JPH0240635A - Intermediate frequency stabilizing method - Google Patents
Intermediate frequency stabilizing methodInfo
- Publication number
- JPH0240635A JPH0240635A JP63191497A JP19149788A JPH0240635A JP H0240635 A JPH0240635 A JP H0240635A JP 63191497 A JP63191497 A JP 63191497A JP 19149788 A JP19149788 A JP 19149788A JP H0240635 A JPH0240635 A JP H0240635A
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- Prior art keywords
- intermediate frequency
- frequency
- signal
- polarization
- light
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- 238000000034 method Methods 0.000 title claims description 24
- 230000000087 stabilizing effect Effects 0.000 title description 2
- 230000010355 oscillation Effects 0.000 claims abstract description 22
- 230000010287 polarization Effects 0.000 claims description 29
- 230000003287 optical effect Effects 0.000 claims description 28
- 230000006641 stabilisation Effects 0.000 claims description 6
- 238000011105 stabilization Methods 0.000 claims description 6
- 230000003111 delayed effect Effects 0.000 abstract description 3
- 239000002131 composite material Substances 0.000 abstract 2
- 238000001514 detection method Methods 0.000 description 12
- 238000004891 communication Methods 0.000 description 8
- 238000010586 diagram Methods 0.000 description 6
- 230000001427 coherent effect Effects 0.000 description 5
- 230000001360 synchronised effect Effects 0.000 description 5
- 238000001308 synthesis method Methods 0.000 description 5
- 230000035945 sensitivity Effects 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 3
- 230000005540 biological transmission Effects 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- 238000001228 spectrum Methods 0.000 description 2
- 238000003786 synthesis reaction Methods 0.000 description 2
- 230000015556 catabolic process Effects 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000013307 optical fiber Substances 0.000 description 1
- 239000002023 wood Substances 0.000 description 1
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Abstract
Description
【発明の詳細な説明】
（産業上の利用分野）
この発明は光通信システムに用いられる光ヘテロダイン
受信方法における中間周波数安定化方法に関するもので
ある。DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an intermediate frequency stabilization method in an optical heterodyne reception method used in an optical communication system.
（従来の技術）
光ヘテロダイン検波通信（コヒーレント光通信）は、光
の強度を変調する直接検波通信比べ受信感度が高く、ま
た周波数利用効率が高いため、長距離高密度伝送が可能
であるという利点を有する。（斉藤、白木、木材「コヒ
ーレント光ファイバ伝送変調技術−ＦＳＫ光ヘテロダイ
ン検波」電々公社電球実用化報告第３１巻第１２号、１
９８２年）このコヒーレント光通信は、信号光と局部発
振光の合波光を光検出器で受光し、信号光と局部発振光
の周波数差に相当するビートを中間周波数信号として得
、これを復調することによってベースバンド信号を得る
ものである。(Conventional technology) Optical heterodyne detection communication (coherent optical communication) has higher reception sensitivity than direct detection communication, which modulates the intensity of light, and has higher frequency utilization efficiency, so it has the advantage of being capable of long-distance, high-density transmission. has. (Saito, Shiraki, Wood "Coherent optical fiber transmission modulation technology - FSK optical heterodyne detection" Electric Corporation Light Bulb Practical Report Vol. 31 No. 12, 1
982) This coherent optical communication uses a photodetector to receive the combined light of the signal light and the local oscillation light, obtains a beat corresponding to the frequency difference between the signal light and the local oscillation light as an intermediate frequency signal, and demodulates this. By doing this, a baseband signal is obtained.
ところでこの方法では、信号光偏波変動によって信号光
と局部発振光の偏波状態に不一致が生じ、受信感度が劣
化する。また、信号光と局部発振光の周波数変動によっ
て中間周波数が変動し、受信特性が劣化する。従って光
ヘテロダイン検波通信においては、信号光の偏波変動の
補償と中間周波数の安定化が必要である。However, in this method, a mismatch occurs between the polarization states of the signal light and the local oscillation light due to signal light polarization fluctuations, and reception sensitivity deteriorates. Further, the intermediate frequency changes due to frequency fluctuations of the signal light and the local oscillation light, and the reception characteristics deteriorate. Therefore, in optical heterodyne detection communication, it is necessary to compensate for polarization fluctuations of signal light and stabilize the intermediate frequency.
光ヘテロダイン検波通信では、従来この信号光の偏波変
動の補償方法の１つとして、偏波ダイバーシチ光受信方
法が知られている。これは信号光と局部発振光の合波光
を偏波分離部で互いに偏波状態が直交する第１、第２の
合波光に分離し、それぞれ個別の受光器で受光して第１
および第２の中間周波数信号に変換し、この２つの中間
周波数信号を処理部で復調、合成をすることにより、信
号光の偏波状態に依存し５ない安定なベースバンド信号
を得るものである。この処理部における信号の復調、お
よび合成方法として、２つの中間周波数信号の位相を一
致させた上で合成し、その後復調する方法と、２つの中
間周波数信号を個別に復調した後に合成する方法（ベー
スバンド合成方法）とがある。このうち後者のベースバ
ンド合成方法は中間周波数信号の位相を調整する必要が
ないため構成が単純で、受信感度劣化を小さくすること
が可能である為、盛んに研究が行なわれている。例えば
グランス（Ｂ、 Ｇｌａｎｃｅ）はＰＳＫ差動同期検波
によって復調を行うベースバンド合成方法を用いた偏波
ダイバーシチ光受信方法における感度劣化は０．４ｄＢ
であることを理論的に明らかにしている。（グランス（
Ｂ。In optical heterodyne detection communication, a polarization diversity optical reception method is conventionally known as one of the methods of compensating for the polarization fluctuation of signal light. In this method, the combined light of the signal light and the local oscillation light is separated into first and second combined lights whose polarization states are orthogonal to each other in a polarization splitter, and each light is received by an individual receiver.
and a second intermediate frequency signal, and by demodulating and combining these two intermediate frequency signals in a processing section, a stable baseband signal that does not depend on the polarization state of the signal light is obtained. . The signal demodulation and synthesis methods in this processing section include a method in which two intermediate frequency signals are matched in phase and then synthesized, and then demodulated, and a method in which two intermediate frequency signals are individually demodulated and then synthesized ( There is a baseband synthesis method). Among these, the latter baseband synthesis method is being actively researched because it does not require adjusting the phase of the intermediate frequency signal, has a simple configuration, and can reduce reception sensitivity degradation. For example, Glance (B, Glance) has a sensitivity deterioration of 0.4 dB in a polarization diversity optical reception method that uses a baseband synthesis method that performs demodulation using PSK differential synchronous detection.
It is theoretically clarified that (Grance (
B.
Ｇｌａｎｃｅ）、“ポーラリゼーションインデペンデン
トコヒーレントオプティカルレシーバ″
（“Ｐｏ１ａｒｉｚａｔｉｏｎ １ｎｄｅｐｅｎｄｅｎ
ｔ ｃｏｈｅｒｅｎｔ ｏｐｔｉｃａｌｒｅｃｅｉｖｅ
ｒ”′）ジャーナルオブライトウェイブテクノロジー（
Ｊｏｕｒｎａｌ ｏｆ Ｌｉｇｈｔｗａｖｅ Ｔｅｃｈ
ｎｏｌｏｇｙ）第５巻、１９８７年、２７４ページ）
一方、光へテロダイン検波通信のもう１つの課題である
中間周波数安定化方法としては、中間周波数信号を周波
数弁別器に入力し、その出力によって局部発振光源の発
振周波数を制御する方法等が用いられていた。Glance), “Polarization Independent Coherent Optical Receiver” (“Polarization 1ndependent Optical Receiver”)
t coherent optical receive
r”′) Journal of Lightwave Technology (
Journal of Lightwave Tech
On the other hand, as an intermediate frequency stabilization method, which is another issue in optical heterodyne detection communication, the intermediate frequency signal is input to a frequency discriminator, and the output is used to generate a local oscillator. Methods such as controlling the oscillation frequency of the light source were used.
（発明が解決しようとする課題）
しかしながら、ベースバンド合成方法を用いた偏波ダイ
バーシチ光受信方法では中間周波数信号が２系統あり、
それぞれの中間周波数信号の位相、強度は信号光の偏波
状態に従って変動するため、この２つの中間周波数信号
をそのまま加え合せた場合、信号光の偏波状態によって
は２つの中間周波数信号が打消し合ってしまうことがあ
る。従って中間周波数の安定化を行うためには２つの中
間周波数信号を２つの周波数弁別器でそれぞれ周波数弁
別した後、その出力を合成することによって制御信号を
得る必要があり、システム規模が大きくなる等の課題が
あった。(Problem to be solved by the invention) However, in the polarization diversity optical reception method using the baseband synthesis method, there are two systems of intermediate frequency signals.
The phase and intensity of each intermediate frequency signal vary depending on the polarization state of the signal light, so if these two intermediate frequency signals are added together as they are, the two intermediate frequency signals may cancel depending on the polarization state of the signal light. Sometimes they match. Therefore, in order to stabilize the intermediate frequency, it is necessary to frequency-discriminate the two intermediate frequency signals using two frequency discriminators and then synthesize the outputs to obtain a control signal, which increases the system scale, etc. There was a problem.
したがって、本発明の目的はベースバント合成方法を用
いた偏波ダイバーシチ光受信方法において、信号光の偏
波変動に影響されない、構成の簡単な中間周波数安定化
方法を提供することにある。Therefore, an object of the present invention is to provide a simple intermediate frequency stabilization method that is not affected by polarization fluctuations of signal light in a polarization diversity optical reception method using a baseband combining method.
（課題を解決するための手段）
本発明は、光送信部より送信されてきた信号光を偏波分
離部で直交する２つの偏波成分に分離し、この偏波分離
された信号光と局部発振光とのビート成分を２つの光検
出器で検出し得られた２つの中間周波数信号をそれぞれ
復調した後に合成することによって復調信号出力を取り
出す偏波ダイバーシチ光ヘテロダイン受信方法において
、前記２つの中間周波数信号の一部をとりだし、一方の
中間周波数信号を遅延させた後に両者を合成し、この合
成された中間周波数信号の周波数変動を周波数弁別器で
検出し、この周波数弁別器の出力によって局部発振光源
の発振周波数を制御することを特徴とする中間周波数安
定化方法である。(Means for Solving the Problems) The present invention separates a signal light transmitted from an optical transmitter into two orthogonal polarization components in a polarization separation section, and combines this polarization-separated signal light with a local component. In a polarization diversity optical heterodyne reception method in which a demodulated signal output is obtained by detecting a beat component with oscillation light using two photodetectors and demodulating and combining the two obtained intermediate frequency signals, the two intermediate frequency signals are A part of the frequency signal is extracted, one intermediate frequency signal is delayed, and then both are combined.The frequency fluctuation of this combined intermediate frequency signal is detected by a frequency discriminator, and the local oscillator is detected by the output of this frequency discriminator. This is an intermediate frequency stabilization method characterized by controlling the oscillation frequency of a light source.
（作用）
本発明では上記のように２つの中間周波数信号のうち片
方に遅延を与えることによって両者の相関を小さくし、
両者を合成しても互いに打消し合うことがなくなる。し
たがってこの合成された中間周波数信号を用いて周波数
弁別を行ない局部発振光源の発振周波数に帰還をかける
ことにより、信号光の偏波状態に依らず中間周波数安定
化を行うことができる。(Function) In the present invention, as described above, by giving a delay to one of the two intermediate frequency signals, the correlation between the two is reduced,
Even if the two are combined, they will not cancel each other out. Therefore, by performing frequency discrimination using this synthesized intermediate frequency signal and applying feedback to the oscillation frequency of the local oscillation light source, it is possible to stabilize the intermediate frequency regardless of the polarization state of the signal light.
（実施例）
第１図に本発明の第１の実施例の構成図、第２図に本発
明の詳細な説明図を示す。(Embodiment) FIG. 1 shows a configuration diagram of a first embodiment of the present invention, and FIG. 2 shows a detailed explanatory diagram of the present invention.
第１図の実施例は２Ｇｂ／５ＰｓＫ差動同期光ヘテロダ
イン検波受信器に本発明を適用したものである。The embodiment shown in FIG. 1 is an example in which the present invention is applied to a 2Gb/5PsK differential synchronous optical heterodyne detection receiver.
２Ｇｂ／ｓでＰＳＫ変調された信号光１は光合波器２で
局部発振光３と合波された後、偏波分離部４で２つの直
交する偏波成分に分離され、それぞれ光検出器５．６で
受光され、中間周波数信号７．８が出力される。The signal light 1 PSK-modulated at 2 Gb/s is multiplexed with the local oscillation light 3 by the optical multiplexer 2, and then separated into two orthogonal polarized components by the polarization splitter 4, and each is sent to the photodetector 5. .6, and an intermediate frequency signal of 7.8 is output.
処理部９でこの中間周波数信号７．８はＰＳＫ差動同期
光ヘテロダイン検波方式によってそれぞれ復調された後
合成され、ベースバンド信号１０が出力される。このＰ
ＳＫ差動同期光ヘテロダイン検波方式については、例え
ば注封による“４００Ｍｂ／ｓオプティカルＤＰＳＫヘ
テロダインデイテクションイクスパリメンツユージング
ＤＢＲレーザーダイオードウイズイクスターナルオブテ
イ力ルフイードバツｏｐｔｉｋａｌ ｆｅｅｄｂａｃｋ
”）アイ・オー・オー・シイー−シ−・オー−シー’８
５ （１００Ｃ−ＥＣＯＣ’８５）テクニカルダイジェ
スト、第４０１ページ等の文献に詳細な解説がなされて
いる。In the processing unit 9, the intermediate frequency signals 7 and 8 are demodulated by the PSK differential synchronous optical heterodyne detection method, and then combined, and a baseband signal 10 is output. This P
Regarding the SK differential synchronous optical heterodyne detection method, for example, the "400 Mb/s optical DPSK heterodyne detection equipment using DBR laser diode with external optical feedback" is available.
”) I.O.C.C.O.C.'8
5 (100C-ECOC'85) Technical Digest, page 401, and other documents provide detailed explanations.
ここで中間周波数信号の周波数安定化のため２つの中間
周波数信号７．８の一部がとりだされ、遅延回路１１に
よって片方の中間周波数信号にＩの遅延が与えられた後
、両者は合成回路１２で合成される。Here, in order to stabilize the frequency of the intermediate frequency signal, a part of the two intermediate frequency signals 7.8 is taken out, and after a delay of I is given to one of the intermediate frequency signals by the delay circuit 11, the two intermediate frequency signals are combined by a combining circuit. 12 is synthesized.
この合成された中間周波数信号１３のスペクトルを第２
図に示す。このスペクトルにおいて、１への周波数間隔
で谷が生じているが、これは中間周波数信号７．８が互
いに打消しあっているため生じるものであり、両者の強
度が等しいとき、つまり信号光１の偏波分離部における
分岐比が１：１になったときこの谷は最も深くなる。し
かし遅延量Ｉを大きくとってこの谷の周波数間隔を十分
に小さくすることにより、この谷の周波数安定度に対す
る影響を無視できるほど小さくすることが可能である。The spectrum of this synthesized intermediate frequency signal 13 is
As shown in the figure. In this spectrum, a valley appears at the frequency interval to 1, but this occurs because the intermediate frequency signals 7 and 8 cancel each other out, and when the intensity of both signals is equal, that is, when the signal light 1 This valley becomes the deepest when the branching ratio in the polarization separation section becomes 1:1. However, by making the delay amount I large and making the frequency interval of this valley sufficiently small, it is possible to make the effect of this valley on the frequency stability so small that it can be ignored.
本実施例では遅延回路１１として長さ６ｍの同軸ケーブ
ルを用いた
この合成された中間周波数信号１３は、周波数弁別器１
４によって周波数弁別され、周波数制御信号１５が出力
されこれによって局部発振光源１６の発振周波数に帰還
がかけられる。本実施例では遅延線１７とミクサ１８と
第１のローパスフィルタ１９によって構成される周波数
弁別器１４によって中間周波数を４ＧＨｚに安定化する
ことができ、その周波数変動量は信号光の偏波状態変動
にかかわらず１０ＭＨｚ０ＭＨｚ以下ことができた。In this embodiment, a 6 m long coaxial cable is used as the delay circuit 11. This synthesized intermediate frequency signal 13 is transmitted to the frequency discriminator 1.
4, the frequency is discriminated, and a frequency control signal 15 is output, whereby feedback is applied to the oscillation frequency of the local oscillation light source 16. In this embodiment, the intermediate frequency can be stabilized at 4 GHz by the frequency discriminator 14 composed of the delay line 17, the mixer 18, and the first low-pass filter 19, and the amount of frequency fluctuation is determined by the polarization state fluctuation of the signal light. I was able to achieve a frequency of 10MHz or less regardless of the frequency.
第３図は第２の実施例の構成図を示す。第２の実施例で
は周波数弁別器１４において、合成された中間周波数信
号１３の高域成分と低域成分のレベルを比較することに
よって周波数弁別を行っている。すなわち、しゃ断層波
数がいずれも４ＧＨｚであるバイパスフィルタ２０とロ
ーパスフィルタ２１によって、合成された中間周波数信
号１３の高域成分と低域成分をとりだし、第１の電力検
出器２２と第２の電力検出器２３によってそれぞれの信
号レベルを検出する。この第１および第２の電力検出器
２２．２３の出力は加算器２４と引算器２５とに入力さ
れ、割算器２６において引算器２５の出力は加算器２４
の出力で割算される。これにより割算器２６の出力は中
間周波数信号レベルに依存せず中間周波数信号の周波数
変動のみに応じて変化するのでこれを制御信号とじて局
部発振光源１６の発振周波数を制御し中間周波数信号の
周波数を４ＧＨｚに安定化することができその周波数変
動量を５ＭＨｚ以下に抑えることができた。FIG. 3 shows a configuration diagram of the second embodiment. In the second embodiment, the frequency discriminator 14 performs frequency discrimination by comparing the levels of the high frequency component and the low frequency component of the synthesized intermediate frequency signal 13. That is, the bypass filter 20 and the low-pass filter 21, both of which have cut-off layer wavenumbers of 4 GHz, extract high-frequency components and low-frequency components of the synthesized intermediate frequency signal 13, and output them to the first power detector 22 and the second power detector. A detector 23 detects each signal level. The outputs of the first and second power detectors 22 and 23 are input to an adder 24 and a subtracter 25, and in a divider 26, the output of the subtracter 25 is input to an adder 24 and a subtracter 25.
divided by the output of As a result, the output of the divider 26 does not depend on the intermediate frequency signal level and changes only according to the frequency fluctuation of the intermediate frequency signal, so this is used as a control signal to control the oscillation frequency of the local oscillation light source 16, and the output of the intermediate frequency signal is The frequency could be stabilized at 4 GHz and the amount of frequency fluctuation could be suppressed to 5 MHz or less.
以上、本発明の２つの実施例を説明したが本発明はこれ
らの実施例に限定されるものではなく、本発明の範囲内
で種々の変形、変更が可能であることが言うまでもない
。Although two embodiments of the present invention have been described above, it goes without saying that the present invention is not limited to these embodiments, and that various modifications and changes can be made within the scope of the present invention.
例えば第１、第２の実施例では信号の変復調方法に２Ｇ
ｂ／５ＰＳＫ差動同期検波方法を用いたが、本発明は信
号の変調方法及びビットレートにかかわりなく適用する
ことが可能である。又、中間周波数信号の周波数弁別を
行なうのに、第１、第２の実施例に示した以外の周波数
弁別器を用いることも可能である。又、第１、第２の実
施例では同軸ケーブルを用いて中間周波数信号の遅延を
行ったが、周波数弁別に必要な帯域と十分な遅延量が確
保されてる限り、どのような遅延方法をとってもかまわ
ない。例えばストリップラインを用いた遅延線や広帯域
アンプ等を遅延回路として用いることも可能であり、信
号のビットレートが低いときはＬＣ回路による遅延回路
を用いる等も可能である。For example, in the first and second embodiments, the signal modulation/demodulation method is 2G.
Although the b/5PSK differential synchronous detection method is used, the present invention can be applied regardless of the signal modulation method and bit rate. Furthermore, it is also possible to use frequency discriminators other than those shown in the first and second embodiments to perform frequency discrimination of intermediate frequency signals. Furthermore, in the first and second embodiments, a coaxial cable was used to delay the intermediate frequency signal, but as long as the necessary band and sufficient delay amount for frequency discrimination are secured, any delay method can be used. I don't mind. For example, it is possible to use a delay line using a strip line, a broadband amplifier, etc. as a delay circuit, and when the bit rate of the signal is low, it is also possible to use a delay circuit using an LC circuit.
（発明の効果）
以上、詳細に述べたように本発明では２つの中間周波数
信号の片方を遅延させた後に合成するため、信号光の偏
波変動により２つの中間周波数信号間の位相差が変化し
ても２つの中間周波数信号が打消し合うことがない。こ
のため、２つの中間周波数信号を別々に周波数弁別する
必要はなく、合成された中間周波数信号を１つの周波数
弁別器で周波数弁別することによって中間周波数安定化
のための制御信号が得られる。したがって本発明によっ
てベースバンド合成型の偏波ダイバーシチ光受信方法に
おいて簡易な構成で信号光の偏波状態に依存せず中間周
波数安定化を行うことができる。(Effects of the Invention) As described above in detail, in the present invention, one of the two intermediate frequency signals is delayed and then synthesized, so the phase difference between the two intermediate frequency signals changes due to polarization fluctuation of the signal light. Even if the two intermediate frequency signals do not cancel each other out. Therefore, it is not necessary to separately frequency discriminate the two intermediate frequency signals, and a control signal for stabilizing the intermediate frequency can be obtained by frequency discriminating the synthesized intermediate frequency signal using one frequency discriminator. Therefore, according to the present invention, intermediate frequency stabilization can be performed with a simple configuration in a baseband synthesis type polarization diversity optical reception method without depending on the polarization state of signal light.
第１図は本発明の第１の実施例を説明する図であり、第
２図は本発明の詳細な説明する図であり、第３図は本発
明の第２の実施例を説明する図である。
各図において
１、信号光、２．光合波器、３０局部発振光、７．８．
中間周波数信号、９．処理部、１０、ベースバンド信号
、１１．遅延回路、１２、合成回路、１３１合成された
中間周波数信号、１４、周波数弁別器、１５．中間周波
数制御信号、１６、局部発振光源、１７．遅延線、１８
．ミクサ、１９、第１のローパスフィルタ、
２０、バイパスフィルタ、
２１、第２のローパスフィルタ、
２２、第１の電力検出器、２３．第２の電力検出器、２
４、加算器、９５．引算器、２６１割算器である。FIG. 1 is a diagram for explaining a first embodiment of the present invention, FIG. 2 is a diagram for explaining the present invention in detail, and FIG. 3 is a diagram for explaining a second embodiment of the present invention. It is. In each figure, 1. Signal light; 2. Optical multiplexer, 30 local oscillation light, 7.8.
intermediate frequency signal, 9. Processing unit, 10, baseband signal, 11. delay circuit, 12, synthesis circuit, 131 synthesized intermediate frequency signal, 14, frequency discriminator, 15. intermediate frequency control signal, 16, local oscillation light source, 17. delay line, 18
．． mixer, 19, first low-pass filter, 20, bypass filter, 21, second low-pass filter, 22, first power detector, 23. second power detector, 2
4. Adder, 95. They are a subtracter and a 261 divider.
Claims (1)
交する２つの偏波成分に分離し、この偏波分離された信
号光と局部発振光とのビート成分を２つの光検出器で検
出し得られた２つの中間周波数信号をそれぞれ復調した
後に合成することによって復調信号出力を取り出す偏波
ダイバーシチ光ヘテロダイン受信方法において、前記２
つの中間周波数信号の一部をとりだし、一方の中間周波
数信号を遅延させた後に両者を合成し、この合成された
中間周波数信号の周波数変動を周波数弁別器で検出し、
この周波数弁別器の出力によって局部発振光源の発振周
波数を制御することを特徴とする中間周波数安定化方法
。The signal light transmitted from the optical transmitter is separated into two orthogonal polarization components by the polarization splitter, and the beat components of the polarization-separated signal light and local oscillation light are detected by two photodetectors. In the polarization diversity optical heterodyne reception method in which a demodulated signal output is extracted by demodulating and combining two detected intermediate frequency signals,
extracting a part of the two intermediate frequency signals, delaying one intermediate frequency signal, then combining both, detecting the frequency fluctuation of this combined intermediate frequency signal with a frequency discriminator,
An intermediate frequency stabilization method characterized in that the oscillation frequency of a local oscillation light source is controlled by the output of the frequency discriminator.
Priority Applications (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63191497A JPH0795178B2 (en) | 1988-07-29 | 1988-07-29 | Intermediate frequency stabilization method |
| DE68927969T DE68927969T2 (en) | 1988-07-29 | 1989-07-28 | Optical heterodyne polarization diversity receiver with phase adjustment of two intermediate frequency signals to control a local light source |
| US07/386,072 US5023946A (en) | 1988-07-29 | 1989-07-28 | Polarization diversity optical heterodyne receiver with phase adjustment of two I.F. signals for control of a local optical source |
| EP89113983A EP0352809B1 (en) | 1988-07-29 | 1989-07-28 | Polarization diversity optical heterodyne receiver with phase adjustment of two i.f. signals for control of a local optical source |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63191497A JPH0795178B2 (en) | 1988-07-29 | 1988-07-29 | Intermediate frequency stabilization method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0240635A true JPH0240635A (en) | 1990-02-09 |
| JPH0795178B2 JPH0795178B2 (en) | 1995-10-11 |
Family
ID=16275632
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP63191497A Expired - Lifetime JPH0795178B2 (en) | 1988-07-29 | 1988-07-29 | Intermediate frequency stabilization method |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0795178B2 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH07183841A (en) * | 1993-12-24 | 1995-07-21 | Nec Corp | Optical signal receiver |
| JP2009038801A (en) * | 2007-07-31 | 2009-02-19 | Fujitsu Ltd | Frequency offset monitoring device and coherent optical receiver |
-
1988
- 1988-07-29 JP JP63191497A patent/JPH0795178B2/en not_active Expired - Lifetime
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH07183841A (en) * | 1993-12-24 | 1995-07-21 | Nec Corp | Optical signal receiver |
| JP2009038801A (en) * | 2007-07-31 | 2009-02-19 | Fujitsu Ltd | Frequency offset monitoring device and coherent optical receiver |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0795178B2 (en) | 1995-10-11 |
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