JP2817102B2 - Light modulation circuit - Google Patents
Light modulation circuitInfo
- Publication number
- JP2817102B2 JP2817102B2 JP1177890A JP17789089A JP2817102B2 JP 2817102 B2 JP2817102 B2 JP 2817102B2 JP 1177890 A JP1177890 A JP 1177890A JP 17789089 A JP17789089 A JP 17789089A JP 2817102 B2 JP2817102 B2 JP 2817102B2
- Authority
- JP
- Japan
- Prior art keywords
- signal
- circuit
- bias current
- auxiliary signal
- 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 - Lifetime
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Description
【発明の詳細な説明】 〔産業上の利用分野〕 本発明は分岐干渉型光変調器を用いた光変調回路に関
し，特に，光ディジタル主信号に低周波アナログ信号等
の補助信号を重畳する光変調回路に関する。Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical modulation circuit using a branching interference type optical modulator, and more particularly, to an optical modulator for superimposing an auxiliary signal such as a low-frequency analog signal on an optical digital main signal. The present invention relates to a modulation circuit.
一般に，ディジタル主信号で光を変調する場合には，
第２図に示す光変調回路が用いられる。Generally, when modulating light with a digital main signal,
The light modulation circuit shown in FIG. 2 is used.
第２図を参照して，半導体レーザダイオード（以下LD
と略す）１は直流電流源６によって駆動されて発光し，
その出力光が分岐干渉型光変調器２に与えられる。ディ
ジタル主信号が入力端子４から主信号駆動回路３に与え
られ，主信号駆動回路３はディジタル主信号に応じて駆
動パルスを出力する。そして，この駆動パルスによって
分岐干渉型光変調器２が駆動され,LD1からの出力の光強
度変調が行われ，変調光信号が出力される。Referring to FIG. 2, a semiconductor laser diode (hereinafter referred to as an LD)
1) is driven by the DC current source 6 to emit light,
The output light is provided to the branch interference optical modulator 2. A digital main signal is supplied from an input terminal 4 to a main signal drive circuit 3, and the main signal drive circuit 3 outputs a drive pulse according to the digital main signal. Then, the branching interference optical modulator 2 is driven by the drive pulse, the light intensity of the output from the LD 1 is modulated, and a modulated optical signal is output.
ところで，ディジタル主信号に低周波アナログ信号等
の補助信号を重畳する際には，上記の光変調信号を一旦
電気信号に変換した後，補助信号を重畳し，再び光信号
に変換している。つまり，補助信号を重畳する際には，
別に電気回路が必要となる。By the way, when an auxiliary signal such as a low-frequency analog signal is superimposed on a digital main signal, the optical modulation signal is temporarily converted into an electric signal, then the auxiliary signal is superimposed, and the optical signal is converted again into an optical signal. That is, when superimposing the auxiliary signal,
Separately, an electric circuit is required.
上述のように，従来ディジタル主信号に補助信号を重
畳する際，補助信号を重畳するための電気回路を備えな
ければならず，特にディジタル主信号がGb/S領域を超え
る高周波信号の場合には，光電気変換を行うことによっ
て主信号パルス波形劣化等があり，補助信号が重畳でき
ないという問題点がある。As described above, when an auxiliary signal is superimposed on a conventional digital main signal, an electric circuit for superimposing the auxiliary signal must be provided, especially when the digital main signal is a high-frequency signal exceeding the Gb / S range. In addition, there is a problem that the main signal pulse waveform deteriorates due to the photoelectric conversion, and the auxiliary signal cannot be superimposed.
さらに，従来の光変調回路では，温度変動,LD素子経
時劣化等によるLD微分量子効率の変動によって先出力電
力が変動してしまうという問題点がある。Further, in the conventional optical modulation circuit, there is a problem that the output power fluctuates due to the fluctuation of the LD differential quantum efficiency due to temperature fluctuation, aging of the LD element, and the like.
本発明の目的は主信号パルス波形が劣化することなく
補助信号を容易に重畳することのできる光変調回路を提
供することにある。An object of the present invention is to provide an optical modulation circuit that can easily superimpose an auxiliary signal without deteriorating a main signal pulse waveform.
本発明の他の目的は先出力電力が変動することのない
光変調器を提供することにある。Another object of the present invention is to provide an optical modulator whose output power does not fluctuate.
本発明の光変調回路は、半導体レーザと、補助信号が
入力され半導体レーザを補助信号に基づいて駆動する補
助信号駆動回路と、半導体レーザの出射光を強度変調す
る分岐干渉型変調器と、主信号が入力され、分岐干渉型
光変調器を主信号に応じて駆動する主信号駆動回路とを
備えている。そして、半導体レーザの出射光をモニタし
て、この出射光に応じたモニタ電流を出力するモニタ回
路と、モニタ電流をモニタ電圧に変換して予め設定され
た基準電圧と上記モニタ電圧とを比較してバイアス電流
制御信号を出力するバイアス電流制御回路と、バイアス
電流制御信号に応じて半導体レーザにバイアス電流を供
給するバイアス電流供給回路とを備えていることを特徴
としている。An optical modulation circuit according to the present invention includes: a semiconductor laser; an auxiliary signal driving circuit that receives an auxiliary signal and drives the semiconductor laser based on the auxiliary signal; a branch interference modulator that intensity-modulates light emitted from the semiconductor laser; A main signal driving circuit for receiving a signal and driving the branch interference optical modulator in accordance with the main signal; The monitor circuit monitors the output light of the semiconductor laser and outputs a monitor current corresponding to the output light. The monitor circuit converts the monitor current into a monitor voltage and compares the monitor voltage with a preset reference voltage. And a bias current supply circuit for supplying a bias current to the semiconductor laser in accordance with the bias current control signal.
次に，本発明について実施例によって説明する。 Next, the present invention will be described with reference to examples.
第１図を参照して，補助信号（低周波アナログ信号）
は入力端子７より補助信号駆動回路８に入力され，補助
信号駆動回路８はこの補助信号に基づいてLD1を駆動す
る。つまりLD1を直接変調する。この結果,LD1からは第
３図（ａ）に示す光出力が出力される。そして，この光
出力は分岐干渉型光変調器２に入力される。Referring to FIG. 1, auxiliary signal (low-frequency analog signal)
Is input to the auxiliary signal drive circuit 8 from the input terminal 7, and the auxiliary signal drive circuit 8 drives the LD1 based on the auxiliary signal. That is, LD1 is directly modulated. As a result, the optical output shown in FIG. 3A is output from LD1. Then, this optical output is input to the branch interference optical modulator 2.
一方，ディジタル主信号は入力端子４より主信号駆動
回路３に入力され，主信号駆動回路３はディジタル主信
号に応じた主信号駆動パルスを分岐干渉型光変調器２に
与え，分岐干渉型光変調器２は主信号駆動パレスによっ
て駆動される。その結果，補助信号（低周波アナログ信
号）による直接変調光が主信号駆動パルスによって強度
変調され，第３図（ｂ）に示すように補助信号に準じた
振幅変調光が得られる。そして，この振幅変調光は光フ
ァイバ５に結合される。On the other hand, the digital main signal is input from the input terminal 4 to the main signal drive circuit 3, which supplies a main signal drive pulse corresponding to the digital main signal to the branch interference optical modulator 2, and outputs the branch interference light. The modulator 2 is driven by the main signal drive palace. As a result, the intensity of the directly modulated light by the auxiliary signal (low-frequency analog signal) is modulated by the main signal drive pulse, and amplitude modulated light according to the auxiliary signal is obtained as shown in FIG. 3 (b). Then, this amplitude modulated light is coupled to the optical fiber 5.
次に，第４図を参照して，本発明の他の実施例につい
て説明する。Next, another embodiment of the present invention will be described with reference to FIG.
第１図で説明したように補助信号駆動回路８でLD1が
直接変調される。主信号駆動回路３はディジタル主信号
に応じた主信号駆動パルスにより分岐干渉型光変調器２
を駆動し，補助信号（低周波アナログ信号）による直接
変調光を強度変調し補助信号に準じた振動変調光を得
る。As described with reference to FIG. 1, the LD1 is directly modulated by the auxiliary signal drive circuit 8. The main signal driving circuit 3 uses the main signal driving pulse corresponding to the digital main signal to generate the branch interference optical modulator 2.
Is driven to intensity-modulate the light directly modulated by the auxiliary signal (low-frequency analog signal) to obtain vibration-modulated light according to the auxiliary signal.
一方,LD1後方より出射される直接変調光は光出力電力
モニタ用のフォトダイオード11に入力される。フォトダ
イオード11によって得られた光電流は,LDバイアス電流
制御回路12に入力され電流・電圧変換される。つまり，
光出力に応じた電圧に変換され，予め設定された基準電
圧Vrefと比較され，差電圧信号が出力される。LDバイア
ス電流供給回路13は差信号に応じたバイアス電流をチョ
ークコイル14を介してLD1に与える。つまり，光出力に
応じた電圧と基準電圧Vrefの差を圧縮するようにLDに直
流頁帰還を催すことにより,LDバイアス電流を制御し，
補助信号によって直接変調されたLD1の光出力電力（平
均値）を一定に保っている。On the other hand, the directly modulated light emitted from the rear of the LD 1 is input to the photodiode 11 for monitoring the optical output power. The photocurrent obtained by the photodiode 11 is input to the LD bias current control circuit 12 and is subjected to current / voltage conversion. That is,
The voltage is converted to a voltage corresponding to the light output, compared with a preset reference voltage Vref, and a difference voltage signal is output. The LD bias current supply circuit 13 supplies a bias current corresponding to the difference signal to the LD 1 via the choke coil 14. In other words, the LD bias current is controlled by applying a DC page feedback to the LD so as to compress the difference between the voltage according to the optical output and the reference voltage Vref,
The optical output power (average value) of LD1 directly modulated by the auxiliary signal is kept constant.
以上設明したように本発明では，補助信号により直接
変調されたLD出力光を主信号により駆動される分岐干渉
型光変調器に結合しているから，主信号パルス波形が劣
化することなく主信号に補助信号を重畳できるという効
果がある。As described above, in the present invention, since the LD output light directly modulated by the auxiliary signal is coupled to the branch interference optical modulator driven by the main signal, the main signal pulse waveform is not degraded. There is an effect that the auxiliary signal can be superimposed on the signal.
また，補助信号によって直接変調されたLD出力光をフ
ォトダイオードにてモニタし,LD出力光電力を一定に保
つよう制御しているからLDの温度変動あるいは素子経時
劣化等による先出力変動をなくすことができる。In addition, the LD output light directly modulated by the auxiliary signal is monitored by a photodiode and controlled so that the LD output light power is kept constant, so that there is no prior output fluctuation due to LD temperature fluctuation or element aging deterioration. Can be.
第１図は本発明による光変調器の一実施例を示すブロッ
ク図，第２図は従来の光変調器のブロック図，第３図
（ａ）は補助信号によを直接変調光出力波形を示す図，
第３図（ｂ）は主信号に補助信号を重畳した時の光出力
波形を示す図，第４図は本発明による光変調器の他の実
施例を示すブロック図である。 １……半導体レーザダイオード,2……分岐干渉型光変調
器,3……主信号駆動回路,4……主信号入力端子,5……光
ファイバ,6……直流電流源,7……補助信号入力端子,8…
…補助信号駆動回路,9……コンデンサ,10……直流電圧
源,11……フォトダイオード,12……LDバイアス電流制御
回路,13……LDバイアス電流供給回路,14……チョークコ
イル。FIG. 1 is a block diagram showing an embodiment of an optical modulator according to the present invention, FIG. 2 is a block diagram of a conventional optical modulator, and FIG. 3 (a) shows a directly modulated optical output waveform based on an auxiliary signal. Figure,
FIG. 3B is a diagram showing an optical output waveform when an auxiliary signal is superimposed on the main signal, and FIG. 4 is a block diagram showing another embodiment of the optical modulator according to the present invention. 1 ... Semiconductor laser diode, 2 ... Branch interference light modulator, 3 ... Main signal drive circuit, 4 ... Main signal input terminal, 5 ... Optical fiber, 6 ... DC current source, 7 ... Auxiliary Signal input terminal, 8 ...
... Auxiliary signal drive circuit, 9 ... Capacitor, 10 ... DC voltage source, 11 ... Photodiode, 12 ... LD bias current control circuit, 13 ... LD bias current supply circuit, 14 ... Choke coil.
Claims (1)
半導体レーザを前記補助信号に基づいて駆動する補助信
号駆動回路と、前記半導体レーザの出射光を強度変調す
る分岐干渉型変調器と、主信号が入力され、前記分岐干
渉型光変調器を前記主信号に応じて駆動する主信号駆動
回路とを有する光変調回路であって、 前記半導体レーザの出射光をモニタして、該出射光に応
じたモニタ電流を出力するモニタ回路と、 前記モニタ電流をモニタ電圧に変換して、予め設定され
た基準電圧と前記モニタ電圧とを比較してバイアス電流
制御信号を出力するバイアス電流制御回路と、 前記バイアス電流制御信号に応じて前記半導体レーザに
バイアス電流を供給するバイアス電流供給回路と を有することを特徴とする光変調回路。A semiconductor laser; an auxiliary signal drive circuit to which an auxiliary signal is input and which drives the semiconductor laser based on the auxiliary signal; a branch interference type modulator for intensity-modulating the light emitted from the semiconductor laser; And a main signal driving circuit for driving the branching interference optical modulator in accordance with the main signal. A monitor circuit that outputs a corresponding monitor current, a bias current control circuit that converts the monitor current into a monitor voltage, compares the monitor voltage with a preset reference voltage, and outputs a bias current control signal, A bias current supply circuit for supplying a bias current to the semiconductor laser in response to the bias current control signal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1177890A JP2817102B2 (en) | 1989-07-12 | 1989-07-12 | Light modulation circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1177890A JP2817102B2 (en) | 1989-07-12 | 1989-07-12 | Light modulation circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0343712A JPH0343712A (en) | 1991-02-25 |
| JP2817102B2 true JP2817102B2 (en) | 1998-10-27 |
Family
ID=16038851
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1177890A Expired - Lifetime JP2817102B2 (en) | 1989-07-12 | 1989-07-12 | Light modulation circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2817102B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114039669B (en) * | 2021-11-04 | 2023-03-21 | 金雷 | Light roof device |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH02240627A (en) * | 1989-03-15 | 1990-09-25 | Fujitsu Ltd | Optical modulation control system |
-
1989
- 1989-07-12 JP JP1177890A patent/JP2817102B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0343712A (en) | 1991-02-25 |
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