JPS62136932A - Optical transmission equipment - Google Patents
Optical transmission equipmentInfo
- Publication number
- JPS62136932A JPS62136932A JP60278699A JP27869985A JPS62136932A JP S62136932 A JPS62136932 A JP S62136932A JP 60278699 A JP60278699 A JP 60278699A JP 27869985 A JP27869985 A JP 27869985A JP S62136932 A JPS62136932 A JP S62136932A
- Authority
- JP
- Japan
- Prior art keywords
- laser diode
- circuit
- bias
- output
- optical output
- 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.)
- Pending
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- Semiconductor Lasers (AREA)
- Optical Communication System (AREA)
Abstract
Description
【発明の詳細な説明】 〈産業上の利用分野〉 本発明はレーザダイオードを用いた光送信機に関する。[Detailed description of the invention] <Industrial application field> The present invention relates to an optical transmitter using a laser diode.
〈従来の技術〉
第２図は光送信機におけるレーザダイオードの光出力を
一定に保持するオートマチイックパワーコントロール回
路、（ＡＰＣ回路）を示し、２１は入力信号、２２はレ
ーザダイオードドライブ回路、２３はレーザダイオード
、２４は受光素子、２５は積分回路、２６は比較回路、
２７は基準電圧、２８はバイアス駆動回路、２９はバイ
アス制御信号である。このＡＰＣ回路においては、入力
信号２１によりスイッチング動作をするレーザダイオー
ドドライブ回路２２により駆動されるレーザダイオード
２３の後方光出力を近接して固定設置された受光素子２
４により検出し、この受光素子２４の出力を積分回路２
５により平均化した後、比較回路２６における基準電圧
２７との比較の結果に応じてバイアス制御信号２９によ
りレーザダイオード２３の平均光出力が一定となるよう
にレーザダイオード２３のバイアス電流を制御する。<Prior art> Fig. 2 shows an automatic power control circuit (APC circuit) that keeps the optical output of a laser diode constant in an optical transmitter, 21 is an input signal, 22 is a laser diode drive circuit, 23 is a laser diode, 24 is a light receiving element, 25 is an integration circuit, 26 is a comparison circuit,
27 is a reference voltage, 28 is a bias drive circuit, and 29 is a bias control signal. In this APC circuit, the rear light output of a laser diode 23 driven by a laser diode drive circuit 22 that performs a switching operation in response to an input signal 21 is connected to a light receiving element 2 fixedly installed in close proximity.
4, and the output of this light receiving element 24 is detected by the integrating circuit 2.
5, the bias current of the laser diode 23 is controlled by the bias control signal 29 according to the result of the comparison with the reference voltage 27 in the comparator circuit 26 so that the average optical output of the laser diode 23 is constant.
関係文献
ｒＡｔｒａｎＬａ Ｆｉｂｅｒ Ｓｙｓｔｅｍ Ｅｘｐ
ｅｒｉｍｅｎｔ Ｐｒａｃｔｉｃａｌ ４５Ｍｂ／ｓ
Ｒｅｇｅｎｅｒａｔｏｒ ｆｏｒ Ｌｉｇｈｔｗａｖｅ
ＴｒａｎｓｍｉｓｓｉｏｎＪＢＳＴＪ Ｖｏｌ、５
７ Ｎｏ、６．１９７８〈発明が解決しようとする問
題点〉
上述のＡＰＣ回路においては、以下のような問題点があ
る。Related Literature rAtranLa Fiber System Exp
erimentPractical 45Mb/s
Regenerator for Lightwave
TransmissionJBSTJ Vol, 5
7 No. 6.1978 <Problems to be solved by the invention> The above-mentioned APC circuit has the following problems.
第３図は周囲温度をパラメータとしたレーザダイオード
の一般的な光出力−駆動電流特性を示す。FIG. 3 shows general optical output-drive current characteristics of a laser diode with ambient temperature as a parameter.
レーザダイオード２３の周囲温度が上昇すると、曲線Ｃ
で示すように傾きが小さくなり、温度上昇前後のパルス
電流１ｐを一定とすると、温度上昇後の平均光出力Ｐａ
ｖｅを一定とするためには、信号成分であるパルス電流
１ｐに直流成分のバイアス電流■ｏ′を重畳する必要が
ある。しかしながら、光出力に直流成分を含むことは、
消光比の劣化を招き、受信側においてパワーペナルティ
の増加をもたらす。また同時に、最大光出力の減少は、
受信側ＡＧＣ回路の負荷増大につながる。When the ambient temperature of the laser diode 23 increases, the curve C
If the slope becomes smaller as shown in and the pulse current 1p before and after the temperature rise is constant, the average optical output Pa after the temperature rise becomes
In order to keep ve constant, it is necessary to superimpose the DC component bias current ■o' on the pulse current 1p, which is the signal component. However, including a DC component in the optical output means that
This causes deterioration of the extinction ratio and increases the power penalty on the receiving side. At the same time, the decrease in maximum light output is
This leads to an increase in the load on the AGC circuit on the receiving side.
一方、レーザダイオード２３の周囲温度が下降した場合
、光出力−駆動電流特性は曲線ａで示すように傾きが大
きくなる。したがって、パルス電流ｉｐを一定に保持し
て平均光出力Ｐａｖｅを一定に保つためには、レーザダ
イオード２３のバイアス電流ＩＢ″ をレーザダイオー
ドのしきい値組流Ｉｔｈ”より低く設定する必要がある
。しかしながら、このようなバイアス設定を行なうと、
入力信号２１のパルス列の発生の仕方により光出力パル
スの振幅が変化したり、パルス遅延時間が変化したりす
るいわゆるパターン効果が発生し、高速動作時において
光出力信号のＳ／Ｎの劣化を招く。On the other hand, when the ambient temperature of the laser diode 23 decreases, the slope of the optical output-drive current characteristic increases as shown by curve a. Therefore, in order to keep the pulse current ip constant and the average optical output Pave constant, it is necessary to set the bias current IB'' of the laser diode 23 lower than the threshold current Ith'' of the laser diode. However, with such a bias setting,
A so-called pattern effect occurs in which the amplitude of the optical output pulse changes or the pulse delay time changes depending on how the pulse train of the input signal 21 is generated, leading to deterioration of the S/N of the optical output signal during high-speed operation. .
このように、バイアス電流のみを制御する従来のＡＰＣ
回路においては、温度条件等の変化によるレーザダイオ
ードの特性変化を充分に？！償できないとう欠点を有し
ていた。In this way, the conventional APC that controls only the bias current
In the circuit, should the characteristics of the laser diode be adequately taken care of due to changes in temperature conditions, etc.? ! It had flaws that could not be compensated for.
く問題点を解決するための手段〉
本発明は、特定の符号遷移則を有する伝送符号からなる
入力信号に応じた光出力を発生するレーザダイオードを
有する光送信機において、上記レーザダイオードの光出
力に応じて上記レーザダイオードのバイアス電流を制御
するバイアス電流制御手段と、上記光出力における伝送
符号遷移則誤りの発生頻度がほぼ一定になるように上記
レーザダイオードのパルス電流を制御するパルス電流制
御手段とを備えたことを特徴とする。Means for Solving the Problems> The present invention provides an optical transmitter having a laser diode that generates an optical output according to an input signal consisting of a transmission code having a specific code transition rule. bias current control means for controlling the bias current of the laser diode according to the pulse current of the laser diode, and pulse current control means for controlling the pulse current of the laser diode so that the frequency of occurrence of transmission code transition rule errors in the optical output is approximately constant. It is characterized by having the following.
〈実施例〉 第１図は本実施例の光送信機の基本構成を示す。<Example> FIG. 1 shows the basic configuration of the optical transmitter of this embodiment.
■は特定の遷移則を有する伝送符号からなる入力信号、
２はレーザダイオードドライブ回路、３はレーザダイオ
ード、４は受光素子、５は積分回路、６は比較回路、７
は基準電圧、８はバイアス駆動回路、９はバイアス制御
信号、１０は高速電流電圧変換回路である２Ｒ回路、１
１は伝送符号の復号回路、１２は伝送符号遷移則誤りを
検出するＣＲＶ検出回路、１３はパルス電流制御回路、
１４はピークパワー検出信号、１５はパルス電流制御信
号、１６はパルス電流源、１７は積分回路である。■ is an input signal consisting of a transmission code with a specific transition rule,
2 is a laser diode drive circuit, 3 is a laser diode, 4 is a light receiving element, 5 is an integration circuit, 6 is a comparison circuit, 7
is a reference voltage, 8 is a bias drive circuit, 9 is a bias control signal, 10 is a 2R circuit which is a high-speed current-voltage conversion circuit, 1
1 is a transmission code decoding circuit, 12 is a CRV detection circuit for detecting a transmission code transition law error, 13 is a pulse current control circuit,
14 is a peak power detection signal, 15 is a pulse current control signal, 16 is a pulse current source, and 17 is an integration circuit.
以下、動作を説明する。The operation will be explained below.
入力信号ｌによりレーザダイオードドライブ回路２がス
イッチング動作し、レーザダイオード３は入力信号１に
応じた光出力を発生する。このレーザダイオード３の後
方光出力を受光素子４により検出し、積分回路５にて受
光素子４の出力を平均化し、さらに、比較回路６にて基
準電圧７との比較により、レーザダイオード３の平均光
出力が一定となるように制御信号をバイアス駆動回路８
に与え、このバイアス駆動回路８からのバイアス制御信
号９によりレーザダイオード３のバイアス電流を制御す
る。The input signal 1 causes the laser diode drive circuit 2 to perform a switching operation, and the laser diode 3 generates an optical output according to the input signal 1. The rear light output of the laser diode 3 is detected by the light receiving element 4, the output of the light receiving element 4 is averaged by the integrating circuit 5, and the output of the light receiving element 4 is averaged by the comparator circuit 6, and the average of the laser diode 3 is A bias drive circuit 8 applies a control signal so that the optical output is constant.
The bias current of the laser diode 3 is controlled by the bias control signal 9 from the bias drive circuit 8.
また、受光素子４の出力を２Ｒ回路１０において識別再
生し、さらに復号回路１１にて復号化した後、ＣＲＶ検
出回路１２において伝送符号遷移則誤りを検出する。こ
のＣＲＶ検出回路１２からの伝送符号遷移則誤りの検出
信号と２Ｒ回路１０にて検出したピークパワー検出信号
１４をパルス電流制御回路１３へ入力する。パルス電流
制御回路１３は、この伝送符号遷移則誤り検出信号とピ
ークパワー検出信号を参照し、伝送符号遷移則誤りの発
生頻度が初期設定値に収束するようにパルス電流制御信
号１５をパルス電流源１６に与え、レーザダイオード３
のパルス電流を制御する。Furthermore, after the output of the light receiving element 4 is identified and reproduced in a 2R circuit 10 and further decoded in a decoding circuit 11, a transmission code transition law error is detected in a CRV detection circuit 12. The transmission code transition law error detection signal from the CRV detection circuit 12 and the peak power detection signal 14 detected by the 2R circuit 10 are input to the pulse current control circuit 13. The pulse current control circuit 13 refers to the transmission code transition law error detection signal and the peak power detection signal, and controls the pulse current control signal 15 to a pulse current source so that the frequency of occurrence of transmission code transition law errors converges to the initial setting value. 16, laser diode 3
control the pulse current of
パルス電流制御回路１３においては、温度上昇時または
レーザダイオード３の素子劣化時には消光比の劣化によ
り伝送符号遷移則誤りの発生頻度が増加するとともにピ
ークパワーが減少するので、この２つのパラメータを参
照しながら伝送符号遷移則誤りの発生頻度が初期設定さ
れた一定の範囲内に収束するようにレーザダイオード３
のパルス電流を増加させる。また、温度下降時には、パ
ターン効果等により伝送符号遷移則誤りの発生頻度が増
加するとともにピークパワーが増大するので、両パラメ
ータを参照しなからレーザダイオード３のパルス電流を
減少させる。In the pulse current control circuit 13, when the temperature rises or the element of the laser diode 3 deteriorates, the frequency of occurrence of transmission code transition law errors increases due to deterioration of the extinction ratio, and the peak power decreases, so these two parameters should be referred to. However, the laser diode 3 is
increase the pulse current. Furthermore, when the temperature decreases, the frequency of transmission code transition law errors increases due to pattern effects and the like, and the peak power also increases, so the pulse current of the laser diode 3 is decreased without referring to both parameters.
〈発明の効果〉
以上説明したように本発明においては、レーザダイオー
ドの平均光出力を検出してバイアス電流を制御するとと
もに、光出力のＳ／Ｎに依存する伝送符号遷移則誤りの
発生頻度とピークパワーを検出して伝送符号遷移則誤り
の発生頻度が一定範囲内になるようにパルス電流を制御
するようにしたので、レーザダイオードの周囲温度条件
や素子特性に依存せず、さらにバイアス電流をレーザダ
イオードのしきい値近傍に自動的に設定できることから
、高速動作時においても常に一定のＳ／Ｎを有する光信
号を出力することができる。<Effects of the Invention> As explained above, in the present invention, the average optical output of the laser diode is detected to control the bias current, and the frequency of occurrence of transmission code transition law errors depending on the S/N of the optical output is determined. Since the peak power is detected and the pulse current is controlled so that the frequency of occurrence of transmission code transition law errors is within a certain range, the bias current can be controlled independently of the ambient temperature conditions and device characteristics of the laser diode. Since it can be automatically set near the threshold value of the laser diode, it is possible to output an optical signal having a constant S/N ratio even during high-speed operation.
第１図は本発明実施例の基本構成を示すブロック図、第
２図は従来例の構成を示すブロック図、第３図はレーザ
ダイオードの光出力−駆動電流特性を示す図である。
１・・・入力信号
２・・・レーザダイオードドライブ回路３・・・レーザ
ダイオード
４・・・受光素子、 ５・・・積分回路６・−・
比較回路、 ８・・・バイアス駆動回路１０・・
・２Ｒ回路、 １１・・・復号回路１２・・・Ｃ
ＲＶ検出回路
１３・・・パルス電流制御回路
１４・・・ピークパワー検出信号
１５・・・パルス電流制御信号
１６・・・パルス電流源
特許出願人 シャープ株式会社
代 理 人 弁理士 西１）新
’：＋Ｓ ｉ ＩＡ
フ
第２ｉ！１
第３図FIG. 1 is a block diagram showing the basic configuration of an embodiment of the present invention, FIG. 2 is a block diagram showing the configuration of a conventional example, and FIG. 3 is a diagram showing the optical output-drive current characteristics of a laser diode. 1... Input signal 2... Laser diode drive circuit 3... Laser diode 4... Light receiving element, 5... Integrating circuit 6...
Comparison circuit, 8...bias drive circuit 10...
・2R circuit, 11...decoding circuit 12...C
RV detection circuit 13...Pulse current control circuit 14...Peak power detection signal 15...Pulse current control signal 16...Pulse current source patent applicant Sharp Corporation Agent Patent attorney Nishi 1) Shin' :+S i IA F 2nd i! 1 Figure 3
Claims (1)
応じた光出力を発生するレーザダイオードを有する光送
信機において、上記レーザダイオードの光出力に応じて
上記レーザダイオードのバイアス電流を制御するバイア
ス電流制御手段と、上記光出力における伝送符号遷移則
誤りの発生頻度がほぼ一定になるように上記レーザダイ
オードのパルス電流を制御するパルス電流制御手段とを
備えたことを特徴とする光送信機。In an optical transmitter having a laser diode that generates an optical output according to an input signal consisting of a transmission code having a specific code transition rule, a bias current that controls the bias current of the laser diode according to the optical output of the laser diode. An optical transmitter comprising: a control means; and a pulse current control means for controlling the pulse current of the laser diode so that the frequency of occurrence of transmission code transition rule errors in the optical output becomes approximately constant.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP60278699A JPS62136932A (en) | 1985-12-10 | 1985-12-10 | Optical transmission equipment |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP60278699A JPS62136932A (en) | 1985-12-10 | 1985-12-10 | Optical transmission equipment |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS62136932A true JPS62136932A (en) | 1987-06-19 |
Family
ID=17600950
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP60278699A Pending JPS62136932A (en) | 1985-12-10 | 1985-12-10 | Optical transmission equipment |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS62136932A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5073983A (en) * | 1990-03-05 | 1991-12-17 | Motorola, Inc. | Optical communication system with reduced distortion |
| US5412675A (en) * | 1991-12-26 | 1995-05-02 | Fujitsu Limited | Semiconductor optical source capable of compensating for temperature-induced variation of laser oscillation threshold |
| US5526164A (en) * | 1993-05-19 | 1996-06-11 | U.S. Philips Corporation | Optical transmission system comprising a laser diode |
-
1985
- 1985-12-10 JP JP60278699A patent/JPS62136932A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5073983A (en) * | 1990-03-05 | 1991-12-17 | Motorola, Inc. | Optical communication system with reduced distortion |
| US5412675A (en) * | 1991-12-26 | 1995-05-02 | Fujitsu Limited | Semiconductor optical source capable of compensating for temperature-induced variation of laser oscillation threshold |
| US5526164A (en) * | 1993-05-19 | 1996-06-11 | U.S. Philips Corporation | Optical transmission system comprising a laser diode |
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