JP3024246B2 - Modulation degree stabilization circuit - Google Patents

Modulation degree stabilization circuit

Info

Publication number
JP3024246B2
JP3024246B2 JP3090051A JP9005191A JP3024246B2 JP 3024246 B2 JP3024246 B2 JP 3024246B2 JP 3090051 A JP3090051 A JP 3090051A JP 9005191 A JP9005191 A JP 9005191A JP 3024246 B2 JP3024246 B2 JP 3024246B2
Authority
JP
Japan
Prior art keywords
signal
low
frequency sub
main digital
digital signal
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 - Lifetime
Application number
JP3090051A
Other languages
Japanese (ja)
Other versions
JPH04299589A (en
Inventor
健次 金納
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
NEC Corp
Original Assignee
NEC Corp
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by NEC Corp filed Critical NEC Corp
Priority to JP3090051A priority Critical patent/JP3024246B2/en
Publication of JPH04299589A publication Critical patent/JPH04299589A/en
Application granted granted Critical
Publication of JP3024246B2 publication Critical patent/JP3024246B2/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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  • Semiconductor Lasers (AREA)
  • Optical Communication System (AREA)

Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION

【0001】[0001]

【産業上の利用分野】本発明は、PCM光通信装置に使
用する光送信器に利用する。特に、低周波副信号を主信
号に重畳して伝送する光送信器に関する。
The present invention is applied to an optical transmitter used in a PCM optical communication device. In particular, the present invention relates to an optical transmitter that transmits a low-frequency sub-signal superimposed on a main signal.

【0002】[0002]

【従来の技術】従来の低周波信号を主信号に振幅変調す
る光送信器では、低周波信号の変調度安定化のために光
出力の一部をモニタ用フォトダイオードで光電気変換
し、この出力から低域通過フィルタにより低周波信号を
抽出し、ピーク検出を行い、この電圧を基準電圧と比較
して低周波信号の振幅が一定となるようにフィードバッ
ク制御を行っていた。
2. Description of the Related Art In a conventional optical transmitter for amplitude-modulating a low-frequency signal into a main signal, a part of an optical output is photoelectrically converted by a monitor photodiode in order to stabilize the degree of modulation of the low-frequency signal. A low-frequency signal is extracted from the output by a low-pass filter, peak detection is performed, and this voltage is compared with a reference voltage to perform feedback control so that the amplitude of the low-frequency signal becomes constant.

【0003】[0003]

【発明が解決しようとする課題】このような従来の変調
度安定化回路では、低周波信号の振幅だけを一定に制御
を行うので、光出力の主信号成分の振幅が変化した場合
に変調度が変化してしまう欠点があった。
In such a conventional modulation degree stabilizing circuit, only the amplitude of the low-frequency signal is controlled to be constant, so that when the amplitude of the main signal component of the optical output changes, the modulation degree becomes small. However, there was a drawback that was changed.

【0004】本発明は、このような欠点を除去するもの
で、低周波副信号による変調度が主ディジタル信号の振
幅の変化に影響されない変調度安定化回路を提供するこ
とを目的とする。
An object of the present invention is to provide a modulation degree stabilizing circuit in which the above-mentioned drawbacks are eliminated and the degree of modulation by the low-frequency sub-signal is not affected by changes in the amplitude of the main digital signal.

【0005】[0005]

【課題を解決するための手段】本発明は、出力される光
信号の一部を電気信号に変換するフォトダイオードを内
蔵するレーザモジュールに接続され、このレーザモジュ
ールを低周波副信号で振幅変調された主ディジタル信号
に相当の電気信号で駆動するレーザ駆動回路に与える低
周波副信号の振幅値を自動制御する変調度安定化回路に
おいて、上記フォトダイオードで変換された電気信号か
ら主ディジタル信号と低周波副信号とを抽出する抽出手
段と、この抽出手段で抽出された主ディジタル信号の平
均値および低周波副信号のピーク値を求め、この2つの
値の比を演算する演算手段と、この演算手段で演算され
た比と所定値との差分に応じて振幅値が補正される低周
波副信号を上記レーザ駆動回路に帰還する帰還制御回路
とを備えたことを特徴とする。
According to the present invention, a laser module having a built-in photodiode for converting a part of an output optical signal into an electric signal is connected, and the laser module is amplitude-modulated by a low-frequency sub-signal. In a modulation degree stabilizing circuit for automatically controlling the amplitude value of a low-frequency sub-signal given to a laser drive circuit driven by an electric signal corresponding to the main digital signal, the main digital signal and the low- Extracting means for extracting the frequency sub-signal; calculating means for obtaining the average value of the main digital signal and the peak value of the low frequency sub-signal extracted by the extracting means and calculating the ratio of the two values; A feedback control circuit that feeds back the low frequency sub-signal whose amplitude value is corrected according to the difference between the ratio calculated by the means and the predetermined value to the laser drive circuit. And butterflies.

【0006】ここで、上記演算手段は、主ディジタル信
号の平均値が主ディジタル信号のマーク率で補償される
構成であっても良い。
Here, the arithmetic means may be configured so that the average value of the main digital signal is compensated by the mark rate of the main digital signal.

【0007】[0007]

【作用】モニタ用のフォトダイオードが出力する電気信
号から抽出した主ディジタル信号の平均値と低周波副信
号のピーク値との比を一定に保つように低周波副信号の
変調度を自動制御する。
The modulation degree of the low-frequency sub-signal is automatically controlled so that the ratio between the average value of the main digital signal extracted from the electric signal output from the monitor photodiode and the peak value of the low-frequency sub-signal is kept constant. .

【0008】[0008]

【実施例】以下、本発明の一実施例について図面を参照
して説明する。図1はこの実施例の構成を示すブロック
図である。この実施例は、図1に示すように、出力され
る光信号の一部を電気信号に変換するフォトダイオード
を内蔵するレーザモジュール2に接続され、このレーザ
モジュール2を低周波副信号で振幅変調された主ディジ
タル信号に相当の電気信号で駆動するレーザ駆動回路1
に与える低周波副信号の振幅値を自動制御する変調度安
定化回路であり、上記フォトダイオードで変換された電
気信号から主ディジタル信号と低周波副信号とを抽出す
る抽出手段およびこの抽出手段で抽出された主ディジタ
ル信号の平均値および低周波副信号のピーク値を求め、
この2つの値の比を演算する演算手段である電流電圧変
換回路3、低域通過フィルタ4、ピーク値検出回路5、
平均値検出回路6および割算回路7と、上記演算手段で
演算された比と所定値との差分に応じて振幅値が補正さ
れる低周波副信号をレーザ駆動回路1に帰還する帰還制
御回路である差動増幅回路8および変調度設定回路9と
を備える。ここで、上記演算手段は、主ディジタル信号
の平均値が主ディジタル信号のマーク率で補償される構
成である。
An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of this embodiment. In this embodiment, as shown in FIG. 1, a laser module 2 having a built-in photodiode for converting a part of an output optical signal into an electric signal is connected. Drive circuit 1 driven by an electrical signal corresponding to the main digital signal
A degree-of-modulation stabilization circuit for automatically controlling the amplitude value of the low-frequency sub-signal given to the main signal, extracting means for extracting the main digital signal and the low-frequency sub-signal from the electric signal converted by the photodiode, and Find the average value of the extracted main digital signal and the peak value of the low-frequency sub-signal,
A current-voltage conversion circuit 3, a low-pass filter 4, a peak value detection circuit 5, and a calculation means for calculating the ratio of these two values.
An average value detection circuit 6 and a division circuit 7; and a feedback control circuit for feeding back to the laser drive circuit 1 a low-frequency sub-signal whose amplitude value is corrected according to the difference between the ratio calculated by the calculation means and a predetermined value. , And a modulation degree setting circuit 9. Here, the arithmetic means is configured so that the average value of the main digital signal is compensated by the mark ratio of the main digital signal.

【0009】次に、この実施例の動作を説明する。トラ
ンジスタで構成された電流切替形のレーザ駆動回路1を
用いて光出力のモニタ用のフォトダイオードを内蔵する
モニタ内蔵形のレーザモジュール2を駆動し、入力され
る主信号(ディジタル信号)を光出力信号に変換する。
低周波副信号はレーザ駆動回路1の電流を変化させて光
出力に重畳される。光出力波形は図2に示すように主信
号の振幅に低周波信号が変調される。光出力信号の一部
分はレーザモジュール2に内蔵されるフォトダイオード
で光電気変換された後に電流電圧変換回路3で電圧に変
換される。低域通過フィルタ4で抽出された低周波信号
はピーク値検出回路5でそのピーク値(Y)が検出され
る。一方、主信号の平均値(X)は電流電圧変換回路3
の出力を低域ろ波器等で構成された平均値検出回路6で
検出する。ここで、この平均値(X)は主信号のマーク
率で変化するので、マーク率検出回路12の出力によりマ
ーク率補償を行い変調度(Y/X)がマーク率で変化し
ないようにしている。割算回路7の出力は基準電圧(所
定の変調度を得るための基準電圧)と比較され、差動増
幅回路8の出力により変調度設定回路9を制御して変調
度の制御を行う。
Next, the operation of this embodiment will be described. Using a current switching type laser drive circuit 1 composed of transistors, a monitor built-in type laser module 2 having a built-in photodiode for monitoring optical output is driven, and an input main signal (digital signal) is output as an optical output. Convert to a signal.
The low frequency sub-signal changes the current of the laser drive circuit 1 and is superimposed on the optical output. As shown in FIG. 2, the low frequency signal of the optical output waveform is modulated to the amplitude of the main signal. A part of the optical output signal is photoelectrically converted by a photodiode built in the laser module 2 and then converted into a voltage by the current-voltage converter 3. The peak value (Y) of the low-frequency signal extracted by the low-pass filter 4 is detected by a peak value detection circuit 5. On the other hand, the average value (X) of the main signal
Is detected by an average value detection circuit 6 composed of a low-pass filter or the like. Here, since the average value (X) changes with the mark rate of the main signal, the mark rate is compensated by the output of the mark rate detection circuit 12 so that the modulation factor (Y / X) does not change with the mark rate. . The output of the division circuit 7 is compared with a reference voltage (a reference voltage for obtaining a predetermined modulation degree), and the modulation degree setting circuit 9 is controlled by the output of the differential amplifier circuit 8 to control the modulation degree.

【0010】[0010]

【発明の効果】本発明は、以上説明したように、半導体
レーザモジュールに内蔵されたモニタ用フォトダイオー
ドの出力から光出力波形の平均値と低周波副信号のピー
ク値とを検出し、この2つの値から得られた変調度に対
応する電圧と所定の変調度を得るための基準電圧とを比
較して変調度を制御するので、半導体レーザの温度特性
によるI−L特性(電流光出力特性)の変化や入力する
低周波副信号の振幅の変化にかかわらず一定の変調度を
得ることができる効果がある。
As described above, according to the present invention, the average value of the light output waveform and the peak value of the low-frequency sub-signal are detected from the output of the monitoring photodiode incorporated in the semiconductor laser module. Since the modulation degree is controlled by comparing a voltage corresponding to the modulation degree obtained from the two values with a reference voltage for obtaining a predetermined modulation degree, an IL characteristic (current light output characteristic) due to a temperature characteristic of the semiconductor laser is obtained. ) And a change in the amplitude of the input low-frequency sub-signal can be obtained at a constant modulation degree.

【図面の簡単な説明】[Brief description of the drawings]

【図1】 本発明実施例の構成を示すブロック構成図。FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.

【図2】 図1に示す光送信が出力する光信号の波形
図。
FIG. 2 is a waveform diagram of an optical signal output by the optical transmission shown in FIG.

【符号の説明】[Explanation of symbols]

1 レーザ駆動回路 2 レーザモジュール 3 電流電圧変換回路 4 低域通過フィルタ 5 ピーク値検出回路 6 平均値検出回路 7 割算回路 8 差動増幅回路 9 変調度設定回路 10 自動光出力制御回路 11 バイアス供給用トランジスタ 12 マーク率検出回路 REFERENCE SIGNS LIST 1 laser drive circuit 2 laser module 3 current-voltage conversion circuit 4 low-pass filter 5 peak value detection circuit 6 average value detection circuit 7 division circuit 8 differential amplifier circuit 9 modulation factor setting circuit 10 automatic optical output control circuit 11 bias supply Transistor 12 mark ratio detection circuit

───────────────────────────────────────────────────── フロントページの続き (58)調査した分野(Int.Cl.7,DB名) H01S 5/00 JICSTファイル(JOIS)──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. 7 , DB name) H01S 5/00 JICST file (JOIS)

Claims (2)

(57)【特許請求の範囲】(57) [Claims] 【請求項1】 出力される光信号の一部を電気信号に変
換するフォトダイオードを内蔵するレーザモジュールに
接続され、このレーザモジュールを低周波副信号で振幅
変調された主ディジタル信号に相当の電気信号で駆動す
るレーザ駆動回路に与える低周波副信号の振幅値を自動
制御する変調度安定化回路において、上記フォトダイオ
ードで変換された電気信号から主ディジタル信号と低周
波副信号とを抽出する抽出手段と、この抽出手段で抽出
された主ディジタル信号の平均値および低周波副信号の
ピーク値を求め、この2つの値の比を演算する演算手段
と、この演算手段で演算された比と所定値との差分に応
じて振幅値が補正される低周波副信号を上記レーザ駆動
回路に帰還する帰還制御回路とを備えたことを特徴とす
る変調度安定化回路。
1. A laser module having a built-in photodiode for converting a part of an output optical signal into an electric signal. The laser module converts an electric signal corresponding to a main digital signal amplitude-modulated by a low-frequency sub-signal. A modulation stabilization circuit for automatically controlling the amplitude value of a low-frequency sub-signal given to a laser drive circuit driven by a signal, wherein a main digital signal and a low-frequency sub-signal are extracted from the electric signal converted by the photodiode. Means for calculating the average value of the main digital signal and the peak value of the low-frequency sub-signal extracted by the extracting means, and calculating the ratio of the two values; A feedback control circuit for feeding back the low frequency sub-signal whose amplitude value is corrected in accordance with the difference between the low-frequency signal and the laser drive circuit to the laser drive circuit. .
【請求項2】 上記演算手段は、主ディジタル信号の平
均値が主ディジタル信号のマーク率で補償される構成で
ある請求項1記載の変調度安定化回路。
2. The modulation degree stabilizing circuit according to claim 1, wherein said arithmetic means has a configuration in which an average value of the main digital signal is compensated by a mark rate of the main digital signal.
JP3090051A 1991-03-27 1991-03-27 Modulation degree stabilization circuit Expired - Lifetime JP3024246B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP3090051A JP3024246B2 (en) 1991-03-27 1991-03-27 Modulation degree stabilization circuit

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP3090051A JP3024246B2 (en) 1991-03-27 1991-03-27 Modulation degree stabilization circuit

Publications (2)

Publication Number Publication Date
JPH04299589A JPH04299589A (en) 1992-10-22
JP3024246B2 true JP3024246B2 (en) 2000-03-21

Family

ID=13987806

Family Applications (1)

Application Number Title Priority Date Filing Date
JP3090051A Expired - Lifetime JP3024246B2 (en) 1991-03-27 1991-03-27 Modulation degree stabilization circuit

Country Status (1)

Country Link
JP (1) JP3024246B2 (en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2546152B2 (en) * 1993-06-15 1996-10-23 日本電気株式会社 Light modulation amplifier
JPH08265259A (en) * 1995-03-20 1996-10-11 Fujitsu Ltd Light amplification repeater

Also Published As

Publication number Publication date
JPH04299589A (en) 1992-10-22

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