部への電圧の印加によって前記液晶の分子の配向方向を制御することにより、Ｓ偏光に対する屈折率と、Ｐ偏光に対する屈折率とを異なる所定値とし、
前記電極部への印加電圧値を変えることで、Ｓ偏光の回折効率とＰ偏光の回折効率とを可変としたことを特徴とする請求項６ないし請求項１１のいずれか１項に記載の回折格子。 A first substrate made of an optically isotropic material provided with a lattice-shaped groove;
A liquid crystal filled in the groove of the first substrate;
A second substrate provided on the first substrate and provided with a liquid crystal alignment film that contacts the liquid crystal and aligns the liquid crystal in a predetermined direction;
An electrode portion provided on a bottom surface of each groove of the first substrate and a position on the first substrate side surface of the second substrate facing the groove;
Have
By controlling the orientation direction of the molecules of the liquid crystal by applying a voltage to the electrode unit, the refractive index for S-polarized light and the refractive index for P-polarized light are different from each other, and
The diffraction according to any one of claims 6 to 11, wherein the diffraction efficiency of S-polarized light and the diffraction efficiency of P-polarized light are made variable by changing a voltage value applied to the electrode portion. lattice. 請求項１ないし請求項１２のいずれか１項に記載の回折格子を、格子周期方向に伸びる直線状または曲線状とし、その回折格子がコア材およびクラッド材に埋め込まれた構造であることを特徴とする光導波路。   The diffraction grating according to any one of claims 1 to 12, wherein the diffraction grating has a linear or curved shape extending in a grating period direction, and the diffraction grating is embedded in a core material and a cladding material. An optical waveguide. 屈折率が正弦波状に変調された格子構造である透過型ＶＰＨ回折格子の設計方法であって、
光学異方性媒質を用い、その光学異方性媒質のＳ偏光に対する最大屈折率と最少屈折率との差と、Ｐ偏光に対する最大屈折率と最少屈折率との差によって、Ｓ偏光の回折効率とＰ偏光の回折効率とを所望の特性に制御することを特徴とする回折格子の設計方法。 A method of designing a transmissive VPH diffraction grating having a grating structure with a refractive index modulated in a sinusoidal shape,
Using an optically anisotropic medium, the diffraction efficiency of S-polarized light is determined by the difference between the maximum refractive index and the minimum refractive index of the optically anisotropic medium for S-polarized light and the difference between the maximum refractive index and the minimum refractive index for P-polarized light. And a diffraction efficiency of P-polarized light are controlled to have desired characteristics. Ｓ偏光に対する最大屈折率をｎＳｍａx、最少屈折率をｎＳｍｉｎ、Ｐ偏光に対する最大屈折率をｎＰｍａx、最少屈折率をｎＰｍｉｎとして、
ｎＳｍａx、ｎＳｍｉｎ、ｎＰｍａx、およびｎＰｍｉｎを、
（ｎＳｍａx−ｎＳｍｉｎ）／ｃｏｓθＳ＝（ｎＰｍａx−ｎＰｍｉｎ）＊ｃｏｓ２θＰ／ｃｏｓθＰ
を満たす値に設計することで、Ｓ偏光の回折効率およびＰ偏光の回折効率の平均を、所望の波長、入射角において９０％以上とすることを特徴とする請求項１４に記載の回折格子の設計方法。 The maximum refractive index for S-polarized light is n Smax , the minimum refractive index is n Smin , the maximum refractive index for P-polarized light is n Pmax , and the minimum refractive index is n Pmin ,
n Smax , n Smin , n Pmax , and n Pmin ,
(N Smax −n Smin ) / cos θ S = (n Pmax −n Pmin ) * cos 2θ P / cos θ P
The diffraction grating according to claim 14, wherein an average of diffraction efficiency of S-polarized light and diffraction efficiency of P-polarized light is set to 90% or more at a desired wavelength and an incident angle by designing to a value satisfying Design method. Ｓ偏光に対する最大屈折率をｎＳｍａx、最少屈折率をｎＳｍｉｎ、Ｐ偏光に対する最大屈折率をｎＰｍａx、最少屈折率をｎＰｍｉｎとして、
ｎＳｍａx、ｎＳｍｉｎ、ｎＰｍａx、およびｎＰｍｉｎを、
（ｎＳｍａx−ｎＳｍｉｎ）／ｃｏｓθＳ＝２（ｎＰｍａx−ｎＰｍｉｎ）＊ｃｏｓ２θＰ／ｃｏｓθＰ
または、
２（ｎＳｍａx−ｎＳｍｉｎ）／ｃｏｓθＳ＝（ｎＰｍａx−ｎＰｍｉｎ）＊ｃｏｓ２θＰ／ｃｏｓθＰ
を満たす値に設計することで、Ｓ偏光およびＰ偏光の回折効率のうち、一方を９０％以上、他方を１％以下とすることを特徴とする請求項１４に記載の回折格子の設計方法。 The maximum refractive index for S-polarized light is n Smax , the minimum refractive index is n Smin , the maximum refractive index for P-polarized light is n Pmax , and the minimum refractive index is n Pmin ,
n Smax , n Smin , n Pmax , and n Pmin ,
(N Smax −n Smin ) / cos θ S = 2 (n Pmax −n Pmin ) * cos 2θ P / cos θ P
Or
2 (n Smax −n Smin ) / cos θ S = (n Pmax −n Pmin ) * cos 2θ P / cos θ P
The method for designing a diffraction grating according to claim 14, wherein one of the diffraction efficiencies of S-polarized light and P-polarized light is set to 90% or more and the other is set to 1% or less by designing to a value satisfying the above. ２種類の屈折率が異なる材料が交互に周期的に配置された格子構造である透過型の回折格子の設計方法であって、
２種類の材料のうち少なくとも一方が光学異方性媒質であり、その光学異方性媒質のＳ偏光に対する屈折率と他方の材料の屈折率との差と、前記光学異方性媒質のＰ偏光に対する屈折率と他方の材料の屈折率との差によって、Ｓ偏光の回折効率とＰ偏光の回折効率とを所望の特性に制御することを特徴とする回折格子の設計方法。 A method of designing a transmissive diffraction grating having a grating structure in which two types of materials having different refractive indexes are alternately and periodically arranged,
At least one of the two types of materials is an optically anisotropic medium, the difference between the refractive index of the optically anisotropic medium with respect to S-polarized light and the refractive index of the other material, and the P-polarized light of the optically anisotropic medium. A method for designing a diffraction grating, wherein the diffraction efficiency of S-polarized light and the diffraction efficiency of P-polarized light are controlled to have desired characteristics based on the difference between the refractive index of the second material and the refractive index of the other material. 前記光学異方性媒質のＳ偏光に対する最大屈折率をｎ２ｃＳ、Ｐ偏光に対する最大屈折率をｎ２ｃＰとし、２種類の材料のうち他方の材料の屈折率をｎ２ａとして、ｎ２ａ、ｎ２ｃＳ、およびｎ２ｃＰを、
ｎ２ｃＰ＞ｎ２ｃＳ＞ｎ２ａまたはｎ２ｃＰ＜ｎ２ｃＳ＜ｎ２ａの場合には、Ａ１＊（ｎ２ｃＳ−ｎ２ａ）／ｃｏｓθＳ＝Ｂ１＊（ｎ２ｃＰ−ｎ２ａ）＊ｃｏｓ２θＰ／ｃｏｓθＰ
ｎ２ｃＰ＞ｎ２ａ＞ｎ２ｃＳまたはｎ２ｃＰ＜ｎ２ａ＜ｎ２ｃＳの場合には、Ａ２＊（ｎ２ｃＳ−ｎ２ａ）／ｃｏｓθＳ＝−Ｂ２＊（ｎ２ｃＰ−ｎ２ａ）＊ｃｏｓ２θＰ／ｃｏｓθＰ
を満たす値に設計することで、Ｓ偏光の回折効率およびＰ偏光の回折効率の平均を、所望の波長、入射角において９０％以上とすることを特徴とする請求項１７に記載の回折格子の設計方法。
ただし、上記式においてθＳはＳ偏光に対するブラッグ角、θＰはＰ偏光に対するブラッグ角である。また、Ａ１、Ａ２はＲＣＷＡ法によって求めた前記回折格子のＳ偏光の回折効率の格子の厚さに対する周期を、２波結合解析法によって求めた透過型ＶＰＨ回折格子のＳ偏光の回折効率の厚さに対する周期で割った値である。また、Ｂ１とＢ２はＲＣＷＡ法によって求めた前記回折格子のＰ偏光の回折効率の厚さに対する周期を、２波結合解析法によって求めた透過型ＶＰＨ回折格子のＰ偏光の回折効率の厚さに対する周期で割った値である。 The maximum refractive index for S-polarized light of the optically anisotropic medium is n 2cS , the maximum refractive index for P-polarized light is n 2cP, and the refractive index of the other material is n 2a , and n 2a , n 2cS. , And n 2cP
In the case of n 2cP > n 2cS > n 2a or n 2cP <n 2cS <n 2a , A 1 * (n 2cS −n 2a ) / cos θ S = B 1 * (n 2cP −n 2a ) * cos 2θ P / cosθ P
In the case of n 2cP > n 2a > n 2cS or n 2cP <n 2a <n 2cS , A 2 * (n 2cS −n 2a ) / cos θ S = −B 2 * (n 2cP −n 2a ) * cos 2θ P / Cosθ P
The diffraction grating according to claim 17, wherein an average of diffraction efficiency of S-polarized light and diffraction efficiency of P-polarized light is set to 90% or more at a desired wavelength and an incident angle by designing to a value satisfying Design method.
In the above equation, θ S is the Bragg angle for S-polarized light, and θ P is the Bragg angle for P-polarized light. A 1 and A 2 are the diffraction efficiency of the S-polarized light of the transmission-type VPH diffraction grating obtained by the two-wave coupling analysis method with respect to the grating thickness of the diffraction efficiency of the S-polarized light of the diffraction grating obtained by the RCWA method. It is the value divided by the period for the thickness. B 1 and B 2 are the periods of the diffraction efficiency of the P-polarized light of the diffraction grating obtained by the RCWA method with respect to the thickness of the diffraction efficiency of the P-polarized light of the transmission type VPH diffraction grating obtained by the two-wave coupling analysis method. It is the value divided by the period for the length. 前記光学異方性媒質のＳ偏光に対する最大屈折率をｎ２ｃＳ、Ｐ偏光に対する最大屈折率をｎ２ｃＰとし、２種類の材料のうち他方の材料の屈折率をｎ２ａとして、ｎ２ａ、ｎ２ｃＳ、およびｎ２ｃＰを、
ｎ２ｃＰ＞ｎ２ｃＳ＞ｎ２ａまたはｎ２ｃＰ＜ｎ２ｃＳ＜ｎ２ａの場合には、２Ａ１＊（ｎ２ｃＳ−ｎ２ａ）／ｃｏｓθＳ＝Ｂ１＊（ｎ２ｃＰ−ｎ２ａ）＊ｃｏｓ２θＰ／ｃｏｓθＰ、あるいは、Ａ１＊（ｎ２ｃＳ−ｎ２ａ）／ｃｏｓθＳ＝２Ｂ１＊（ｎ２ｃＰ−ｎ２ａ）＊ｃｏｓ２θＰ／ｃｏｓθＰ
ｎ２ｃＰ＞ｎ２ａ＞ｎ２ｃＳまたはｎ２ｃＰ＜ｎ２ａ＜ｎ２ｃＳの場合には、２Ａ２＊（ｎ２ｃＳ−ｎ２ａ）／ｃｏｓθＳ＝−Ｂ２＊（ｎ２ｃＰ−ｎ２ａ）＊ｃｏｓ２θＰ／ｃｏｓθＰ、あるいは、Ａ２＊（ｎ２ｃＳ−ｎ２ａ）／ｃｏｓθＳ＝−２Ｂ２＊（ｎ２ｃＰ−ｎ２ａ）＊ｃｏｓ２θＰ／ｃｏｓθＰを満たす値に設計することで、Ｓ偏光およびＰ偏光の回折効率のうち、一方を９０％以上、他方を１％以下としたことを特徴とする請求項１７に記載の回折格子の設計方法。
ただし、上記式においてθＳはＳ偏光に対するブラッグ角、θＰはＰ偏光に対するブラッグ角である。また、Ａ１、Ａ２はＲＣＷＡ法によって求めた前記回折格子のＳ偏光の回折効率の格子の厚さに対する周期を、２波結合解析法によって求めた透過型ＶＰＨ回折格子のＳ偏光の回折効率の厚さに対する周期で割った値である。また、Ｂ１とＢ２はＲＣＷＡ法によって求めた前記回折格子のＰ偏光の回折効率の厚さに対する周期を、２波結合解析法によって求めた透過型ＶＰＨ回折格子のＰ偏光の回折効率の厚さに対する周期で割った値である。 The maximum refractive index for S-polarized light of the optically anisotropic medium is n 2cS , the maximum refractive index for P-polarized light is n 2cP, and the refractive index of the other material is n 2a , and n 2a , n 2cS. , And n 2cP
In the case of n 2cP > n 2cS > n 2a or n 2cP <n 2cS <n 2a , 2A 1 * (n 2cS −n 2a ) / cos θ S = B 1 * (n 2cP −n 2a ) * cos 2θ P / cos θ P or A 1 * (n 2cS −n 2a ) / cos θ S = 2B 1 * (n 2cP −n 2a ) * cos 2θ P / cos θ P
In the case of n 2cP > n 2a > n 2cS or n 2cP <n 2a <n 2cS , 2A 2 * (n 2cS −n 2a ) / cos θ S = −B 2 * (n 2cP −n 2a ) * cos 2θ P / cos [theta] P or,, a 2 * (n 2cS -n 2a) / cosθ S = -2B 2 * (n 2cP -n 2a) * cos2θ P / cosθ P to design a value satisfying, S polarized light and P 18. The method of designing a diffraction grating according to claim 17, wherein one of the polarization diffraction efficiencies is 90% or more and the other is 1% or less.
In the above equation, θ S is the Bragg angle for S-polarized light, and θ P is the Bragg angle for P-polarized light. A 1 and A 2 are the diffraction efficiency of the S-polarized light of the transmission-type VPH diffraction grating obtained by the two-wave coupling analysis method with respect to the grating thickness of the diffraction efficiency of the S-polarized light of the diffraction grating obtained by the RCWA method. It is the value divided by the period for the thickness. B 1 and B 2 are the periods of the diffraction efficiency of the P-polarized light of the diffraction grating obtained by the RCWA method with respect to the thickness of the diffraction efficiency of the P-polarized light of the transmission type VPH diffraction grating obtained by the two-wave coupling analysis method. It is the value divided by the period for the length.
JP2012082527A 2012-03-30 2012-03-30 Diffraction grating and manufacturing method thereof, optical waveguide Expired - Fee Related JP6168642B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2012082527A JP6168642B2 (en) 2012-03-30 2012-03-30 Diffraction grating and manufacturing method thereof, optical waveguide

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2012082527A JP6168642B2 (en) 2012-03-30 2012-03-30 Diffraction grating and manufacturing method thereof, optical waveguide

Publications (2)

Publication Number Publication Date
JP2013210589A true JP2013210589A (en) 2013-10-10
JP6168642B2 JP6168642B2 (en) 2017-07-26

Family

ID=49528457

Family Applications (1)

Application Number Title Priority Date Filing Date
JP2012082527A Expired - Fee Related JP6168642B2 (en) 2012-03-30 2012-03-30 Diffraction grating and manufacturing method thereof, optical waveguide

Country Status (1)

Country Link
JP (1) JP6168642B2 (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2015121726A (en) * 2013-12-25 2015-07-02 国立研究開発法人産業技術総合研究所 Diffraction grating and manufacturing method thereof
CN110146989A (en) * 2019-05-21 2019-08-20 京东方科技集团股份有限公司 Optical waveguide components and its display methods, display device and its display methods
CN110537142A (en) * 2018-03-27 2019-12-03 松下知识产权经营株式会社 Light device and optical detection system

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH11271536A (en) * 1997-10-16 1999-10-08 Matsushita Electric Ind Co Ltd Image display device, polarizated-light illumination device, polarized light separating element, diffraction optical element, hologram element, and manufacture of diffraction optical element and hologram element
JP2000075130A (en) * 1998-06-16 2000-03-14 Ricoh Co Ltd Polarized light separating element and formation of this polarized light separating element
JP2004021220A (en) * 2002-06-20 2004-01-22 Sumitomo Electric Ind Ltd Manufacture method of plane waveguide type diffraction grating element
JP2005055773A (en) * 2003-08-06 2005-03-03 Ricoh Co Ltd Polarizing diffraction grating
JP2006133603A (en) * 2004-11-08 2006-05-25 Ricoh Co Ltd Polarizing and splitting element and method of manufacturing the same, optical head device and optical disk drive device

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH11271536A (en) * 1997-10-16 1999-10-08 Matsushita Electric Ind Co Ltd Image display device, polarizated-light illumination device, polarized light separating element, diffraction optical element, hologram element, and manufacture of diffraction optical element and hologram element
JP2000075130A (en) * 1998-06-16 2000-03-14 Ricoh Co Ltd Polarized light separating element and formation of this polarized light separating element
JP2004021220A (en) * 2002-06-20 2004-01-22 Sumitomo Electric Ind Ltd Manufacture method of plane waveguide type diffraction grating element
JP2005055773A (en) * 2003-08-06 2005-03-03 Ricoh Co Ltd Polarizing diffraction grating
JP2006133603A (en) * 2004-11-08 2006-05-25 Ricoh Co Ltd Polarizing and splitting element and method of manufacturing the same, optical head device and optical disk drive device

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
DICKSON,L. ET AL.: "Holographic polarization-separation elements", APPLIED OPTICS, vol. 33, no. 23, JPN6015052315, 10 August 1994 (1994-08-10), US, pages 5378 - 5385, XP000462255, ISSN: 0003225953, DOI: 10.1364/AO.33.005378 *
辻内順平, ホログラフィー, JPN6015052311, 5 November 1997 (1997-11-05), JP, pages 87, ISSN: 0003225954 *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2015121726A (en) * 2013-12-25 2015-07-02 国立研究開発法人産業技術総合研究所 Diffraction grating and manufacturing method thereof
CN110537142A (en) * 2018-03-27 2019-12-03 松下知识产权经营株式会社 Light device and optical detection system
CN110146989A (en) * 2019-05-21 2019-08-20 京东方科技集团股份有限公司 Optical waveguide components and its display methods, display device and its display methods

Also Published As

Publication number Publication date
JP6168642B2 (en) 2017-07-26

Similar Documents

Publication Publication Date Title
US10036886B2 (en) Broadband optics for manipulating light beams and images
Xiang et al. Nanoscale liquid crystal polymer Bragg polarization gratings
US10802302B2 (en) Waveplate lenses and methods for their fabrication
JP5669964B2 (en) Low twist chiral liquid crystal polarization gratings and related fabrication methods
US9575366B2 (en) Fast switchable and high diffraction efficiency grating ferroelectric liquid crystal cell
US7079202B2 (en) Multi-layer diffraction type polarizer and liquid crystal element
KR101506950B1 (en) Multi-layer achromatic liquid crystal polarization gratings and related fabrication methods
US20150177688A1 (en) Apparatus for copying a hologram
CN109983378B (en) Optical element and optical element manufacturing method
KR20170037884A (en) Bragg liquid crystal polarization gratings
JP6168642B2 (en) Diffraction grating and manufacturing method thereof, optical waveguide
JP4792679B2 (en) Isolator and variable voltage attenuator
Wahle et al. Two-dimensional switchable blue phase gratings manufactured by nanosphere lithography
US11099446B2 (en) High-speed optical switching engine
JP2007249027A (en) Polarized light conversion film and its manufacturing method, polarizing element, and liquid crystal display device
JP2006215186A (en) Diffraction element, manufacturing method of the same, and polarization selecting device using diffraction element
JP5195024B2 (en) Diffraction element, optical attenuator, optical head device, and projection display device
Ghadimi Nassiri et al. High-order Laguerre-Gauss polychromatic beams from Bragg-Berry flat optics
Xu et al. Real-time angular sensitivity compensation of guided-mode resonance filter
WO2005078485A1 (en) Multilayer film optical member and production method theerfor
Hu et al. Photoinduced liquid crystal domain engineering for optical field control
JP5152366B2 (en) Isolator and variable voltage attenuator
JP2013007781A (en) Liquid crystal device
Nersisyan et al. Vector vortex waveplates with tunable spectrum and switchable topological charge
Belyaev et al. Numerical modeling of the diffraction of light at periodic anisotropic gratings with rectangular surface microrelief

Legal Events

Date Code Title Description
A621 Written request for application examination

Free format text: JAPANESE INTERMEDIATE CODE: A621

Effective date: 20150327

A521 Request for written amendment filed

Free format text: JAPANESE INTERMEDIATE CODE: A523

Effective date: 20150406

A521 Request for written amendment filed

Free format text: JAPANESE INTERMEDIATE CODE: A523

Effective date: 20150528

A977 Report on retrieval

Free format text: JAPANESE INTERMEDIATE CODE: A971007

Effective date: 20151224

A131 Notification of reasons for refusal

Free format text: JAPANESE INTERMEDIATE CODE: A131

Effective date: 20160106

A521 Request for written amendment filed

Free format text: JAPANESE INTERMEDIATE CODE: A523

Effective date: 20160304

A131 Notification of reasons for refusal

Free format text: JAPANESE INTERMEDIATE CODE: A131

Effective date: 20160830

RD13 Notification of appointment of power of sub attorney

Free format text: JAPANESE INTERMEDIATE CODE: A7433

Effective date: 20161018

A601 Written request for extension of time

Free format text: JAPANESE INTERMEDIATE CODE: A601

Effective date: 20161024

A521 Request for written amendment filed

Free format text: JAPANESE INTERMEDIATE CODE: A821

Effective date: 20161019

A521 Request for written amendment filed

Free format text: JAPANESE INTERMEDIATE CODE: A523

Effective date: 20161228

TRDD Decision of grant or rejection written
A01 Written decision to grant a patent or to grant a registration (utility model)

Free format text: JAPANESE INTERMEDIATE CODE: A01

Effective date: 20170606

A711 Notification of change in applicant

Free format text: JAPANESE INTERMEDIATE CODE: A712

Effective date: 20170613

A61 First payment of annual fees (during grant procedure)

Free format text: JAPANESE INTERMEDIATE CODE: A61

Effective date: 20170623

R150 Certificate of patent or registration of utility model

Ref document number: 6168642

Country of ref document: JP

Free format text: JAPANESE INTERMEDIATE CODE: R150

A521 Request for written amendment filed

Free format text: JAPANESE INTERMEDIATE CODE: A523

Effective date: 20170721

LAPS Cancellation because of no payment of annual fees