JPS6122328A

JPS6122328A - Optical bistable element

Info

Publication number: JPS6122328A
Application number: JP14232684A
Authority: JP
Inventors: Toshio Katsuyama; 俊夫勝山; Hiroyoshi Matsumura; 宏善松村
Original assignee: Hitachi Ltd
Current assignee: Hitachi Ltd
Priority date: 1984-07-11
Filing date: 1984-07-11
Publication date: 1986-01-30
Anticipated expiration: 2010-03-06
Also published as: JPH0719005B2

Abstract

PURPOSE:To obtain the optical bistable element which is easily manufactured and has good performance by forming a film of HgI2 or PbI2, etc., which absorbs excitons on a substrate which transmits a wave of exciton absorption wavelength to film thickness which is an integral multiple of the exciton absorption wavelength. CONSTITUTION:The substrate 1 is made of a material which transmits light of wavelength necessary for the operation of the optical bistable element like glass and thin-film crystal 12 of a material (exciton material), such as HgI2 and PbI2, having the large coupling energy of excitons is formed on the substrate to film thickness which is nearly an integral multiple of the exciton absorption wavelength. The C axis 22 of the thin-film crystal 12 is perpendicular to the surface of the substrate 1 and when light is incident in this direction, optical bistable characteristics are obtained. Thus, the optical bistable element of simple structure which is extremely easily manufactured and operates at room temperatures is obtained.

Description

【発明の詳細な説明】〔発明の利用分野〕本発明は光計算機等の論理回路や記憶回路を構成できる
光双安定素子に係り、特に製造が容易で性能の良い光双
安定素子に関する。DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an optical bistable device that can constitute a logic circuit or a storage circuit of an optical computer, and particularly to an optical bistable device that is easy to manufacture and has good performance.

〔発明の背景〕[Background of the invention]

これまで光双安定素子としてはＧ　ａ　Ａ　ｓ単結晶０
エタロンを用いたもの（Ｈ，Ｍ、Ｇｉｂｂｓ　ｅｔ、ａ
ｌ、　。Until now, as an optical bistable element, GaAs single crystal 0
Using an etalon (H, M, Gibbs et a.
l.

“０ｐｔｉｃａｌ　　ｂｉｓｔａｂｉｌｉｔｙ　　ｉｎ
　　ｓｅｍｉｃｏｎｄｕｃｔｏｒｓ”Ａｐｐｌ。“0ptical stability in
semiconductors”Appl.

Ｐｈｙｓ、Ｌｅｔｔ、３５（６）、１５，５ｅｐｔ、１
９７９．ｐ４５１−４５３参照）、あるいはＩｎＳｂ単
結晶エタロンを用いたもの（Ｄ、Ａ、Ｂ、Ｍｉｌｌｅｒ
　ｅｔ、ａｌ、”Ｔｗｏ　ｂｅａｍ　ｏｐｔｊｃａｌｓ
ｉｇｎａｌ　ａｍｐｌｉｆｉｃａｔｊ、ｏｎ　ａｎｄ　
ｂｉｓｔａｂｊｌｉｔｙ　ｉｎ　ＴｎＳｂ”０ｐｔｉｃ
ｓ　　Ｃｏｗ＋ｍｕｎｉｃａｔｉｏｎｓ　　Ｖｏｌ、３
１．＆１．Ｏｃ七、、１９７９゜ｐ１０１〜１０４参照
）が報告されている。しかし、これらの光双安定素子は
１２０°にの低温でしか動作しなかった。その後、Ｇ　
ａ　Ａ　ｓとＡ　Ｑ　Ａ　ｓによる超格子を用いた光双
安定素子が室温で動作した（Ｈ，Ｎ、Ｇｉｂｂｓ　　ｅ
七、ａｌ、”Ｒｏｏｍ　　ｔｅｍｐｅｒａｔｕｒｅ　　
ｅｘｃｉ七ｏｎｊｃｏｐｔｉｃａｌ　　ｂｉｓｔａｂｉ
ｌｉｔｙ　　ｉｎ　　ａ　　ＧａＡｓ−ＧａＡ　Ｑ　Ａ
ｓｇｕｐｅｒｌａｔｔｉｃｅ　　ｅｔａｌｏｎ”Ａｐｐ
ｌ、Ｐｈｙｓ、Ｌｅｔｔ、、４１（３）、ＩＡｕｇ、１
９ｇ２．ｐ２２１〜２２２参照）。このような室温にお
ける動作は、超格子構造にすることにより励起子の結合
エネルギーが増加し、その結果励起子が安定に存在する
ことによる。励起子の存在は屈折率の増加をもたらす。Phys, Lett, 35(6), 15,5ept, 1
979. (see p. 451-453), or one using an InSb single crystal etalon (D, A, B, Miller
et, al, “Two beam optjcals
ignal amplificatj, on and
bistabjlity in TnSb”0ptic
s Cow+communications Vol, 3
1. &1. Oct. 7, 1979, p. 101-104) has been reported. However, these optical bistable devices operated only at temperatures as low as 120°. After that, G
An optical bistable device using a superlattice consisting of a A s and A Q A s operated at room temperature (H, N, Gibbs e
7.al.”Room temperature
exci7onjcoptical bistabi
property in a GaAs-GaA Q A
sguperlattice etalon"App
l,Phys,Lett,,41(3),IAug,1
9g2. (See pages 221-222). Such operation at room temperature is due to the fact that the superlattice structure increases the binding energy of excitons, resulting in the stable existence of excitons. The presence of excitons results in an increase in the refractive index.

第１図に示すように基板ｌの上に形成されたエタロン２
に第２図に示すように光を入射すると、入射光３と反射
光３′がエタロン２の内部で干渉する。エタロン２の厚
さを入射光の波長の整数倍にしておくと、入射光３と反
射光３′のピークが重なりエタロン内部の光量は増加す
る。このとき入射光３の量が少ない場合は励起子の量は
少なく、したがって屈折率も大きくならない。その結果
、入射光３の大部分はエタロン２を通過して、出射する
が、その出射光４の光量は当然少ない。An etalon 2 formed on a substrate l as shown in FIG.
When light is incident as shown in FIG. 2, the incident light 3 and the reflected light 3' interfere inside the etalon 2. If the thickness of the etalon 2 is set to an integral multiple of the wavelength of the incident light, the peaks of the incident light 3 and the reflected light 3' overlap, and the amount of light inside the etalon increases. At this time, when the amount of incident light 3 is small, the amount of excitons is small, and therefore the refractive index does not increase. As a result, most of the incident light 3 passes through the etalon 2 and is emitted, but the amount of the emitted light 4 is naturally small.

入射光の量が多い場合には励起子が多く励起されるため
屈折率が増加する。その結果、反射光３′の量も増加し
、それが入射光３と干渉して重なり、ますますエタロン
内の光量は増加する。したがって励起子の量もますます
増加し、屈折率も増加してエタロン内の光量は更に増加
する。すなわち入射光の量は一定でもエタロン内の光量
は入射時より増加する。この光の一部はエタロンの外に
出射するが、その光量は入射光量が少ない場合に較べて
はるかに大きい。また、この状態では入射光を減少させ
てもエタロン内の光量の減少は少なく、入射光３と出射
光３′の関係は第３図に示すごとく、いわゆる双安定性
を示す。この特性が論理機能や記憶機能と関連すること
はここで述べるまでもない。When the amount of incident light is large, many excitons are excited, so the refractive index increases. As a result, the amount of reflected light 3' also increases, which interferes and overlaps with the incident light 3, and the amount of light inside the etalon further increases. Therefore, the amount of excitons increases, the refractive index also increases, and the amount of light inside the etalon further increases. That is, even if the amount of incident light is constant, the amount of light inside the etalon increases compared to when it is incident. A portion of this light exits the etalon, but the amount of light is much greater than when the amount of incident light is small. Furthermore, in this state, even if the incident light is reduced, the amount of light inside the etalon will not decrease much, and the relationship between the incident light 3 and the output light 3' exhibits so-called bistability, as shown in FIG. It goes without saying here that this characteristic is related to logical and memory functions.

前述のようにＧ　ａ　Ａ　ｓとＡ　Ｑ　Ａ　ｓによる超
格子が室温において光双安定性を示したが、超格子は製
造方法が複雑で、かつ高度の技術を要するという欠点が
あり、その実用化は極めて難かしいと云える。As mentioned above, superlattices made of GaAs and AQAs have shown optical bistability at room temperature, but superlattices have the drawback of being complicated to manufacture and requiring advanced technology, making their practical use difficult. It can be said that it is extremely difficult to convert.

〔発明の目的〕[Purpose of the invention]

本発明の目的は、室温で動作し、かつ構造が簡単で製造
が容易な光双安定素子を提供することにある。An object of the present invention is to provide an optical bistable device that operates at room temperature, has a simple structure, and is easy to manufacture.

〔発明の概要〕[Summary of the invention]

本発明者は、励起子の結合エネルギー（束縛エネルギー
と呼ばれることもある）が大きいと想定され、かつ構造
が簡単な物質について光双安定性の研究を行った結果、
ＨｇＩ２．ＰｂＩ２あるいはＧ　ａ　Ｓ　ｅの薄膜結晶
で構成されたエタロンが安定な光双安定性を有すること
を見出した。これらの物質の結晶構造は層状構造で、層
間が弱いｌ／ａｎｄｅｒ　Ｗａａｌ、ｓ力で結合してい
る。このような物質は物理学的考察から励起子の結合エ
ネルギーが大きいと判断した。またこのような物質の薄
膜結晶の蒸着法などの簡単な方法で製作でき、かつ基板
の結晶性にもよらないことがわかった。As a result of research on optical bistability of materials that are assumed to have a large exciton binding energy (sometimes called binding energy) and have a simple structure, the present inventor found that
HgI2. We have found that an etalon composed of thin film crystals of PbI2 or GaSe has stable optical bistability. The crystal structure of these materials is a layered structure, and the layers are bonded by weak l/under Waal and s forces. From physical considerations, it was determined that such materials have a large exciton binding energy. It has also been found that it can be manufactured by a simple method such as a thin film crystal vapor deposition method of such a substance, and that it does not depend on the crystallinity of the substrate.

さらにこの薄膜結晶は基板面の垂直な方向がＣ軸となる
ように成長、形成されるので極めて使い易い光双安定素
子ができる。Furthermore, since this thin film crystal is grown and formed so that the C-axis is perpendicular to the substrate surface, an extremely easy-to-use optical bistable device can be produced.

第４図に本発明の光双安定素子の構造を示す。FIG. 4 shows the structure of the optical bistable device of the present invention.

基板１は光双安定素子の動作に必要な波長の光を透過す
る物質で、−例としてガラスがある。The substrate 1 is a material that transmits light of a wavelength necessary for the operation of the optical bistable device, for example glass.

基板１の上にＨｇＩ、、ＰｂＩ２．Ｇａ５５などの励起
子の結合エネルギーの大きい物質（以下励起子物質と記
す）の薄膜結晶１２を形成する。HgI, PbI2 . A thin film crystal 12 of a material such as Ga55 having a large exciton binding energy (hereinafter referred to as exciton material) is formed.

第５図に示すように薄膜結晶１２のＣ軸２２は基板１の
面と垂直になり、この方向に光を入射した時に光双安定
特性が得られた。すなわち第６図に示すように光双安定
素子２１にほぼ垂直に入射光３を入射すると入射光３と
出射光４の間に第３図に示した光双安定特性が得られた
。As shown in FIG. 5, the C-axis 22 of the thin film crystal 12 was perpendicular to the surface of the substrate 1, and optical bistable characteristics were obtained when light was incident in this direction. That is, as shown in FIG. 6, when the incident light 3 was made almost perpendicularly incident on the optical bistable element 21, the optical bistable characteristic shown in FIG. 3 was obtained between the incident light 3 and the output light 4.

第７図に示すように励起子物質の薄膜結晶１２の両面に
反射率の大きい物質の薄膜５を付着すると、より少ない
光量で光双安定特性が実現した。As shown in FIG. 7, when a thin film 5 of a substance with a high reflectance was attached to both sides of a thin film crystal 12 of an exciton substance, optical bistable characteristics were realized with a smaller amount of light.

〔発明の実施例〕[Embodiments of the invention]

以下、本発明の一実施例を第８図により説明する。 An embodiment of the present invention will be described below with reference to FIG.

純度９９．９９９％のＨｇＩ、を真空蒸着装置のボート
に入れ、ボートを８００℃に加熱してシリカガラス基板
１１上に薄膜結晶１２を形成し、光双安定素子を製作し
た。薄膜結晶１２の厚さは２．６５μｍとした。この薄
膜結晶に基板１１側から波長５３０ｎｍのレーザ光（Ｎ
、光励起色素レーザ光）をスポット径５μｍで入射した
。次に入射光の強度と出射光の関係を室温（２０℃）に
て測定したところ、第９図のように双安定特性を示した
。HgI with a purity of 99.999% was placed in a boat of a vacuum evaporation apparatus, and the boat was heated to 800° C. to form a thin film crystal 12 on a silica glass substrate 11 to produce an optical bistable device. The thickness of the thin film crystal 12 was 2.65 μm. A laser beam with a wavelength of 530 nm (N
, photoexcited dye laser beam) was incident with a spot diameter of 5 μm. Next, when the relationship between the intensity of the incident light and the emitted light was measured at room temperature (20° C.), bistable characteristics were shown as shown in FIG. 9.

ＨｇＩ２の代りに、ＰｂＩ２またはＧａＳｅの薄膜結晶
を形成させた素子によっても同様の光双安定特性が示さ
れた。Similar optical bistability characteristics were also exhibited by devices in which thin film crystals of PbI2 or GaSe were formed instead of HgI2.

〔発明の効果〕〔Effect of the invention〕

本発明によれば、構造が極めて簡単で製造が容易な、か
つ室温で動作する光双安定素子が製作できるので、実用
的効果が大きい。According to the present invention, it is possible to manufacture an optical bistable device that has an extremely simple structure, is easy to manufacture, and operates at room temperature, so it has great practical effects.

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

第１図はエタロンの構成図、第２図は光双安定特性を説
明する図、第３図は光双安定特性の屋形図、第４図は本
発明の構成図、第５図は薄膜結晶のＣ軸を示す図、第６
図は入射光および出射光を示す図、第７図は本発明の一
実施態様図、第８図は実施例を説明する図、第９図は実
施例の光双安定特性を示す図、である。１・・・基板、２・・・エタロン、３・・・入射光、３
′・・・反射光、４・・・出射光、５・・・反射膜、６
・・・ボート、７・・・ボート支持電極、８・・・電源
、１１・・・シリカガラス基板、１２・・・励起子物質
の薄膜結晶、２１・・・光第　１　図第２　図第３０入射光量％ｇ　　図警　９　図人力光グ煮麿（π１）Figure 1 is a block diagram of the etalon, Figure 2 is a diagram explaining optical bistable characteristics, Figure 3 is a house diagram of optical bistable characteristics, Figure 4 is a block diagram of the present invention, and Figure 5 is a thin film crystal. Diagram showing the C axis of , No. 6
7 is a diagram showing an embodiment of the present invention, FIG. 8 is a diagram explaining an embodiment, and FIG. 9 is a diagram showing optical bistability characteristics of the embodiment. be. 1... Substrate, 2... Etalon, 3... Incident light, 3
′... Reflected light, 4... Emitted light, 5... Reflective film, 6
. . . Boat, 7. Boat supporting electrode, 8. Power source, 11. Silica glass substrate, 12. Thin film crystal of exciton material, 21. Light. 30 Incident light amount %g Figure 9 Figure Jinrikikogu Nimaro (π1)

Claims

【特許請求の範囲】１、励起子吸収をするＨｇＩ＿２、ＰｂＩ＿２あるいは
ＧａＳｅのうちのいずれかをその励起子吸収波長を透過
する基板上に膜厚が前記励起子吸収波長のほぼ整数倍と
なるように膜形成をしたことを特徴とする光双安定素子
。２、上記基板をガラスとすることを特徴とする特許請求
の範囲第１項記載の光双安定素子。３、上記膜形成を蒸着法によつて行うことを特徴とする
特許請求の範囲第１項記載の光双安定素子。[Claims] 1. Either HgI_2, PbI_2 or GaSe, which absorbs excitons, is deposited on a substrate that transmits the exciton absorption wavelength so that the film thickness is approximately an integral multiple of the exciton absorption wavelength. An optical bistable device characterized by having a film formed on it. 2. The optical bistable device according to claim 1, wherein the substrate is made of glass. 3. The optical bistable device according to claim 1, wherein the film formation is performed by a vapor deposition method.