JPS63254778A - Semiconductor-laser driving system - Google Patents
Semiconductor-laser driving systemInfo
- Publication number
- JPS63254778A JPS63254778A JP62090168A JP9016887A JPS63254778A JP S63254778 A JPS63254778 A JP S63254778A JP 62090168 A JP62090168 A JP 62090168A JP 9016887 A JP9016887 A JP 9016887A JP S63254778 A JPS63254778 A JP S63254778A
- Authority
- JP
- Japan
- Prior art keywords
- converter
- optical output
- current
- output
- constant
- 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
Links
- 230000003287 optical effect Effects 0.000 claims abstract description 23
- 239000004065 semiconductor Substances 0.000 claims description 12
- 238000013139 quantization Methods 0.000 description 5
- 238000010586 diagram Methods 0.000 description 4
- 238000000034 method Methods 0.000 description 3
- 239000003990 capacitor Substances 0.000 description 2
- 230000010355 oscillation Effects 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
Classifications
-
- 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
- H01S5/062—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium by varying the potential of the electrodes
- H01S5/06209—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium by varying the potential of the electrodes in single-section lasers
-
- 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
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
- H05B45/10—Controlling the intensity of the light
- H05B45/14—Controlling the intensity of the light using electrical feedback from LEDs or from LED modules
-
- 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
- H01S5/04—Processes or apparatus for excitation, e.g. pumping, e.g. by electron beams
- H01S5/042—Electrical excitation ; Circuits therefor
-
- 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
- H01S5/0617—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium using memorised or pre-programmed laser characteristics
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
- H05B45/30—Driver circuits
Landscapes
- Physics & Mathematics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Optics & Photonics (AREA)
- Semiconductor Lasers (AREA)
Abstract
Description
【発明の詳細な説明】
〈産業上の利用分野〉
この発明は、半導体レーザを駆動する方法に関するもの
である。DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for driving a semiconductor laser.
〈従来の技術〉
半導体レーザは、ある種のPN接合に順方向電流IFを
流すことによりレーザ光を得るもので、IFと光出力P
oとの関係はリニアでなく、IFを増加していくと、あ
る電流1thでレーザ発振が始まり、以後はIFの増加
と共にレーザ光出力P。<Prior art> A semiconductor laser obtains laser light by passing a forward current IF through a type of PN junction, and the IF and optical output P are
The relationship with o is not linear; as IF is increased, laser oscillation begins at a certain current 1th, and thereafter, as IF increases, laser light output P increases.
も増加する。この特性を第2図に示す。will also increase. This characteristic is shown in FIG.
ところが、1thや微分効率ηと呼ばれるIpの変化に
対するPoの変化の割合は一定ではなく、周囲温度や個
体によって変化する。However, the ratio of change in Po to change in Ip, called 1th or differential efficiency η, is not constant and changes depending on the ambient temperature and the individual.
このような半導体レーザを一定光出力で駆動するために
、第3図に示す方式が一般に用いられている。1は半導
体レーザで、増幅器3の出力で制御される電流源4によ
って駆動される。また光出力はホトダイオード2によっ
てモニタされ、第3図では抵抗5によって電圧に変換さ
れる。この電圧は増幅器3に入力され、全体で負帰還ル
ープを構成している0増幅器3の一方の入力には、基準
電圧Vrefが印加されており、結局光出方は基準電圧
で規定される一定値になる。In order to drive such a semiconductor laser with a constant optical output, a method shown in FIG. 3 is generally used. 1 is a semiconductor laser, which is driven by a current source 4 controlled by the output of an amplifier 3; The light output is also monitored by a photodiode 2 and converted into a voltage by a resistor 5 in FIG. This voltage is input to the amplifier 3, and the reference voltage Vref is applied to one input of the amplifier 3, which constitutes a negative feedback loop as a whole, and the way the light is output is a constant determined by the reference voltage. Becomes a value.
第3図は、定常的に一定光出力を得るための構成である
が、ある種の応用においては、一定光出力を高速でオン
・オフする必要が生じる。その場合は例えば、第4図に
示す構成が用いられる。第4図は第3図の構成に、アナ
ログスイッチ7と静電容量8で構成されるサンプルホー
ルド回路と、高速電流スイッチ6、およびバクファアン
プ9を追加したものである。第4図の動作は次のような
ものである。まず、電流スイッチ6を右側に、スイッチ
7をオンにして、基準電圧Vrefで規定される一定光
出力を得る。次に7をオーブンにする。Although FIG. 3 shows a configuration for constantly obtaining a constant light output, in certain applications, it becomes necessary to turn on and off the constant light output at high speed. In that case, for example, the configuration shown in FIG. 4 is used. FIG. 4 shows the configuration of FIG. 3 with the addition of a sample and hold circuit composed of an analog switch 7 and a capacitance 8, a high-speed current switch 6, and a backup amplifier 9. The operation of FIG. 4 is as follows. First, the current switch 6 is turned to the right side and the switch 7 is turned on to obtain a constant optical output defined by the reference voltage Vref. Next, turn 7 into the oven.
このとき、ホールド容量8で電圧が保持されるので、半
導体レーザを駆動する電流は、変化しない。At this time, since the voltage is held by the hold capacitor 8, the current that drives the semiconductor laser does not change.
そうして電流スイッチ6を高速でオン・オフして、光出
力をオン・オフする。第4図の構成の場合、容量8でホ
ールドされる電圧はアナログ量のため、長時間一定値を
保持するのは困難である。長時間知わだって光出力を一
定に保つことができるように考えられたのが次の第5図
の駆動方法である。Then, the current switch 6 is turned on and off at high speed to turn on and off the optical output. In the case of the configuration shown in FIG. 4, since the voltage held by the capacitor 8 is an analog quantity, it is difficult to maintain a constant value for a long time. The following driving method shown in FIG. 5 was designed to keep the optical output constant over a long period of time.
第5図は、第4図のサンプルホールド部トバッファアン
プを除いて、アップ/ダウン・カウンタIIとD/A変
換器10と発振器12を導入したもので、増幅器3はコ
ンパレータとして働く。アップ/ダウン−カウンタ11
は、コンパレータ3の出力が’HIGH’の場合、発振
器I2の出力パルスをカウントアツプして、逆に’to
w’の場合カウントダウンするQカウント結果はD/A
変換器■0でIFに変換され、レーザダイオード1を駆
動する。第5図では、電流スイッチ6が右側に倒れた場
合に、全体として負帰還ループを構成して光出力は基準
電圧Vrefで規定される値になる。 ′第5図の場
合1力ウント分の誤差は生じるが、帰還ループ中にディ
ジタルコードとなる部分があるため、長時間ホールドに
ついても問題ない。但し、前述のように半導体レーザの
IF−Po特性が17 ニアでないため、高精度で一定
光出力を得るには、高分解能のD/A変換器が必要にな
る。In FIG. 5, an up/down counter II, a D/A converter 10, and an oscillator 12 are introduced, except for the sample-and-hold section and buffer amplifier of FIG. 4, and the amplifier 3 functions as a comparator. Up/Down-Counter 11
When the output of comparator 3 is 'HIGH', the output pulse of oscillator I2 is counted up and conversely 'to'
In the case of w', the Q count result that counts down is D/A
It is converted into an IF by the converter 0 and drives the laser diode 1. In FIG. 5, when the current switch 6 falls to the right, a negative feedback loop is formed as a whole, and the optical output becomes a value defined by the reference voltage Vref. 'In the case of FIG. 5, an error equivalent to one force count occurs, but since there is a part that becomes a digital code in the feedback loop, there is no problem even when holding for a long time. However, as mentioned above, since the IF-Po characteristics of the semiconductor laser are not 17 degrees near, a high-resolution D/A converter is required to obtain a constant optical output with high precision.
〈発明が解決しようとする問題点〉
第5図の方式において、半導体レーザのll−−Po特
性で、IPが1thに満たない場合レーザ発振は起こら
ない。よって、IFが1th以下の領域は制御に用いる
ことができない。そのために、IFの量子化誤差に比べ
てPOの量子化誤差は大きくなる。本発明は上述の問題
点を解決し、Poの制御精度を上げることを目的として
いる。<Problems to be Solved by the Invention> In the system shown in FIG. 5, laser oscillation does not occur if the IP is less than 1th due to the ll--Po characteristics of the semiconductor laser. Therefore, a region where the IF is 1th or less cannot be used for control. Therefore, the quantization error of PO becomes larger than the quantization error of IF. The present invention aims to solve the above-mentioned problems and improve the control accuracy of Po.
く問題点を解決するための手段〉 第5図のD/A変換器を非線形なものにする。Means to solve problems〉 The D/A converter shown in FIG. 5 is made nonlinear.
〈実施例〉
更に詳しく説明すると、ディジタルコードをD/A変換
器の入力、IFを出力と考えた場合、IFがIthに満
たない部分の量子化幅は大きくて、IF ・が1th
以上では小さな量子化幅を有するD/A変換器を用いる
。例えば第6図に示した特性のD/A変換器と同一ビッ
ト数で、ディジタルコードト!Fの関係が第1図(、)
のようなり/A変換器を用いた場合、Poの量子化幅は
、第6図の特性を有するD/A変換器を用いた場合に比
べて小さくすることができ、同一ビット数のD/A変換
器を用いてもより高精度の制御が可能になる。第6図(
b)は、従来の線形なり/A変換器を用いた場合の、デ
ィジタルコードと光出力Po との関係であるが、1t
h以下に対応するディジタルコード部は光出力如寄与し
ないため、実際に有効なコードは制限されて、実効的な
分解能は下がっている。これに対し第1図(b)の場合
、1th以下に対応するディジタルコードの数は、その
非線形性のために少なく、光出力POの制御に有効に用
いることのできるコードの数が多くなる。<Example> To explain in more detail, when considering the digital code as the input of a D/A converter and the IF as the output, the quantization width of the part where IF is less than Ith is large, and IF is 1th.
In the above, a D/A converter having a small quantization width is used. For example, with the same number of bits as the D/A converter with the characteristics shown in FIG. The relationship between F is shown in Figure 1 (,)
When using a D/A converter like this, the quantization width of Po can be made smaller than when using a D/A converter having the characteristics shown in FIG. Even if an A converter is used, more accurate control is possible. Figure 6 (
b) is the relationship between the digital code and the optical output Po when a conventional linear/A converter is used;
Since the digital code portion corresponding to h or less does not contribute much to the optical output, the actually effective codes are limited and the effective resolution is lowered. On the other hand, in the case of FIG. 1(b), the number of digital codes corresponding to 1th or less is small due to its nonlinearity, and the number of codes that can be effectively used for controlling the optical output PO is large.
〈発明の効果〉
同一性能のシステムをよシ簡単な、また実現しやすい低
分解能のD/A変換器を用いて構成できるため、製品の
低価格化が図れる。また、システムの集積回路化も容易
になる。<Effects of the Invention> Since a system with the same performance can be constructed using a simpler and easier to implement low-resolution D/A converter, the cost of the product can be reduced. Furthermore, it becomes easier to integrate the system into an integrated circuit.
第1図は、第5図において非線形なり/A変換器を用い
た場合の、ディジタルコードと、順方向電流IFおよび
光出力Paとの関係の一例を示す図、第2図は、レーザ
ダイオードの順方向電流IFと光出力Poとの関係を示
す図、第3図は、一定光出力を得るための半導体レーザ
駆動回路ブロック例を示す図、第4図は、サンプルホー
ルド回路を用いた一定光出力の高速スイッチングを行う
だめの半導体レーザ駆動回路ブロック例を示す図、第5
図は、光出力設定フィードバックルーズにD/A変換器
を挿入した、一定光出力の高速スイッチングを行うため
の半導体レーザ駆動回路ブロック例を示す図、第6図は
、第5図において線形なり/A変換器を用いた場合の、
ディジタルコードと、順方向電流IFおよび光出力Pa
との関係を示す図である。
符号の説明
1・・・半導体レーザ(レーザダイオード)、2・・・
光出力モニタ用ホトダイオード、3・・・増幅器、4・
・・電流源、5・・・抵抗、6・・・高速電流スイッチ
、7・・・アナログスイッチ、8・・・電圧ホールド用
静電容量、9・・・バッファアンプ、10・・・D/A
変換器、11・・・アップ/ダウン・カウンタ、12・
・・発振器。
代理人 弁理士 杉 山 毅 至(他1名)第 l 図
第2図 第3図
!
$4図
z
第5図
子°゛イジタルフー
ドQ)
軍
(b)
6 図FIG. 1 is a diagram showing an example of the relationship between the digital code, forward current IF, and optical output Pa when the nonlinear A/A converter is used in FIG. 5, and FIG. A diagram showing the relationship between forward current IF and optical output Po, FIG. 3 is a diagram showing an example of a semiconductor laser drive circuit block for obtaining constant optical output, and FIG. 4 is a diagram showing the relationship between forward current IF and optical output Po. Figure 5 shows an example of a semiconductor laser drive circuit block for high-speed output switching.
The figure shows an example of a semiconductor laser drive circuit block for performing high-speed switching with a constant optical output, in which a D/A converter is inserted with loose optical output setting feedback. When using A converter,
Digital code, forward current IF and optical output Pa
FIG. Explanation of symbols 1... Semiconductor laser (laser diode), 2...
Photodiode for optical output monitor, 3...Amplifier, 4...
...Current source, 5...Resistor, 6...High speed current switch, 7...Analog switch, 8...Capacitance for voltage hold, 9...Buffer amplifier, 10...D/ A
Converter, 11...Up/down counter, 12.
...Oscillator. Agent Patent Attorney Takeshi Sugiyama (and 1 other person) Figure 2 Figure 3! $4 Figure z Figure 5 Child°゛Igital Food Q) Army (b) 6 Figure
Claims (1)
D/A変換器を備えたことを特徴とする、半導体レーザ
駆動方式。1. A semiconductor laser driving system characterized by having a nonlinear D/A converter in the feedback loop for obtaining a constant optical output.
Priority Applications (8)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP62090168A JPS63254778A (en) | 1987-04-13 | 1987-04-13 | Semiconductor-laser driving system |
DE3854202T DE3854202T2 (en) | 1987-04-13 | 1988-04-13 | Apparatus for operating a semiconductor laser device. |
EP92201060A EP0497431B1 (en) | 1987-04-13 | 1988-04-13 | An apparatus for driving a semiconductor laser device |
DE8888303348T DE3879250T2 (en) | 1987-04-13 | 1988-04-13 | CONTROL DEVICE FOR A SEMICONDUCTOR LASER. |
EP92201061A EP0497432B1 (en) | 1987-04-13 | 1988-04-13 | An apparatus for driving a semiconductor laser device |
EP88303348A EP0287360B1 (en) | 1987-04-13 | 1988-04-13 | An apparatus for driving a semiconductor laser device |
DE3854094T DE3854094T2 (en) | 1987-04-13 | 1988-04-13 | Apparatus for operating a semiconductor laser device. |
US07/368,106 US4912714A (en) | 1987-04-13 | 1989-06-19 | Apparatus for driving a semiconductor laser device |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP62090168A JPS63254778A (en) | 1987-04-13 | 1987-04-13 | Semiconductor-laser driving system |
Publications (1)
Publication Number | Publication Date |
---|---|
JPS63254778A true JPS63254778A (en) | 1988-10-21 |
Family
ID=13990955
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP62090168A Pending JPS63254778A (en) | 1987-04-13 | 1987-04-13 | Semiconductor-laser driving system |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPS63254778A (en) |
-
1987
- 1987-04-13 JP JP62090168A patent/JPS63254778A/en active Pending
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