JPH0322602B2 - - Google Patents
Info
- Publication number
- JPH0322602B2 JPH0322602B2 JP5745585A JP5745585A JPH0322602B2 JP H0322602 B2 JPH0322602 B2 JP H0322602B2 JP 5745585 A JP5745585 A JP 5745585A JP 5745585 A JP5745585 A JP 5745585A JP H0322602 B2 JPH0322602 B2 JP H0322602B2
- Authority
- JP
- Japan
- Prior art keywords
- diffraction grating
- forming
- transparent body
- regions
- light
- 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.)
- Expired
Links
- 238000000034 method Methods 0.000 claims description 19
- 230000003287 optical effect Effects 0.000 claims description 11
- 230000004907 flux Effects 0.000 claims description 4
- 230000010287 polarization Effects 0.000 claims 1
- 230000010355 oscillation Effects 0.000 description 6
- 238000004519 manufacturing process Methods 0.000 description 4
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 4
- 229910004298 SiO 2 Inorganic materials 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000011521 glass Substances 0.000 description 3
- 230000001678 irradiating effect Effects 0.000 description 3
- 238000010894 electron beam technology Methods 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- 230000010363 phase shift Effects 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 238000004544 sputter deposition Methods 0.000 description 1
- 239000012780 transparent material Substances 0.000 description 1
- 238000007740 vapor deposition Methods 0.000 description 1
Landscapes
- Diffracting Gratings Or Hologram Optical Elements (AREA)
Description
【発明の詳細な説明】
〔概要〕
DFBレーザなどを製造する際の回折格子を形
成する方法であつて、２つの光束を照射して干渉
縞を形成する際に、媒体との間に透明体を配置
し、かつ該透明体に段差をつけるなどの手法で光
路長を変え、しかも２つの光束を非対称に照射す
ることにより、回折格子に位相シフトを与える。[Detailed Description of the Invention] [Summary] This is a method for forming a diffraction grating when manufacturing a DFB laser, etc., in which a transparent material is placed between the medium and the medium when irradiating two light beams to form interference fringes. By arranging the transparent body, changing the optical path length by adding steps to the transparent body, and irradiating the two light beams asymmetrically, a phase shift is imparted to the diffraction grating.
第８図に示すようにDFBレーザは、半導体チ
ツプ７上に、回折格子８を形成し、その上にレー
ザ９が作成された構造に成つている。このレーザ
に通電すると回折格子８およびレーザ９の部分で
レーザ発振を起こし、レーザ光を放出する。
As shown in FIG. 8, the DFB laser has a structure in which a diffraction grating 8 is formed on a semiconductor chip 7, and a laser 9 is formed on the diffraction grating 8. When this laser is energized, the diffraction grating 8 and the laser 9 cause laser oscillation and emit laser light.
ところが単に回折格子を形成しただけでは、回
折格子における位相関係がずれるために、DFB
レーザの縦モードが２つ発生するという不都合が
ある。これを解消するには、第９図のように、回
折格子８のピツチをレーザ発振の中心部Ｃを境に
してずらすことで、左右の位相関係を予めずらし
ておくことが知られている。本発明は、このよう
に回折格子の位相をずらして形成する方法に関す
る。 However, simply forming a diffraction grating causes the phase relationship in the diffraction grating to shift, resulting in a DFB
There is a disadvantage that two longitudinal modes of the laser are generated. In order to solve this problem, it is known to shift the pitch of the diffraction grating 8 with the center C of laser oscillation as a boundary, as shown in FIG. 9, thereby shifting the left and right phase relationship in advance. The present invention relates to a method of forming a diffraction grating with the phase shifted in this manner.
ところでDFBレーザの回折格子を形成するに
は、従来は電子ビームで回折格子を描画する手法
が採られている。ところがこのように電子ビーム
で露光する方法は、作業が複雑なうえに、時間を
要し、量産的でない。また別の方法として、光の
当たつた領域が食刻されるレジストと光の当たら
ない領域が食刻されるレジストを隣接して配置
し、露光することで回折格子を作成することも知
られている。しかしながらこのような特性を発揮
できる２種のレジストの特性が異なり、実用化に
至つていない。
By the way, in order to form a diffraction grating for a DFB laser, conventionally a method has been adopted in which the diffraction grating is drawn using an electron beam. However, this method of exposing with an electron beam is complicated and time-consuming, and is not suitable for mass production. Another method is to create a diffraction grating by arranging a resist in which the areas exposed to light are etched and a resist in which areas not exposed to light are etched adjacent to each other and exposing them to light. ing. However, the two types of resists that can exhibit these characteristics have different characteristics and have not been put into practical use.
本発明の技術的課題は、従来の回折格子の形成
方法におけるこのような問題を解消し、簡単な装
置で容易に、かつ確実に位相差をもつた回折格子
が作成できるようにすることにある。
The technical problem of the present invention is to solve these problems in the conventional method of forming a diffraction grating, and to make it possible to easily and reliably create a diffraction grating with a phase difference using a simple device. .
第１図は本発明による回折格子の形成方法の基
本原理を示す側面図で、イは全容を示し、ロは要
部の拡大図である。４は回折格子を形成する媒体
であり、その上にガラスなどの透明体３が載置さ
れる。この透明体３は、発振中心部Ｃ上で段差が
つき、その両側の光路長が異なる。あるいは叛振
中心部Ｃ上を境にして、左右の屈折率が異なる構
成としてもよい。
FIG. 1 is a side view showing the basic principle of the method for forming a diffraction grating according to the present invention, in which A shows the entire structure and B shows an enlarged view of the main part. 4 is a medium forming a diffraction grating, on which a transparent body 3 such as glass is placed. This transparent body 3 has a step above the oscillation center C, and the optical path lengths on both sides thereof are different. Alternatively, a configuration may be adopted in which the left and right refractive indexes are different from each other with the top of the oscillation center C as a boundary.
この媒体４の面に、前記透明体３を介して、２
つの光束５と６が照射される。その際光束５と６
が角度2θの角度をなして入射し、媒体４上で２つ
の光束の干渉が行なわれる。また２つの光束５と
６の成す中心軸Ａは、法線Ｖに対し角度φだけ傾
き、非対称の状態で照射される。 2 on the surface of this medium 4 through the transparent body 3.
Two light beams 5 and 6 are emitted. At that time, luminous fluxes 5 and 6
is incident at an angle of 2θ, and the two light beams interfere on the medium 4. Moreover, the central axis A formed by the two light beams 5 and 6 is inclined by an angle φ with respect to the normal line V, and the light beams are irradiated in an asymmetrical state.
第１図ロに示すように、透明体３の厚さは、段
差部１１を境にして異なり、左側の厚さt1より右
側の厚さt2が小さい。そのため段差部１１の左側
と右側とでは、光路長が異なり、また２つの光束
５，６が角度φだけ傾き非対称に照射されるの
で、段差部１１を境にして干渉縞の位相がずれ
る。その結果、２つの光束による干渉縞を露光し
て形成される回折格子８も、段差部１１を境にし
て位相がずれる。
As shown in FIG. 1B, the thickness of the transparent body 3 varies across the stepped portion 11, with the thickness t 2 on the right side being smaller than the thickness t 1 on the left side. Therefore, the optical path lengths are different on the left side and the right side of the stepped portion 11, and the two light beams 5 and 6 are irradiated asymmetrically with an angle φ, so that the phase of the interference fringes is shifted with the stepped portion 11 as a boundary. As a result, the phase of the diffraction grating 8, which is formed by exposing the interference fringes of the two light beams, is also shifted across the stepped portion 11.
第２図は本発明による回折格子の形成方法を使
用して、DFBレーザを製造する例を示す側面図
である。同時に多数のDFBレーザを製造できる
ように、透明体３に、レーザの寸法ｌと同じピツ
チで多数の段差部１１…が形成されている。２つ
の光束５，６を照射すると、それぞれの段差部１
１…を境にして、両側の光路長が異なり、かつ光
束５，６の入射方向を垂線Ｖに対し角度φだけ傾
けて非対称に照射することで、それぞれの段差部
１１を境にして位相のずれた回折格子が形成され
る。露光して回折格子を形成した後に、段差部１
１が中心にくるように、鎖線１２…の位置で切り
離される。
FIG. 2 is a side view showing an example of manufacturing a DFB laser using the method for forming a diffraction grating according to the present invention. In order to manufacture a large number of DFB lasers at the same time, a large number of stepped portions 11 are formed on the transparent body 3 at the same pitch as the laser dimension l. When two light beams 5 and 6 are irradiated, each stepped portion 1
1..., the optical path lengths on both sides are different, and the incident directions of the light beams 5 and 6 are tilted by an angle φ with respect to the perpendicular line V to irradiate the beams asymmetrically. A shifted diffraction grating is formed. After exposing to light to form a diffraction grating, the stepped portion 1
It is cut off at the position of chain line 12 so that 1 is in the center.
次に第３図において、段差寸法ｔと２光束５，
６の傾き角φを求める。透明体３として、屈折率
がｎのガラスを使用し、DFBレーザの寸法（キ
ヤビテイ長）をｌ、段差寸法をｔとする。いま回
折格子の周期をＡとすると、
2Λ sinθ cosφ＝λ (1)
となる。光源として、波長λが3250ÅのHeCdレ
ーザ光を使用し、θ＝54.3度、φ＝５度とする
と、Λ＝2009Åとなる。ガラスの屈折率ｎ＝1.5
のとき、段差寸法ｔ＝2.03μｍとすれば、段差部
１１を境にして、回折格子の位相を反転できるこ
とになる。ガラスとしては、紫外光の吸収の少な
い石英を用いるのが良い。 Next, in FIG. 3, the step dimension t and the two luminous fluxes 5,
Find the inclination angle φ of 6. Glass with a refractive index of n is used as the transparent body 3, the dimension of the DFB laser (cavity length) is l, and the step dimension is t. Now, if the period of the diffraction grating is A, then 2Λ sinθ cosφ=λ (1). When a HeCd laser beam with a wavelength λ of 3250 Å is used as a light source, and θ=54.3 degrees and φ=5 degrees, Λ=2009 Å. Glass refractive index n=1.5
In this case, if the step size t=2.03 μm, the phase of the diffraction grating can be inverted at the step portion 11 as a boundary. As the glass, it is preferable to use quartz, which absorbs little ultraviolet light.
なお透明体３の両面にARコートと呼ばれる反
射防止処理を行なえば、透明体３中で光が多重反
射して回折格子が乱れるのを防止できる。 Note that by applying an antireflection treatment called AR coating to both sides of the transparent body 3, it is possible to prevent multiple reflections of light within the transparent body 3 and disorder of the diffraction grating.
第４図は透明体の段差形成方法の第１実施例で
ある。３１は石英ガラスであり、その表面に、幅
がｌで、厚さｔのSiO2の膜１３を形成する。す
ると、膜１３の領域の板厚がt1、膜１３の無い領
域の板厚がt2となる。この膜１３は、蒸着やスパ
ツタリングなどの手法で形成される。 FIG. 4 shows a first embodiment of a method for forming a step in a transparent body. 31 is quartz glass, and a SiO 2 film 13 having a width l and a thickness t is formed on the surface thereof. Then, the plate thickness in the region of the film 13 becomes t 1 and the plate thickness in the region without the film 13 becomes t 2 . This film 13 is formed by a method such as vapor deposition or sputtering.
第５図は段差形成方法の別の実施例で、透明体
３２を幅ｌの領域だけ、エツチングによつて除去
し、深さがｔの窪みを形成することで、段差部１
１を形成している。 FIG. 5 shows another embodiment of the step forming method, in which the transparent body 32 is removed by etching only a region with a width l, and a recess with a depth t is formed.
1 is formed.
以上は、透明体に段差部１１を形成することで
光路長を変えているが、第６図のように、発振中
心部を境にして、両側の透明体３３と３４屈折率
を変えることでも同様な効果が得られる。すなわ
ち同図イのような石英ガラスなどの透明平板３５
に、それと屈折率の異なるZrO2などの膜３３を
被着形成し、ロの形状にする。次にハのように、
膜３３の無い領域に、石英ガラス３５と屈折率の
等しいSiO2の膜３４をZrO2膜３３と同じ厚さま
で成膜する。この構成は、透明体の板厚は一定で
あるが、ZrO2膜３３の領域とSiO2膜３４の領域
とで屈折率が異なるので、照射される光束の光路
長も異なる。 In the above, the optical path length is changed by forming the stepped portion 11 in the transparent body, but as shown in Fig. 6, it is also possible to change the refractive index of the transparent bodies 33 and 34 on both sides of the oscillation center as a boundary. A similar effect can be obtained. In other words, a transparent flat plate 35 made of quartz glass or the like as shown in FIG.
Then, a film 33 of ZrO 2 or the like having a different refractive index is deposited on the film 33 to form the shape shown in FIG. Then, like Ha,
A SiO 2 film 34 having the same refractive index as the quartz glass 35 is formed to the same thickness as the ZrO 2 film 33 in an area where the film 33 is not present. In this configuration, although the thickness of the transparent body is constant, the refractive index differs between the ZrO 2 film 33 region and the SiO 2 film 34 region, so the optical path length of the irradiated light beam also differs.
第７図は三角柱形状をした透明体の例であり、
光路長の異なる２つの領域１，２を有する面３６
と光束５の入射面３７と光束６の入射面３８によ
つて囲まれる三角柱状を成している。 Figure 7 is an example of a triangular prism-shaped transparent body.
Surface 36 having two regions 1 and 2 with different optical path lengths
It has a triangular prism shape surrounded by an incident surface 37 for the light beam 5 and an incident surface 38 for the light beam 6.
〔発明の効果〕
以上のように本発明によれば、光源と回折格子
を形成する媒体との間に置く透明体の光路長を変
え、かつ光束を傾けて照射するだけで、位相差を
もつて回折格子を形成できるので、簡単な装置で
容易にかつ確実に回折格子が得られる。[Effects of the Invention] As described above, according to the present invention, by simply changing the optical path length of the transparent body placed between the light source and the medium forming the diffraction grating, and irradiating the light beam at an angle, it is possible to create a system with a phase difference. Since the diffraction grating can be formed using a simple device, the diffraction grating can be easily and reliably obtained.
第１図は本発明による回折格子の形成方法の基
本原理を示す側面図、第２図は本発明による回折
格子の形成方法の実施例を示す側面図、第３図は
段差寸法の算出例を示す側面図、第４図〜第７図
は透明体の各実施例を示す断面図、第８図は
DFBレーザの断面図、第９図は位相差をもつた
回折格子を示す断面図である。
図において、３は透明体、４は回折格子を形成
する媒体、５，６は光束、Ｃは発振中心部、Ｖは
法線、１１は段差部をそれぞれ示す。
FIG. 1 is a side view showing the basic principle of the method for forming a diffraction grating according to the present invention, FIG. 2 is a side view showing an embodiment of the method for forming a diffraction grating according to the present invention, and FIG. 3 is an example of calculating step dimensions. 4 to 7 are cross-sectional views showing each embodiment of the transparent body, and FIG. 8 is a side view showing each embodiment of the transparent body.
FIG. 9 is a cross-sectional view of the DFB laser, showing a diffraction grating with a phase difference. In the figure, 3 is a transparent body, 4 is a medium forming a diffraction grating, 5 and 6 are luminous fluxes, C is an oscillation center, V is a normal line, and 11 is a stepped portion.
Claims (1)
する方法において、回折格子を形成する媒体４の
上に、光の光路長の異なる２つの領域１，２を有
する透明体３を該表面が媒体４と同じ側となるよ
うに媒体４に接触させ、かつ２つの光束５，６を
角度2θをつけて照射し、 しかも２つの光束５，６のなす中心軸Ａを、媒
体４の上面および透明体３の領域１，２の面の法
線Ｖに対し、相対的に角度φだけ傾けることで、
２つの光束５と６の入射方向を、法線Ｖに対し非
対称とすることを特徴とする回折格子の形成方
法。 ２ 前記光の光路長の異なる２つの領域が、表面
の高さが異なる２つの領域よりなることを特徴と
する特許請求の範囲第１項記載の回折格子の形成
方法。 ３ 前記光の光路長の異なる２つの領域が、異な
る屈折率よりなる層を選択的に設けることより形
成されることを特徴とする特許請求の範囲第１項
記載の回折格子の形成方法。 ４ 前記透明体３が、領域１，２およびそれに平
行な平面により挟まれた平板状であることを特徴
とする特許請求の範囲第１項記載の回折格子の形
成方法。 ５ 前記透明体３が、領域１，２および光束５、
光束６の各々の入射面より成る三角柱形状である
ことを特徴とする特許請求の範囲第１項記載の回
折格子の形成方法。 ６ 前記透明体３の光束入射面および領域１，２
に該光束の偏光状態、入射角、波長に対応した反
射防止膜を形成したことを特徴とする特許請求の
範囲第１項記載の回折格子の形成方法。[Claims] 1. In a method of forming a diffraction grating by interference exposure of two light beams, a transparent body 3 having two regions 1 and 2 with different optical path lengths on a medium 4 forming a diffraction grating is provided. is brought into contact with the medium 4 so that its surface is on the same side as the medium 4, and the two light beams 5 and 6 are irradiated at an angle 2θ, and the central axis A formed by the two light beams 5 and 6 is set to the medium 4. By tilting by an angle φ relative to the normal V of the upper surface of 4 and the surfaces of regions 1 and 2 of the transparent body 3,
A method for forming a diffraction grating, characterized in that the directions of incidence of the two light beams 5 and 6 are asymmetrical with respect to the normal V. 2. The method of forming a diffraction grating according to claim 1, wherein the two regions having different optical path lengths of the light are comprised of two regions having different surface heights. 3. The method of forming a diffraction grating according to claim 1, wherein the two regions having different optical path lengths of the light are formed by selectively providing layers having different refractive indexes. 4. The method of forming a diffraction grating according to claim 1, wherein the transparent body 3 has a flat plate shape sandwiched between regions 1 and 2 and a plane parallel thereto. 5. The transparent body 3 has areas 1 and 2 and a light beam 5,
2. The method of forming a diffraction grating according to claim 1, wherein the diffraction grating has a triangular prism shape formed by each incident surface of the light beam 6. 6 Light flux incident surface and regions 1 and 2 of the transparent body 3
2. The method for forming a diffraction grating according to claim 1, wherein an antireflection film is formed on the surface of the surface of the surface of the surface of the surface of the surface of the surface of the surface of the surface of the surface of the surface of the surface of the surface of the surface of the surface of the surface of the surface of the surface of the surface of the surface of the surface of the surface of the surface of the surface of the diffraction grating that corresponds to the polarization state, incident angle, and wavelength of the light beam.
Priority Applications (5)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5745585A JPS61246701A (en) | 1985-03-20 | 1985-03-20 | Formation of diffraction grating |
| CA504383A CA1270934C (en) | 1985-03-20 | 1986-03-18 | Spatial phase modulating masks and production processes thereof, and processes for the formation of phase-shifted diffraction gratings |
| EP86400592A EP0195724B1 (en) | 1985-03-20 | 1986-03-20 | Spatial phase modulating masks and production processes thereof, and processes for the formation of phase-shifted diffraction gratings |
| DE8686400592T DE3687845T2 (en) | 1985-03-20 | 1986-03-20 | SPATIAL PHASE MODULATION MASKS, METHOD FOR THE PRODUCTION THEREOF AND METHOD FOR THE FORMATION OF PHASE-SHIFTED GRADES. |
| US06/841,801 US4806442A (en) | 1985-03-20 | 1986-03-20 | Spatial phase modulating masks and production processes thereof, and processes for the formation of phase-shifted diffraction gratings |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5745585A JPS61246701A (en) | 1985-03-20 | 1985-03-20 | Formation of diffraction grating |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS61246701A JPS61246701A (en) | 1986-11-04 |
| JPH0322602B2 true JPH0322602B2 (en) | 1991-03-27 |
Family
ID=13056139
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP5745585A Granted JPS61246701A (en) | 1985-03-20 | 1985-03-20 | Formation of diffraction grating |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS61246701A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2809809B2 (en) * | 1990-04-19 | 1998-10-15 | 株式会社東芝 | Manufacturing method of phase shift type diffraction grating |
-
1985
- 1985-03-20 JP JP5745585A patent/JPS61246701A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS61246701A (en) | 1986-11-04 |
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