JPH0244420B2 - - Google Patents
Info
- Publication number
- JPH0244420B2 JPH0244420B2 JP60039352A JP3935285A JPH0244420B2 JP H0244420 B2 JPH0244420 B2 JP H0244420B2 JP 60039352 A JP60039352 A JP 60039352A JP 3935285 A JP3935285 A JP 3935285A JP H0244420 B2 JPH0244420 B2 JP H0244420B2
- Authority
- JP
- Japan
- Prior art keywords
- current
- reference current
- output
- current source
- laser diode
- 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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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
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/06—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium
- H01S5/068—Stabilisation of laser output parameters
- H01S5/0683—Stabilisation of laser output parameters by monitoring the optical output parameters
Landscapes
- Physics & Mathematics (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】
〔産業上の利用分野〕
この発明は光出力を容易に設定可能な光送信器
に関するものである。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical transmitter whose optical output can be easily set.
第４図は例えば昭和56年度電子通信学会総合全
国大会2246「キヤリア検出回路付100MD／Ｓレー
ザダイオード光送信器」に示された従来の光送信
器を示す構成図であり、第４図において、１は送
信データ入力端子、２は入力端子１に接続された
変調器、３は発光素子としてのレーザダイオー
ド、４は送信データの平均値検出回路、５は平均
値検出回路に接続された電圧増幅器、６は電圧増
幅器の基準電圧源、７は抵抗、８はレーザダイオ
ードの出力光の一部を受光する受光素子、９はこ
の受光素子８に並列接続されたコンデンサ、１０
は受光素子８のバイアス用電源、１１は電流増幅
器である。
FIG. 4 is a configuration diagram showing a conventional optical transmitter, which was shown in the 1981 IEICE National Conference 2246 "100MD/S Laser Diode Optical Transmitter with Carrier Detection Circuit". 1 is a transmission data input terminal, 2 is a modulator connected to input terminal 1, 3 is a laser diode as a light emitting element, 4 is a transmission data average value detection circuit, and 5 is a voltage amplifier connected to the average value detection circuit. , 6 is a reference voltage source of the voltage amplifier, 7 is a resistor, 8 is a light receiving element that receives a part of the output light of the laser diode, 9 is a capacitor connected in parallel to this light receiving element 8, 10
1 is a bias power source for the light receiving element 8, and 11 is a current amplifier.
従来の光送信器は上記の様に構成されていて、
送信データ入力端子１に加えられた送信データに
対応した電流が変調器２によつて変調され、レー
ザダイオード３に印加される。また、送信データ
は平均値検出回路４に加えられ、送信データの平
均値に比例した電圧が平均値検出回路４から出力
され、電圧増幅器５の一方の入力端に加えられ
る。電圧増幅器５の他方の入力端子には、基準電
圧源６が接続されている。電圧増幅器５は平均値
検出回路４と基準電流源６の差の電圧を増幅す
る。電圧増幅器５の出力電圧と電流増幅器１１の
入力電圧の溝を抵抗７で除した電流と受光素子８
を流れる電流の平均値の差が電流増幅器１１で増
幅され、レーザダイオード３に印加される。変調
器２と電流増幅器１１の出力電流の和がレーザダ
イオード３を流れ、光に変換され、その一部が光
出力として取り出される。また一部の光が受光素
子８に入射し、それに比例した電流が上記の受光
素子８を流れる電流である。 A conventional optical transmitter is configured as described above.
A current corresponding to the transmission data applied to the transmission data input terminal 1 is modulated by the modulator 2 and applied to the laser diode 3. Further, the transmitted data is applied to the average value detection circuit 4, and a voltage proportional to the average value of the transmitted data is outputted from the average value detection circuit 4 and applied to one input terminal of the voltage amplifier 5. A reference voltage source 6 is connected to the other input terminal of the voltage amplifier 5. The voltage amplifier 5 amplifies the voltage difference between the average value detection circuit 4 and the reference current source 6. The current obtained by dividing the gap between the output voltage of the voltage amplifier 5 and the input voltage of the current amplifier 11 by the resistor 7 and the light receiving element 8
The difference between the average values of the currents flowing through is amplified by the current amplifier 11 and applied to the laser diode 3. The sum of the output currents of the modulator 2 and the current amplifier 11 flows through the laser diode 3 and is converted into light, a part of which is taken out as optical output. Further, a part of the light enters the light receiving element 8, and a current proportional to the light is a current flowing through the light receiving element 8.
したがつて、レーザダイオード３の光出力が大
きくなると受光素子８を流れる電流が増え、電流
増幅器１１の出力電流が少なくなり、レーザダイ
オード３の光出力が減少する。レーザダイオード
３の光出力が減少した場合は上記と逆の理由でレ
ーザダイオード３の光出力が大きくなる。この負
帰還動作によつて、レーザダイオード３の光出力
がある一定値に保たれる。デイジタル信号を伝送
する際の光信号のピーク値に着目すると、レーザ
ダイオード３の光出力のピーク値Pputは次の様に
表わされる。 Therefore, when the optical output of the laser diode 3 increases, the current flowing through the light receiving element 8 increases, the output current of the current amplifier 11 decreases, and the optical output of the laser diode 3 decreases. When the optical output of the laser diode 3 decreases, the optical output of the laser diode 3 increases for the opposite reason to the above. This negative feedback operation maintains the optical output of the laser diode 3 at a certain constant value. Focusing on the peak value of an optical signal when transmitting a digital signal, the peak value P put of the optical output of the laser diode 3 is expressed as follows.
Pput＝Ａ（IB＋IOP−Ith） ……(1)
ただし
IB＝β（IO−IPD） ……(2)
IPD＝ｍ・Ｄ・Ｌ・Pput ……(3)
IB：バイアス電流（電流増幅器出力電流）
IOP：変調電流（変調器出力電流）
Ith：レーザダイオードしきい値電流
β：電流増幅器増幅率
IPD：受光素子電流
IO：基準電流
ｍ：デイジタル信号のマーク率（０＜ｍ≦１）
Ｌ：光出力と受光素子電流変換効率
Ａ：レーザダイオード電流・光変換効率
Ｄ：パルス占有率
なお、レーザダイオード３は第５図に示すよう
に、しきい値電流Ith以下では発光しないものと
する。 P put = A (I B + I OP − I th ) …(1) However, I B = β (I O − I PD ) …(2) I PD = m・D・L・P put …(3 ) I B : Bias current (current amplifier output current) I OP : Modulation current (modulator output current) I th : Laser diode threshold current β: Current amplifier amplification factor I PD : Photodetector current I O : Reference current m : Mark rate of digital signal (0<m≦1) L: Light output and photodetector current conversion efficiency A: Laser diode current/light conversion efficiency D: Pulse occupancy rate The laser diode 3 is as shown in FIG. , it is assumed that no light is emitted below the threshold current I th .
第(1)式、第(2)式、第(3)式より
PputＡ・βIO＋Ａ（IOP−Ith）／１＋Ａ・β・ｍ・Ｄ
・Ｌ……(4)
となる。 From equations (1), (2), and (3), P put A・βI O +A(I OP −I th )/1+A・β・m・D
・L...(4) becomes.
第(4)式において、マーク率ｍが変化しても光出
力Pputが一定であるためにはマーク率に応じて基
準電流IOを制御する必要がある。そこで、Pput＝
Ｋ（一定）とおくと、
IO＝IO1＋mIO2 ……(5)
ただし、
IO1＝Ｋ／Ａ・β−IOP−Ith／β
IO2＝Ｋ・Ｄ・Ｌ
となる。したがつて第(5)式に従つて基準電流IOを
設定すれば、光出力Pputは一定となる。 In equation (4), in order to keep the optical output P put constant even if the mark rate m changes, it is necessary to control the reference current I O according to the mark rate. Therefore, P put =
Assuming K (constant), I O = I O1 + mI O2 ... (5) However, I O1 = K/A・β−I OP −I th /β I O2 = K・D・L. Therefore, if the reference current I O is set according to equation (5), the optical output P put will be constant.
第４図において基準電流は抵抗７を流れる電流
であり、抵抗７を流れる電流IO′は次式で表わさ
れる。 In FIG. 4, the reference current is the current flowing through the resistor 7, and the current I O ' flowing through the resistor 7 is expressed by the following equation.
IO′＝Ｇ（ｍ・Ｄ・VP−Vref）−Vio／Ｒ
＝−（GVref＋Vio）／Ｒ＋ｍ・Ｄ・GVP／Ｒ……(6)
ただし、
VP：平均値検出回路のｍ＝１のときの出力電
圧
Vref：基準電圧源電圧
Vio：電流増幅器入力電圧
Ｇ：電圧増幅器の増幅率
Ｒ：抵抗７の抵抗値
所定の光出力を得るには、基準電流源６と抵抗
７を調整することにより、
IO1＝−（GVref＋Vio）／Ｒ ……(7)
IO2＝GDVP／Ｒ ……(8)
に設定する。第(7)式はｍ＝０のときの基準電流で
ある。 I O ′=G(m・D・V P −V ref )−V io /R =−(GV ref +V io )/R+m・D・GV P /R……(6) However, V P : Average value Output voltage of the detection circuit when m=1 V ref : Reference voltage source voltage V io : Current amplifier input voltage G : Amplification factor of voltage amplifier R : Resistance value of resistor 7 In order to obtain a predetermined optical output, the reference current is By adjusting the source 6 and the resistor 7, the following is set: I O1 =-(GV ref +V io )/R (7) I O2 = GDV P /R (8). Equation (7) is the reference current when m=0.
以上の様に従来の光送信器は構成されていたの
で、第(6)式において、抵抗７の値Ｒが、マーク率
ｍの影響を受ける項と受けない項の両方に含まれ
ている。抵抗７によりIO2を設定する場合、IO1も
変化するので、Vrefを再度調整し、両者が目標値
に達するまで繰り返し設定する必要があり、光出
力の設定方法が複雑であるという問題点があつ
た。
Since the conventional optical transmitter is configured as described above, in equation (6), the value R of the resistor 7 is included in both the term affected by the mark ratio m and the term not affected. When setting I O2 using resistor 7, I O1 also changes, so it is necessary to readjust V ref and set it repeatedly until both reach the target value, making the method for setting the optical output complicated. It was hot.
この発明は、この様な問題点を解決するために
なされたもので、光出力の設定、すなわち基準電
流の設定が容易な光送信器を得ることを目的とし
ている。 The present invention was made to solve these problems, and an object of the present invention is to provide an optical transmitter in which the setting of the optical output, that is, the setting of the reference current is easy.
この発明による光送信器は、基準電流源を、第
１の基準電流源と、第２の基準電流源と、上記第
２の基準電流源の出力端に接続され送信データに
対応してオン・オフするスイツチ回路と、上記第
１の基準電流源の出力と上記スイツチ回路の出力
とを合成する合成手段とにより構成したものであ
る。
The optical transmitter according to the present invention has a reference current source connected to a first reference current source, a second reference current source, and an output terminal of the second reference current source, and turned on and off in response to transmission data. It is constructed of a switch circuit that turns off, and a synthesizing means that synthesizes the output of the first reference current source and the output of the switch circuit.
この発明においては、使用する２個の基準電流
源の出力をそれぞれ独立に設定できるため、マー
ク率変動に対する光出力設定が容易になる。
In this invention, since the outputs of the two reference current sources used can be set independently, it becomes easy to set the optical output in response to mark rate fluctuations.
第１図はこの発明の一実施例を示す光送信器の
構成図であり、１は送信データ入力端子、２は入
力端子１に接続された変調器、３はレーザダイオ
ード、８はレーザダイオード３の出力光の一部を
受光する受光素子、９はこの受光素子８に並列接
続されたコンデンサ、１０は受光素子８のバイア
ス用電源、１１は電流増幅器、１２は第１の基準
電流源、１３は第２の基準電流源、１４は第２の
基準電流源１３の出力端に接続され、２値送信デ
ータに対応して切換えるスイツチ回路である。い
ま、送信データが“１”のとき、レーザダイオー
ド１が発光するように変調器２は動作し、スイツ
チ回路１４は導通状態になるものとする。
FIG. 1 is a configuration diagram of an optical transmitter showing an embodiment of the present invention, in which 1 is a transmission data input terminal, 2 is a modulator connected to the input terminal 1, 3 is a laser diode, and 8 is a laser diode 3. 9 is a capacitor connected in parallel to the light receiving element 8; 10 is a power supply for biasing the light receiving element 8; 11 is a current amplifier; 12 is a first reference current source; is a second reference current source, and 14 is a switch circuit connected to the output terminal of the second reference current source 13 and switched in response to binary transmission data. Assume now that when the transmission data is "1", the modulator 2 operates so that the laser diode 1 emits light, and the switch circuit 14 becomes conductive.
上記のように構成された光送信器において第２
の基準電流源１３の出力は送信データに対応して
スイツチ回路１４でオン・オフされた電流として
出力され、第１の基準電流源１２の出力と加算合
成される。レーザダイオード３の出力光の一部が
受光素子８に入射し、それに比例した電流が受光
素子８を流れる。受光素子８を流れる電流と上記
合成された電流の差がコンデンサ９で平均化され
電流増幅器１１で増幅されレーザダイオード３に
印加される。 In the optical transmitter configured as above, the second
The output of the reference current source 13 is outputted as a current that is turned on and off by the switch circuit 14 in accordance with the transmission data, and is added and synthesized with the output of the first reference current source 12. A portion of the output light from the laser diode 3 is incident on the light receiving element 8, and a current proportional to the amount enters the light receiving element 8. The difference between the current flowing through the light receiving element 8 and the combined current is averaged by a capacitor 9, amplified by a current amplifier 11, and applied to the laser diode 3.
ここで、第１の基準電流源１２の電流値を式(5)
のIO1、第２の基準電流源１３の電流値を第(5)式
のIO2に対応させることができる。そこで、マー
ク率ｍ＝０のときにIO1を設定し、しかる後に適
当なマーク率ｍにてIO2を設定すれば、基準電流IO
が決定できる。したがつて、IO1IO2が独立に設定
することができ、容易に基準電流、すなわち光出
力が設定できる。 Here, the current value of the first reference current source 12 is expressed by equation (5).
The current value of the second reference current source 13 can be made to correspond to I O2 in equation (5). Therefore, if I O1 is set when the mark rate m=0, and then I O2 is set at an appropriate mark rate m, the reference current I O
can be determined. Therefore, I O1 I O2 can be set independently, and the reference current, that is, the optical output, can be easily set.
第２図は第１図に示したこの発明の一実施例の
回路図である。第２図では、スイツチ回路１４を
論理ゲートＧおよびトランジスタTrを備えてな
る電流切換スイツチで構成している。スイツチ回
路に電流切換スイツチ回路を用いることで高速の
スイツチングが可能となり、高ビツトレートの光
送信器が構成できる。また第２図では第１、第２
の基準電流源１２，１３をトランジスタTrおよ
び抵抗r1でそれぞれ構成し、又電流増幅器１１を
トランジスタTr、抵抗r2で構成している例を示し
ている。 FIG. 2 is a circuit diagram of one embodiment of the invention shown in FIG. In FIG. 2, the switch circuit 14 is constituted by a current changeover switch comprising a logic gate G and a transistor Tr . By using a current changeover switch circuit as the switch circuit, high-speed switching becomes possible and a high bit rate optical transmitter can be constructed. Also, in Figure 2, the first and second
An example is shown in which the reference current sources 12 and 13 are each composed of a transistor T r and a resistor r 1 , and the current amplifier 11 is composed of a transistor T r and a resistor r 2 .
なおここでは第１の基準電流源１２と、第２の
基準電流源１３が加算される構成としたが減算さ
れる構成した場合の実施例を第３図に示す。第３
図において、スイツチ回路１４が、送信データ
“０”に対して導通状態とすると、マーク率ｍ＝
１でIO1を設定すれば同様の効果が得られる。 Here, the first reference current source 12 and the second reference current source 13 are configured to be added, but FIG. 3 shows an embodiment in which they are configured to be subtracted. Third
In the figure, if the switch circuit 14 is in a conductive state for transmission data "0", the mark rate m=
A similar effect can be obtained by setting I O1 to 1.
この発明は以上説明したとおり、基準電流源と
して第１の基準電流源の出力と、別の第２の基準
電流源に接続した送信データと対応して切換える
切換回路の出力との合成出力を用いているため、
使用する２個の基準電流源の出力がそれぞれ独立
に設定できるため、光出力の設定が容易になる効
果がある。
As explained above, this invention uses, as a reference current source, a composite output of the output of a first reference current source and the output of a switching circuit connected to another second reference current source and switched in response to transmission data. Because
Since the outputs of the two reference current sources used can be set independently, the optical output can be easily set.
第１図はこの発明の一実施例を示す光送信器の
構成図、第２図は、第１図に示したこの発明の一
実施例の具体的な回路を示す図、第３図はこの発
明の他の実施例を示す構成図、第４図は従来の光
送信器を示す構成図、第５図はレーザダイオード
の電流・光出力の関係を示す図である。
図において、１は送信データ入力端子、２は変
調器、３はレーザダイオード、４は平均値検出回
路、５は電圧増幅器、６は基準電圧源、７は抵
抗、８は受光素子、９はコンデンサ、１０は受光
素子バイアス用電源、１１は電流増幅器、１２，
１３は第１，第２の基準電流源、１４はスイツチ
回路である。なお、各図中同一符号は同一または
相当部分を示す。
FIG. 1 is a block diagram of an optical transmitter showing an embodiment of the present invention, FIG. 2 is a diagram showing a specific circuit of the embodiment of the invention shown in FIG. FIG. 4 is a block diagram showing another embodiment of the invention, FIG. 4 is a block diagram showing a conventional optical transmitter, and FIG. 5 is a diagram showing the relationship between current and light output of a laser diode. In the figure, 1 is a transmission data input terminal, 2 is a modulator, 3 is a laser diode, 4 is an average value detection circuit, 5 is a voltage amplifier, 6 is a reference voltage source, 7 is a resistor, 8 is a light receiving element, and 9 is a capacitor , 10 is a light receiving element bias power supply, 11 is a current amplifier, 12,
13 is a first and second reference current source, and 14 is a switch circuit. Note that the same reference numerals in each figure indicate the same or corresponding parts.
Claims (1)
子に印加する変調器と、上記発光素子の出力光の
一部を受光する受光素子と、上記受光素子を流れ
る信号電流と基準電流源の電流の差に比例した電
流を上記発光素子に印加する手段とを備えた光送
信器において、上記基準電流源を、第１の基準電
流源と、第２の基準電流源と、上記第２の基準電
流源の出力端に接続され２値送信データに応じて
オン・オフするスイツチ回路と、上記第１の基準
電流源の出力と上記スイツチ回路の出力とを合成
する合成手段とにより構成したことを特徴とする
光送信器。 ２ スイツチ回路として電流切換スイツチを用い
たことを特徴とする特許請求範囲第１項記載の光
送信器。[Scope of Claims] 1. A modulator that applies a binary current to a light emitting element in response to binary transmission data, a light receiving element that receives part of the output light of the light emitting element, and a signal flowing through the light receiving element. and means for applying a current proportional to the difference between a current and a current of a reference current source to the light emitting element, wherein the reference current source is a first reference current source and a second reference current source. , a switch circuit connected to the output terminal of the second reference current source and turned on/off according to the binary transmission data, and a synthesis circuit for synthesizing the output of the first reference current source and the output of the switch circuit. An optical transmitter comprising: 2. The optical transmitter according to claim 1, characterized in that a current changeover switch is used as the switch circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP60039352A JPS61198934A (en) | 1985-02-28 | 1985-02-28 | Optical transmitter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP60039352A JPS61198934A (en) | 1985-02-28 | 1985-02-28 | Optical transmitter |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS61198934A JPS61198934A (en) | 1986-09-03 |
| JPH0244420B2 true JPH0244420B2 (en) | 1990-10-03 |
Family
ID=12550680
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP60039352A Granted JPS61198934A (en) | 1985-02-28 | 1985-02-28 | Optical transmitter |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS61198934A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH1093170A (en) * | 1996-09-10 | 1998-04-10 | Fuji Xerox Co Ltd | Laser diode drive circuit, semiconductor integrated circuit for driving laser diode, and image recorder |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| IT1239537B (en) * | 1989-01-20 | 1993-11-05 | Mitsubishi Electric Corp | OPTICAL TRANSMISSION EQUIPMENT. |
| DE19503410A1 (en) * | 1995-02-02 | 1996-08-08 | Siemens Ag | Regulation of two values of the optical power emitted by a laser diode using only one controller |
| JP4655457B2 (en) * | 2003-08-08 | 2011-03-23 | 富士ゼロックス株式会社 | Light quantity control device and image forming apparatus using the same |
-
1985
- 1985-02-28 JP JP60039352A patent/JPS61198934A/en active Granted
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH1093170A (en) * | 1996-09-10 | 1998-04-10 | Fuji Xerox Co Ltd | Laser diode drive circuit, semiconductor integrated circuit for driving laser diode, and image recorder |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS61198934A (en) | 1986-09-03 |
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