JPS6143693B2 - - Google Patents
Info
- Publication number
- JPS6143693B2 JPS6143693B2 JP55125287A JP12528780A JPS6143693B2 JP S6143693 B2 JPS6143693 B2 JP S6143693B2 JP 55125287 A JP55125287 A JP 55125287A JP 12528780 A JP12528780 A JP 12528780A JP S6143693 B2 JPS6143693 B2 JP S6143693B2
- Authority
- JP
- Japan
- Prior art keywords
- frequency
- optical
- injection
- light
- semiconductor laser
- 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
Links
- 230000003287 optical effect Effects 0.000 claims description 24
- 239000004065 semiconductor Substances 0.000 claims description 12
- 238000004891 communication Methods 0.000 claims description 11
- 238000002347 injection Methods 0.000 claims description 7
- 239000007924 injection Substances 0.000 claims description 7
- 230000005540 biological transmission Effects 0.000 description 7
- 230000010355 oscillation Effects 0.000 description 6
- 230000001427 coherent effect Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 230000003321 amplification Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000003199 nucleic acid amplification method Methods 0.000 description 1
- 239000013307 optical fiber Substances 0.000 description 1
Classifications
-
- 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
- G02F1/0009—Materials therefor
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/60—Receivers
- H04B10/61—Coherent receivers
- H04B10/64—Heterodyne, i.e. coherent receivers where, after the opto-electronic conversion, an electrical signal at an intermediate frequency [IF] is obtained
Landscapes
- Physics & Mathematics (AREA)
- Nonlinear Science (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Electromagnetism (AREA)
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Optical Communication System (AREA)
Description
【発明の詳細な説明】
本発明は光ヘテロダイン方式における信号のキ
ヤリア波に追随したコヒーレントな光を中間周波
数だけシフトして局部発振光として供給する光通
信用ヘテロダイン受信回路に関するものである。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heterodyne receiving circuit for optical communication that shifts coherent light following a carrier wave of a signal in an optical heterodyne system by an intermediate frequency and supplies the shifted light as locally oscillated light.
従来、光通信はPCM−IM方式が実用化面から
有利であるとされてきた。しかし、さらに大容
量、長中継距離をめざす場合には現行方式とし
て、光の可干渉性を利用するコヒーレント伝送が
有利である（山本電通学会通信方式研究会資料
CS−79−144）。光ヘテロダイン技術は従来気体
レーザで検討されている（Ｆ・Ｅ・Goodwin，
“3.39Micron Infraved Optical Heterodyne
Communication System”、IEEE、J.Q.E.QE−
３，No.11，NOV.，1967，PP.524−531）。 Conventionally, the PCM-IM method has been considered to be advantageous in terms of practical use in optical communications. However, when aiming for even higher capacity and longer relay distances, coherent transmission, which utilizes the coherence of light, is advantageous as the current method (Yamamoto Institute of Electrical Engineers of Japan Communication Systems Study Group Materials)
CS-79-144). Optical heterodyne technology has been previously investigated using gas lasers (F.E. Goodwin,
“3.39Micron Infrared Optical Heterodyne
Communication System”, IEEE, JQEQE−
3, No. 11, NOV., 1967, PP. 524-531).
従つて、光通信系における送受信装置は大形に
なり、周波数変動を制御するための温度制御系が
複雑となる。さらに気体レーザの発振波長が光通
信用フアイバの有する低損失波長領域と一致して
いないため光通信用光源として不適である。 Therefore, the transmitting/receiving device in the optical communication system becomes large in size, and the temperature control system for controlling frequency fluctuation becomes complicated. Furthermore, the oscillation wavelength of the gas laser does not match the low-loss wavelength region of the optical communication fiber, making it unsuitable as a light source for optical communication.
光領域における注入同期技術は既にStover等に
よつて確認されている（H.L.Stover and W.H.
Steier，“Locking of Laser Oscillations by
Light Injection”，Applied Phys.Lett.，vol.8，
No.４，Feb.，1966，pp.91−93）。しかし、気体
レーザの場合は利得が小さく共振器のＱ値が高い
ため、同期幅、同期増幅利得が充分とれない欠点
がある。以上の観点から、気体レーザを注入同期
動作させたヘテロダイン局部発振器として用い、
光通信用ヘテロダイン受信系を構成する場合には
技術的問題が多い。 Injection locking technology in the optical domain has already been confirmed by Stover et al. (HLStover and WH
Steier, “Locking of Laser Oscillations by
Light Injection”, Applied Phys. Lett., vol.8,
No. 4, Feb., 1966, pp. 91-93). However, in the case of a gas laser, since the gain is small and the Q value of the resonator is high, there is a drawback that a sufficient synchronization width and synchronization amplification gain cannot be obtained. From the above viewpoint, using a gas laser as an injection-locked heterodyne local oscillator,
There are many technical problems when constructing a heterodyne receiving system for optical communication.
本発明は、これらの点を解決するために、局部
発振器に半導体レーザを用い注入同期動作させる
ことによつて信号の可干渉性を保存した光を作成
し、かつ正確に中間周波数に相当するだけシフト
した局部発振光を供給することを目的としてい
る。 In order to solve these problems, the present invention creates light that preserves signal coherence by using a semiconductor laser as a local oscillator and performs injection-locked operation. The purpose is to supply shifted local oscillation light.
以下、図面について詳細に説明する。 The drawings will be described in detail below.
図は本発明の一実施例であつて、１は送信光源
系、２は光伝送路系、３，６はハーフミラー、
４，５はミラー、７は注入同期半導体レーザ、８
は光周波数シフター、９は二乗検波器である。点
線で示した部分１０が本発明の受信回路である。 The figure shows an embodiment of the present invention, in which 1 is a transmission light source system, 2 is an optical transmission line system, 3 and 6 are half mirrors,
4 and 5 are mirrors, 7 is an injection-locked semiconductor laser, 8
is an optical frequency shifter, and 9 is a square law detector. A portion 10 indicated by a dotted line is a receiving circuit of the present invention.
送信光源系１から出た変調信号は光伝送路系２
を通つて受信回路１０に入射される。入射した変
調光はハーフミラー３によつて２分され、一方は
ハーフミラー６を介して２乗検波器へ入り、他方
はミラー４によつて反射されて、注入同期半導体
レーザ７へ入る。注入同期を信号のキヤリア周波
数で行ない、注入同期半導体レーザ７からの発振
周波数は可干渉的にキヤリア周波数に等しくな
る。半導体レーザの注入同期特性は実験的に確認
されており、最大同期幅２Δ＝3GHz（このと
き同期利得23dB）、最大同期利得40dB（このとき
同期幅は２Δ＝500MHz）が得られている（S.
Kobayashi and T. Kimura， “Injection
locking characteristics of AlGaAS
semiconductor laser “to be Published in
IEEE J.Quantum Electrom.，Sep.，1980）。従
つてキヤリア周波数変動が大きい場合には同期利
得が得られないため、前置光増幅器を必要とす
る。注入同期半導体レーザ７から出た光は光周波
数シフター８へ入射される。光周波数シフター８
は変調周波数がヘテロダイン用の中間周波数IF
に等しい値で変調され、キヤリア周波数cに対
しL＝c＋IFの周波数の光が得られる光周波
数シフターである。これには例えば超音波周波数
シフターが相当するが、信号の変調周波数が高い
場合にはＧHzオーダの高速変調器が必要となり、
電気光学効果による周波数シフターが望ましい。
光周波数シフター８から出たLの周波数を持つ
光はミラー５で反射し、ハーフミラー６で再び信
号と合波され、２乗検波器９へ入射される。２乗
検波器９からの出力はヘテロダイン検波され、中
間周波数IFを中心にベースバンド周波数を両側
に持つ信号となる。以下は電気系によつてベース
バンド信号を識別する。 The modulated signal output from the transmission light source system 1 is transmitted to the optical transmission line system 2.
The signal is input to the receiving circuit 10 through the receiving circuit 10. The incident modulated light is split into two by the half mirror 3, one of which enters the square-law detector via the half mirror 6, and the other reflected by the mirror 4 and enters the injection-locked semiconductor laser 7. Injection locking is performed using the carrier frequency of the signal, and the oscillation frequency from the injection-locked semiconductor laser 7 becomes coherently equal to the carrier frequency. The injection locking characteristics of semiconductor lasers have been experimentally confirmed, and a maximum locking width of 2Δ = 3 GHz (in this case, the locking gain is 23 dB) and a maximum locking gain of 40 dB (in this case, the locking width is 2Δ = 500 MHz) has been obtained (S .
Kobayashi and T. Kimura, “Injection
locking characteristics of AlGaAS
semiconductor laser “to be published in
IEEE J. Quantum Electrom., Sep., 1980). Therefore, if the carrier frequency fluctuation is large, a synchronization gain cannot be obtained, and a pre-optical amplifier is required. Light emitted from the injection-locked semiconductor laser 7 is input to an optical frequency shifter 8 . Optical frequency shifter 8
is the intermediate frequency IF for heterodyne modulation frequency.
This is an optical frequency shifter that is modulated with a value equal to , and obtains light with a frequency of L = c + IF for the carrier frequency c . For example, an ultrasonic frequency shifter corresponds to this, but if the modulation frequency of the signal is high, a high-speed modulator on the GHz order is required.
Frequency shifters based on electro-optic effects are preferred.
The light having the frequency L emitted from the optical frequency shifter 8 is reflected by the mirror 5, is combined with a signal again by the half mirror 6, and is input to the square law detector 9. The output from the square law detector 9 is subjected to heterodyne detection, and becomes a signal having a baseband frequency on both sides around the intermediate frequency IF . The following identifies baseband signals by electrical systems.
変調信号はASK，FSK，PSKの場合が考えら
れるが変調度に依存せずキヤリア成分が確保でき
るASK変調信号が本発明には適している。 The modulation signal may be ASK, FSK, or PSK, but the ASK modulation signal, which does not depend on the degree of modulation and can ensure a carrier component, is suitable for the present invention.
以上説明したように、ヘテロダイン方式におい
ては信号周波数変動に追随した局発光周波数が必
要であり、本発明をそれを半導体レーザによる注
入同期動作により満足させている。従つて、信号
のキヤリア周波数が送信用光源の不安定性もしく
は送信側の変調器の不安定性によつてドリフトし
ても局発光は常にキヤリア周波数よりIFの中間
周波数だけシフトした光を供給することが可能で
あり、従来の自由発振レーザと電気系による帰還
回路の構成と比較して非常に簡便に受信回路を設
計することができる利点がある。さらに半導体レ
ーザを使うことによつて小形化が可能となり、光
フアイバの低損失領域での光伝送が可能である利
点もある。 As explained above, the heterodyne system requires a local oscillation frequency that follows signal frequency fluctuations, and the present invention satisfies this requirement by injection locking operation using a semiconductor laser. Therefore, even if the carrier frequency of the signal drifts due to the instability of the transmitting light source or the instability of the modulator on the transmitting side, the local light source can always supply light that is shifted from the carrier frequency by the intermediate frequency of the IF . This has the advantage that the receiving circuit can be designed very easily compared to the conventional configuration of a feedback circuit using a free oscillation laser and an electric system. Furthermore, by using a semiconductor laser, it is possible to reduce the size of the device, and there is also the advantage that it is possible to transmit light in the low-loss region of an optical fiber.
図は本発明の半導体レーザを用いた光通信用ヘ
テロダイン受信回路である。
１……送信光源系、２……光伝送路系、３……
ハーフミラー、４……ミラー、５……ミラー、６
……ハーフミラー、７……注入同期半導体レー
ザ、８……光周波数変調器、９……二乗検波器、
１０……光通信用ヘテロダイン受信回路。
The figure shows a heterodyne receiving circuit for optical communication using the semiconductor laser of the present invention. 1... Transmission light source system, 2... Optical transmission line system, 3...
Half mirror, 4...Mirror, 5...Mirror, 6
... Half mirror, 7 ... Injection-locked semiconductor laser, 8 ... Optical frequency modulator, 9 ... Square law detector,
10...Heterodyne receiving circuit for optical communication.
Claims (1)
ーザを用いた局部発振器と、その局部発振器の出
力に対し中間周波数に相当する周波数シフトを生
じさせる光周波数シフターを具備することを特徴
とする注入同期による光通信用ヘテロダイン受信
回路。1. Injection locking characterized by comprising a local oscillator using a semiconductor laser that is injection-locked by an input modulation signal and an optical frequency shifter that generates a frequency shift corresponding to an intermediate frequency in the output of the local oscillator. Heterodyne receiver circuit for optical communication.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP55125287A JPS5749925A (en) | 1980-09-11 | 1980-09-11 | Heterodyne receiving circuit for optical communication by injection synchronism |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP55125287A JPS5749925A (en) | 1980-09-11 | 1980-09-11 | Heterodyne receiving circuit for optical communication by injection synchronism |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5749925A JPS5749925A (en) | 1982-03-24 |
| JPS6143693B2 true JPS6143693B2 (en) | 1986-09-29 |
Family
ID=14906336
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP55125287A Granted JPS5749925A (en) | 1980-09-11 | 1980-09-11 | Heterodyne receiving circuit for optical communication by injection synchronism |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5749925A (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4768852A (en) * | 1983-01-28 | 1988-09-06 | University Of Delaware | Apparatus for optical fiber communication using travelling wave acousto-optical modulator and injection locked lasers |
| US4579417A (en) * | 1983-01-28 | 1986-04-01 | University Of Delaware | Apparatus for optical fiber communications using standing wave acousto-optical modulator |
| JPS6374331A (en) * | 1986-09-18 | 1988-04-04 | Kokusai Denshin Denwa Co Ltd <Kdd> | Diversity optical reception system |
-
1980
- 1980-09-11 JP JP55125287A patent/JPS5749925A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5749925A (en) | 1982-03-24 |
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