JPS6389817A - Face type optical logic element - Google Patents

Abstract

PURPOSE:To obtain a face type optical logic element having a large ratio of ON to OFF by making light having vertical electromagnetic vector incident upon an interface consisting of a clad layer and a quantum well layer 13 and controlling outgoing light from the interface by an electric field impressed to the quantum well layer. CONSTITUTION:Light 19, i.e. p-polarized light, having vertical electromagnetic vector is made incident upon the interface 18 consisting of the n-type clad layer 12 and the quantum well layer 13 at its critical angle. Since the light 19 is fully reflected by the interface 18, the reflected light 21 having high intensity can be obtained from the interface 18. When an electric field is impressed to the layer 13, the intensity of a vibrator in an exciton is reduced and the refractive index of the layer 13 is reduced. Thereby, the incident angle of light is reduced to a value smaller than the critical angle and the light is transmitted from the interface 18 without being fully reflected. In case of p-polarization, the change of a reflection factor is larger than that of the refractive index. Since the change of the reflection factor at the interface 18 is used without using the change of absorption, the output ratio of ON to OFF can be increased even if the face type logical element is used.

Description

【発明の詳細な説明】 〔産業上の利用分野〕 本発明は光情報処理等に用いる固型光論理素子に関する
。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a solid-state optical logic element used for optical information processing and the like.

〔従来の技術〕[Conventional technology]

近年、光の持つ高度な並列性を利用したデジタル情報処
理が注目されているにの並列光デジタル情報処理の実現
には光を２次元的に制御する固型光論理素子の開発が必
要である。その基本素子の一つとして光信号を電気信号
でオン・オフする光ゲートが考えられる。従来、固型光
ゲートとして第３図に示す構造がアプライド・フイジッ
クスレターズ（Ａｐｐｌｉｅｄ　Ｐｈｙｓｉｃｓ　Ｌｅ
ｔｔｅｒｓ）４４巻、１６頁（１９８４）においてウッ
ド（Ｗｏｏｄ。In recent years, digital information processing that takes advantage of the high degree of parallelism inherent in light has attracted attention.To realize parallel optical digital information processing, it is necessary to develop solid-state optical logic elements that control light two-dimensionally. . One of the basic elements is an optical gate that turns on and off optical signals using electrical signals. Conventionally, the structure shown in Fig. 3 as a solid-state optical gate was developed by Applied Physics Letters.
Wood (1984), Volume 44, Page 16 (1984).

Ｔ、Ｈ，）等によって報告されている。この固型光ゲー
トは量子井戸層１３を導電型がｐ型のクラッド層１４と
ｎ型のクラッド層１２ではさんだＰｉｎ構造を有してい
る。表面から入射した光１９は量子井戸層１３を通って
裏面から出射光２０となって出射する。ｐ側電極１５と
ｎ側電極１６の間の電圧が０■のとき、量子井戸層１３
の励起子吸収のため光は裏面に透過しない。ところが、
ｐ側電極１５とｎ側電極１６との間に逆方向に８Ｖの電
圧を印加すると励起子による吸収がおさえられるため光
は裏側から透過するようになる。It has been reported by T, H,) et al. This solid optical gate has a PIN structure in which a quantum well layer 13 is sandwiched between a cladding layer 14 of p-type conductivity and a cladding layer 12 of n-type conductivity. Light 19 incident from the front surface passes through the quantum well layer 13 and exits as light 20 from the back surface. When the voltage between the p-side electrode 15 and the n-side electrode 16 is 0, the quantum well layer 13
Light does not pass through the back surface due to exciton absorption. However,
When a voltage of 8 V is applied in the opposite direction between the p-side electrode 15 and the n-side electrode 16, absorption by excitons is suppressed, so that light is transmitted from the back side.

以上のように、電極間の電圧を変化することによって量
子井戸層１３の透過率を制御して光をスイッチングでき
る。As described above, light can be switched by controlling the transmittance of the quantum well layer 13 by changing the voltage between the electrodes.

〔発明が解決しようとする問題点〕[Problem that the invention seeks to solve]

上述の構造では量子井戸層の電場による吸収係数の変化
を利用しているため、固型素子のように光が吸収を受け
る長さが短い場合にはオン状態とオン状態の出力比が大
きくできないという欠点がある。The above structure utilizes changes in the absorption coefficient due to the electric field in the quantum well layer, so if the length at which light is absorbed is short, such as in a solid-state device, the output ratio between the on-state and the on-state cannot be large. There is a drawback.

本発明の目的は、オン・オフ比の大きな固型光論理素子
を提供することにある。An object of the present invention is to provide a solid-state optical logic element with a large on-off ratio.

〔問題点を解決するための手段〕[Means for solving problems]

本発明の固型光論理素子は、クラッド層と量子井戸層と
から成る界面に垂直な電場ベクトルを持つ光を界面の臨
界角に等しいかそれより少し大きい入射角で量子井戸層
側から入射させ、界面から出射する光を量子井戸層に印
加する電場で制御することを特徴とする。The solid-state optical logic device of the present invention allows light having an electric field vector perpendicular to the interface between a cladding layer and a quantum well layer to be incident from the quantum well layer side at an incident angle equal to or slightly larger than the critical angle of the interface. , the light emitted from the interface is controlled by an electric field applied to the quantum well layer.

〔作用〕[Effect]

クラッド層と量子井戸層の界面に対して垂直方向の電場
ベクトルを持つ光（ｐ偏光）が界面に臨界角で入射する
。このとき、光は界面で全反射されるため界面から強度
の大きな反射光が得られる。Light (p-polarized light) having an electric field vector perpendicular to the interface between the cladding layer and the quantum well layer is incident on the interface at a critical angle. At this time, since the light is totally reflected at the interface, a high-intensity reflected light is obtained from the interface.

量子井戸層に電場が印加されると励起子の振動子強度が
減少するため、量子井戸層の屈折率が小さくなる。この
ため、光の入射角は臨界角よりも小さくなって光は全反
射せずに界面から透過する。When an electric field is applied to the quantum well layer, the oscillator strength of excitons decreases, so the refractive index of the quantum well layer decreases. Therefore, the incident angle of light becomes smaller than the critical angle, and the light is transmitted through the interface without being totally reflected.

ｐ偏光の場合、偏光角が存在するため、屈折率変化に対
する反射率の変化は大きく、第２図に示すように２．５
％の屈折率変化で反射率は１０倍変化する３本発明は吸
収の変化ではなく界面での反射率の変化を利用している
ため、固型素子であってもオン・オフの出力比は大きい
。In the case of p-polarized light, since there is a polarization angle, the change in reflectance with respect to the change in refractive index is large, and as shown in Figure 2, the change in reflectance is 2.5.
% change in refractive index changes reflectance by a factor of 10 big.

〔実施例〕〔Example〕

第１図は本発明の一実施例を示す構成図である。 FIG. 1 is a block diagram showing an embodiment of the present invention.

ＩｎＰの基板１１上に厚さ１μｍのｎ型ＩｎＰのクラッ
ド層１２　、　Ｉ　ｎ　０．４７Ｇ　ａ　Ｏ，％３Ａ　
Ｓからなる厚さ１００人のウェル層とＩｎＰからなる厚
さ１５０人のバリア層とを交互に８０層積層した量子井
戸層１３．厚さ１μｍのｐ型ＩｎＰのクラッド層１４を
順次積層し、ｎ型クラッド層１４の上にｐ側の電極１５
、基板裏面にｎ側の電極１６を形成する。幅５μｍのス
トライブを残してｎ側電極１５とｎ型クラッド層１４を
除去した後、量子井戸層１３を層面に対して６８°の角
をなすように反応性イオンビーム（ＲＩＢＥ）によりエ
ツチングして入射面１７を形成する。量子井戸層１３と
ｎ型クラッド層１２との界面１８に垂直な電場ベクトル
を持ち、量子井戸層１３の励起子に相当するエネルギー
０．８９５ｅＶの入射光１９を入射面１７から垂直に入
射する。電極１５．１６の間に電圧が印加されていない
場合、量子井戸層１３の屈折率は３．４６であり、ｎ型
クラッド層１２の屈折率は３．２であるから、界面１８
での臨界角は６７．６°となる。一方、′入射光１９の
界面１８に対する入射角は６８°であり臨界角より大き
く、界面１８で入射光１９は全反射され、大きな反射光
２１が得られる。電極１５．１６間に２０Ｖの電圧を印
加すると、量子井戸層１３にかかる電場は１０に、Ｖ／
ｃｍとなり、励起子の振動子強度が減少するため、量子
井戸１層１３の屈折率は３．４２に減少する。このとき
の界面１８での臨界角は６９．１°となり入射光１９は
全反射されず大部分が透過する。ｐ偏光に対しては偏光
角があるため反射率の変化は急激である。An n-type InP cladding layer 12 with a thickness of 1 μm on an InP substrate 11, I n 0.47G a O,%3A
Quantum well layer 13. Quantum well layer 13. 80 well layers made of S with a thickness of 100 and barrier layers made of InP with a thickness of 150 are laminated alternately. A p-type InP cladding layer 14 with a thickness of 1 μm is laminated in sequence, and a p-side electrode 15 is placed on the n-type cladding layer 14.
, an n-side electrode 16 is formed on the back surface of the substrate. After removing the n-side electrode 15 and the n-type cladding layer 14 leaving stripes with a width of 5 μm, the quantum well layer 13 was etched using a reactive ion beam (RIBE) so as to form an angle of 68° with respect to the layer plane. An incident surface 17 is formed. Incident light 19 having an electric field vector perpendicular to the interface 18 between the quantum well layer 13 and the n-type cladding layer 12 and having an energy of 0.895 eV corresponding to an exciton in the quantum well layer 13 is incident perpendicularly from the entrance surface 17 . When no voltage is applied between the electrodes 15 and 16, the refractive index of the quantum well layer 13 is 3.46 and the refractive index of the n-type cladding layer 12 is 3.2, so the interface 18
The critical angle at is 67.6°. On the other hand, the angle of incidence of the incident light 19 on the interface 18 is 68°, which is larger than the critical angle, and the incident light 19 is totally reflected at the interface 18, resulting in a large reflected light 21. When a voltage of 20 V is applied between the electrodes 15 and 16, the electric field applied to the quantum well layer 13 becomes 10 V/
cm, and the oscillator strength of the excitons decreases, so the refractive index of the first quantum well layer 13 decreases to 3.42. At this time, the critical angle at the interface 18 is 69.1°, and the incident light 19 is not totally reflected and most of it is transmitted. Since there is a polarization angle for p-polarized light, the change in reflectance is rapid.

〔発明の効果〕〔Effect of the invention〕

以上詳述したように、本発明によれば、オン・オフ比の
大きな固型光論理素子を得ることかできる。As described in detail above, according to the present invention, it is possible to obtain a solid-state optical logic element with a large on/off ratio.

【図面の簡単な説明】[Brief explanation of the drawing]

第１図は本発明の一実施例を示す断面図、第２図は本発
明の原理を示す図で、入射角が臨界角に近いときの屈折
率変化に対する反射率の変化を示す図、第３図は従来の
技術の一例の断面図である。 １１・・・基板、１２・・・ｎ型クラッド層、１３・・
・量子井戸層、１４・・・ｐ型クラッド層、１５・・・
ｎ側電極、１６・・・ｎ側電極、１７・・・入射面、１
８・・・界面、１９・・・入射光、２０・・・出射光、
２１・・・反射光。 峯１面　　　　　　？？り電梧 基竹牟１２FIG. 1 is a cross-sectional view showing an embodiment of the present invention, FIG. 2 is a diagram showing the principle of the invention, and is a diagram showing the change in reflectance with respect to the change in refractive index when the incident angle is close to the critical angle. FIG. 3 is a sectional view of an example of a conventional technique. 11... Substrate, 12... N-type cladding layer, 13...
・Quantum well layer, 14...p-type cladding layer, 15...
n-side electrode, 16... n-side electrode, 17... incident surface, 1
8... Interface, 19... Incident light, 20... Outgoing light,
21...Reflected light. Mine 1? ? Riden Gokichikumu 12

Claims (1)

【特許請求の範囲】[Claims] クラッド層と量子井戸層とから成る界面に垂直な電場ベ
クトルを持つ光を前記界面の臨界角に等しいかそれより
少し大きい角度で量子井戸層側から入射し、前記界面か
ら反射する光を前記量子井戸層に印加する電場で制御す
ることを特徴とする面型光論理素子。Light having an electric field vector perpendicular to the interface between the cladding layer and the quantum well layer is incident from the quantum well layer side at an angle equal to or slightly larger than the critical angle of the interface, and the light reflected from the interface is reflected from the quantum well layer. A planar optical logic element characterized by being controlled by an electric field applied to a well layer.