JPS62145224A - Optical waveguide element - Google Patents
Optical waveguide elementInfo
- Publication number
- JPS62145224A JPS62145224A JP28605785A JP28605785A JPS62145224A JP S62145224 A JPS62145224 A JP S62145224A JP 28605785 A JP28605785 A JP 28605785A JP 28605785 A JP28605785 A JP 28605785A JP S62145224 A JPS62145224 A JP S62145224A
- Authority
- JP
- Japan
- Prior art keywords
- liquid crystal
- refractive index
- waveguides
- optical waveguide
- 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.)
- 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
- G02F1/13—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 liquid crystals, e.g. single liquid crystal display cells
- G02F1/1326—Liquid crystal optical waveguides or liquid crystal cells specially adapted for gating or modulating between optical waveguides
Landscapes
- Physics & Mathematics (AREA)
- Nonlinear Science (AREA)
- Chemical & Material Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Liquid Crystal (AREA)
- Optical Integrated Circuits (AREA)
Abstract
Description
【発明の詳細な説明】
産業上の利用分野
本発明は光通信および光情報処理の分野において使用さ
れる光導波路素子に関するものである。DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an optical waveguide element used in the fields of optical communication and optical information processing.
従来の技術
光導波路素子の代表例として方向性結合器を利用したも
のがある。この素子は2本の近接した光導波路で構成さ
れており、また各導波路は伝搬定数を変化すべき手段が
設けられている。ここで素子の長さは完全結合長り。に
なるべく設計されているのが普通である。完全結合長と
は、一方の導波路に光を入射した時、出力端側では他方
の導波路からのみ光が出射するような長さである。つぎ
に(たとえば電気光学効果を用いて)2つの導波路間に
伝搬定数の差を作ることにより光のスイッチングが実現
される。この他にも内部全対型の光スィッチなどが考案
されている。A typical example of a conventional optical waveguide device is one using a directional coupler. The device consists of two adjacent optical waveguides, and each waveguide is provided with means for varying the propagation constant. Here, the length of the element is the fully bonded length. Usually, it is designed as much as possible. The perfect coupling length is a length such that when light enters one waveguide, the light is emitted only from the other waveguide at the output end side. Light switching is then achieved by creating a difference in propagation constants between the two waveguides (eg, using electro-optic effects). In addition, internal all-pair type optical switches have also been devised.
発明が解決しようとする問題点
しかし実際には導波路の屈折率変動、導波路作製誤差等
により素子長を完全結合長に制御することが非常に困難
である。また従来の光導波素子はLiNb0.や化合物
半導体を用いて作製されているが、それらの電気光学定
数が小さいため、素子の高性能化や素子作製後の微調整
が困難であった。Problems to be Solved by the Invention However, in reality, it is extremely difficult to control the element length to a perfect coupling length due to variations in the refractive index of the waveguide, errors in waveguide fabrication, and the like. Furthermore, the conventional optical waveguide device is LiNb0. However, due to their small electro-optic constants, it has been difficult to improve the performance of the device and make fine adjustments after device fabrication.
本発明はこのような欠点を除去するため屈折率制御範囲
の大きい液晶を利用した光導波路素子である。The present invention provides an optical waveguide element using liquid crystal with a wide refractive index control range in order to eliminate such drawbacks.
問題点を解決するための手段
電気的に屈折率制御可能な液晶を近接並置された2つの
凸型光導波路間の凹部に満たすことにより、両溝波路間
の光の分布を制御する。またこの液晶に電界を印加する
だめの手段として凸型導波路側面に電極を構成している
。ここで用いる液晶は正の誘電異方性を有し、電界方向
に対し電圧無印加時に垂直に分子配列されているもので
ある。Means for Solving the Problems By filling the concave portion between two convex optical waveguides juxtaposed in close proximity with a liquid crystal whose refractive index can be electrically controlled, the distribution of light between both groove waveguides is controlled. Further, as a means for applying an electric field to the liquid crystal, electrodes are formed on the side surfaces of the convex waveguide. The liquid crystal used here has positive dielectric anisotropy, and its molecules are aligned perpendicular to the direction of the electric field when no voltage is applied.
作用
2つの光導波路結合部に液晶を配置し、その屈折率を変
化させることにより導波路間の結合度合が変化する。す
なわち液晶の屈折率が高くなると各導波路からの光のし
み出しが大きくなり、導波路間の相互作用が大きくなる
。これは液晶の屈折率が低い場合に比べ2つの導波路間
隔が狭くなったのと同じ効果を生む。この場合本発明の
光導波素子の完全結合長は短かくなる。また逆に液晶の
屈折率が小さい場合は、同様の原理より完全結合長は長
くなる。このように液晶の屈折率をバイアス電圧により
変化させることが可能となり素子性能の向上が期待でき
る。また液晶は通常の誘電体結晶に比べ大きな電界によ
り屈折率変化が期待でき、この特性を近接並置された凸
型導波素子に適用することにより、たとえば全反射型光
スイッチ等の構成も可能となる。Effect: By arranging a liquid crystal between two optical waveguide coupling parts and changing its refractive index, the degree of coupling between the waveguides is changed. That is, as the refractive index of the liquid crystal increases, the amount of light seeping out from each waveguide increases, and the interaction between the waveguides increases. This produces the same effect as when the distance between the two waveguides becomes narrower than when the refractive index of the liquid crystal is low. In this case, the complete coupling length of the optical waveguide element of the present invention becomes short. On the other hand, if the refractive index of the liquid crystal is small, the perfect bond length becomes longer based on the same principle. In this way, it is possible to change the refractive index of the liquid crystal by the bias voltage, and it is expected that the device performance will be improved. In addition, liquid crystals can be expected to change their refractive index due to a larger electric field than normal dielectric crystals, and by applying this property to convex waveguide elements arranged in close proximity, it is possible to construct, for example, total internal reflection type optical switches. Become.
実施例
第1図は本発明の実施例を示す光導波路素子の構造図で
ある。1はn型半導体基板、2は光導波層、3はショッ
トキー電極、4は絶縁膜、5は液晶制御電極、6は基板
側オーミック電極、7は液晶制御用電源、8は光導波路
制御電源、9は液晶の屈折率変化に伴ない実効的屈折率
変化が生じる導波路結合部、10は液晶である。ここで
使用する半導体材料はGaAs 、 InP等の化合物
半導体であるがこれらのみに限定するものではない。Embodiment FIG. 1 is a structural diagram of an optical waveguide device showing an embodiment of the present invention. 1 is an n-type semiconductor substrate, 2 is an optical waveguide layer, 3 is a Schottky electrode, 4 is an insulating film, 5 is a liquid crystal control electrode, 6 is an ohmic electrode on the substrate side, 7 is a liquid crystal control power supply, 8 is an optical waveguide control power supply , 9 is a waveguide coupling portion where an effective refractive index change occurs as the refractive index of the liquid crystal changes, and 10 is a liquid crystal. The semiconductor material used here is a compound semiconductor such as GaAs or InP, but is not limited to these.
第1図は方向性結合器型光スイッチに本発明を適用した
ものである。片方の導波路にTEモードの導波光が励振
するように入射された光(Pin)は導波路間の結合に
よりPlおよびP2 として出力側で観測されるが通
常、ショットキー電極3にバイアスを加えない場合は、
Plはほとんど零になるように素子長(完全結合長)を
選ぶ。しかしこの完全結合長に素子長を制御するのは非
常に困難である。そこで図に示すように凸型光導波路間
に液晶1oを配置することによりこの完全結合長の電気
的制御が可能となる。この様子を第2図を用いて説明す
る。第2図において第1図と同一のものには同一番号を
付している。ここで液晶1゜は正の誘電異方性を有し、
第2図aに示すように液晶制御電源7が接続されていな
い時は分子配列が光の進行方向に配列されている。ここ
でTEモードの光に対する液晶1oの屈折率は比較的小
さく導波路間の結合も小さくなり完全結合長は比較的長
いものである。FIG. 1 shows the present invention applied to a directional coupler type optical switch. The light (Pin) that is incident on one of the waveguides so that the guided light in TE mode is excited is observed on the output side as Pl and P2 due to the coupling between the waveguides, but normally, a bias is applied to the Schottky electrode 3. If not,
The element length (complete bond length) is selected so that Pl is almost zero. However, it is very difficult to control the element length to this perfect bond length. Therefore, by arranging a liquid crystal 1o between the convex optical waveguides as shown in the figure, it becomes possible to electrically control this complete coupling length. This situation will be explained using FIG. 2. In FIG. 2, the same parts as in FIG. 1 are given the same numbers. Here, the liquid crystal 1° has positive dielectric anisotropy,
As shown in FIG. 2a, when the liquid crystal control power source 7 is not connected, the molecules are aligned in the direction in which the light travels. Here, the refractive index of the liquid crystal 1o for TE mode light is relatively small, the coupling between the waveguides is also small, and the complete coupling length is relatively long.
しかし同図すに示すように液晶制御電源7をONにする
と液晶分子配列は電界に対し平行となり、この場合の液
晶の屈折率は同図すのそれより大きくなる。この際液晶
の屈折率の変化は、適当な材料を選ぶことにより1.4
から1.8程度までの〜Q・4の変化が実現でき、この
値は化合物半導体や、誘電体のそれが10−3〜10−
4オーダであることを考えると非常に大きなものといえ
る。このような状態では導波路結合部9における実効的
屈折率は大きくなり、したがって完全結合長は短かくな
る。これらの様子を第3図に示す。第3図はP2のパワ
ーの素子長依存性を示したものである。However, as shown in the figure, when the liquid crystal control power source 7 is turned on, the liquid crystal molecules are aligned parallel to the electric field, and the refractive index of the liquid crystal in this case becomes larger than that shown in the figure. At this time, the change in the refractive index of the liquid crystal can be adjusted to 1.4 by selecting an appropriate material.
It is possible to realize a change in ~Q・4 from 1.8 to about 1.8, and this value is 10-3 to 10-1 for compound semiconductors and dielectrics.
Considering that it is on the order of 4, it can be said to be extremely large. In such a state, the effective refractive index in the waveguide coupling portion 9 becomes large, and therefore the complete coupling length becomes short. These conditions are shown in FIG. FIG. 3 shows the dependence of the power of P2 on the element length.
今実際の素子長をLとする。その時素子の完全結合長が
LOであり、Lよりも長いと仮定する。この状態を図中
の実線で示す。このような素子において液晶10に電圧
を印加することにより、破線で示すように完全結合長に
制御可能となる。以上のように素子長を完全結合長より
少し短かめに設計することによりその結合長を液晶21
0により制御が可能となる。これは特に光集積回路等の
ように多くの素子が存在する場合特に有効と考えられる
。Let L be the actual element length. It is then assumed that the complete bond length of the element is LO, which is longer than L. This state is shown by the solid line in the figure. In such an element, by applying a voltage to the liquid crystal 10, it is possible to control the bond length to be perfect as shown by the broken line. As described above, by designing the element length to be slightly shorter than the complete bond length, the bond length can be adjusted to
0 enables control. This is considered to be particularly effective when many elements are present, such as in an optical integrated circuit.
また図では示していないが、液晶充填後、液晶が流れ出
ないように光導波路凸部作製法と同じ方法で凸部を作成
しこれにより液晶を囲み、さらに上部はガラス板等によ
り密封をする必要がある。Although not shown in the figure, after filling the liquid crystal, it is necessary to create a convex part using the same method as the optical waveguide convex fabrication method to prevent the liquid crystal from flowing out, surround the liquid crystal, and seal the upper part with a glass plate, etc. There is.
ここで本来の信号光が導波する光導波路114ζ以外に
形成さtzた凸r’(<に光がス、17波しないよう凸
導彼路どうしの交叉部をY合波構成にする。Here, the intersection of the convex guide paths is made into a Y-combining configuration so that the light does not pass through the convex r'(<<17 waves formed on the optical waveguide 114ζ through which the original signal light is guided.
発明の効果
液晶の大きな屈折率変化を利用することにより、先導波
素子の特性を広い範囲でfliIt御できる。また凸型
光導波路を用いることにより液晶を安定に保持すること
が可能となり、素子の安定な動作が可能となる。Effects of the Invention By utilizing the large refractive index change of liquid crystal, the characteristics of the leading wave element can be controlled over a wide range. Further, by using a convex optical waveguide, it becomes possible to stably hold the liquid crystal, and stable operation of the device becomes possible.
萬1図は本発明の一実施例を示す光導波路素子の斜視図
、第2図は素子の結合長制御の原理を示す素子断面図、
第3図は結合長の変化を示す図である。
1 ・・・・半導体結晶基板、2・・・・・・半導体光
導波層、3・・・・・ショットキー電極、4・・・・・
・絶縁膜、5・・・・・・1夜晶171I龍j電極、6
・・・・・・オーミック電極、7・・・・・・液晶!t
i制御電源、8・・・・・・光導波路制御電源。
代理人の氏名 弁理士 中 尾 敏 男 ほか1名第1
図
第2図
第3図
L LθFigure 1 is a perspective view of an optical waveguide device showing one embodiment of the present invention, and Figure 2 is a cross-sectional view of the device showing the principle of coupling length control of the device.
FIG. 3 is a diagram showing changes in bond length. 1... Semiconductor crystal substrate, 2... Semiconductor optical waveguide layer, 3... Schottky electrode, 4...
・Insulating film, 5...1 night crystal 171I dragon j electrode, 6
...Ohmic electrode, 7...Liquid crystal! t
i control power supply, 8... optical waveguide control power supply. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 3 L Lθ
Claims (3)
もった光導波路が近接並置されており、上記2本の導波
路間に形成されるくぼんだ領域が液晶で満たされている
ことを特徴とする光導波路素子。(1) Two convex optical waveguides, at least some of which are parallel to each other, are juxtaposed in close proximity, and a recessed area formed between the two waveguides is filled with liquid crystal. An optical waveguide device characterized by:
ることを特徴とする特許請求の範囲第1項記載の光導波
路素子。(2) The optical waveguide device according to claim 1, further comprising an electrode so that an electric field can be applied to the liquid crystal.
方向に対し垂直に分子配列されていることを特徴とする
特許請求の範囲第2項記載の光導波路素子。(3) The optical waveguide device according to claim 2, wherein the liquid crystal has positive dielectric anisotropy and molecules are aligned perpendicular to the direction of the electric field when no voltage is applied.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP28605785A JPS62145224A (en) | 1985-12-19 | 1985-12-19 | Optical waveguide element |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP28605785A JPS62145224A (en) | 1985-12-19 | 1985-12-19 | Optical waveguide element |
Publications (1)
Publication Number | Publication Date |
---|---|
JPS62145224A true JPS62145224A (en) | 1987-06-29 |
Family
ID=17699397
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP28605785A Pending JPS62145224A (en) | 1985-12-19 | 1985-12-19 | Optical waveguide element |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPS62145224A (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2002103443A1 (en) * | 2001-06-15 | 2002-12-27 | Nemoptic | Liquid crystal-based electrooptical device forming, in particular, a switch |
-
1985
- 1985-12-19 JP JP28605785A patent/JPS62145224A/en active Pending
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2002103443A1 (en) * | 2001-06-15 | 2002-12-27 | Nemoptic | Liquid crystal-based electrooptical device forming, in particular, a switch |
US6959124B2 (en) | 2001-06-15 | 2005-10-25 | Nemoptic | Liquid crystal-based electro-optical device forming, in particular, a switch |
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