JPS5994482A - Semiconductor laser drive circuit - Google Patents
Semiconductor laser drive circuitInfo
- Publication number
- JPS5994482A JPS5994482A JP20307082A JP20307082A JPS5994482A JP S5994482 A JPS5994482 A JP S5994482A JP 20307082 A JP20307082 A JP 20307082A JP 20307082 A JP20307082 A JP 20307082A JP S5994482 A JPS5994482 A JP S5994482A
- Authority
- JP
- Japan
- Prior art keywords
- modulation
- signal
- current
- level
- section
- 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.)
- Granted
Links
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
- H01S5/068—Stabilisation of laser output parameters
- H01S5/0683—Stabilisation of laser output parameters by monitoring the optical output parameters
- H01S5/06832—Stabilising during amplitude modulation
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- 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】 (a) 発明の技術分野 本発明は半導体レーザ駆動回路の改良に関する。[Detailed description of the invention] (a) Technical field of the invention The present invention relates to improvements in semiconductor laser drive circuits.
(b) 技術の背景
半導体レーザ素子は通常ダブルへテロ構造による化合物
半導体の接合面に垂直な2つの平行平面を研摩またはへ
き開して光反射面とし、素子の胆方同にバイアス電流を
流して得られる接合の活性層に訃ける電子正孔再結合エ
ネルギによる光子放射を増幅発振して得るコヒーレント
光を該反射面よシ出力せしめる′1流−光変換素子であ
る。エネルギの大部分はpおよびn領域を通りこれ等の
領域に固有の吸収係数で減衰するが、このモード損失の
他両端面の反射面からの透過損等が存在し、この損失金
上廻るレーザ発振の開始条件即ちバイアス電流のしきい
値が存在する。レーザ半導体におけるしきい値電流密度
は150A以上/dに及び、発光効率が低いので直流バ
イアスによる駆動′直流の大部分は熱として消費される
ため素子の冷却条件が厳しい上素子間におけるしきい値
電流の力
バラツキおよび先出11rt流特性の接合部温度に対す
る依存性も極めて大きい。(b) Background of the technology Semiconductor laser devices are usually made by polishing or cleaving two parallel planes perpendicular to the junction surface of a compound semiconductor with a double heterostructure to create light-reflecting surfaces, and applying a bias current to both sides of the device. This is a 1st current-to-light conversion element that amplifies and oscillates photon radiation due to electron-hole recombination energy in the active layer of the resulting junction and outputs coherent light from the reflective surface. Most of the energy passes through the p and n regions and is attenuated by absorption coefficients specific to these regions, but in addition to this mode loss, there are transmission losses from the reflective surfaces on both end faces, and this loss is exceeded by the laser. There is a condition for starting oscillation, ie a threshold of bias current. The threshold current density in a laser semiconductor is over 150 A/d, and the luminous efficiency is low, so it is driven by a DC bias.Most of the DC is consumed as heat, so the cooling conditions for the device are severe, and the threshold voltage between the devices is low. The dependence of the current force variation and the aforementioned 11rt flow characteristics on the junction temperature is also extremely large.
(e) 従来技術と問題点
従来より半導体レーザ素子に上記のようにしきい値′−
流のバラツキおよび特性の温度依存性が大きいため、通
常素子のレーザ光出力側とは逆側のレーザ光出力に比例
する後方モニタ元ヲ受光する受光素子の検出電流に従い
直流バイアス電流を制御する手段によって実用化してお
り、開放制御による一意的な直流バイアス電流による駆
動方式は少い。従来のモニタ光の検出′直流に基く帰還
制御による駆動方法によっても半導体レーザ素子は特性
にバラツキが多く、且非可視光となる場合が多いので、
その光出力を規定値に設定する手段は、試行錯誤的に測
定データに基いてNuする方法によっており、手数が煩
わしい上にコストが嵩む欠点があった。(e) Conventional technology and problems Conventionally, semiconductor laser devices have a threshold value of
Since the current variation and the temperature dependence of the characteristics are large, there is a means to control the DC bias current according to the detection current of the light receiving element that receives light from the rear monitor source, which is proportional to the laser light output on the side opposite to the laser light output side of the element. There are few drive systems using a unique DC bias current based on open control. Detection of conventional monitor light 'Due to the drive method using feedback control based on direct current, semiconductor laser elements have many variations in characteristics and often produce invisible light.
The means for setting the optical output to a specified value is based on a trial-and-error method of determining Nu based on measurement data, which has the drawbacks of being troublesome and increasing costs.
(d) 発明の目的
本発明の目的は上記の欠点を除去し、半導体レーザの駆
動における調竪を容易に効率良く行うことが出来る半導
体レーザ駆動回路を提供しようとするものである。(d) Object of the Invention An object of the present invention is to eliminate the above-mentioned drawbacks and to provide a semiconductor laser drive circuit that can easily and efficiently adjust the driving pitch of a semiconductor laser.
(e) 発明の構成
本発明の目的は半導体レーザ素子の直流バイアス電流を
送出する駆動部、該半纏体レーザ素子の後方モニタ光を
受光検出して検出電流を送出する検出部、入力変調信号
に従い該直流バイアス′区流に重畳する変調信号ならび
にその変調レベル信号を送出する変調部および該検出電
流と別途基準電圧源による設定電流との加算信号ならび
にに調レベル信号を差動入力してその比較値を制御信号
として該駆動部に送出する比較部を備えてなり、変調時
において比較部の非反転端子に変調部より変割高レベル
に対応するu Opy信号を入力し、反転端子に検出部
より検出電流を入力して、比較部における変調高レベル
の制御信号を得るに際して、該制御信号による直流バイ
アス電流と変調信号との重畳による半導体レーザの光出
力が予め設定した値になるように、検知電流に加算する
基準′電圧源による電流を設定すると共に、変調低レベ
ル時において反転端子に検出電流と該基準電圧源による
電流との加算信号を入力し、非反転端子に変調部より送
出する変調低レベルに対応するtlljj信号を入力し
て比較部における変調低レベルの制御信号を得るに際し
、駆動部により送出する直流バイアス電流が前記変調高
レベル時における値に一致するよう非反転端子に入力す
る該″′1”信号の電圧を設運することを特徴とする半
導体レーザ駆動回路を提供することによって達成するこ
とが出来る。(e) Structure of the Invention The object of the present invention is to provide a drive section that sends out a DC bias current for a semiconductor laser device, a detection section that receives and detects the rear monitor light of the semi-integrated laser device and sends out a detection current, and a drive section that sends out a DC bias current of a semiconductor laser device, a detection section that receives and detects the rear monitor light of the semi-integrated laser device and sends out a detection current, and a drive section that sends out a DC bias current of a semiconductor laser device. A modulation section that sends out a modulation signal to be superimposed on the DC bias current and its modulation level signal, and a differential signal of the detected current and a set current from a separate reference voltage source and a differential level signal are input and compared. It is equipped with a comparison section that sends the value as a control signal to the drive section, and during modulation, the uOpy signal corresponding to the variable rate high level is input from the modulation section to the non-inverting terminal of the comparison section, and the uOpy signal corresponding to the variable high level is input to the inversion terminal from the detection section. When inputting the detection current and obtaining a modulation high-level control signal in the comparator section, detection is performed so that the optical output of the semiconductor laser due to the superposition of the DC bias current caused by the control signal and the modulation signal becomes a preset value. In addition to setting the current generated by the reference voltage source to be added to the current, when the modulation level is low, an addition signal of the detected current and the current generated by the reference voltage source is input to the inverting terminal, and the modulation unit sends it to the non-inverting terminal. When inputting a tlljj signal corresponding to a low level to obtain a modulation low level control signal in the comparison section, the DC bias current sent out by the drive section is input to the non-inverting terminal so that it matches the value at the time of the modulation high level. This can be achieved by providing a semiconductor laser drive circuit characterized by driving the voltage of the "'1" signal.
(f) 発明の実施例
以下、図面を参照しつつ本発明の一実施例について説明
する。第1図は本発明の一実施例における半導体レーザ
駆動回路、第2図にその変調部における具体例ブロック
図を示す。図において、1は半導体レーザ素子、2は駆
動部、3は検出部、4は変調部、5は比較部、Rは抵抗
、VRI 、 VB2は可変抵抗器、■は定電流回路、
Qo、QtはNP N、 )ランジスタおよびRLは負
荷抵抗である。(f) Embodiment of the Invention An embodiment of the invention will be described below with reference to the drawings. FIG. 1 shows a semiconductor laser drive circuit according to an embodiment of the present invention, and FIG. 2 shows a concrete example block diagram of its modulation section. In the figure, 1 is a semiconductor laser element, 2 is a drive section, 3 is a detection section, 4 is a modulation section, 5 is a comparison section, R is a resistor, VRI, VB2 is a variable resistor, ■ is a constant current circuit,
Qo, Qt are NP N, ) transistors and RL are load resistances.
半導体レーザ素子1は、変調低レベル時においては駆動
部2よpの直流バイアス′電流の印加を受け、変調高レ
ベル時においては該直流バイアス′延流に重畳して変調
部4よシ変調入力に従って送出される変調信号の印加全
党けて発光動作を行う。駆動部2は比較部5より送出さ
れる制御信号に従って直流バイアス電流を送出する。検
出部3は半導体レーザ素子の出力光に比例する後方モニ
タ光を受光素子により光・電流変換を検出して検出信号
として比較部5に送出する。変調部4は例えば第2図の
具体例ブロック図に示すように構成される。When the modulation level is low, the semiconductor laser element 1 receives a DC bias current from the drive unit 2, and when the modulation level is high, it is superimposed on the DC bias current and the modulation input is applied to the modulation unit 4. A light emitting operation is performed by applying a modulation signal sent out according to the following. The drive section 2 sends out a DC bias current according to the control signal sent from the comparison section 5. The detection section 3 uses a light receiving element to detect the light/current conversion of the rear monitor light which is proportional to the output light of the semiconductor laser element, and sends it to the comparison section 5 as a detection signal. The modulator 4 is configured, for example, as shown in the specific example block diagram of FIG.
トランジスタQ+ 、Qsはエミッタ結合論理回路によ
るスイッチ機能であり、予め変調入力信号の高および低
レベルの中間に設定されたしきい値電圧Vf と変調入
力信号が上廻るときはトランジスタQ1がオンl Q2
がオフ、下相るときはトランジスタQ4がオフ、Q、が
オン動作を行うので変調レベルに伴ってトランジスタQ
2のコレクタ電位を送出する比較器5への変調レベル信
号としてしきい値Vfを上相る高レベルを検出したとき
は″′0″信号即ち接地レベルを、低レベルのときは1
”信号即ち電流源■及び負荷抵抗RLにより決定される
トランジスタQ2のコレクタ電位を送出する。次に比較
部5は例えばその反転入力端子には検出部3よυの検出
信号・電流と別途基準・電圧源の基準・ば圧Vrefを
可変抵抗器VR1の設定による電流が加算して注入され
、非反転入力端子には変調部4から変調レベル信号tl
O”′1〃が変調の有無に応じて送出され、可変抵抗器
VR2と抵抗Rにより分割されて注入される。比較器5
はその比較差出力を制御信号として駆動部2に送出する
。ここで変調入力を高レベルとして変調レベル信号をO
”とすれば比較器50反転入力端子に接地・′α位が与
えられ、可変抵抗器VR2および抵抗Rの設定値は無視
出来る。この時は駆動部2の直流バイアス′屯流と変調
信号電流の電流即ち加算電流(でよって出力される。こ
のとき半導体レーザ素子1の光出力を別途測定して設定
値となるように駆動部2即ち比較器5の制御信号を得る
よう可変抵抗器VR1の値を調整して検出部3の検出信
号屯MLに刀lうべき、基準電圧Vrefよりの加算電
流を設定する。次に変調入力を低レベルとして変調レベ
ル信号を1”とする。このと@検出部3からは変調信号
′1流の重畳されていない直流バイアス′電流たけの駆
動による検出信号が印加されている。ここで駆動部30
直流バイアス亀流が前述の変調レベルが高レベルのとき
に得られた直流バイアス電流と変調信号電流重畳時にお
いて予め測定しておいた直流バイアス電流だけの篭扼値
に制御信号により制御されるように非反転端子に入力さ
れる変調レベル信号の11”を可変抵抗器VR2により
設定すれば、誦レベル時には接地′ば位が変調レベル信
号の′電0”として出力されているので、前述のように
可変抵抗器VR2の設定が高レベル時の調整には殆んど
影響することなく、壕だ高レベル時における可変抵抗器
VR,による設定は変調信号=mによる高レベル対低レ
ベルの光出力比が大きければ低レベル時におよばず可変
抵抗器VR。Transistors Q+ and Qs have a switching function using an emitter-coupled logic circuit, and when the modulation input signal exceeds a threshold voltage Vf, which is preset between the high and low levels of the modulation input signal, transistor Q1 is turned on.
When Q is off and in low phase, transistor Q4 turns off and Q turns on, so transistor Q
When a high level exceeding the threshold value Vf is detected as a modulation level signal to the comparator 5 that sends out the collector potential of 2, a ``0'' signal, that is, the ground level is sent, and when it is a low level, a 1
``signal, that is, the collector potential of the transistor Q2 determined by the current source ■ and the load resistor RL.Next, the comparator 5 sends out the detection signal and current of the detector 3 and a separate reference signal to its inverting input terminal, for example. The reference voltage Vref of the voltage source is injected with a current set by the variable resistor VR1, and the modulation level signal tl from the modulation unit 4 is injected into the non-inverting input terminal.
O'''1〃 is sent out depending on the presence or absence of modulation, and is divided by variable resistor VR2 and resistor R and injected. Comparator 5
sends the comparison difference output to the drive section 2 as a control signal. Here, the modulation input is set to high level and the modulation level signal is set to O.
”, the ground/α position is given to the inverting input terminal of the comparator 50, and the set values of the variable resistor VR2 and the resistor R can be ignored.At this time, the DC bias current of the drive unit 2 and the modulation signal current The current, that is, the addition current (is output. At this time, the optical output of the semiconductor laser element 1 is separately measured, and the variable resistor VR1 is adjusted so as to obtain a control signal for the drive section 2, that is, the comparator 5, so that the optical output of the semiconductor laser element 1 becomes the set value. Adjust the value and set the addition current from the reference voltage Vref that should be applied to the detection signal ML of the detection section 3.Next, the modulation input is set to a low level and the modulation level signal is set to 1''.In this case, @ A detection signal driven by a DC bias current on which the modulation signal '1 stream is not superimposed is applied from the detection unit 3. Here, the drive unit 30
The DC bias current is controlled by the control signal to a value equal to the DC bias current obtained when the above-mentioned modulation level is high and the DC bias current measured in advance when the modulation signal current is superimposed. If the modulation level signal input to the non-inverting terminal is set to 11" by the variable resistor VR2, the ground level is output as the modulation level signal '0' at the recitation level, so as mentioned above, The setting of variable resistor VR2 has almost no effect on the adjustment at high level, and the setting by variable resistor VR at high level is the optical output of high level vs. low level according to the modulation signal = m. If the ratio is large, the variable resistor VR will not reach the low level.
の設定による基準゛電圧Vrefによる加算′i流の影
響は少く、各レベルに対して各1回ずつの調量にて半導
体レーザ素子1の駆動回路を所定値に設定することが出
来る。The influence of the addition 'i current by the reference voltage Vref due to the setting of is small, and the driving circuit of the semiconductor laser element 1 can be set to a predetermined value by adjusting once for each level.
(g) 発明の詳細
な説明したように本発明によれば、半導体レーザ素子の
特性バラツキ、特にレーザ発振のしきい値′電流を調量
確認することなく、変調時の高レベルおよび低レベルに
ついてそれぞれ互に影響することなく、独立して設定出
来るので半導体レーザ素子駆動における調整が答易にな
る上、変調信号の高レベルおよび低レベル時に流れる直
流ノくイアス寛流が等しいのでデータのマーク率に対し
て光出力の変動がない回路が得られ有用である。(g) As described in detail, according to the present invention, it is possible to eliminate variations in the characteristics of a semiconductor laser device, especially high and low levels during modulation, without checking the threshold current of laser oscillation. Since they can be set independently without affecting each other, adjustment in driving the semiconductor laser element is easy, and since the direct current flowing at high and low levels of the modulation signal is equal, the data mark rate can be improved. This is useful because a circuit with no fluctuation in optical output can be obtained.
第1図は本発明の一実施例における半導体ンーザ駆!助
回路によるブロック図および第2図はその変調部の具体
例ブロック図である。
図に2いて、1は半導体レーザ菓子、2は、駆動部、3
は検出部、4:d変調部、5は比較部およびVR,、V
R2h4可変抵抗器である。FIG. 1 shows a semiconductor laser driver according to an embodiment of the present invention. A block diagram of the auxiliary circuit and FIG. 2 are specific example block diagrams of the modulation section. In the figure, 1 is a semiconductor laser confectionery, 2 is a drive unit, and 3 is a semiconductor laser confectionery.
is a detection section, 4: d modulation section, 5 is a comparison section and VR, , V
It is an R2h4 variable resistor.
Claims (1)
、該半導体レーザ素子の後方モニタ光を受光検出して検
出電流を送出する検出部、入力変調信号に従い該直流バ
イアス電流に重畳する変調信号ならびにその変調レベル
信号を送出する変調部および該検出′電流と別途基準電
圧源による設定電流との加算信号ならびに変調レベル信
号を差動入力してその比較値を制御信号として該駆動部
に送出する比[部を備えてな9、変調時において比較部
の非反転端子に変調部より変調高レベルに対応する0”
信号を入カレ、反転端子に検出部よシ検出電流を入力し
て、比較部における変調高レベルの制御信号を得るに除
して、該制御信号による直流バイアス電流と変調信号と
の重畳による半導体レーザの出力光が予め設定した値に
なるように、検知電流に加算する基準電圧源による電流
を設定すると共に、変調低レベル時に2いて反転端子に
検出電流と該基準電圧源による電流との加算信号を入力
し、非反転端子に変調部より送出する変調低レベルに対
応する0 1 j)信号を入力して比較部における変詞
低レベルの制御信号を得るに際し、駆動部によシ送出す
る直流バイアス電流が前記変調高レベル時における値に
一致するよう非反転端子に入力する該u 1 n信号の
電圧を設定することを特徴とする半導体レーザ駆動回路
。A drive unit that sends out a DC bias current of a semiconductor laser element, a detection unit that receives and detects the rear monitor light of the semiconductor laser element and sends out a detection current, a modulation signal that is superimposed on the DC bias current according to an input modulation signal, and its modulation. A modulation section that sends out a level signal, a ratio [section] that differentially inputs the sum signal of the detected current and a set current from a separate reference voltage source, and the modulation level signal, and sends the comparison value as a control signal to the drive section. 9. During modulation, the non-inverting terminal of the comparison section is supplied with 0" corresponding to the modulation high level from the modulation section.
By inputting the signal and the detection current from the detection unit to the inverting terminal to obtain a control signal with a high level of modulation in the comparison unit, the DC bias current caused by the control signal and the modulation signal are superimposed, and the semiconductor In order to make the output light of the laser become a preset value, the current by the reference voltage source to be added to the detection current is set, and when the modulation level is low, the detection current and the current by the reference voltage source are added to the inverting terminal. 0 1 j) When inputting a signal corresponding to the modulation low level sent from the modulation section to the non-inverting terminal and obtaining the control signal of the transversal low level in the comparison section, the signal is sent to the drive section. A semiconductor laser drive circuit characterized in that the voltage of the u 1 n signal input to the non-inverting terminal is set so that the DC bias current matches the value at the time of the modulation high level.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP20307082A JPS5994482A (en) | 1982-11-19 | 1982-11-19 | Semiconductor laser drive circuit |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP20307082A JPS5994482A (en) | 1982-11-19 | 1982-11-19 | Semiconductor laser drive circuit |
Publications (2)
Publication Number | Publication Date |
---|---|
JPS5994482A true JPS5994482A (en) | 1984-05-31 |
JPH0142514B2 JPH0142514B2 (en) | 1989-09-13 |
Family
ID=16467844
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP20307082A Granted JPS5994482A (en) | 1982-11-19 | 1982-11-19 | Semiconductor laser drive circuit |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPS5994482A (en) |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS628664U (en) * | 1985-06-28 | 1987-01-19 | ||
JPS6238044A (en) * | 1985-08-12 | 1987-02-19 | Matsushita Electric Ind Co Ltd | Automatic output control device for mark rate compensation |
US5350151A (en) * | 1991-12-09 | 1994-09-27 | Matsushita Electric Industrial Co., Ltd. | Load supporting apparatus |
WO2006000957A2 (en) * | 2004-06-22 | 2006-01-05 | Arima Devices Corporation | A laser diode drive arrangement |
JP2008051679A (en) * | 2006-08-25 | 2008-03-06 | Audio Technica Corp | Marker |
-
1982
- 1982-11-19 JP JP20307082A patent/JPS5994482A/en active Granted
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS628664U (en) * | 1985-06-28 | 1987-01-19 | ||
JPS6238044A (en) * | 1985-08-12 | 1987-02-19 | Matsushita Electric Ind Co Ltd | Automatic output control device for mark rate compensation |
US5350151A (en) * | 1991-12-09 | 1994-09-27 | Matsushita Electric Industrial Co., Ltd. | Load supporting apparatus |
WO2006000957A2 (en) * | 2004-06-22 | 2006-01-05 | Arima Devices Corporation | A laser diode drive arrangement |
WO2006000957A3 (en) * | 2004-06-22 | 2006-04-06 | Koninkl Philips Electronics Nv | A laser diode drive arrangement |
JP2008051679A (en) * | 2006-08-25 | 2008-03-06 | Audio Technica Corp | Marker |
Also Published As
Publication number | Publication date |
---|---|
JPH0142514B2 (en) | 1989-09-13 |
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