JPS625743A - Semiconductor laser modulation circuit - Google Patents

Semiconductor laser modulation circuit

Info

Publication number
JPS625743A
JPS625743A JP60144338A JP14433885A JPS625743A JP S625743 A JPS625743 A JP S625743A JP 60144338 A JP60144338 A JP 60144338A JP 14433885 A JP14433885 A JP 14433885A JP S625743 A JPS625743 A JP S625743A
Authority
JP
Japan
Prior art keywords
semiconductor laser
signal
modulation
circuit
transistor
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
Application number
JP60144338A
Other languages
Japanese (ja)
Inventor
Koichi Saito
公一 斉藤
Fumio Ogawa
小川　富美雄
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.)
Fujitsu Ltd
Original Assignee
Fujitsu Ltd
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 Fujitsu Ltd filed Critical Fujitsu Ltd
Priority to JP60144338A priority Critical patent/JPS625743A/en
Publication of JPS625743A publication Critical patent/JPS625743A/en
Pending legal-status Critical Current

Links

Classifications

    • 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
    • H04B10/50—Transmitters
    • H04B10/516—Details of coding or modulation
    • H04B10/524—Pulse modulation
    • 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
    • H04B10/50—Transmitters
    • H04B10/501—Structural aspects
    • H04B10/503—Laser transmitters
    • H04B10/504—Laser transmitters using direct modulation

Landscapes

  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Optics & Photonics (AREA)
  • Dc Digital Transmission (AREA)
  • Optical Communication System (AREA)

Abstract

PURPOSE:To suppress the influence of pattern effect against the output waveform of semiconductor laser by setting an RZ binary code, after converted to an NRZ signal, as the modulation input of a semiconductor laser modulator, and overlapping the RZ binary code, after the phase of which is shifted, on the reference voltage of the semiconductor laser modulator. CONSTITUTION:The modulation signal of binary RZ signal form, after it is inputted to an RZ NRZ conversion circuit 7 and is converted to the NRZ signal, is impressed on the base of a transistor 1 in a semiconductor laser pulse modulator. At the same time, the modulation signal of the binary RZ signal form is inputted to a phase shifting circuit 6 and after the phase is shifted, it is impressed on the base of a transistor 2 in the semiconductor laser pulse modulator. Therefore, the binary RZ signal, the phase of which is shifted, and reference voltage Vref are overlapped and impressed on the base of the transistor 2. Thus, the pulse width of an input signal is made variable equivalently and the fluctuation of a leading time and the pulse width due to the pattern effect can be suppressed.

Description

【発明の詳細な説明】 〔概要〕 ＲＺＺ値符号から構成されるパルス信号により変調を行
う半導体レーザ変調回路に於いて、前記パルス信号をＮ
ＲＺ信号に変換して変調入力とし、又前記パルス信号か
ら１７２タイムスロツトずらしたＲＺ倍信号作り、此の
ＲＺ倍信号基準電圧に重畳する。[Detailed Description of the Invention] [Summary] In a semiconductor laser modulation circuit that performs modulation using a pulse signal composed of RZZ value codes, the pulse signal is
It is converted into an RZ signal and used as a modulation input, and an RZ multiplied signal is produced by shifting 172 time slots from the pulse signal, and this RZ multiplied signal is superimposed on the reference voltage.

〔産業上の利用分野〕[Industrial application field]

本発明は光通信装置等に使用される半導体レーザ変調回
路に係り、特に半導体レーザの出力パルス信号に応じて
オン・オフするパルス変調方式に関するものである。The present invention relates to a semiconductor laser modulation circuit used in optical communication devices and the like, and particularly to a pulse modulation method that turns on and off according to an output pulse signal of a semiconductor laser.

上記従来のパルス変調方式に於いては高速度になると光
出力波形が入力波形に追従出来なくなると云う欠点があ
り、此の改善策が強く求められていた。The conventional pulse modulation method described above has a drawback in that the optical output waveform cannot follow the input waveform when the speed becomes high, and there has been a strong demand for an improvement measure.

〔従来の技術〕[Conventional technology]

従来半導体レーザパルス変調回路に於いて、半導体レー
ザに注入する電流を直接変化させる直接変調方式が高速
度、高能率等の理由で一般的に広く利用されている。In conventional semiconductor laser pulse modulation circuits, a direct modulation method that directly changes the current injected into a semiconductor laser is generally widely used because of its high speed and efficiency.

第３図は従来の半導体レーザパルス変調回路の一例を示
す図である。FIG. 3 is a diagram showing an example of a conventional semiconductor laser pulse modulation circuit.

図中、１．２は夫々トランジスタ、３は抵抗、４はＬＤ
、５は電流源である。In the figure, 1 and 2 are transistors, 3 is a resistor, and 4 is an LD.
, 5 is a current source.

以下図に従って本発明の詳細な説明する。The present invention will be described in detail below with reference to the drawings.

回路はトランジスタ１とトランジスタ２からなる差動増
幅器で構成される。トランジスタ１のベースに変調信号
Ｓが印加され、トランジスタ２のベースには基準電圧Ｖ
　ｒ＊ｆが印加されて差動増幅器のスレッショルドレベ
ルを規定スる。The circuit consists of a differential amplifier consisting of transistor 1 and transistor 2. A modulation signal S is applied to the base of transistor 1, and a reference voltage V is applied to the base of transistor 2.
r*f is applied to define the threshold level of the differential amplifier.

変調信号Ｓが“１”、“０”と変化すると、トランジス
タ１がスイッチングしてトランジスタ２を駆動し、トラ
ンジスタ２のコレクタ回路に挿入されているレーザダイ
オードＬＤ４に電流が流れ、変調信号Ｓに応じた光出力
を発生する。When the modulation signal S changes from "1" to "0", the transistor 1 switches and drives the transistor 2, and current flows through the laser diode LD4 inserted in the collector circuit of the transistor 2, which changes according to the modulation signal S. generates a light output.

〔発明が解決しようとする問題点〕[Problem that the invention seeks to solve]

一方此の直接変調方式に於ける問題点は入力パルスがオ
フになった場合、キャリア密度が急には減少せず、略指
数関数的に減少し、定常状態に達するには半導体レーザ
の材料等によっても異なるが、数ナノセカンド（ｎｓ）
の時間を要する。On the other hand, the problem with this direct modulation method is that when the input pulse is turned off, the carrier density does not decrease suddenly, but almost exponentially, and it takes a long time, such as the material of the semiconductor laser, to reach a steady state. Depending on the situation, a few nanoseconds (ns)
It takes time.

従って入力パルスの繰り返し周期が此の時間より十分大
きい場合には問題ないが、入力パルスの繰り返し周期が
此の時間と同程度か、より小さい場合にはキャリア密度
が定常状態に達する前に次の入力パルスが入力され、所
謂パターン効果が発生する。Therefore, if the repetition period of the input pulse is sufficiently larger than this time, there will be no problem, but if the repetition period of the input pulse is about the same as or smaller than this time, the next carrier density will reach the steady state. An input pulse is input, and a so-called pattern effect occurs.

第４図は従来の半導体レーザパルス変調回路に於けるパ
ターン効果の説明図である。FIG. 4 is an explanatory diagram of pattern effects in a conventional semiconductor laser pulse modulation circuit.

此の影響により半導体レーザの出力波形の立ち上がり時
間、パルス幅に変動を与える。即ち、入力信号が“ｌ、
■”の連続、又は°０．１”の連続の場合には出力波形
の立ち上がり時間、パルス幅が其の都度変動し、半導体
レーザの出力波形に乱れを生ずると云う問題点が起きる
。This effect causes fluctuations in the rise time and pulse width of the output waveform of the semiconductor laser. That is, the input signal is “l,
In the case of a series of 1" or a series of 0.1", the rise time and pulse width of the output waveform vary each time, causing a problem in that the output waveform of the semiconductor laser is disturbed.

此処で問題となるのは、入力＊調信号Ｓが第４図（ａ）
に示す様に“０”−“１”と変化した場合、第４図（ｂ
）に示す様に光出力波形が入力変調信号Ｓに追従出来な
い点であり、“０”から“１”への立ち上がりが遅れる
のでパルス幅がτだけ狭くなる。The problem here is that the input * tonal signal S is as shown in Figure 4(a).
When the change is from “0” to “1” as shown in Figure 4 (b
), the optical output waveform cannot follow the input modulation signal S, and the rise from "0" to "1" is delayed, so the pulse width becomes narrower by τ.

此の出力パルス幅の差は、変調信号Ｓが“１”−“Ｏ”
の連続信号である場合にも其の侭発生する。This difference in output pulse width means that the modulation signal S is "1" - "O"
Even when the signal is a continuous signal, the delay occurs.

本発明の目的は前記半導体レーザパルス変調回路が高速
度で動作する場合でも、大規模な回路を追加することな
くパターン効果を取り除くことである。An object of the present invention is to eliminate pattern effects without adding a large-scale circuit even when the semiconductor laser pulse modulation circuit operates at high speed.

〔問題点を解決するための手段〕[Means for solving problems]

上記問題点は第１図に示す様にＲＺ２値符号から構成さ
れるパルス信号を入力とし、差動回路を使用する半導体
レーザ変調回路に於いて、ＲＺ２値符号をＲＺ→ＮＲＺ
変換回路７によりＮＲＺ信号に変換して半導体レーザ変
調回路の変調入力とし、ＲＺ２値符号を位相シフト回路
６により位相をずらした後半導体レーザ変調回路の基準
電圧に重畳することにより其のスレッショルドレベルを
変化させて半導体レーザ出力波形に対するパターン効果
の影響を抑えることにより解決される。As shown in Figure 1, the above problem occurs when a pulse signal composed of an RZ binary code is input and the RZ binary code is converted from RZ to NRZ in a semiconductor laser modulation circuit using a differential circuit.
The conversion circuit 7 converts the signal into an NRZ signal, which is used as the modulation input of the semiconductor laser modulation circuit.The phase shift circuit 6 shifts the phase of the RZ binary code, and then superimposes it on the reference voltage of the semiconductor laser modulation circuit, thereby adjusting its threshold level. This is solved by changing the pattern effect to suppress the influence of the pattern effect on the semiconductor laser output waveform.

〔作用〕[Effect]

本発明に依ると入力信号が“Ｏｌｌ”と変化する場合の
パターン効果が半導体レーザ出力波形劣化の支配的要因
であることに着目し、ＲＺ倍信号ＮＲＺ信号に変換して
から変調入力として印加すると共に、半導体レーザパル
ス変調回路の基準電圧に位相をずらしたＲＺ倍信号重畳
することにより基準電圧を変化させ、等両市に入力信号
のパルス幅を可変とし、パターン効果に依る立ち上がり
時間、パルス幅の変動を抑えることが出来ると云う効果
が生まれる。According to the present invention, focusing on the fact that the pattern effect when the input signal changes to "Oll" is a dominant factor in the deterioration of the semiconductor laser output waveform, the RZ multiplied signal is converted into an NRZ signal and then applied as a modulation input. At the same time, the reference voltage is changed by superimposing an RZ multiplied signal with a phase shift on the reference voltage of the semiconductor laser pulse modulation circuit, and the pulse width of the input signal is made variable, and the rise time and pulse width due to the pattern effect are changed. This has the effect of suppressing fluctuations.

〔実施例〕〔Example〕

第１図は本発明に依る半導体レーザ変調回路の一実施例
を示す図である。FIG. 1 is a diagram showing an embodiment of a semiconductor laser modulation circuit according to the present invention.

第２図は本発明の動作原理の説明図である。FIG. 2 is an explanatory diagram of the operating principle of the present invention.

図中、６は位相シフト回路、７はＲＺ→ＮＲＺ変換回路
である。In the figure, 6 is a phase shift circuit, and 7 is an RZ→NRZ conversion circuit.

本発明では第１図に示す様に従来の半導体レーザパルス
変調回路を其の侭利用する。但しＬＤ４はトランジスタ
１のコレクタ回路に、抵抗３はトランジスタ２のコレク
タ回路に挿入する。In the present invention, as shown in FIG. 1, a conventional semiconductor laser pulse modulation circuit is utilized on its side. However, LD4 is inserted into the collector circuit of transistor 1, and resistor 3 is inserted into the collector circuit of transistor 2.

２値ＲＺ信号形式の変調信号ＳをＲＺ→ＮＲＺ変換回路
７に入力してＮＲＺ信号とした後半導体レーザパルス変
調回路のトランジスタ１のベースに印加する。The modulation signal S in the binary RZ signal format is input to the RZ→NRZ conversion circuit 7 to be converted into an NRZ signal, and then applied to the base of the transistor 1 of the semiconductor laser pulse modulation circuit.

同時に此の２値ＲＺ信号形弐の変調信号Ｓを位相シフト
回路６に入力して位相をずらす。例えば１／２タイムス
ロフト位相を後らせてから半導体レーザパルス変調回路
のトランジスタ２のベースに印加する。従ってトランジ
スタ２のベースには位相がずれた２値ＲＺ信号と基準電
圧Ｖ　ｒｏｔが重畳されて印加される。At the same time, the modulated signal S of this binary RZ signal type 2 is input to the phase shift circuit 6 and its phase is shifted. For example, the signal is applied to the base of the transistor 2 of the semiconductor laser pulse modulation circuit after delaying the phase by 1/2 time loft. Therefore, the phase-shifted binary RZ signal and the reference voltage V rot are applied to the base of the transistor 2 in a superimposed manner.

此の印加信号により第２図に示す様に基準電圧を変化さ
せ、スレッショルドレベルを下げて等両市に立ち上がり
時間を早くする。This applied signal changes the reference voltage as shown in FIG. 2, lowering the threshold level and speeding up the rise time.

第２図（ａ）は２値ＲＺ信号の位相を１／２タイムスロ
フトずらした波形である。此の波形を基準電圧Ｖ、、ｓ
ｆに重畳すると第２図［ｂ）の太線の様にスレッショル
ドレベルが変化スル。FIG. 2(a) shows a waveform in which the phase of the binary RZ signal is shifted by 1/2 time loft. This waveform is set as the reference voltage V,,s
When superimposed on f, the threshold level changes as shown by the thick line in Figure 2 [b].

此の為“０”から“１″へ移動する点がＸからｙへ移動
してパルスの立ち上がり点が早くなり、パルス幅はθだ
け広くなる。For this reason, the point moving from "0" to "1" moves from X to Y, the rising point of the pulse becomes earlier, and the pulse width becomes wider by θ.

此の様にパルス幅を広くしてパターン効果による時間遅
れ、従ってパルス幅が狭くなるのを改善することが出来
る。By widening the pulse width in this manner, it is possible to improve the time delay caused by the pattern effect and therefore the narrowing of the pulse width.

〔発明の効果〕〔Effect of the invention〕

以上詳細に説明した様に本発明によれば簡単な付加回路
を設けることにより従来の半導体レーザパルス変調回路
の高速変調時に発生するパターン効果の影響を抑えるこ
とが可能となると云う大きい効果がある。As described in detail above, the present invention has the great effect of suppressing the influence of pattern effects that occur during high-speed modulation in conventional semiconductor laser pulse modulation circuits by providing a simple additional circuit.

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

第１図は本発明に依る半導体レーザパルス変調回路の一
実施例を示す図である。 第２図は本発明の動作原理の説明図である。 第３図は従来の半導体レーザパルス変調回路の一例を示
す図である。 第４図は従来の半導体レーザパルス変調回路に於けるパ
ターン効果の説明図である。 図中、１．２は夫々トランジスタ、３は抵抗、４はＬＤ
、５は電流源である。 本手ミ１７月［＝ｊＢ牛１４７令し一１７′；λ・ルズ
変捌弓εｆト亨　１　口FIG. 1 is a diagram showing an embodiment of a semiconductor laser pulse modulation circuit according to the present invention. FIG. 2 is an explanatory diagram of the operating principle of the present invention. FIG. 3 is a diagram showing an example of a conventional semiconductor laser pulse modulation circuit. FIG. 4 is an explanatory diagram of pattern effects in a conventional semiconductor laser pulse modulation circuit. In the figure, 1 and 2 are transistors, 3 is a resistor, and 4 is an LD.
, 5 is a current source. Hontemi 17 month [=jB cow 147 orders 1 17';

Claims (1)

【特許請求の範囲】 ＲＺ２値符号から構成されるパルス信号により変調を行
う半導体レーザ変調回路に於いて、前記ＲＺ２値符号を
ＲＺ→ＮＲＺ変換回路（７）によりＮＲＺ信号に変換し
て前記半導体レーザ変調回路の変調入力とし、 前記ＲＺ２値符号を位相シフト回路（６）により位相を
ずらした後前記半導体レーザ変調回路の基準電圧に重畳
することにより、其のスレッショルドレベルを変化させ
ることを特徴とする半導体レーザ変調回路。[Claims] In a semiconductor laser modulation circuit that performs modulation using a pulse signal composed of an RZ binary code, the RZ binary code is converted into an NRZ signal by an RZ→NRZ conversion circuit (7), and the semiconductor laser The RZ binary code is used as a modulation input of a modulation circuit, and its threshold level is changed by shifting the phase of the RZ binary code by a phase shift circuit (6) and then superimposing it on a reference voltage of the semiconductor laser modulation circuit. Semiconductor laser modulation circuit.
JP60144338A 1985-07-01 1985-07-01 Semiconductor laser modulation circuit Pending JPS625743A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP60144338A JPS625743A (en) 1985-07-01 1985-07-01 Semiconductor laser modulation circuit

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP60144338A JPS625743A (en) 1985-07-01 1985-07-01 Semiconductor laser modulation circuit

Publications (1)

Publication Number Publication Date
JPS625743A true JPS625743A (en) 1987-01-12

Family

ID=15359783

Family Applications (1)

Application Number Title Priority Date Filing Date
JP60144338A Pending JPS625743A (en) 1985-07-01 1985-07-01 Semiconductor laser modulation circuit

Country Status (1)

Country Link
JP (1) JPS625743A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0304075A2 (en) * 1987-08-19 1989-02-22 Fujitsu Limited Semiconductor laser modulation control system
JPH0531422U (en) * 1991-09-30 1993-04-23 日本電気株式会社 Foldable electronic device structure

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0304075A2 (en) * 1987-08-19 1989-02-22 Fujitsu Limited Semiconductor laser modulation control system
JPH0531422U (en) * 1991-09-30 1993-04-23 日本電気株式会社 Foldable electronic device structure

Similar Documents

Publication Publication Date Title
US5574392A (en) Asymmetrical ramp generator system
KR840008229A (en) Driving Method of Semiconductor Laser
KR100809241B1 (en) Pwm limiter
JPH0983050A (en) Method and circuit for driving semiconductor laser and external modulator
US3925735A (en) Modulation apparatus of semiconductor laser device
JPS625743A (en) Semiconductor laser modulation circuit
JPH04283978A (en) Laser diode drive circuit
US6643040B2 (en) Optical signal converter from RZ format to NRZ format
US4521766A (en) Code generator
JPH02246632A (en) Laser diode driving circuit
JP2661026B2 (en) Data strobe device
JPS6139650A (en) Clock phase fine adjusting circuit
JPH04130685A (en) Semiconductor laser driving circuit
JPH0334734A (en) Optical transmission circuit
JPH0666731B2 (en) Optical pulse train generation circuit
JPH0327633A (en) Laser diode driving system
JPH0142513B2 (en)
JPS59151481A (en) Driving circuit laser diode
JPH02281975A (en) Semiconductor laser light quantity control signal generator
JPH04121064A (en) Pwm control method for inverter
JP2833193B2 (en) Duty ratio variable circuit
WO2001022413A1 (en) Optically readable data carrier and manufacture thereof
JPH02151090A (en) Light emission driving circuit
JPS62257778A (en) Drive circuit for laser diode
JPH1155043A (en) Control circuit for amplifier