JPS59129949A - Automatic photoelectric power controlling circuit - Google Patents
Automatic photoelectric power controlling circuitInfo
- Publication number
- JPS59129949A JPS59129949A JP58004322A JP432283A JPS59129949A JP S59129949 A JPS59129949 A JP S59129949A JP 58004322 A JP58004322 A JP 58004322A JP 432283 A JP432283 A JP 432283A JP S59129949 A JPS59129949 A JP S59129949A
- Authority
- JP
- Japan
- Prior art keywords
- output
- semiconductor laser
- circuit
- video signal
- led
- 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
- 239000004065 semiconductor Substances 0.000 claims abstract description 41
- 230000003287 optical effect Effects 0.000 claims abstract description 21
- 238000006243 chemical reaction Methods 0.000 claims description 9
- 230000000737 periodic effect Effects 0.000 claims 1
- 239000003990 capacitor Substances 0.000 abstract description 7
- 230000008878 coupling Effects 0.000 abstract description 7
- 238000010168 coupling process Methods 0.000 abstract description 7
- 238000005859 coupling reaction Methods 0.000 abstract description 7
- 238000010586 diagram Methods 0.000 description 5
- 238000001514 detection method Methods 0.000 description 4
- 230000001360 synchronised effect Effects 0.000 description 2
- 230000006866 deterioration Effects 0.000 description 1
- 239000000284 extract Substances 0.000 description 1
- 238000001615 p wave Methods 0.000 description 1
Classifications
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
- G11B7/125—Optical beam sources therefor, e.g. laser control circuitry specially adapted for optical storage devices; Modulators, e.g. means for controlling the size or intensity of optical spots or optical traces
- G11B7/126—Circuits, methods or arrangements for laser control or stabilisation
-
- 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
Landscapes
- Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Optical Head (AREA)
- Semiconductor Lasers (AREA)
Abstract
Description
【発明の詳細な説明】
本発明は自動光電力制御に関し、特にベースバンドビデ
オ信号による半導体レーザのアナログ直接強度変調器に
使用される自動光電力制御回路に関する。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to automatic optical power control, and more particularly to automatic optical power control circuits used in analog direct intensity modulators of semiconductor lasers with baseband video signals.
第１図は、ベースバンドビデオ信号で半導体レーザを直
接強要変調する際の従来の自動光電力制御回路を使用し
た変調器の一例である。図において、１１は半導体レー
ザ、１２ｕ前記半導体レーザの出力光の一部を受光し電
流に変換する光・電気変換素子、１３は前記光・電気変
換素子の出力電流を電圧に変換する検出、抵抗、１５は
前記検出抵抗の両端の電圧と１４の基準電圧を比較−増
幅する比較器、１６は前記比較器の誤差出力を帯域制限
する低域戸波器、１７は前記低域戸波器の出力により駆
動され、１１の半導体レーザのバイアスを制御する半導
体レーザバイアス回路である。FIG. 1 is an example of a modulator using a conventional automatic optical power control circuit for direct forced modulation of a semiconductor laser with a baseband video signal. In the figure, 11 is a semiconductor laser, 12u is an optical/electrical conversion element that receives a part of the output light of the semiconductor laser and converts it into a current, and 13 is a detection resistor that converts the output current of the optical/electrical conversion element into a voltage. , 15 is a comparator that compares and amplifies the voltage across the detection resistor and the reference voltage of 14, 16 is a low frequency door filter that limits the band of the error output of the comparator, and 17 is a comparator that uses the output of the low band door filter. This is a semiconductor laser bias circuit that is driven and controls the bias of eleven semiconductor lasers.
ここで１１．１２，１３，１４，１５，１６．１７の負
帰還ループは半導体レーザの出力光電力を一定に保つ自
動光電力制御回路を構成している。従って１６の低域Ｐ
波器のカットオフ周波数はビデオ信号のフレームスロー
プ特性に与える影響を少なくする為出来るだけ低くしで
ある。一方、ベースバンドビデオ信号は２１の入力端子
へ入力され、２２０カツプリングコンデンサで直流成分
を阻止され、２３の電圧電流変換器でレーザ駆動電流に
変換された後、あらかじめ自動光電力制御回路によシ直
流バイアスを与えら扛ている半導体レーザへ導かれ、半
導体レーザの直接強度変調が達成される。Here, the negative feedback loops 11, 13, 14, 15, and 16.17 constitute an automatic optical power control circuit that keeps the output optical power of the semiconductor laser constant. Therefore, 16 low range P
The cutoff frequency of the waveform generator is set as low as possible in order to reduce the influence on the frame slope characteristics of the video signal. On the other hand, the baseband video signal is input to the input terminal 21, the DC component is blocked by the 220 coupling capacitor, and the voltage-current converter 23 converts it into a laser driving current. Direct current modulation of the semiconductor laser is achieved by direct current bias applied to the semiconductor laser.
すなわち半導体レーザ１１は第２図に示す駆動電流（１
１対光出力（Ｌ）曲線（以下、「Ｉ−’Ｌ凸曲線という
。）において、光出力りがある一定値Ｌｃとなる電、流
Ｉｓに常にバイアスされ、その電流値を中心にして、合
わせて示しであるベースバンドビデオ信号によって駆動
されることになる。第２図でベースバンドビデオ信号の
平均映像レベル（以下、「ＡＰＬ」という。）が低いと
きには（同図でＡで示す。）、Ｉ−Ｌ曲線のａｂ間、高
いときには（同図でＢで示す。）ｃｄ間に絵成分が存在
し、半導体レーザ１１のＩ−Ｌ曲線の広い部分に渡って
絵成分が存在することになり、このＩ−Ｌ曲線の非直線
歪によって信号光の歪が増加するととがある。したがっ
て、ベースバンドビデオ信号のＡＰＬにかかわらず歪を
ある規定値以下に抑えるためには、光変調度（光信号の
ｐ−ｐ値の半分と平均直流光の比）を大きくとることが
難しくなること、また自動光電、力制御回路と２２のカ
ップリングコンデンサの影響でベースバンドビデオ信号
の低周波特性（フレームスロープ特性）が劣化すること
等の欠点を有していた。That is, the semiconductor laser 11 has a driving current (1
In the 1 vs. light output (L) curve (hereinafter referred to as the "I-'L convex curve"), the light output is always biased to a current Is such that the light output is a certain constant value Lc, and with that current value as the center, It is also driven by the baseband video signal shown in FIG. 2. When the average video level (hereinafter referred to as "APL") of the baseband video signal is low (indicated by A in the same figure). , a picture component exists between ab and cd of the I-L curve when it is high (indicated by B in the figure), and a picture component exists over a wide part of the I-L curve of the semiconductor laser 11. Therefore, the distortion of the signal light increases due to the non-linear distortion of the IL curve. Therefore, in order to suppress the distortion below a certain specified value regardless of the APL of the baseband video signal, it is difficult to increase the optical modulation degree (the ratio of half the pp value of the optical signal to the average DC light). In addition, the low frequency characteristics (frame slope characteristics) of the baseband video signal deteriorated due to the influence of the automatic photoelectric, force control circuit, and the coupling capacitor No. 22.
本発明は、半導体レーザの光出力波形の同期パルス先端
をある一定値に保つよう半導体レーザのバイアス電流を
制御することによｐ上記欠点を除去するものであシ、光
変調度を大きくとれ、半導体レーザの寿命も長くなり、
かつベースバンドビデオ信号のフレームスロープ特性に
劣化のない自動光電力制御回路を提供するものである。The present invention eliminates the above-mentioned drawbacks by controlling the bias current of the semiconductor laser so as to keep the tip of the synchronous pulse of the optical output waveform of the semiconductor laser at a certain constant value, and increases the degree of optical modulation. The lifespan of semiconductor lasers is also longer,
Moreover, the present invention provides an automatic optical power control circuit that does not deteriorate the frame slope characteristics of a baseband video signal.
本発明による自動光電力制御回路は、半導体レーザの出
力光の一部を受光し電気出力に変換する光・電気変換素
子と、前記光・電気変換素子の出力のうち同期パルスの
部分より、ＡＰＬ変化のため重畳されている低周波歪成
分を分離する手段と、前記低周波歪成分と別に設けた基
準直流電圧を比較する比較器と、前記比較器の誤差出力
を増幅・帯域制限して半導体レーザへ導き、半導体レー
ザのバイアス電流を制御する手段とによシ構成される０
次に第３図を参照して本発明の一実施例を説明する。The automatic optical power control circuit according to the present invention includes an optical-electrical conversion element that receives a part of the output light of a semiconductor laser and converts it into electrical output, and an APL from the synchronous pulse part of the output of the optical-electrical conversion element. means for separating low-frequency distortion components superimposed due to changes; a comparator for comparing the low-frequency distortion components with a separately provided reference DC voltage; and a semiconductor device for amplifying and band-limiting the error output of the comparator. An embodiment of the present invention will now be described with reference to FIG. 3.
図において、２１の入力端子へ入力されたベースバンド
ビデオ信号は２２０カツプリングコンデンサで直流成分
を除去された後、２３の電圧＠電流変換器によシ半導体
レーザ駆動電流に変換さ扛、１１の半導体レーザへ導か
扛、半導体レーザを直接強度変調する。一方、前記半導
体レーザの出力光は一部光・電気変換素子（例えば、Ｐ
ＩＮフォトダイオード／）２へ導かれ電流へ変換される
。In the figure, the baseband video signal input to the input terminal 21 has its DC component removed by the 220 coupling capacitor, and is then converted into a semiconductor laser driving current by the voltage @ current converter 23. Directly modulates the intensity of the semiconductor laser by guiding it to the semiconductor laser. On the other hand, the output light of the semiconductor laser is partially transmitted through a light-to-electrical conversion element (for example, P
IN photodiode/)2 and is converted into a current.
光・電気変換素子の出力電流は検出抵抗１３によシミ圧
に変換された後、スライス回路３１に縛かれる。スライ
ス回路３１はベースバンドビデオ信号の同期パルスの部
分を取り出し、その出力は２分され、一方は増幅器３２
で増幅され、もう一方はカップリングコンデンサ３３で
ＡＰＬ変化にょシ同期パルスに重畳されている低周波Φ
成分をある程度除去したあと増幅器３４で増幅され、リ
ミッタ３５によりある一定の振幅をもったパルス列に変
換される。増幅器３２の出方から前記リミッタ３５の出
力が減算されて残ったＡＰＬ変化による低周波歪成分は
比較器１５へ入力され１４の基準電圧と比較される。前
記比較器の出方は低域ｐ波器１６により帯域制限された
後レーザバイアス回路１７へ導かれる。前記レーザバイ
アス回路の出力は２３の電圧・電流変換器の出方と加え
あわさｎた後１１の半導体レーザへ導かれ半導体レーザ
のバイアス電流を制御する。The output current of the photoelectric conversion element is converted into a spot pressure by the detection resistor 13 and then bound to the slice circuit 31. The slice circuit 31 extracts the synchronization pulse part of the baseband video signal, and its output is divided into two parts, one of which is sent to the amplifier 32.
and the other is a low frequency Φ which is superimposed on the APL change synchronization pulse by the coupling capacitor 33.
After removing some of the components, it is amplified by an amplifier 34, and converted by a limiter 35 into a pulse train having a certain amplitude. The output of the limiter 35 is subtracted from the output of the amplifier 32, and the remaining low frequency distortion component due to the APL change is input to the comparator 15 and compared with the reference voltage 14. The output of the comparator is band-limited by a low-pass p-wave generator 16 and then guided to a laser bias circuit 17. The output of the laser bias circuit is added to the output of the voltage/current converter 23 and then guided to the semiconductor laser 11 to control the bias current of the semiconductor laser.
第４図に本発明による半導体レーザの出方波形を示す。FIG. 4 shows the output waveform of the semiconductor laser according to the present invention.
ベースバンドビデオ信号のＡＰＬ変化による。同期パル
ス先端のＩ−Ｌ曲線上の移動は、比較器１５の誤差出力
を生じさせ、半導体レーザ１１のバイアス電流がコント
ロールされる結果、圧縮される。つまシ半導体レーザ出
力波形は第４図に示すようにベースバンドビデオ信号の
ＡＰＬ変化によらず同期パルスの先端がある値Ｌｌに固
定さ扛ることになる。また温度変化や劣化によって半導
体レーザのしきい値電流（Ｉｔｈ）が変化しても以上の
動作が達成されることは明らかである。This is due to APL changes in the baseband video signal. The movement of the synchronizing pulse tip on the IL curve causes an error output of the comparator 15, which is compressed as a result of controlling the bias current of the semiconductor laser 11. As shown in FIG. 4, the output waveform of the oscillating semiconductor laser is such that the leading edge of the synchronizing pulse is fixed at a certain value Ll regardless of the APL change of the baseband video signal. Furthermore, it is clear that the above operation can be achieved even if the threshold current (Ith) of the semiconductor laser changes due to temperature changes or deterioration.
つまり１１，１２，１３，３１．３２（３３，３４゜３
５）、１５．’１６．１７ の負帰還ループはビデオ
クランプ回路と自動光電力制御回路の両方の機能を備え
ていることになる。In other words, 11, 12, 13, 31.32 (33, 34°3
5), 15. The '16.17 negative feedback loop has the functions of both a video clamp circuit and an automatic optical power control circuit.
以上の説明から明らかな様に、半導体レーザの自動光電
力制御回路にビデオクランプ機能を合わせ持たせるとい
う簡単な構成により、ベースバンドビデオ信号のＩ−Ｌ
［ｉｌｌ線上の存在範囲はＡＰＬ変化によらず変化せず
、半導体レーザのＩ−Ｌ曲線の非線型歪を受けにくくな
り、シたがって光変調度を大きくすることができ、半導
体レーザの出力光は同期パルスの先端が一定値に揃って
いるためにフレームスロープ特性が極めて良好になるとAs is clear from the above explanation, the I-L of baseband video signals can be
[The existing range on the ill line does not change regardless of the APL change, and is less susceptible to nonlinear distortion of the IL curve of the semiconductor laser. Therefore, the degree of optical modulation can be increased, and the output light of the semiconductor laser Since the leading edge of the sync pulse is aligned at a constant value, the frame slope characteristics are extremely good.
第１図は従来の自動光電力制御回路を使用した半導体の
直接強度変調器を示すブロック図、第２図は第１図に示
す変調器における半導体レーザのＩ−Ｌ曲線と半導体レ
ーザを駆動するベースバンドビデオ信号波形を示す線図
、第３図は本発明に係る自動光電力制御回路を使用した
半導体レーザの直接強度変調器の一実施例を示すブロッ
ク図、第４図は半導体レーザのＩ−Ｌ曲線と本発明にお
ける半導体レーザの光出力波形を示す線図である。
図において、１１・・・・・・半導体レーザ、１２・・
・・・・光・電気変換素子、１３・・・・・・検出抵抗
、１４・・・・・・基準電圧、１５・・・・・・比較器
、１６・・・・・・低域Ｐ波器、１７・・・・・・レー
ザバイアス回路、２１・・・・・・入力端子、２２・・
・・・・カップリングコンデンサ、２３・・・・・・電
圧昏電流変換器、３１・・・・・・スライス回路、３２
．３４・・・・・・増幅器、３３・・・・・・カップリ
ングコンデンサ、３５・・・・・・リミッタ。Fig. 1 is a block diagram showing a semiconductor direct intensity modulator using a conventional automatic optical power control circuit, and Fig. 2 shows the IL curve of the semiconductor laser in the modulator shown in Fig. 1 and how to drive the semiconductor laser. A diagram showing a baseband video signal waveform, FIG. 3 is a block diagram showing an embodiment of a direct intensity modulator for a semiconductor laser using the automatic optical power control circuit according to the present invention, and FIG. 4 is a diagram showing the I of the semiconductor laser. -L curve and a diagram showing the optical output waveform of the semiconductor laser in the present invention. In the figure, 11... semiconductor laser, 12...
...Photoelectric conversion element, 13...Detection resistor, 14...Reference voltage, 15...Comparator, 16...Low frequency P Wave device, 17... Laser bias circuit, 21... Input terminal, 22...
... Coupling capacitor, 23 ... Voltage current converter, 31 ... Slice circuit, 32
．． 34...Amplifier, 33...Coupling capacitor, 35...Limiter.
Claims (1)
直接強度変調器に使用される自動光電力制御回路におい
て、半導体レーザの出力光の一部を受光し電気出力に変
換する光−電気変換素子と、前記光・電気変換素子に接
続され、ベースバンドビデオ信号の周期パルスの部分か
ら低周波歪成分を分離する手段と、前記低周波歪成分と
別に設けた基準直流電圧を比較する比較器と、前記比較
器のｉ差出力を増幅・帯域制限して半導体レーザへ導き
、半導体レーザのバイアス電流を制御する手段とを含む
ことを特徴とする自動光電力制御回路。An automatic optical power control circuit used in an analog direct intensity modulator of a semiconductor laser using a baseband video signal includes an optical-to-electrical conversion element that receives a part of the output light of the semiconductor laser and converts it into electrical output; means connected to the electrical conversion element to separate low frequency distortion components from periodic pulse portions of the baseband video signal; a comparator for comparing the low frequency distortion components with a separately provided reference DC voltage; An automatic optical power control circuit comprising means for amplifying and band-limiting the i difference output and guiding it to a semiconductor laser to control a bias current of the semiconductor laser.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP58004322A JPS59129949A (en) | 1983-01-14 | 1983-01-14 | Automatic photoelectric power controlling circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP58004322A JPS59129949A (en) | 1983-01-14 | 1983-01-14 | Automatic photoelectric power controlling circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS59129949A true JPS59129949A (en) | 1984-07-26 |
Family
ID=11581219
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP58004322A Pending JPS59129949A (en) | 1983-01-14 | 1983-01-14 | Automatic photoelectric power controlling circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS59129949A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1381036A3 (en) * | 2002-07-03 | 2006-07-12 | Ricoh Company, Ltd. | Light source drive circuit, optical information recording apparatus and optical information recording method |
-
1983
- 1983-01-14 JP JP58004322A patent/JPS59129949A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1381036A3 (en) * | 2002-07-03 | 2006-07-12 | Ricoh Company, Ltd. | Light source drive circuit, optical information recording apparatus and optical information recording method |
| US7193957B2 (en) | 2002-07-03 | 2007-03-20 | Ricoh Company, Ltd. | Light source drive, optical information recording apparatus, and optical information recording method |
| US7480230B2 (en) | 2002-07-03 | 2009-01-20 | Ricoh Company, Ltd. | Light source drive, optical information recording apparatus, and optical information recording method |
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