JPS6143694B2 - - Google Patents
Info
- Publication number
- JPS6143694B2 JPS6143694B2 JP55125288A JP12528880A JPS6143694B2 JP S6143694 B2 JPS6143694 B2 JP S6143694B2 JP 55125288 A JP55125288 A JP 55125288A JP 12528880 A JP12528880 A JP 12528880A JP S6143694 B2 JPS6143694 B2 JP S6143694B2
- Authority
- JP
- Japan
- Prior art keywords
- signal
- injection
- light
- frequency
- 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
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
- G02F2/00—Demodulating light; Transferring the modulation of modulated light; Frequency-changing of light
- G02F2/002—Demodulating light; Transferring the modulation of modulated light; Frequency-changing of light using optical mixing
-
- 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)
- General Physics & Mathematics (AREA)
- Nonlinear Science (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いて信号光の
キヤリア周波数に追随した可干渉性な光を中間周
波数だけシフトして局部発信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 communications in which coherent light following the carrier frequency of signal light is shifted by an intermediate frequency and supplied as local oscillation light in an optical heterodyne system. .
従来、光通信はPCM−IM方式が実用化されて
いる。さらに大容量、長中継距離をめざす場合に
はPCM−IM方式に対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 Infrared
Optical Heterodyne Communication
System”、IEEE、J.Quantum Electron.，QE−
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。 Conventionally, the PCM-IM method has been put into practical use for optical communications. When aiming for even higher capacity and longer relay distances, coherent transmission, which utilizes the coherence of light, is more advantageous than the PCM-IM system (Yamamoto, IEICE Communication Systems Study Group Material CS-79-144). Optical heterodyne technology has been previously investigated using gas lasers (F.E. Goodwin, “3.39Micron Infrared
Optical Heterodyne Communication
System”, IEEE, J. Quantum Electron., QE−
3, No. 11, Nov., 1967, PP. 524-531). Therefore, the transmitting and receiving equipment in optical communication systems has become large and
The temperature control system for controlling frequency fluctuation becomes complicated. Furthermore, since the oscillation wavelength of the gas laser does not match the low-loss wavelength range of the optical communication fiber, it is 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）。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得られない欠点があ
る。 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). In the case of gas lasers, the gain is small and the Q value of the resonator is high, so there is a drawback that sufficient synchronization width and synchronization amplification gain cannot be obtained.
光ヘテロダイン受信系において自由発振するレ
ーザを用いる方式では、信号のキヤリア周波数の
変動に伴い、受信後の周波数識別器から帰還され
た信号によつて局部発振器の周波数を制御するこ
とになる。従つて制御系は複雑となり、かつ帰還
信号を制御信号としてレーザに加える方式によつ
ては、応答速度制限により信号のキヤリア周波数
変動に追随できない場合もある。 In a method using a freely oscillating laser in an optical heterodyne receiving system, the frequency of the local oscillator is controlled by the signal fed back from the frequency discriminator after reception as the carrier frequency of the signal changes. Therefore, the control system becomes complicated, and depending on the method of applying the feedback signal to the laser as a control signal, it may not be possible to follow the carrier frequency fluctuation of the signal due to response speed limitations.
本発明は、これらの欠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
フトした信号のキヤリア周波数変動に追随する光
を局部発信光として供給することを目的としてい
る。 In order to solve these drawbacks, the present invention uses a semiconductor laser as a local oscillator and performs injection-locked operation to create light that preserves signal coherence and that accurately corresponds to the intermediate frequency. The purpose of this invention is to supply light that follows the carrier frequency fluctuation of a signal shifted by the amount as local oscillation light.
以下図面について詳細に説明する。第１図は本
発明の実施例を示すものであり、１は送信光源
系、２は光伝速路系、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
は二乗検波器である。点線で示した部分９が本発
明の受信回路である。 The drawings will be explained in detail below. FIG. 1 shows an embodiment of the present invention, in which 1 is a transmitting light source system, 2 is an optical transmission path system, 3 and 6 are half mirrors,
4 and 5 are mirrors, 7 is an injection-locked semiconductor laser, 8
is a square law detector. A portion 9 indicated by a dotted line is the receiving circuit of the present invention.
送信光源系１からの変調された信号は光伝送路
系２を通つて受信回路９に入る。信号はハーフミ
ラー３で２分され、一方はハーフミラー６を介し
て二乗検波器８へ入り、他方はミラー４で反射さ
れ、注入同期半導体レーザ７へ入る。この注入同
期半導体レーザ７は既にヘテロダイン用の中間周
波数IFで直接変調されており、キヤリア周波数
の両側にIFに相当するサイドバンド成分を有し
ている。信号光のキヤリア周波数成分は注入同期
半導体レーザ７へ注入することにより、サイドバ
ンドへ同期させる。第１図においてａの信号光の
周波数はc±nであり、キヤリア周波数cを
注入同期半導体レーザ７のサイドバンドへ同期す
ることによりｂの光はキヤリア周波数′c＝c
＋IFとなる。注入同期半導体レーザから出た光
ｂはミラー５で反射され、ハーフミラー６でａ周
波数成分を持つ信号光と合波され、二乗検波器８
へ入る。二乗検波器８からは中間周波数IFの回
りに信号のサイドバンドを持つIF±nの周波
数成分の電気信号が得られる。以下、電気系によ
つて元に変調信号を再生する。 The modulated signal from the transmitting light source system 1 enters the receiving circuit 9 through the optical transmission line system 2. The signal is divided into two by a half mirror 3, one of which enters a square law detector 8 via a half mirror 6, and the other is reflected by a mirror 4 and enters an injection-locked semiconductor laser 7. This injection-locked semiconductor laser 7 has already been directly modulated with a heterodyne intermediate frequency IF , and has sideband components corresponding to the IF on both sides of the carrier frequency. By injecting the carrier frequency component of the signal light into the injection-locked semiconductor laser 7, it is synchronized to the sideband. In FIG. 1, the frequency of the signal light a is c ± n , and by synchronizing the carrier frequency c to the sideband of the injection-locked semiconductor laser 7, the light signal b has a carrier frequency ' c = c.
+ IF . The light b emitted from the injection-locked semiconductor laser is reflected by the mirror 5, combined with the signal light having the frequency component a by the half mirror 6, and then sent to the square law detector 8.
Enter. The square-law detector 8 obtains an electrical signal having a frequency component of IF ± n having signal sidebands around the intermediate frequency IF . Thereafter, the modulated signal is originally reproduced by an electrical system.
第２図は各光の周波数成分を示すもので、ａは
信号光の周波数成分であり中心キヤリア周波数
cの回りに、c±nを中心に信号成分を有する
サイドバンドを持つている。一方、注入同期半導
体レーザ７は、ｂの成分を有している。ａの光が
注入同期半導体レーザ７のサイドバンドに同期す
ると、ｂのキヤリア周波数は′c＝＋IFある
いは′c＝c−IFとなる。ｂの両側サイドバ
ンドのいずれに同期してもヘテロダイン後は中間
周波数IFを中心とする電気信号が得られる。ａ
とｂが二乗検波器内で合波され、電気信号ｃの成
分が得られる。 Figure 2 shows the frequency components of each light, where a is the frequency component of the signal light and the center carrier frequency.
Around c , there is a sideband with signal components centered at c ± n . On the other hand, the injection-locked semiconductor laser 7 has a component b. When the light of a is synchronized with the sideband of the injection-locked semiconductor laser 7, the carrier frequency of b becomes ' c =+ IF or'c= c - IF . No matter which of the sidebands on both sides of b is synchronized, an electrical signal centered at the intermediate frequency IF is obtained after heterodyne. a
and b are combined in a square law detector to obtain the component of electric signal c.
以上説明したように、光ヘテロダイン方式にお
いて必要な中間周波数が常に一定に保たれること
が本発明によつて満足される。従つて局部発振器
の周波数制御系が簡単となり、受信系が小形化さ
れる利点がある。半導体レーザを注入同期用とし
て用いることにより、同期幅を広くとれ、増幅利
得が大きくとれる利点がある。 As explained above, the present invention satisfies the fact that the intermediate frequency required in the optical heterodyne system is always kept constant. Therefore, the frequency control system for the local oscillator is simplified, and the receiving system is advantageously miniaturized. By using a semiconductor laser for injection locking, there is an advantage that the locking width can be widened and the amplification gain can be large.
第１図は本発明の一実施例の光通信用ヘテロダ
イン受信回路、第２図は信号光、同期光、電気信
号の周波数成分を示している。
１……送信光源系、２……光伝送路系、３，６
……ハーフミラー、４，５……ミラー、７……注
入同期半導体レーザ、８……二乗検波器、９……
光通信用ヘテロダイン受信回路。
FIG. 1 shows a heterodyne receiving circuit for optical communication according to an embodiment of the present invention, and FIG. 2 shows frequency components of signal light, synchronization light, and electric signals. 1... Transmission light source system, 2... Optical transmission line system, 3, 6
... Half mirror, 4, 5 ... Mirror, 7 ... Injection-locked semiconductor laser, 8 ... Square law detector, 9 ...
Heterodyne receiver circuit for optical communication.
Claims (1)
入同期半導体レーザのサイドバンドへ、入力のキ
ヤリア周波数を注入同期させ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. An injection-locked heterodyne receiver circuit for optical communication, characterized by injection-locking an input carrier frequency to the sideband of an injection-locked semiconductor laser modulated at a frequency corresponding to an intermediate frequency.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP55125288A JPS5749926A (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 |
|---|---|---|---|
| JP55125288A JPS5749926A (en) | 1980-09-11 | 1980-09-11 | Heterodyne receiving circuit for optical communication by injection synchronism |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5749926A JPS5749926A (en) | 1982-03-24 |
| JPS6143694B2 true JPS6143694B2 (en) | 1986-09-29 |
Family
ID=14906361
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP55125288A Granted JPS5749926A (en) | 1980-09-11 | 1980-09-11 | Heterodyne receiving circuit for optical communication by injection synchronism |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5749926A (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH01147437A (en) * | 1987-12-02 | 1989-06-09 | Nec Corp | Optical heterodyne and homodyne detecting and receiving device |
| JPH06350529A (en) * | 1993-06-11 | 1994-12-22 | Nec Corp | Autocorrelative optical heterodyne communication system |
-
1980
- 1980-09-11 JP JP55125288A patent/JPS5749926A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5749926A (en) | 1982-03-24 |
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