JPH0850267A - Acoustooptical filter - Google Patents
Acoustooptical filterInfo
- Publication number
- JPH0850267A JPH0850267A JP18505194A JP18505194A JPH0850267A JP H0850267 A JPH0850267 A JP H0850267A JP 18505194 A JP18505194 A JP 18505194A JP 18505194 A JP18505194 A JP 18505194A JP H0850267 A JPH0850267 A JP H0850267A
- Authority
- JP
- Japan
- Prior art keywords
- surface acoustic
- difference
- substrate
- polarized light
- acoustic waves
- 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.)
- Pending
Links
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/11—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on acousto-optical elements, e.g. using variable diffraction by sound or like mechanical waves
- G02F1/125—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on acousto-optical elements, e.g. using variable diffraction by sound or like mechanical waves in an optical waveguide structure
Landscapes
- Physics & Mathematics (AREA)
- Nonlinear Science (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は光フィルタに関し、特に
コリニア結合による音響光学効果を利用した光波長フィ
ルタに関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical filter, and more particularly to an optical wavelength filter utilizing the acousto-optic effect by collinear coupling.
【０００２】[0002]
【従来の技術】音響光学効果を利用した光波長フィルタ
は、高速に動作する、同調可変幅が広く選択チャネル数
を多く取れる、複数波長を同時に選択できるなどの特長
がある。2. Description of the Related Art An optical wavelength filter utilizing the acousto-optic effect has the features that it operates at high speed, has a wide tuning variable width, can take a large number of selected channels, and can simultaneously select a plurality of wavelengths.
【０００３】図４は従来の光波長フィルタを例示する平
面図であり、ジャーナル・オブ・クウァンタム・エレク
トロニクス第１３巻、２号、４３〜４６頁（ＪＯＵＮＡ
ＬＯＦＱＵＡＮＴＵＭ ＥＬＥＣＴＲＯＮＩＣＳ，Ｖｏ
ｌ．ＱＥ−１３，ＮＯ．２，ｐｐ４３−４６，１９７
７）に記載された音響光学フィルタである。ニオブ酸リ
チウム基板４１上に作成されたチタン拡散の光導波路４
２において、これに装荷された表面波励振用電極４３か
らの励振で発生する表面弾性波により、表面波励振用電
極４３と音波吸収体４５との間の領域（相互作用領域４
４）での周期的な屈折率変化が生じる。入力端で励起さ
れた、基板に対して水平な電解成分を有する直線偏光
（以後ＴＥ偏光と呼ぶ）のうち、光導波路４２の周期的
な屈折率変化により位相整合条件が満たされる特定波長
のＴＥ偏光が、基板に対して垂直な電解成分を有する直
線偏光（以後ＴＭ偏光と呼ぶ）に変換される。音波吸収
体４５とフィルタチップの終端との間に設けたＺカット
のニオブ酸リチウムウェハー片を使用したＴＭ偏光検光
素子４６で、光導波路４２中のＴＭ偏光を透過し、ＴＥ
偏光を放射して、特定波長（λｉ）の光のみを光導波路
４２の終端から取り出すことができる。FIG. 4 is a plan view illustrating a conventional optical wavelength filter. Journal of Quantum Electronics Vol. 13, No. 2, pp. 43-46 (JOUNA).
LOFQUANTUM ELECTRONICS, Vo
l. QE-13, NO. 2, pp43-46,197
The acousto-optic filter described in 7). Titanium-diffused optical waveguide 4 formed on a lithium niobate substrate 41
2, the surface acoustic wave generated by the excitation from the surface acoustic wave excitation electrode 43 loaded therein has a region (interaction region 4) between the surface acoustic wave excitation electrode 43 and the acoustic wave absorber 45.
A periodic refractive index change in 4) occurs. Of linearly polarized light (hereinafter referred to as TE polarized light) excited at the input end and having an electrolytic component horizontal to the substrate, TE of a specific wavelength satisfying the phase matching condition due to the periodic refractive index change of the optical waveguide 42. The polarized light is converted into linearly polarized light (hereinafter referred to as TM polarized light) having an electrolytic component perpendicular to the substrate. A TM polarized light analyzer 46 using a Z-cut lithium niobate wafer piece provided between the sound wave absorber 45 and the end of the filter chip transmits the TM polarized light in the optical waveguide 42, and TE
It is possible to emit polarized light and extract only light of a specific wavelength (λi) from the end of the optical waveguide 42.
【０００４】[0004]
【発明が解決しようとする課題】上述した従来の音響光
学フィルタにおける透過波長半値全幅は、The full width at half maximum of the transmission wavelength in the above-mentioned conventional acousto-optic filter is
【０００５】 [0005]
【０００６】で論理的に与えられる（λｉ：光波長，｜
ｎo −ｎe ｜：複屈折率差，ｂ：比例定数，Ｌ：相互作
用長）。従って、透過波長半値全幅の狭帯域化を図るに
は、相互作用長（Ｌ）を大きく設定せねばならず、フィ
ルタチップを長尺化する必要がある。しかし、Ｌの長尺
化はウエハサイズ等で決まる物理的な限界があり、また
長尺化に伴う弾性表面波の減衰増大に起因するフィルタ
特性の劣化が無視できなくなる等の問題点がある。Logically given by (λi: optical wavelength, |
n o -n e |: birefringence difference, b: proportional constant, L: interaction length). Therefore, in order to narrow the full width at half maximum of the transmission wavelength, the interaction length (L) must be set large, and the filter chip must be elongated. However, the lengthening of L has a physical limit determined by the wafer size and the like, and there is a problem that the deterioration of the filter characteristics due to the increase in the attenuation of surface acoustic waves accompanying the lengthening cannot be ignored.
【０００７】[0007]
【課題を解決するための手段】本発明の音響光学フィル
タは、基板上に形成された光導波路の入力端で励起され
た単一直線偏光を、前記光導波路上に装荷した弾性表面
波励振電極で発生した弾性表面波により特定の波長成分
のみを前上記偏光の方向と直交する直線偏光に変換し
て、その直線偏光を透過し出力端へ導く音響光学フィル
タにおいて、前記弾性表面波励振電極から前記出力端ま
での間に相互作用領域を設けて、これに前記基板が有す
る複屈折率差よりも大きな複屈折率差を付与するドーピ
ングを施してある。The acousto-optic filter of the present invention is a surface acoustic wave excitation electrode in which a single linearly polarized light excited at the input end of an optical waveguide formed on a substrate is loaded on the optical waveguide. In the acousto-optic filter that converts only a specific wavelength component by the generated surface acoustic wave into linearly polarized light orthogonal to the direction of the above-mentioned polarized light and guides the linearly polarized light to the output end, from the surface acoustic wave excitation electrode An interaction region is provided up to the output end, and doping is applied to the interaction region so as to give a birefringence difference larger than that of the substrate.
【０００８】[0008]
【作用】適切なドーピング物質の選定によりｎo （常光
線に対する屈折率）より大きなｎe （異常光線に対する
屈折率）の減少、或いはｎe より大きなｎo の増加を図
り、その結果、複屈折率差｜ｎo −ｎe ｜を増大させて
透過波長幅をより狭くすることができる。By selecting an appropriate doping material, n e (refractive index for ordinary rays) larger than n o (refractive index for extraordinary rays) can be reduced or n o larger than n e can be increased, resulting in birefringence. rate difference | n o -n e | can the increase narrower transmission wavelength width.
【０００９】さらに、相互作用領域内のドーピング量を
空間的に粗密分布させることによって、弾性表面波と導
波光の重み付け結合を実現することができる。Furthermore, the weighted coupling of the surface acoustic wave and the guided light can be realized by spatially and densely distributing the doping amount in the interaction region.
【００１０】[0010]
【実施例】次に本発明について図面を参照して説明す
る。The present invention will be described below with reference to the drawings.
【００１１】図１は本発明の第一の実施例を説明するた
めの斜視図であり、ニオブ酸リチウム（ＬｉＮｂ3 ）基
板１１の上に幅６〜１０μｍ、膜厚６００〜１４００
のチタンストライプを形成し、９５０〜１１００℃で熱
拡散を行い、単一モードチタン拡散形の光導波路１２を
作製する。フォトリソグラフィ法を用いて、電極指周期
１０〜５０μｍのすだれ状の弾性表面波励振電極１３を
その上に形成する。弾性表面波励振電極１３と音波吸収
体と１５の間の相互作用領域１４に、例えば酸化マグネ
シウムドーピングを行い、複屈折差を変化させる。酸化
マグネシウムドーピングによって大きなｎe の減少が生
じ、その結果、複屈折率差｜ｎo −ｎe｜は、基板が有
している複屈折率差よりも増大する。FIG. 1 is a perspective view for explaining a first embodiment of the present invention. A lithium niobate (LiNb 3 ) substrate 11 has a width of 6 to 10 μm and a thickness of 600 to 1400.
The titanium stripe is formed, and thermal diffusion is performed at 950 to 1100 ° C. to produce the single mode titanium diffusion type optical waveguide 12. By using a photolithography method, a comb-shaped surface acoustic wave excitation electrode 13 having an electrode finger period of 10 to 50 μm is formed thereon. The interaction region 14 between the surface acoustic wave excitation electrode 13 and the acoustic wave absorber 15 is doped with, for example, magnesium oxide to change the birefringence difference. Reduction of large n e of the MgO doping occurs, as a result, the birefringence index difference | n o -n e | is increased than the birefringence difference substrate has.
【００１２】図２は本実施例の効果を説明するためのフ
ィルタ特性図である。複屈折率差｜ｎo −ｎe ｜が増大
することによって、本実施例のフィルタ特性Ａの透過波
長幅を従来のフィルタ特性Ｂよりも狭くすることができ
る。FIG. 2 is a filter characteristic diagram for explaining the effect of this embodiment. Birefringence index difference | n o -n e | by increases, the transmission wavelength width of the filter characteristic A of the present embodiment can be smaller than conventional filter characteristic B.
【００１３】図３は本発明の第二の実施例を説明するた
めの斜視図である。本実施例では、相互作用領域３４内
に酸化マグネシウムを空間的に粗密分布させてドーピン
グすることにより、弾性表面波と導波光との重み付け結
合を実現して、狭い透過波長幅と低サイドローブレベル
とをもつフィルタ特性が得られる。FIG. 3 is a perspective view for explaining the second embodiment of the present invention. In the present embodiment, magnesium oxide is spatially sparsely and densely distributed and doped in the interaction region 34 to realize weighted coupling between the surface acoustic wave and the guided light, thereby narrowing the transmission wavelength width and the low sidelobe level. A filter characteristic with and is obtained.
【００１４】[0014]
【発明の効果】以上説明したように本発明によれば、適
切なドーピング物質を使用してｎo より大きなｎe の減
少、或いはｎe より大きなｎo の増大を相互作用領域に
与え、複屈折差｜ｎo −ｎe ｜を増加することにより、
相互作用長を長尺化することなく、透過波長幅を狭くす
ることができる。According to the present invention described above, according to the present invention, given a decrease in larger n e than n o with the appropriate doping material, or an increase in the larger n o than n e in the interaction region, double By increasing the refractive index | no −ne |
The transmission wavelength width can be narrowed without increasing the interaction length.
【００１５】さらに、相互作用領域内でのドーピング量
を空間的に粗密分布させることによって、弾性表面波と
導波光との重み付け結合を実現し、狭帯域な透過波長幅
と低サイドローブレベルとをもつフィルタ特性を得るの
が可能となる。Furthermore, the doping amount in the interaction region is spatially and densely distributed to realize the weighted coupling between the surface acoustic wave and the guided light, thereby achieving a narrow transmission wavelength width and a low sidelobe level. It is possible to obtain the filter characteristic that has.
【００１６】光波長選択機能を必要とする光通信・光交
換システムにおいて、小サイズで、狭帯域な透過波長幅
を有し、低サイドローブレベルをもつ音響光学フィルタ
を供給できる効果は極めて大きい。In an optical communication / optical switching system requiring an optical wavelength selection function, it is very effective to supply an acousto-optic filter having a small size, a narrow band transmission wavelength width, and a low sidelobe level.
【図１】本発明の一実施例を説明するための斜視図であ
る。FIG. 1 is a perspective view for explaining an embodiment of the present invention.
【図２】本発明の実施例の効果を説明するためのフィル
タ特性図である。FIG. 2 is a filter characteristic diagram for explaining the effect of the embodiment of the present invention.
【図３】本発明の他の実施例を説明するための斜視図で
ある。FIG. 3 is a perspective view for explaining another embodiment of the present invention.
【図４】従来の音響光学フィルタを例示する平面図であ
る。FIG. 4 is a plan view illustrating a conventional acousto-optic filter.
１１，３１，４１ ニオブ酸リチウム（ＬｉＮｂＯ3
）基板 １２，３２，４２ 光導波路 １３，３３，４３ 弾性表面波励振電極 １５，３５，４５ 音波吸収体 １６，３６，４６ ＴＭ偏光検光素子11,31,41 Lithium niobate (LiNbO3
) Substrate 12, 32, 42 Optical waveguide 13, 33, 43 Surface acoustic wave excitation electrode 15, 35, 45 Sound wave absorber 16, 36, 46 TM polarization analyzer
Claims (3)
励起された単一直線偏光を、前記光導波路上に装荷した
弾性表面波励振電極で発生した弾性表面波により特定の
波長成分のみを前上記偏光の方向と直交する直線偏光に
変換して、その直線偏光を透過し出力端へ導く音響光学
フィルタにおいて、前記弾性表面波励振電極から前記出
力端までの間に相互作用領域を設けて、これに前記基板
が有する複屈折率差よりも大きな複屈折率差を付与する
ドーピングを施してあることを特徴とする音響光学フィ
ルタ。1. A single linearly polarized light excited at an input end of an optical waveguide formed on a substrate, and only a specific wavelength component is generated by a surface acoustic wave generated by a surface acoustic wave excitation electrode loaded on the optical waveguide. In the acousto-optic filter that converts the linearly polarized light orthogonal to the direction of the above polarized light and guides the linearly polarized light to the output end, an interaction region is provided between the surface acoustic wave excitation electrode and the output end. The acousto-optic filter is characterized in that it is doped to give a difference in birefringence larger than that of the substrate.
前記ドーピングを施している請求項１記載の音響光学フ
ィルタ。2. The acousto-optic filter according to claim 1, wherein the interaction region is subjected to the spatially uniform doping.
布した前記ドーピングを施している請求項１記載の音響
光学フィルタ。3. The acousto-optic filter according to claim 1, wherein the interaction region is provided with the doping that is spatially and densely distributed.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP18505194A JPH0850267A (en) | 1994-08-08 | 1994-08-08 | Acoustooptical filter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP18505194A JPH0850267A (en) | 1994-08-08 | 1994-08-08 | Acoustooptical filter |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0850267A true JPH0850267A (en) | 1996-02-20 |
Family
ID=16163945
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP18505194A Pending JPH0850267A (en) | 1994-08-08 | 1994-08-08 | Acoustooptical filter |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0850267A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6400881B1 (en) | 1997-08-11 | 2002-06-04 | Fujitsu Limited | Optical device having thin film formed over optical waveguide |
| US7343056B2 (en) | 2003-07-07 | 2008-03-11 | Murata Manufacturing Co., Ltd. | Acoustooptic filter |
| CN104280824A (en) * | 2014-10-27 | 2015-01-14 | 中国电子科技集团公司第二十六研究所 | Polarization maintaining optical fiber coupling acousto-optic device with high polarization extinction ratio |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS62123410A (en) * | 1985-11-25 | 1987-06-04 | Nippon Telegr & Teleph Corp <Ntt> | Production of optical waveguide |
-
1994
- 1994-08-08 JP JP18505194A patent/JPH0850267A/en active Pending
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS62123410A (en) * | 1985-11-25 | 1987-06-04 | Nippon Telegr & Teleph Corp <Ntt> | Production of optical waveguide |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6400881B1 (en) | 1997-08-11 | 2002-06-04 | Fujitsu Limited | Optical device having thin film formed over optical waveguide |
| US7343056B2 (en) | 2003-07-07 | 2008-03-11 | Murata Manufacturing Co., Ltd. | Acoustooptic filter |
| CN104280824A (en) * | 2014-10-27 | 2015-01-14 | 中国电子科技集团公司第二十六研究所 | Polarization maintaining optical fiber coupling acousto-optic device with high polarization extinction ratio |
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|---|---|---|---|
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