JPH0156546B2 - - Google Patents
Info
- Publication number
- JPH0156546B2 JPH0156546B2 JP56160830A JP16083081A JPH0156546B2 JP H0156546 B2 JPH0156546 B2 JP H0156546B2 JP 56160830 A JP56160830 A JP 56160830A JP 16083081 A JP16083081 A JP 16083081A JP H0156546 B2 JPH0156546 B2 JP H0156546B2
- Authority
- JP
- Japan
- Prior art keywords
- semiconductor laser
- transistor
- light
- receiving element
- output
- 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
Links
- 239000004065 semiconductor Substances 0.000 claims description 52
- 230000003287 optical effect Effects 0.000 claims description 14
- 238000010586 diagram Methods 0.000 description 5
- 239000000758 substrate Substances 0.000 description 5
- 229910001218 Gallium arsenide Inorganic materials 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 238000012544 monitoring process Methods 0.000 description 2
- 230000006641 stabilisation Effects 0.000 description 2
- 238000011105 stabilization Methods 0.000 description 2
- 239000003990 capacitor Substances 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000010365 information processing Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000013307 optical fiber Substances 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 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
- H01S5/068—Stabilisation of laser output parameters
- H01S5/0683—Stabilisation of laser output parameters by monitoring the optical output parameters
Landscapes
- Physics & Mathematics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Optics & Photonics (AREA)
- Semiconductor Lasers (AREA)
Description
【発明の詳細な説明】
本発明は半導体レーザの駆動回路に関し、特に
半導体レーザと光出力モニター用受光素子の両Ｎ
型電極が電気的に共通接続されてなる半導体レー
ザの駆動回路に関するものである。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a driving circuit for a semiconductor laser, and particularly to a driving circuit for driving a semiconductor laser and a light receiving element for monitoring optical output.
The present invention relates to a semiconductor laser drive circuit in which mold electrodes are electrically connected in common.
最近、光フアイバ通信、レーザビームプリン
タ、コンパクトデイスク方式のデイジタルオーデ
イオデイスク、光方式のビデオデイスク等に半導
体レーザの需要が急速に高まつてきている。特に
発光波長が790nｍ以下の可視レーザは、光軸合
せが容易であり、光ビームを小さく絞り込むこと
ができる等の利点があつて、情報処理機器の分野
における利用が大いに期待されている。 Recently, demand for semiconductor lasers has been rapidly increasing for optical fiber communications, laser beam printers, compact disk type digital audio disks, optical type video disks, and the like. In particular, visible lasers with an emission wavelength of 790 nm or less have advantages such as easy optical axis alignment and the ability to focus a light beam into a small size, and are highly expected to be used in the field of information processing equipment.
この種の可視レーザの材料としては、
GaAlAs、GaAsP、InGaP等があるが、現在のと
ころ信頼性よく製作できるのはGaAlAs系半導体
レーザである。ところがGaAlAs系半導体レーザ
においても短波長化につれてAlAsの混晶比が多
くなると、Alの酸化や不純物との複合欠陥が多
くなり、寿命及び信頼性が極端に悪くなる。しか
しＮ型電極GaAs基板の代りにＰ型GaAs基板を
用いると、不純物との複合欠陥が少なくできるた
め、信頼性が非常によくなることが提案されてい
る。 Materials for this type of visible laser include:
There are GaAlAs, GaAsP, InGaP, etc., but GaAlAs semiconductor lasers can currently be manufactured with high reliability. However, even in GaAlAs semiconductor lasers, as the wavelength becomes shorter and the AlAs mixed crystal ratio increases, complex defects with Al oxidation and impurities increase, resulting in extremely poor lifetime and reliability. However, it has been proposed that if a P-type GaAs substrate is used instead of the N-type electrode GaAs substrate, the reliability can be greatly improved because composite defects with impurities can be reduced.
ところで半導体レーザが上記機器に組み込まれ
て用いられる場合、通常光出力を一定にするため
レーザ光の一部を検知し得る位置に受光素子が設
けられ、受光素子の出力を半導体レーザの駆動部
分に帰還させて一定出力が得られるように制御さ
れる。 By the way, when a semiconductor laser is incorporated into the above-mentioned equipment, a light-receiving element is usually installed at a position where part of the laser light can be detected in order to keep the light output constant, and the output of the light-receiving element is transferred to the driving part of the semiconductor laser. It is controlled to feed back and obtain a constant output.
上述のようなＰ型基板を用いた半導体レーザ
は、第１図に示す如く、半導体基板の動作中にお
ける熱抵抗を下げるために通常半導体レーザ１の
Ｎ型電極がステム３側になるようにロウ付けされ
る。一方半導体レーザ１と光結合された受光素子
２はＮ型半導体基板を用いて作製されるため、同
様にＮ型電極がステム３側になるようにAgペー
スト等によつて接着される。従つて半導体レーザ
１のＮ型電極と受光素子２のＮ型電極はステム３
を通して電気的に接続されることになる。 As shown in FIG. 1, a semiconductor laser using a P-type substrate as described above is usually mounted in a row so that the N-type electrode of the semiconductor laser 1 is on the stem 3 side in order to lower the thermal resistance during operation of the semiconductor substrate. will be attached. On the other hand, since the light-receiving element 2 optically coupled to the semiconductor laser 1 is manufactured using an N-type semiconductor substrate, it is similarly bonded with Ag paste or the like so that the N-type electrode is on the stem 3 side. Therefore, the N-type electrode of the semiconductor laser 1 and the N-type electrode of the light receiving element 2 are connected to the stem 3.
It will be electrically connected through.
上記のような光結合構造を採る受光素子付半導
体レーザの従来から用いられている駆動回路を第
２図に示す。即ち半導体レーザ１に直列にトラン
ジスタQ0が接続され、該トランジスタQ0のベー
スをオペレーシヨンアンプ（以下オペアンプと呼
ぶ）OP0で制御することによつて一定出力の半導
体レーザ光が得られるように制御するものであ
る。尚上記オペアンプOP0は非反転端子に一定出
力を導出させるための基準電圧V0が予め与えら
れ、反転端子に受光素子２の光出力が与えられ
て、両入力信号の比較によりトランジスタQ0が
制御される。 FIG. 2 shows a drive circuit conventionally used for a semiconductor laser with a light-receiving element that employs the optical coupling structure as described above. That is, a transistor Q 0 is connected in series to the semiconductor laser 1, and by controlling the base of the transistor Q 0 with an operational amplifier (hereinafter referred to as an operational amplifier) OP 0 , semiconductor laser light with a constant output can be obtained. It is something to control. The operational amplifier OP 0 has a non-inverting terminal supplied with a reference voltage V 0 for deriving a constant output, and an inverting terminal supplied with the optical output of the light-receiving element 2. By comparing both input signals, the transistor Q 0 is controlled.
上記受光素子２は入射光量と光出力との間に良
好なリニアリテイを得るため、通常逆バイアスが
印加された状態で光電流が得られるように回路が
構成される。従つて上記のようにＮ型電極が電気
的に共通となる半導体レーザ装置の駆動回路で
は、第２図に示す如くプラス側及びマイナス側の
２電源が必要になり、経済的に割高になるだけで
なく、サージ電流のためにレーザ素子が破壊され
易いという欠点があつた。 In order to obtain good linearity between the amount of incident light and the optical output, the light-receiving element 2 is usually configured with a circuit so that a photocurrent can be obtained in a state where a reverse bias is applied. Therefore, in the drive circuit of a semiconductor laser device in which the N-type electrode is electrically common as described above, two power supplies are required for the positive side and the negative side as shown in Figure 2, which is only economically expensive. However, the disadvantage was that the laser element was easily destroyed by the surge current.
本発明は上記従来回路の欠点を除去し、受光素
子と半導体レーザの両Ｎ型電極が電気的に共通端
子になつている光結合型半導体レーザ装置を、プ
ラス側の単一電源で駆動することにより、経済性
にすぐれ、また回路設計の容易な半導体レーザの
駆動回路を提供するものである。 The present invention eliminates the drawbacks of the conventional circuit described above, and enables an optically coupled semiconductor laser device in which both the N-type electrodes of the light receiving element and the semiconductor laser are electrically connected to a common terminal to be driven by a single positive power source. This provides a semiconductor laser drive circuit that is highly economical and easy to design.
以下実施例を挙げて本発明を詳細に説明する。 The present invention will be explained in detail below with reference to Examples.
第３図は、Ｎ型電極が電気的に共通接続され、
且つ光結合関係にある半導体レーザ１及びPiNフ
オトダイオード２を備えた本発明による一実施例
の電気回路図である。 FIG. 3 shows that the N-type electrodes are electrically connected in common,
FIG. 2 is an electrical circuit diagram of an embodiment of the present invention including a semiconductor laser 1 and a PiN photodiode 2 in an optically coupled relationship.
同図において、半導体レーザ１のＰ型電極側は
単一電源となるプラス電源（本実施例では＋5V）
に接続され、Ｎ型電極側はNPNトランジスタQ1
のコレクタに接続されている。該トランジスタ
Q1のエミツタは抵抗R1を介してアース電位に接
続されている。尚上記エミツタ抵抗R1は電流安
定化のために挿入されており、必ずしも必要とす
るものではない。 In the figure, the P-type electrode side of the semiconductor laser 1 is a single positive power source (+5V in this example).
, and the N-type electrode side is an NPN transistor Q 1
connected to the collector. the transistor
The emitter of Q 1 is connected to ground potential via a resistor R 1 . Note that the emitter resistor R1 is inserted for current stabilization, and is not necessarily required.
上記トランジスタQ1とエミツタ抵抗R1との直
列回路には、上記光結合されたPiNフオトダイオ
ード２及び抵抗R2の直列回路が並列に接続され
ている。上記PiNフオトダイオード２の光電流は
抵抗R2の一端から電圧に変換されて取り出され
る。 A series circuit of the optically coupled PiN photodiode 2 and a resistor R 2 is connected in parallel to the series circuit of the transistor Q 1 and the emitter resistor R 1 . The photocurrent of the PiN photodiode 2 is converted into a voltage and taken out from one end of the resistor R2 .
PiNフオトダイオード２に生じた光電流によつ
て上記半導体レーザ１の発光出力を制御するた
め、オペアンプOP1が設けられ、該オペアンプ
OP1の反転端子に上記PiNフオトダイオード２に
よる光出力が与えられる。オペアンプOP1の非反
転端子には、半導体レーザ１を一定出力で発光さ
せるための基準電圧V1が抵抗の分割等によつて
与えられている。オペアンプOP1は各入力端子に
与えられた基準電圧、光出力に対応する電圧間の
信号レベルの大小を比較し、比較結果に基く出力
を導出する。導出されたオペアンプOP1出力は上
記NPNトランジスタQ1のベースに与えられ、ト
ランジスタQ1のコレクタ電流、即ち半導体レー
ザ１の駆動電流を、予め基準電圧によつて設定さ
れているレベルに対応する受光素子出力が得られ
るように制御する。 In order to control the light emission output of the semiconductor laser 1 by the photocurrent generated in the PiN photodiode 2, an operational amplifier OP1 is provided.
The optical output from the PiN photodiode 2 is given to the inverting terminal of OP 1 . A reference voltage V 1 for causing the semiconductor laser 1 to emit light at a constant output is applied to the non-inverting terminal of the operational amplifier OP 1 by dividing a resistor or the like. The operational amplifier OP 1 compares the signal level between the reference voltage applied to each input terminal and the voltage corresponding to the optical output, and derives an output based on the comparison result. The derived operational amplifier OP 1 output is given to the base of the NPN transistor Q 1 , and the collector current of the transistor Q 1 , that is, the drive current of the semiconductor laser 1, is adjusted to a level set in advance by the reference voltage. Control is performed so that the element output is obtained.
上記オペアンプOP1に印加される電源は、ベ
ス・コレクタ間に抵抗R3、ベース・アース間に
コンデンサＣが接続されたトランジスタQ3を含
んでなるリツプルフイルタを介して与えられ、急
峻な電圧がオペアンプOP1の入力に与えられるの
を防ぎ、電源のサージに対する保護が図られてい
る。 The power applied to the operational amplifier OP 1 is applied through a ripple filter comprising a transistor Q 3 with a resistor R 3 connected between its base and collector, and a capacitor C connected between its base and ground, and a steep voltage is applied to the operational amplifier OP 1 . from being applied to the input of op amp OP 1 , providing protection against power surges.
上記構成からなる回路において、半導体レーザ
１はほぼ1.8V程度の順方向電圧を示すため、結
局PiNフオトダイオード２としては＋5V電源よ
り上記1.8Vを引いた3.2Vの逆バイアスが印加さ
れていることになり、ダイオード２自体光出力と
して充分良好なリニアリテイを得ることができ
る。 In the circuit with the above configuration, since the semiconductor laser 1 exhibits a forward voltage of approximately 1.8V, a reverse bias of 3.2V, which is the above 1.8V subtracted from the +5V power supply, is applied to the PiN photodiode 2. Therefore, the diode 2 itself can obtain sufficiently good linearity as an optical output.
一般に、第３図に示す駆動回路のようにPiNフ
オトダイオード２に直列に他の電気的要素を接続
すると、この他の電気的要素に流れる電流によつ
てPiNフオトダイオード２への印加電圧が変動す
るため安定度が悪く、このような回路は考えにく
いものであり、通常は、第２図のように他の電気
的要素、この場合は半導体レーザ１であるが、こ
の半導体レーザ１と別回路になるようにしてPiN
フオトダイオード２へ定電圧を印加する回路とな
る。 Generally, when other electrical elements are connected in series to the PiN photodiode 2, as in the drive circuit shown in Figure 3, the voltage applied to the PiN photodiode 2 varies depending on the current flowing through the other electrical elements. Therefore, the stability is poor, and such a circuit is difficult to imagine.Usually, as shown in Figure 2, other electrical elements, in this case the semiconductor laser 1, are connected to a separate circuit from the semiconductor laser 1. PiN
This is a circuit that applies a constant voltage to the photodiode 2.
しかしながら、本発明では前記他の電気的要素
が特に半導体レーザ１であつて、ここに流れる電
流があまり変動することがなく、従つてPiNフオ
トダイオード２への印加電圧の変動も実用上問題
のないレベルであることが確かめられた。 However, in the present invention, the other electrical element is particularly the semiconductor laser 1, and the current flowing there does not change much, so fluctuations in the voltage applied to the PiN photodiode 2 do not cause any practical problems. It was confirmed that the level was
第４図は本発明による他の実施例を示し、第３
図に示した実施例に対して、半導体レーザ１を駆
動するためのトランジスタがPNPトランジスタ
Q3で構成されている。従つて該PNPトランジス
タQ3のベース電位を制御するオペアンプOP2は、
非反転端子にPiNフオトダイオード２の光出力
が、反転端子に基準電圧V2が与えられる。尚基
準電圧V2は前記実施例と同様に抵抗の分割によ
つて与えられ、電源のサージに対する保護につい
てもトランジスタQ4を含むリツプルフイルタが
設けられている。 FIG. 4 shows another embodiment according to the present invention;
In the embodiment shown in the figure, the transistor for driving the semiconductor laser 1 is a PNP transistor.
Q Consists of 3 . Therefore, the operational amplifier OP2 that controls the base potential of the PNP transistor Q3 is
The optical output of the PiN photodiode 2 is applied to the non-inverting terminal, and the reference voltage V 2 is applied to the inverting terminal. Note that the reference voltage V 2 is provided by dividing a resistor as in the previous embodiment, and a ripple filter including a transistor Q 4 is provided for protection against power surges.
半導体レーザ１のＰ型電極側と電源間に挿入さ
れた抵抗R4は電流安定化のためのエミツタ抵抗
である。 A resistor R4 inserted between the P-type electrode side of the semiconductor laser 1 and the power supply is an emitter resistor for current stabilization.
本実施例においても、半導体レーザの駆動トラ
ンジスタQ3に、抵抗R5と共に並列接続された
PiNフオトダイオード２は逆バイアスされた状態
にあり、動作にあたつては半導体レーザ１の発光
がPiNフオトダイオード２で検知され、受光光量
に対応した光出力がオペアンプOP2に与えられ、
基準電圧V2との比較が実行される。比較結果は
オペアンプOP1出力として導出され、PNPトラ
ンジスタQ3のベースに与えられて、半導体レー
ザ１の動作電流を制御し、半導体レーザの発光出
力が一定になるように制御する。 In this embodiment as well, a transistor Q 3 is connected in parallel with a resistor R 5 to the drive transistor Q 3 of the semiconductor laser.
The PiN photodiode 2 is in a reverse biased state, and during operation, the light emission from the semiconductor laser 1 is detected by the PiN photodiode 2, and an optical output corresponding to the amount of light received is given to the operational amplifier OP2 .
A comparison with the reference voltage V 2 is performed. The comparison result is derived as the output of the operational amplifier OP 1 and is applied to the base of the PNP transistor Q 3 to control the operating current of the semiconductor laser 1 so that the light emission output of the semiconductor laser is constant.
以上のように、本発明によれば、Ｎ型電極が共
通に接続され且つ光結合関係にある半導体レーザ
及び受光素子について、半導体レーザを駆動する
ためのトランジスタに並列に受光素子及び抵抗の
直列回路を接続することにより、単一電源で半導
体レーザ装置を動作させることができ、各種機器
への組み込みに際して電源に対する制限が緩和さ
れ、回路設計が非常にやり易くなると共に経済性
にもすぐれた半導体レーザの駆動回路を得ること
ができる。 As described above, according to the present invention, for a semiconductor laser and a light receiving element whose N-type electrodes are commonly connected and in an optically coupled relationship, a series circuit of a light receiving element and a resistor is connected in parallel to a transistor for driving the semiconductor laser. By connecting the semiconductor laser device, it is possible to operate the semiconductor laser device with a single power supply, which eases restrictions on the power supply when incorporating it into various devices, making circuit design extremely easy and making semiconductor laser devices highly economical. A driving circuit can be obtained.
第１図は光出力モニター用受光素子を備えた半
導体レーザ装置の回路図、第２図は従来の半導体
レーザの駆動回路図、第３図は本発明による一実
施例の電気回路図、第４図は本発明による他の実
施例による電気回路図である。
１：半導体レーザ、２：PiNフオトダイオー
ド、３：ステム、Q1，Q3：半導体レーザ駆動用
トランジスタ、R2，R5：抵抗。
FIG. 1 is a circuit diagram of a semiconductor laser device equipped with a light receiving element for monitoring optical output, FIG. 2 is a driving circuit diagram of a conventional semiconductor laser, FIG. 3 is an electric circuit diagram of an embodiment according to the present invention, and FIG. The figure is an electrical circuit diagram according to another embodiment of the present invention. 1: Semiconductor laser, 2: PiN photodiode, 3: Stem, Q 1 , Q 3 : Semiconductor laser driving transistor, R 2 , R 5 : Resistor.
Claims (1)
と光結合された受光素子のＮ型電極とをステムを
介して電気的に接続してなる半導体レーザ装置で
あり、前記受光素子の光出力に基いて前記半導体
レーザの発光出力を制御する半導体レーザ装置の
駆動回路において、 前記半導体レーザのＮ型電極と直列にトランジ
スタを接続し、該トランジスタと並列に前記受光
素子および抵抗を接続し、当該受光素子の光出力
を前記トランジスタに帰還してなることを特徴と
する半導体レーザ装置の駆動回路。[Scope of Claims] 1. A semiconductor laser device in which an N-type electrode of a semiconductor laser and an N-type electrode of a light-receiving element optically coupled to the semiconductor laser are electrically connected via a stem, and the light-receiving element In a drive circuit for a semiconductor laser device that controls the light emission output of the semiconductor laser based on the optical output of the element, a transistor is connected in series with an N-type electrode of the semiconductor laser, and the light receiving element and a resistor are connected in parallel with the transistor. What is claimed is: 1. A drive circuit for a semiconductor laser device, characterized in that the transistor is connected to the transistor, and the optical output of the light receiving element is fed back to the transistor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP16083081A JPS5861691A (en) | 1981-10-07 | 1981-10-07 | Drive circuit for semiconductor laser |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP16083081A JPS5861691A (en) | 1981-10-07 | 1981-10-07 | Drive circuit for semiconductor laser |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5861691A JPS5861691A (en) | 1983-04-12 |
| JPH0156546B2 true JPH0156546B2 (en) | 1989-11-30 |
Family
ID=15723325
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP16083081A Granted JPS5861691A (en) | 1981-10-07 | 1981-10-07 | Drive circuit for semiconductor laser |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5861691A (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4584687A (en) * | 1983-12-12 | 1986-04-22 | Optical Storage International-U.S. | Calibrated feedback for laser diodes |
| US4819241A (en) * | 1985-08-16 | 1989-04-04 | Kabushiki Kaisha Toshiba | Laser diode driving circuit |
| JP2005026371A (en) * | 2003-06-30 | 2005-01-27 | Sunx Ltd | Semiconductor laser drive circuit and photoelectric sensor |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5612791A (en) * | 1979-07-12 | 1981-02-07 | Fujitsu Ltd | Laser driving control system |
-
1981
- 1981-10-07 JP JP16083081A patent/JPS5861691A/en active Granted
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5612791A (en) * | 1979-07-12 | 1981-02-07 | Fujitsu Ltd | Laser driving control system |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5861691A (en) | 1983-04-12 |
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