JP3365004B2 - Light angle modulation-intensity modulation conversion method - Google Patents
Light angle modulation-intensity modulation conversion methodInfo
- Publication number
- JP3365004B2 JP3365004B2 JP25866993A JP25866993A JP3365004B2 JP 3365004 B2 JP3365004 B2 JP 3365004B2 JP 25866993 A JP25866993 A JP 25866993A JP 25866993 A JP25866993 A JP 25866993A JP 3365004 B2 JP3365004 B2 JP 3365004B2
- Authority
- JP
- Japan
- Prior art keywords
- light
- signal
- optical
- angle
- intensity
- 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 - Fee Related
Links
Description
【発明の詳細な説明】
【０００１】
【産業上の利用分野】本発明は、オプトエレクトロニク
ス、光情報処理、光通信等の分野において用いられる光
角度変調−強度変調変換方法に関する。
【０００２】
【従来の技術およびその問題点】光情報処理は、光が有
する高速性、並列性という優れた特性を十分に発揮させ
る次世代の通信、情報処理の基幹になるものとして注目
されている。光通信、光情報処理は一部で実用化され、
盛んに利用されているが、これらのものは光の強度上に
変調信号を乗せるといった方式が取られており、光の高
速性を十分に発揮できないという問題点があった。そこ
で、大容量、超高速に通信及び信号処理を行う為には光
の振動自身、即ち光の周波数や位相を直接変調する角度
変調方式が必要とされる。
【０００３】
【問題点を解決するための手段】本発明の目的は、前記
問題点を解決し、旋光性物質の旋光分散特性と三次以上
の非線形光学効果を組み合わせることにより、簡単な構
造で角度変調された光信号を強度変調された光信号に変
換することができる新規な変換方法を提供することであ
る。本発明は、角度変調された光信号を強度変調された
光信号に変換する方法であって、入射光として、角度変
調された信号光及び信号光とは周波数の異なる参照光を
用い、信号光及び参照光を同一偏光面で旋光分散要素に
入射させて、参照光及び信号光の相互の偏光面間に角度
を生じさせるとともに、信号光の周波数の変化を旋光角
の変化に変換し、次いで、参照光及び信号光を三次以上
の非線形光学効果を有する非線形光学要素に入射させて
信号光の旋光角の変化による非線形光学要素を励起する
角度の変化を、参照光の偏光変化として取り出し、この
参照光の偏光変化を偏光要素によって光強度の変化とし
て出力することを特徴とする光角度変調−強度変調変換
方法に関する。
【０００４】本発明の旋光分散要素としては、旋光分散
性能を有する物質の結晶やポリマー、あるいは旋光分散
性能を有する物質をポリマーや溶液中にドープしたり、
ポリマーの側鎖に導入したものが挙げられる。あるい
は、旋光性を有するポリマーや低分子中に色素等の発色
物質を導入し発色物質に旋光分散性能を誘起したもので
もよい。また、複数の旋光分散性材料をブレンドしたも
のでもよい。
【０００５】旋光分散性能を有する物質としては、分子
自体が旋光分散性能を有するキラル化合物や、結晶化に
より旋光分散性能を示す物質、あるいは、外部の電場、
磁場、あるいは基板のラビング等により旋光分散性能を
示す物質などが挙げられる。例えば、アミノ酸、ポリペ
プチド、酒石酸、ヘリセン、ポリグルタメート、水晶、
コレステリック液晶、ネマチック液晶等が挙げられる。
【０００６】三次以上の非線形光学効果を有する非線形
光学要素としては、三次以上の非線形性を有する物質の
結晶やポリマー、あるいは三次以上の非線形性を有する
物質をポリマーや溶液中にドープしたり、ポリマーの側
鎖に導入したものが挙げられる。もちろん、前記旋光分
散性能を有する物質が三次以上の非線形性を同時に有す
るものでもよい。
【０００７】三次以上の非線形性を有する物質として
は、大きな非局在化π電子系を有するものが挙げられ、
例えば、ＤＡＮＳＥ（４−ジメチルアミノ−４’−ニト
ロスチルベン）、テトラキス（２，４−キシリル）ブタ
トリエン、９，１０−ビス（３，３−ジフェニル−３−
ヒドロキシプロピニル）アントラセン、２−（４−ニト
ロフェニル）−４，５−ジフェニルイミダゾール、２−
（４−ニトロフェニル）−４，５−ビス（４−メトキシ
フェニル）イミダゾール、テトラチオテトラセン、３，
６−ビス（４，５−ジフェニル−２Ｈ−イミダゾール−
２−イリデン）−１，４−シクロヘキサジエン、２−
（チオピラン−４−イリデン）−１，３−ジチオール、
１，１，６，６−テトラフェニル−ヘキサ−１，５−ジ
エン−３イン、３，３’−ジエチルオキサカルボシアニ
ン、３，３’−ジエチルオキサジカルボシアニン等が挙
げられ、また励起子の効果によるＣｕＣｌ、ＣｄＳｅ、
ＺｎＳｅ等や分子配向効果による二硫化炭素やニトロベ
ンゼン等が挙げられる。また、偏光要素としては、例え
ば、複屈折を利用したもの、二色性を利用したもの、反
射を利用したもの等が挙げられる。
【０００８】本発明においては、旋光性の波長分散、即
ち周波数分散と三次以上の非線形光学効果を利用して角
度変調−強度変調変換を行う。入射信号光の周波数、即
ち波長が変化すると旋光角が変化するため、非線形光学
要素を励起する角度が変化し、一緒に照射した参照光の
偏光を変化させ、その結果、偏光要素を透過する参照光
の量が変化する。したがって、角度変調された光信号を
強度変調された光信号に変換することができる。ここ
で、入射信号光の強度は、非線形光学要素の非線形屈折
率変化が高次の効果により飽和する領域、即ちそれ以上
強度を上げても屈折率があまり変化しない領域にあるこ
とが望ましい。
【０００９】
【実施例】以下に、実施例を示して本発明を具体的に説
明する。
実施例１
図１は、本発明における周波数変調された光信号を周波
数の異なる参照光に強度変調信号に変換して乗せる装置
の概略図である。１１は入射信号光であり周波数変調さ
れたレーザー光であって選択反射ミラー１８により参照
光と重なって同一方向に進行する。１２は参照光であっ
て信号光と異なる一定した周波数を持つ。信号光及び参
照光は、偏光子１３によって直線偏光となって旋光分散
要素１４に入射する。１４により偏光面間に角度を生じ
て信号光と参照光が三次非線形光学要素１５を透過する
と、非線形屈折率変化によって参照光が楕円偏光化す
る。参照光は、検光子１６を一部透過した後、バンドパ
スフィルター１７によって信号光を取り除いて出射され
る。
【００１０】ここで、検光子１６は信号光が無いときに
参照光を消光する方位に設定してある。この時、信号光
が周波数変調を受けていない角周波数ω0であって旋光
分散要素１４を出射したときの信号光と参照光の偏光面
間の角度をηとすると、出射される参照光の強度はｓｉ
ｎ２ηの２乗に比例する。ここで信号光が周波数変調を
受けて角周波数がΔωだけ変化した場合、旋光分散要素
１４を透過した信号光は旋光分散によって旋光角が変化
する。この時の旋光角の変化量をΔη0とすると、出射
される参照光の強度はｓｉｎ（２η＋２Δη0）の２乗
に比例した量になる。
【００１１】このように、入射信号光に乗った周波数変
調信号は、波長の異なる参照光の強度変調に変換されて
出射される。この時の信号強度の変化量は近似的に２Δ
η0ｓｉｎ４ηに比例する。以上、周波数変調について
説明したが、位相変調の場合は微分が出力信号の強度変
化に変換されて取り出される。また、旋光分散要素と三
次非線形光学要素は個別のもので説明したが、旋光分散
要素と三次非線形光学要素が一体化した場合でも同様に
変換が可能であることは言うまでもない。
【００１２】
【発明の効果】本発明によれば、簡単な構成により光の
角度変調を強度変調に変換して波長の異なる別の参照光
に乗せることができる。Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical angle modulation-intensity modulation conversion method used in fields such as optoelectronics, optical information processing, and optical communication. 2. Description of the Related Art Optical information processing is attracting attention as a key to the next generation of communication and information processing in which the excellent characteristics of light, such as high speed and parallelism, are fully exhibited. I have. Optical communication and optical information processing have been partially commercialized,
Although they are widely used, these methods employ a method in which a modulation signal is put on the intensity of light, and there is a problem that the high speed of light cannot be sufficiently exhibited. Therefore, in order to perform communication and signal processing at a large capacity and at a very high speed, an angle modulation method for directly modulating the light vibration itself, that is, the frequency and phase of the light is required. SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to provide a simple structure with a simple structure by combining the optical rotatory dispersion characteristic of an optical rotatory substance with a third-order or higher nonlinear optical effect. It is an object of the present invention to provide a novel conversion method capable of converting a modulated optical signal into an intensity-modulated optical signal. The present invention is a method of converting an angle-modulated optical signal into an intensity-modulated optical signal, wherein the angle-modulated signal light and a reference light having a frequency different from that of the signal light are used as incident light, And the reference light is incident on the optical rotation dispersive element with the same polarization plane to generate an angle between the mutual polarization planes of the reference light and the signal light, and converts a change in the frequency of the signal light into a change in the rotation angle, and A change in the angle at which the reference light and the signal light are incident on a nonlinear optical element having a third-order or higher nonlinear optical effect to excite the nonlinear optical element due to a change in the optical rotation angle of the signal light is extracted as a change in the polarization of the reference light. The present invention relates to an optical angle modulation-intensity modulation conversion method, which outputs a change in the polarization of reference light as a change in light intensity using a polarization element. As the optical rotation dispersing element of the present invention, a crystal or polymer of a substance having an optical rotation dispersing property, a substance having an optical rotation dispersing property can be doped into a polymer or a solution,
Those introduced into the side chain of the polymer can be mentioned. Alternatively, a material having a rotatory power such as a pigment or the like introduced into a polymer or a low molecular compound having optical rotatory power to induce optical rotatory dispersion performance may be used. Further, a material obtained by blending a plurality of optical rotation dispersing materials may be used. [0005] The substance having optical rotation dispersion performance includes a chiral compound whose molecule itself has optical rotation dispersion performance, a substance exhibiting optical rotation dispersion performance by crystallization, an external electric field,
Substances that exhibit optical rotation dispersion performance due to a magnetic field, rubbing of a substrate, or the like can be given. For example, amino acids, polypeptides, tartaric acid, helicene, polyglutamate, quartz,
Cholesteric liquid crystals, nematic liquid crystals and the like are mentioned. Examples of the nonlinear optical element having a third-order or higher nonlinear optical effect include a crystal or polymer of a substance having a third-order or higher nonlinearity, doping a polymer or a solution having a third-order or higher nonlinearity into a polymer or a solution, And those introduced into the side chain of Of course, the substance having the optical rotatory dispersion performance may have a third-order or higher nonlinearity at the same time. A substance having a third-order or higher nonlinearity includes a substance having a large delocalized π-electron system.
For example, DANSE (4-dimethylamino-4'-nitrostilbene), tetrakis (2,4-xylyl) butatriene, 9,10-bis (3,3-diphenyl-3-)
(Hydroxypropynyl) anthracene, 2- (4-nitrophenyl) -4,5-diphenylimidazole, 2-
(4-nitrophenyl) -4,5-bis (4-methoxyphenyl) imidazole, tetrathiotetracene, 3,
6-bis (4,5-diphenyl-2H-imidazole-
2-ylidene) -1,4-cyclohexadiene, 2-
(Thiopyran-4-ylidene) -1,3-dithiol,
1,1,6,6-tetraphenyl-hexa-1,5-diene-3-yne, 3,3′-diethyloxacarbocyanine, 3,3′-diethyloxadicarbocyanine and the like. CuCl, CdSe,
Examples include ZnSe and the like, and carbon disulfide and nitrobenzene due to a molecular orientation effect. Examples of the polarizing element include those using birefringence, those using dichroism, those using reflection, and the like. [0008] In the present invention, angle modulation-intensity modulation conversion is performed using optical rotation wavelength dispersion, that is, frequency dispersion and a third-order or higher nonlinear optical effect. When the frequency of the incident signal light, i.e., the wavelength changes, the angle of rotation changes, so that the angle for exciting the nonlinear optical element changes, thereby changing the polarization of the illuminated reference light and consequently the reference transmitted through the polarizing element. The amount of light changes. Therefore, the angle-modulated optical signal can be converted into an intensity-modulated optical signal. Here, the intensity of the incident signal light is desirably in a region where the change in the nonlinear refractive index of the nonlinear optical element is saturated by a higher-order effect, that is, in a region where the refractive index does not change much even if the intensity is further increased. Hereinafter, the present invention will be described in detail with reference to examples. Embodiment 1 FIG. 1 is a schematic diagram of an apparatus according to the present invention for converting a frequency-modulated optical signal into reference light having a different frequency into an intensity-modulated signal and carrying the signal. Numeral 11 denotes an incident signal light, which is a frequency-modulated laser light, which overlaps with the reference light by the selective reflection mirror 18 and travels in the same direction. Reference numeral 12 denotes a reference light having a constant frequency different from that of the signal light. The signal light and the reference light become linearly polarized light by the polarizer 13 and enter the optical rotatory dispersion element 14. When an angle is generated between the polarization planes by 14 and the signal light and the reference light pass through the third-order nonlinear optical element 15, the reference light becomes elliptically polarized due to a change in the nonlinear refractive index. The reference light partially passes through the analyzer 16 and is then emitted after removing the signal light by the bandpass filter 17. Here, the analyzer 16 is set in such a direction that the reference light is extinguished when there is no signal light. At this time, assuming that the angle between the polarization planes of the signal light and the reference light when the signal light has an angular frequency ω 0 not subjected to frequency modulation and exits the optical rotation dispersing element 14 is η, the emitted reference light has Strength is si
It is proportional to the square of n2η. Here, when the signal light undergoes frequency modulation and the angular frequency changes by Δω, the signal light transmitted through the optical rotation dispersing element 14 changes its optical rotation angle due to optical rotation dispersion. Assuming that the amount of change in the optical rotation angle at this time is Δη 0 , the intensity of the emitted reference light is an amount proportional to the square of sin (2η + 2Δη 0 ). As described above, the frequency modulation signal on the incident signal light is converted into intensity modulation of the reference light having different wavelengths and emitted. The amount of change in signal strength at this time is approximately 2Δ
η 0 is proportional to sin4η. The frequency modulation has been described above. In the case of the phase modulation, the derivative is converted into a change in the intensity of the output signal and extracted. Although the optical rotatory dispersion element and the third-order nonlinear optical element have been described separately, it is needless to say that the conversion can be similarly performed even when the optical rotatory dispersion element and the third-order nonlinear optical element are integrated. According to the present invention, it is possible to convert angle modulation of light into intensity modulation with a simple configuration and to carry the reference light having different wavelengths.
【図面の簡単な説明】
【図１】図１は、本発明における周波数変調された光信
号を周波数の異なる参照光に強度変調信号に変換して乗
せる装置の概略図である。
【符号の説明】
１１ 入射信号光
１２ 参照光
１３ 偏光子
１４ 旋光分散要素
１５ 三次非線形光学要素
１６ 検光子
１７ バンドパスフィルター
１８ ミラーBRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of an apparatus for converting a frequency-modulated optical signal into reference light having a different frequency into an intensity-modulated signal according to the present invention and carrying the signal. [Description of Signs] 11 Incident signal light 12 Reference light 13 Polarizer 14 Optical rotation dispersion element 15 Third-order nonlinear optical element 16 Analyzer 17 Bandpass filter 18 Mirror
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 平１−284827（ＪＰ，Ａ) 実開 昭63−128522（ＪＰ，Ｕ) 特表 昭63−500069（ＪＰ，Ａ) 横沢伊裕，他，キラル物質の施光分散 を利用した光カーシャッター，1993年春 季第40回応用物理学関係連合講演会講演 予稿集，1993年 ３月29日，第３分冊, ｐｐ．1156 (58)調査した分野(Int.Cl.7，ＤＢ名) G02F 2/00 G02F 1/35 ＪＩＣＳＴファイル（ＪＯＩＳ)──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A 1-284827 (JP, A) JP-A 63-128522 (JP, U) JP-T-63-500069 (JP, A) Yokozawa Ihiro, et al. , Optical Car Shutter Utilizing Light Dispersion of Chiral Materials, Proceedings of the 40th Joint Lecture Meeting on Applied Physics, Spring 1993, March 29, 1993, Third Volume, pp. 1156 (58) Fields surveyed (Int. Cl. 7 , DB name) G02F 2/00 G02F 1/35 JICST file (JOIS)
Claims (1)
光信号に変換する方法であって、入射光として、角度変
調された信号光及び信号光とは周波数の異なる参照光を
用い、信号光及び参照光を同一偏光面で旋光分散要素に
入射させて、参照光及び信号光の相互の偏光面間に角度
を生じさせるとともに、信号光の周波数の変化を旋光角
の変化に変換し、次いで、参照光及び信号光を三次以上
の非線形光学効果を有する非線形光学要素に入射させて
信号光の旋光角の変化による非線形光学要素を励起する
角度の変化を、参照光の偏光変化として取り出し、この
参照光の偏光変化を偏光要素によって光強度の変化とし
て出力することを特徴とする光角度変調−強度変調変換
方法。(57) [Claim 1] A method for converting an angle-modulated optical signal into an intensity-modulated optical signal.
The tuned signal light and the reference light with a different frequency from the signal light
Used to convert signal light and reference light into optical rotation dispersion elements with the same polarization plane
The angle between the planes of polarization of the reference light and the signal light
And the change in the frequency of the signal light
And then convert the reference light and signal light into third-order or higher
Incident on a nonlinear optical element having a nonlinear optical effect
Excitation of nonlinear optical elements by changing the optical rotation angle of signal light
The change in the angle is extracted as the change in the polarization of the reference light.
The change in polarization of the reference light is defined as the change in light intensity by the polarization element.
Angle modulation-intensity modulation conversion characterized by output
How .
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP25866993A JP3365004B2 (en) | 1993-10-15 | 1993-10-15 | Light angle modulation-intensity modulation conversion method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP25866993A JP3365004B2 (en) | 1993-10-15 | 1993-10-15 | Light angle modulation-intensity modulation conversion method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH07114051A JPH07114051A (en) | 1995-05-02 |
| JP3365004B2 true JP3365004B2 (en) | 2003-01-08 |
Family
ID=17323458
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP25866993A Expired - Fee Related JP3365004B2 (en) | 1993-10-15 | 1993-10-15 | Light angle modulation-intensity modulation conversion method |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3365004B2 (en) |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB8515499D0 (en) * | 1985-06-19 | 1985-07-24 | British Telecomm | Digital information transmission system |
| JPS63128522U (en) * | 1987-02-16 | 1988-08-23 | ||
| JPH01284827A (en) * | 1988-05-12 | 1989-11-16 | Matsushita Electric Ind Co Ltd | Optical modulating element and its manufacture |
-
1993
- 1993-10-15 JP JP25866993A patent/JP3365004B2/en not_active Expired - Fee Related
Non-Patent Citations (1)
| Title |
|---|
| 横沢伊裕，他，キラル物質の施光分散を利用した光カーシャッター，１９９３年春季第４０回応用物理学関係連合講演会講演予稿集，１９９３年 ３月２９日，第３分冊，ｐｐ．１１５６ |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH07114051A (en) | 1995-05-02 |
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