JP2010060986A - Optical element - Google Patents

Optical element Download PDF

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JP2010060986A
JP2010060986A JP2008228142A JP2008228142A JP2010060986A JP 2010060986 A JP2010060986 A JP 2010060986A JP 2008228142 A JP2008228142 A JP 2008228142A JP 2008228142 A JP2008228142 A JP 2008228142A JP 2010060986 A JP2010060986 A JP 2010060986A
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light
interference
optical element
phase
destructive
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JP4544542B2 (en
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Katsuhito Mure
勝仁 牟禮
Masahide Miyaji
正英 宮地
Tokuichi Miyazaki
徳一 宮崎
Toshio Kataoka
利夫 片岡
Kaoru Hikuma
薫 日隈
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Sumitomo Osaka Cement Co Ltd
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Sumitomo Osaka Cement Co Ltd
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    • 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
    • G02F2/00—Demodulating light; Transferring the modulation of modulated light; Frequency-changing of light
    • 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 
    • G02F1/0121—Operation of devices; Circuit arrangements, not otherwise provided for in this subclass
    • G02F1/0123—Circuits for the control or stabilisation of the bias voltage, e.g. automatic bias control [ABC] feedback loops
    • 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 
    • G02F1/21—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  by interference
    • G02F1/225—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  by interference in an optical waveguide structure

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  • Physics & Mathematics (AREA)
  • Nonlinear Science (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Optical Communication System (AREA)
  • Optical Modulation, Optical Deflection, Nonlinear Optics, Optical Demodulation, Optical Logic Elements (AREA)

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical element which more accurately controls a relative delay of a 1-bit delay interferometer. <P>SOLUTION: The optical element includes: a 1-bit delay interferometer 1; branching means 5 and 6 for branching a portion of constructive light b and a portion of destructive light c, which are interference light outputted from the 1-bit delay interferometer; a second interfering means 7 which causes interference between branched light of the constructive light and branched light of the destructive light, which are branched by the branching means; and a light detection means 8 which detects the intensity of output light from the second interfering means. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

本発明は、光素子に関し、特に、１ビット遅延干渉計内の相対的遅延を検出する光素子に関する。   The present invention relates to optical elements, and more particularly to an optical element that detects relative delay in a 1-bit delay interferometer.

従来、光通信分野において、大量のデータを長距離伝送するため、差動位相偏移変調方式（ＤＰＳＫ，Differential Phase Shift Keying）や差動四相位相偏移変調方式（ＤＱＰＳＫ，Differential Quadrature Phase Shift keying）が利用されている。   Conventionally, in the field of optical communication, in order to transmit a large amount of data over a long distance, differential phase shift keying (DPSK) or differential quadrature phase shift keying (DQPSK) ) Is used.

これらＤＰＳＫやＤＱＰＳＫの位相変調光から元データを復調するのに、１ビット遅延干渉計が利用されている。１ビット遅延干渉計では、特許文献１に示すように、位相変調光を２つの信号光に分け、両者間に１ビット分の遅延を発生させた後、２つの信号光を合波するものであり、この合波を光カプラーの構成を採用することで、相補的関係となる干渉光（コンストラクティブ光とディストラクティブ光）とが出射される。干渉光のいずれか一方を受光素子に入射したり、両者を、デュアルバランス型の受光素子に入射することで、電気信号として送信データが復調される。
特開昭６３−５２５３０号公報 A 1-bit delay interferometer is used to demodulate the original data from the DPSK and DQPSK phase-modulated light. As shown in Patent Document 1, the 1-bit delay interferometer divides the phase-modulated light into two signal lights, generates a delay of 1 bit between them, and then combines the two signal lights. In addition, by adopting an optical coupler configuration for this multiplexing, interference light (constructive light and destructive light) having a complementary relationship is emitted. Transmission data is demodulated as an electrical signal by either one of the interference light entering the light receiving element or both entering the dual balance type light receiving element.
JP-A-63-52530

ＤＰＳＫやＤＱＰＳＫの位相変調光を精度良く受信するには、１ビット遅延干渉計において相対的遅延量を正確に制御することが必要となる。従来の相対的遅延の制御方法としては、特許文献２に示すように、受光素子の検出信号から干渉光の平均光強度を測定し、この値を基に１ビット遅延干渉計の相対的遅延量を制御している。
特開２００５−８０３０４号公報 In order to receive DPSK or DQPSK phase-modulated light with high accuracy, it is necessary to accurately control the relative delay amount in a 1-bit delay interferometer. As a conventional relative delay control method, as shown in Patent Document 2, the average light intensity of the interference light is measured from the detection signal of the light receiving element, and the relative delay amount of the 1-bit delay interferometer is based on this value. Is controlling.
JP 2005-80304 A

しかしながら、平均光強度は、データ信号のマーク率（１，０信号の発生頻度）の影響を受けるため、これを基に１ビット遅延干渉計の相対的遅延を制御することは適当ではない。また、受光信号の高周波成分をモニターすることによって、そのパワーの大小からバイアスを制御する方法もあるが、その場合受光素子も含め高価な部品を使う必要があり、システムのコストが大幅に増大するため現実的ではない。さらに、受光素子の出力信号の一部を電気回路的に分岐して利用する場合には、分岐した影響による所望の信号の劣化の問題も生じる。   However, since the average light intensity is affected by the mark rate of the data signal (frequency of occurrence of 1, 0 signal), it is not appropriate to control the relative delay of the 1-bit delay interferometer based on this. In addition, there is a method of controlling the bias from the magnitude of the power by monitoring the high frequency component of the light receiving signal, but in that case, it is necessary to use expensive parts including the light receiving element, which greatly increases the cost of the system. Therefore it is not realistic. Further, when a part of the output signal of the light receiving element is used after being branched in an electric circuit, there arises a problem of degradation of a desired signal due to the branched effect.

本発明が解決しようとする課題は、上述したような問題を解決し、１ビット遅延干渉計の相対的遅延をより正確に制御可能な光素子を提供することである。   The problem to be solved by the present invention is to solve the above-mentioned problems and to provide an optical element that can control the relative delay of a 1-bit delay interferometer more accurately.

請求項１に係る発明は、１ビット遅延干渉計と、該１ビット遅延干渉計から出力される干渉光であるコンストラクティブ光とディストラクティブ光について、各々その一部を分岐する分岐手段と、該分岐手段で分岐されたコンストラクティブ光及びディストラクティブ光に係る各分岐光を干渉させる第２干渉手段と、該第２干渉手段の出力光の強度を検出する光検出手段とを有することを特徴とする光素子である。   The invention according to claim 1 is a 1-bit delay interferometer, branching means for branching a part of each of the constructive light and the destructive light that are interference lights output from the 1-bit delay interferometer, Characterized in that it has second interference means for causing the respective branched lights related to the constructive light and the destructive light branched by the branch means to interfere, and a light detection means for detecting the intensity of the output light of the second interference means. It is an optical element.

請求項２に係る発明は、請求項１に記載の光素子において、該光検出手段の検出信号に基づき、該１ビット遅延干渉計の相対的遅延を制御する制御手段を有すること特徴とする。   The invention according to claim 2 is characterized in that the optical element according to claim 1 further comprises control means for controlling the relative delay of the 1-bit delay interferometer based on the detection signal of the light detection means.

請求項３に係る発明は、請求項２に記載の光素子において、該制御手段は、該第２干渉手段の出力光の強度が最大もしくは最小となるように、該相対的遅延を制御することを特徴とする。   The invention according to claim 3 is the optical element according to claim 2, wherein the control means controls the relative delay so that the intensity of the output light of the second interference means becomes maximum or minimum. It is characterized by.

請求項４に係る発明は、請求項１乃至３のいずれかに記載の光素子において、コンストラクティブ光又はディストラクティブ光の少なくとも一方の分岐光について、該分岐手段から該第２干渉手段との間に分岐光の位相を調整する位相調整手段が配置されていることを特徴とする。   According to a fourth aspect of the present invention, in the optical element according to any one of the first to third aspects, between at least one of the constructive light and the destructive light between the branch means and the second interference means. And a phase adjusting means for adjusting the phase of the branched light.

請求項５に係る発明は、請求項４に記載の光素子において、該位相調整手段は位相変調器を備え、該位相変調器に低周波信号を入力し、該低周波信号に応じた位相変調された分岐光を、該第２干渉手段に導入し、該第２干渉手段の出力光の強度を検出する光検出手段と、該光検出手段の検出信号のうち、該低周波信号の周波数の整数倍の成分のみ抽出し、抽出した信号成分の大きさが最小もしくは最大となるように該１ビット遅延干渉計の相対的遅延を制御する制御手段を有すること特徴とする。   According to a fifth aspect of the present invention, in the optical element according to the fourth aspect, the phase adjusting means includes a phase modulator, and a low frequency signal is input to the phase modulator, and the phase modulation according to the low frequency signal is performed. The branched light is introduced into the second interference means, the light detection means for detecting the intensity of the output light of the second interference means, and the frequency of the low frequency signal among the detection signals of the light detection means Control means for extracting only the integral multiple components and controlling the relative delay of the 1-bit delay interferometer so that the size of the extracted signal component is minimized or maximized.

請求項６に係る発明は、請求項１乃至５のいずれかに記載の光素子において、コンストラクティブ光及びディストラクティブ光に係る各分岐手段と、該第２干渉手段とは同一基板上に形成されていることを特徴とする。   According to a sixth aspect of the present invention, in the optical device according to any one of the first to fifth aspects, each branching unit related to the constructive light and the destructive light and the second interference unit are formed on the same substrate. It is characterized by.

請求項１に係る発明により、１ビット遅延干渉計から出力される干渉光であるコンストラクティブ光とディストラクティブ光とを合成する光波である、第２干渉手段から得られる出力光を用いるため、信号光に含まれる信号データの影響を受けない出力光を得ることができ、データ信号のマーク率に左右されずより正確な相対的遅延量を把握することが可能となる。   According to the first aspect of the present invention, in order to use the output light obtained from the second interference means, which is a light wave that combines the constructive light and the destructive light that are the interference light output from the 1-bit delay interferometer, Output light that is not affected by the signal data included in the light can be obtained, and a more accurate relative delay amount can be grasped regardless of the mark rate of the data signal.

請求項２に係る発明により、光検出手段の検出信号に基づき、１ビット遅延干渉計の相対的遅延を制御する制御手段を有するため、データ信号のマーク率などの影響を受けずより正確な相対的遅延の制御が可能となる。   According to the second aspect of the present invention, since the control means for controlling the relative delay of the 1-bit delay interferometer based on the detection signal of the light detection means is provided, more accurate relative detection is not affected by the mark rate of the data signal. It is possible to control the delay.

請求項３に係る発明により、制御手段は、第２干渉手段の出力光の強度が最大もしくは最小となるように、相対的遅延を制御するため、相対的遅延を１ビット分により正確に調整することが可能となる。   According to the invention of claim 3, the control means controls the relative delay so that the intensity of the output light of the second interference means is maximized or minimized, and thus adjusts the relative delay more accurately by one bit. It becomes possible.

請求項４に係る発明により、コンストラクティブ光又はディストラクティブ光の少なくとも一方の分岐光について、分岐手段から第２干渉手段との間に分岐光の位相を調整する位相調整手段が配置されているため、コンストラクティブ光とディストラクティブ光との相対的な位相差を適正な状態に調整できる。特に、ファイバーなどで干渉計を構成する場合には、外乱の影響を受けやすく、このような位相差の調整が必要となる。   According to the invention of claim 4, the phase adjusting means for adjusting the phase of the branched light is arranged between the branching means and the second interference means for at least one of the constructive light and the destructive light. The relative phase difference between the constructive light and the destructive light can be adjusted to an appropriate state. In particular, when an interferometer is configured with a fiber or the like, it is easily affected by disturbance, and such a phase difference adjustment is necessary.

請求項５に係る発明により、位相調整手段は位相変調器を備え、該位相変調器に低周波信号を入力し、該低周波信号に応じた位相変調された分岐光を、第２干渉手段に導入し、該第２干渉手段の出力光の強度を検出する光検出手段と、該光検出手段の検出信号のうち、該低周波信号の周波数の整数倍の成分のみ抽出し、抽出した信号成分の大きさが最小もしくは最大となるように１ビット遅延干渉計の相対的遅延を制御する制御手段を有するため、１ビット遅延干渉計の位相差を最適に制御することが可能となる。しかも、低周波信号に応じた位相変調を受ける光波が分岐光であるため、コンストラクティブ光やディストラクティブ光などの信号光に影響を及ぼすこともない。   According to the invention of claim 5, the phase adjusting means includes a phase modulator, a low frequency signal is input to the phase modulator, and the phase-modulated branched light corresponding to the low frequency signal is supplied to the second interference means. A light detecting means for detecting the intensity of the output light of the second interference means, and extracting only a component that is an integral multiple of the frequency of the low frequency signal from the detection signal of the light detecting means; Since the control means for controlling the relative delay of the 1-bit delay interferometer so that the size of the 1-bit delay interferometer is minimized or maximized, the phase difference of the 1-bit delay interferometer can be optimally controlled. In addition, since the light wave that undergoes phase modulation according to the low-frequency signal is branched light, it does not affect signal light such as constructive light or destructive light.

請求項６に係る発明により、コンストラクティブ光及びディストラクティブ光に係る各分岐手段と、第２干渉手段とは同一基板上に形成されているため、コンストラクティブ光やディストラクティブ光に係る光路を、より正確に設定することが可能となると共に、部品点数の削減並びに組み立てや光学調整などの製造工程の簡略化などが可能となる。さらに、１ビット遅延干渉計も同一基板上に形成することで、より一層の改善を図ることも可能となる。   According to the invention of claim 6, since each branching unit related to the constructive light and the destructive light and the second interference unit are formed on the same substrate, the optical path related to the constructive light and the destructive light is It is possible to set more accurately, and it is possible to reduce the number of parts and simplify the manufacturing process such as assembly and optical adjustment. Further, by forming the 1-bit delay interferometer on the same substrate, further improvement can be achieved.

以下、本発明を好適例を用いて詳細に説明する。
本発明は、図１に示すように、１ビット遅延干渉計１と、該１ビット遅延干渉計から出力される干渉光であるコンストラクティブ光ｂとディストラクティブ光ｃについて、各々その一部を分岐する分岐手段５，６と、該分岐手段で分岐されたコンストラクティブ光及びディストラクティブ光に係る各分岐光を干渉させる第２干渉手段７と、該第２干渉手段の出力光の強度を検出する光検出手段８とを有することを特徴とする光素子である。なお、光素子から出射されるコンストラクティブ光Ｂとディストラクティブ光Ｃは、デュアルバランス型の受光素子９，１０に入射することで、電気信号として出力される。 Hereinafter, the present invention will be described in detail using preferred examples.
As shown in FIG. 1, the present invention branches a part of a 1-bit delay interferometer 1 and a constructive light b and a destructive light c that are interference lights output from the 1-bit delay interferometer. Branching means 5 and 6 for detecting, the second interference means 7 for causing the respective branched lights related to the constructive light and the destructive light branched by the branching means to interfere, and the intensity of the output light of the second interference means are detected. An optical element having a light detection means 8. Note that the constructive light B and the destructive light C emitted from the optical element are incident on the dual-balanced light receiving elements 9 and 10 and are output as electrical signals.

図１に示すような１ビット遅延干渉計１から出力されるコンストラクティブ光ｂとディストラクティブ光ｃとは、互いに相補的な関係にあり、両者を合成することにより、データ信号に影響されない、常に一定の光波を得ることが可能となる。従って、１ビット遅延干渉計１内でコンストラクティブ光及びディストラクティブ光とが発生する箇所から、第２干渉手段のコンストラクティブ光とディストラクティブ光とを合波する地点までの光学的距離を、両者で同じとなるように設定することが不可欠となる。   The constructive light b and the destructive light c output from the 1-bit delay interferometer 1 as shown in FIG. 1 are in a complementary relationship with each other, and are not affected by the data signal by combining them. A constant light wave can be obtained. Therefore, the optical distance from the place where the constructive light and the destructive light are generated in the 1-bit delay interferometer 1 to the point where the constructive light and the destructive light of the second interference means are combined is determined by It is indispensable to set it to be the same.

本発明の光素子では、さらに、光検出手段８により検出した信号を利用し、１ビット遅延干渉計の相対的遅延に係る制御を行っている。
１ビット遅延干渉計は、図１に示すように、光導波路２と遅延導波路３から構成される。例えば、図１においては、光導波路２と遅延導波路３とが２箇所で光カプラーを形成し、入射する変調光Ａに対し、最初の光カプラー形成位置で、変調光が光導波路Ａと遅延導波路３とに分けられ、次の光カプラー形成位置で両者を伝搬する光波が合成される。遅延導波路３では、光導波路２を伝搬する光はより１ビット分の相対的遅延量を確保するため、遅延導波路３の光路長が設定されている。１ビット遅延干渉計は図１のものに限定されず、例えば、特許文献１に示されるような、ビームスプリッターや光カプラー等を用いる空間光学系による構成もある。 In the optical element of the present invention, control related to the relative delay of the 1-bit delay interferometer is further performed using the signal detected by the light detection means 8.
The 1-bit delay interferometer includes an optical waveguide 2 and a delay waveguide 3 as shown in FIG. For example, in FIG. 1, the optical waveguide 2 and the delay waveguide 3 form an optical coupler at two locations, and the modulated light is delayed with respect to the optical waveguide A at the first optical coupler formation position with respect to the incident modulated light A. The light wave which is divided into the waveguide 3 and propagates at the next optical coupler formation position is synthesized. In the delay waveguide 3, the optical path length of the delay waveguide 3 is set so that the light propagating through the optical waveguide 2 can secure a relative delay amount of 1 bit. The 1-bit delay interferometer is not limited to the one shown in FIG.

光導波路２又は遅延導波路３のいずれか一方には、光路長を調整するための遅延量調整手段４が設けられている。遅延量調整手段４としては、種々の位相シフターが利用可能であるが、例えば、１ビット遅延干渉計が電気光学効果を有する基板で形成される場合には、光導波路に沿った電極で構成される位相変調器とすることも可能である。また、特許文献３に示されるように、平面光導波路部（ＰＬＣ部）に加える温度を制御することにより光導波路の光路長を変化させるものなども利用可能である。
特開２００４−２３５３７号公報 Either one of the optical waveguide 2 and the delay waveguide 3 is provided with delay amount adjusting means 4 for adjusting the optical path length. As the delay amount adjusting means 4, various phase shifters can be used. For example, when the 1-bit delay interferometer is formed of a substrate having an electro-optic effect, the delay amount adjusting means 4 is composed of electrodes along the optical waveguide. It is also possible to use a phase modulator. Moreover, as shown in Patent Document 3, it is possible to use a device that changes the optical path length of the optical waveguide by controlling the temperature applied to the planar optical waveguide portion (PLC portion).
JP 2004-23537 A

相対的遅延の制御は、制御手段１１によって実行され、具体的には、光検出手段８が受光する第２干渉手段７の出力光の光強度が最大となるように、前記の遅延量調整手段４を制御する。つまり、１ビット遅延干渉計の相対的遅延量が正確に１ビット分を維持している場合には、コンストラクティブ光ｂとディストラクティブ光ｃとの合成光は常に最大輝度となっているはずである。そして、この状態は、第２干渉手段の出力光を検出することで、容易に確認することができる。なお、コンストラクティブ光とディストラクティブ光とが合成した際に合成光が消光するよう作用する場合には、合成光が最小となるように、１ビット遅延干渉計の遅延量調整手段を制御することとなる。   The control of the relative delay is executed by the control means 11, specifically, the delay amount adjusting means described above so that the light intensity of the output light of the second interference means 7 received by the light detecting means 8 is maximized. 4 is controlled. That is, when the relative delay amount of the 1-bit delay interferometer accurately maintains 1 bit, the combined light of the constructive light b and the destructive light c should always have the maximum luminance. is there. This state can be easily confirmed by detecting the output light of the second interference means. When the combined light and the destructive light are combined so that the combined light is extinguished, the delay amount adjusting means of the 1-bit delay interferometer is controlled so that the combined light is minimized. It becomes.

次に、図２に示すように、コンストラクティブ光又はディストラクティブ光の少なくとも一方の分岐光について、分岐手段５，６から第２干渉手段７との間に分岐光の位相を調整する位相調整手段３０が配置されている実施例について説明する。   Next, as shown in FIG. 2, phase adjusting means for adjusting the phase of the branched light between the branching means 5 and 6 and the second interference means 7 with respect to at least one of the constructive light and the destructive light. An embodiment in which 30 is arranged will be described.

位相調整手段３０は、上述したように、１ビット遅延干渉計１内でコンストラクティブ光及びディストラクティブ光とが発生する箇所から、第２干渉手段のコンストラクティブ光とディストラクティブ光とを合波する地点までの光学的距離を、両者で同じとなるように調整する役割を担うことが可能である。   As described above, the phase adjustment unit 30 multiplexes the constructive light and the destructive light of the second interference unit from the place where the constructive light and the destructive light are generated in the 1-bit delay interferometer 1. It is possible to play a role of adjusting the optical distance to the point so that both are the same.

また、位相調整手段３０の他の役割としては、１ビット遅延干渉計の位相差を最適に制御するために利用される。具体的には、位相調整手段に位相変調器を組み込み、該位相変調器に低周波信号であるディザー信号を印加する。該ディザー信号に応じて位相変調された分岐光を、第２干渉手段に導入し、該第２干渉手段の出力光の強度を光検出手段で検出する。該光検出手段の検出信号のうち、該ディザー信号（低周波信号）の周波数の整数倍の成分のみ抽出・モニターし、抽出した信号成分の大きさが最小もしくは最大となるように、制御手段１１で１ビット遅延干渉計の相対的遅延を制御する。これにより、１ビット遅延干渉計の位相差を、外乱の影響に関係なく最適に制御することが可能となる。また、低周波信号に応じた位相変調を受ける光波が分岐光であるため、コンストラクティブ光やディストラクティブ光などの信号光の劣化も発生しない。   Another role of the phase adjusting unit 30 is used to optimally control the phase difference of the 1-bit delay interferometer. Specifically, a phase modulator is incorporated in the phase adjusting means, and a dither signal which is a low frequency signal is applied to the phase modulator. The branched light phase-modulated according to the dither signal is introduced into the second interference means, and the intensity of the output light from the second interference means is detected by the light detection means. Of the detection signal of the light detection means, only the component that is an integral multiple of the frequency of the dither signal (low frequency signal) is extracted and monitored, and the control means 11 is set so that the magnitude of the extracted signal component is minimized or maximized. To control the relative delay of the 1-bit delay interferometer. This makes it possible to optimally control the phase difference of the 1-bit delay interferometer regardless of the influence of disturbance. In addition, since the light wave that undergoes phase modulation according to the low-frequency signal is a branched light, signal light such as constructive light and destructive light does not deteriorate.

位相変調手段としては、遅延量調整手段４と同様に位相を変化させるものであるなら、種々の手段が採用可能であるが、図２に示すように、光導波路２３を電気光学効果を有する基板上に形成する場合には、光導波路２３に沿った電極から構成される位相変調器などが好適に利用でき、しかも、上述のようなディザー信号を位相変調器に印加することで、ディザー信号に対応した位相変調を容易に得ることもできる。   As the phase modulation means, various means can be adopted as long as it changes the phase in the same manner as the delay amount adjustment means 4, but as shown in FIG. 2, the optical waveguide 23 is a substrate having an electro-optic effect. In the case of forming on the top, a phase modulator composed of electrodes along the optical waveguide 23 can be suitably used, and by applying the dither signal as described above to the phase modulator, Corresponding phase modulation can be easily obtained.

本発明の光素子の特徴である、図１に示す分岐手段５，６や第２干渉手段７を含む光学系は、ビームスプリッターや光ファイバーを利用した光カプラーなどを利用して、空間光学系として構成することが可能である。例えば、分岐手段５，６や第２干渉手段７として光カプラーを利用し、１ビット遅延干渉計や該光カプラーを光ファイバーで接続することにより、図１に示す光学系を簡単に構成できる。   The optical system including the branching means 5 and 6 and the second interference means 7 shown in FIG. 1, which is a feature of the optical element of the present invention, is a spatial optical system using a beam splitter or an optical coupler using an optical fiber. It is possible to configure. For example, the optical system shown in FIG. 1 can be easily configured by using an optical coupler as the branching means 5 and 6 and the second interference means 7 and connecting the 1-bit delay interferometer and the optical coupler with an optical fiber.

他方、図２に示すように、分岐手段５，６と第２干渉手段７とを同一基板２０上に形成することも可能である。このような基板としては、光導波路素子で多用されている、例えば、ニオブ酸リチウム、タンタル酸リチウム、ＰＬＺＴ（ジルコン酸チタン酸鉛ランタン）、及び石英系の材料などの電気光学的効果を有する基板を利用することが可能である。光導波路のみを形成する場合には、特に電気光学効果を有する材料を利用する必要はないが、位相調整手段３０として位相変調器を利用する場合には、電気光学効果を有する材料が好ましい。また、基板上の光導波路は、Ｔｉなどを熱拡散法やプロトン交換法などで基板表面に拡散させることにより形成することができる。さらに、位相変調器を構成する変調電極や接地電極などは、Ｔｉ・Ａｕの電極パターンの形成及び金メッキ方法などにより形成することが可能である。さらに、必要に応じて光導波路形成後の基板表面に誘電体ＳｉＯ２等のバッファ層を設け、電極による光波の吸収や散乱を抑制することも可能である。 On the other hand, as shown in FIG. 2, the branching means 5 and 6 and the second interference means 7 can be formed on the same substrate 20. As such a substrate, a substrate having an electro-optical effect such as lithium niobate, lithium tantalate, PLZT (lead lanthanum zirconate titanate), and a quartz-based material, which is widely used in optical waveguide elements. Can be used. In the case of forming only the optical waveguide, it is not necessary to use a material having an electro-optic effect. However, when a phase modulator is used as the phase adjusting means 30, a material having an electro-optic effect is preferable. The optical waveguide on the substrate can be formed by diffusing Ti or the like on the substrate surface by a thermal diffusion method or a proton exchange method. Furthermore, the modulation electrode, the ground electrode, and the like constituting the phase modulator can be formed by forming a Ti / Au electrode pattern, a gold plating method, or the like. Furthermore, provided the buffer layer such as the dielectric SiO 2 on the substrate surface after the optical waveguide formed as needed, it is possible to suppress the absorption and scattering of the light wave due to the electrode.

図２において、基板２０上には、コンストラクティブ光が入力される光導波路２１、該光導波路２１を２つの光導波路２２，２３に分岐する分岐手段５、ディストラクティブ光が入力される光導波路２４、該光導波路２４を２つの光導波路２５，２６に分岐する分岐手段６、さらに、２つの分岐導波路２３，２６を合成し一つの光導波路２７とする第２干渉手段７が形成されている。そして、光導波路２２からはコンストラクティブ光Ｂ、光導波路２５からはディストラクティブ光Ｃ、そして、光導波路２７からは第２干渉手段の出力光が、各々出射される。   In FIG. 2, on a substrate 20, an optical waveguide 21 to which constructive light is input, branching means 5 for branching the optical waveguide 21 into two optical waveguides 22 and 23, and an optical waveguide 24 to which destructive light is input. A branching means 6 for branching the optical waveguide 24 into two optical waveguides 25 and 26 and a second interference means 7 for synthesizing the two branching waveguides 23 and 26 into one optical waveguide 27 are formed. . Then, the constructive light B is emitted from the optical waveguide 22, the destructive light C is emitted from the optical waveguide 25, and the output light of the second interference unit is emitted from the optical waveguide 27.

図２に示すように、同一基板上に複数の光学手段を組み込むことで、コンストラクティブ光やディストラクティブ光に係る光路を、より正確に設定することが可能と共に、部品点数の削減並びに製造工程の簡略化などが可能となる。   As shown in FIG. 2, by incorporating a plurality of optical means on the same substrate, it is possible to set the optical path related to constructive light and destructive light more accurately, reduce the number of parts, and reduce the manufacturing process. Simplification is possible.

以上説明したように、本発明によれば、１ビット遅延干渉計の相対的遅延をより正確に制御可能な光素子を提供することが可能となる。   As described above, according to the present invention, it is possible to provide an optical element that can control the relative delay of the 1-bit delay interferometer more accurately.

本発明に係る光素子を説明する概略図である。It is the schematic explaining the optical element which concerns on this invention. 分岐手段及び第２干渉手段を同一基板上に構成する状態を説明する図である。It is a figure explaining the state which comprises a branch means and a 2nd interference means on the same board | substrate.

符号の説明Explanation of symbols

１ １ビット遅延干渉計
４ 遅延量調整手段
５，６ 分岐手段
７ 第２干渉手段
８ 光検出手段
９，１０ 受光素子
１１ 制御手段
３０ 位相調整手段 1 1-bit delay interferometer 4 delay amount adjusting means 5, 6 branching means 7 second interference means 8 light detecting means 9, 10 light receiving element 11 control means 30 phase adjusting means

Claims (6)

１ビット遅延干渉計と、
該１ビット遅延干渉計から出力される干渉光であるコンストラクティブ光とディストラクティブ光について、各々その一部を分岐する分岐手段と、
該分岐手段で分岐されたコンストラクティブ光及びディストラクティブ光に係る各分岐光を干渉させる第２干渉手段と、
該第２干渉手段の出力光の強度を検出する光検出手段とを有することを特徴とする光素子。 A 1-bit delay interferometer;
Branching means for branching a part of each of the constructive light and the destructive light which are interference lights output from the 1-bit delay interferometer;
Second interference means for causing each branched light related to the constructive light and the destructive light branched by the branch means to interfere,
And an optical detection means for detecting the intensity of the output light of the second interference means. 請求項１に記載の光素子において、該光検出手段の検出信号に基づき、該１ビット遅延干渉計の相対的遅延を制御する制御手段を有すること特徴とする光素子。   2. The optical element according to claim 1, further comprising control means for controlling a relative delay of the 1-bit delay interferometer based on a detection signal of the light detection means. 請求項２に記載の光素子において、該制御手段は、該第２干渉手段の出力光の強度が最大もしくは最小となるように、該相対的遅延を制御することを特徴とする光素子。   3. The optical element according to claim 2, wherein the control unit controls the relative delay so that the intensity of the output light of the second interference unit is maximized or minimized. 請求項１乃至３のいずれかに記載の光素子において、コンストラクティブ光又はディストラクティブ光の少なくとも一方の分岐光について、該分岐手段から該第２干渉手段との間に分岐光の位相を調整する位相調整手段が配置されていることを特徴とする光素子。   4. The optical element according to claim 1, wherein the phase of the branched light is adjusted between the branching unit and the second interference unit with respect to at least one branched light of the constructive light or the destructive light. An optical element in which phase adjusting means is arranged. 請求項４に記載の光素子において、該位相調整手段は位相変調器を備え、該位相変調器に低周波信号を入力し、該低周波信号に応じた位相変調された分岐光を、該第２干渉手段に導入し、該第２干渉手段の出力光の強度を検出する光検出手段と、該光検出手段の検出信号のうち、該低周波信号の周波数の整数倍の成分のみ抽出し、抽出した信号成分の大きさが最小もしくは最大となるように該１ビット遅延干渉計の相対的遅延を制御する制御手段を有すること特徴とする光素子。   5. The optical element according to claim 4, wherein the phase adjusting unit includes a phase modulator, and a low frequency signal is input to the phase modulator, and the phase-modulated branched light corresponding to the low frequency signal is supplied to the phase modulator. 2 introducing into the interference means, detecting the intensity of the output light of the second interference means, and extracting only a component of an integral multiple of the frequency of the low frequency signal from the detection signal of the light detection means, An optical element comprising control means for controlling the relative delay of the 1-bit delay interferometer so that the size of the extracted signal component is minimized or maximized. 請求項１乃至５のいずれかに記載の光素子において、コンストラクティブ光及びディストラクティブ光に係る各分岐手段と、該第２干渉手段とは同一基板上に形成されていることを特徴とする光素子。   6. The optical element according to claim 1, wherein each of the branching means relating to the constructive light and the destructive light and the second interference means are formed on the same substrate. element.
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