JP2900567B2 - Semiconductor optical amplifier - Google Patents
Semiconductor optical amplifierInfo
- Publication number
- JP2900567B2 JP2900567B2 JP2238780A JP23878090A JP2900567B2 JP 2900567 B2 JP2900567 B2 JP 2900567B2 JP 2238780 A JP2238780 A JP 2238780A JP 23878090 A JP23878090 A JP 23878090A JP 2900567 B2 JP2900567 B2 JP 2900567B2
- Authority
- JP
- Japan
- Prior art keywords
- optical amplifier
- optical
- amplifier
- semiconductor
- gain
- 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
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
- H01S5/062—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium by varying the potential of the electrodes
- H01S5/0625—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium by varying the potential of the electrodes in multi-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
- 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
-
- 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
- H01S5/50—Amplifier structures not provided for in groups H01S5/02 - H01S5/30
Landscapes
- Semiconductor Lasers (AREA)
Description
【発明の詳細な説明】 （産業上の利用分野） 本発明は利得安定化手段を持つ半導体光増幅装置に関
する。Description: TECHNICAL FIELD The present invention relates to a semiconductor optical amplifier having gain stabilizing means.
（従来の技術） 近年、半導体や稀土類元素を添加した光ファイバを用
いた光増幅器に於て実用的な特性が得られるようにな
り、光増幅器を種々の光通信・交換システムに適用する
動きが盛んになってきている。このうち、半導体光増幅
器は、半導体レーザーの利得機構を利用して、注入電流
を発振しきい値以下にバイアスし外部からの入射光に対
して増幅器として動作させるものである。小型、広い利
得波長帯域幅、高飽和出力、アレイ化／集積可能等の特
長を持ち、光交換システムの様な多数点対多数点の光ネ
ットワークの規模拡大への応用が期待されている。(Prior Art) In recent years, practical characteristics have been obtained in an optical amplifier using an optical fiber doped with a semiconductor or a rare earth element, and the movement of applying the optical amplifier to various optical communication / switching systems has been increasing. Is becoming popular. Among them, the semiconductor optical amplifier uses the gain mechanism of the semiconductor laser to bias the injection current below the oscillation threshold value and operate as an amplifier for externally incident light. It has features such as small size, wide gain wavelength bandwidth, high saturation output, and arraying / integration, and is expected to be applied to the expansion of the scale of a multipoint-to-multipoint optical network such as an optical switching system.
半導体光増幅器の利得は、周囲の温度、入射光の偏光
状態等により変化する。従って、半導体光増幅器を実際
にシステムの中で用いる際には、光増幅器の利得の安定
化制御が不可欠である。従来、光増幅器の利得安定化方
式としては、送信信号に予め10KHz程度の低周波数パイ
ロット信号を重畳して光ファイバで伝送し、リピータと
して用いる光増幅器の部分で、光増幅器出力の一部を分
岐して分岐光を得、この分岐光を電気信号に変換してパ
イロット信号を検出するか、又は光増幅器の端子電圧変
化からパイロット信号を検出し、そのパイロット信号の
大きさを一定値に保つように制御する方法が知られてい
る。この技術については、雑誌「エレクトロニクス・レ
ターズ（Electronics Letters）」、第25巻、1989年、2
35−236頁や、「電子情報通信学会英文論文誌」、第E72
巻、1989年、1059−1060頁に述べられている。The gain of a semiconductor optical amplifier changes depending on the ambient temperature, the polarization state of incident light, and the like. Therefore, when a semiconductor optical amplifier is actually used in a system, stabilization control of the gain of the optical amplifier is indispensable. Conventionally, as a gain stabilization method of an optical amplifier, a low-frequency pilot signal of about 10 KHz is superimposed on a transmission signal in advance and transmitted through an optical fiber, and a part of an optical amplifier output is branched at an optical amplifier used as a repeater. A branch light is obtained, and the branch light is converted into an electric signal to detect a pilot signal, or a pilot signal is detected from a change in terminal voltage of an optical amplifier, and the magnitude of the pilot signal is maintained at a constant value. There is a known control method. This technology is described in the magazine "Electronics Letters", Volume 25, 1989, 2
Pages 35-236, IEICE English Transactions, E72
Vol., 1989, pp. 1059-1060.
（発明が解決しようとする課題） しかし、従来の光増幅器の利得安定化方法では、周波
信号を伝送信号に重畳するために、光送信器として特殊
な方式のものを採用するか、又は外部変調器を用いる必
要がある。(Problems to be Solved by the Invention) However, in the conventional method for stabilizing the gain of an optical amplifier, in order to superimpose a frequency signal on a transmission signal, a special type of optical transmitter is used, or an external modulator is used. It is necessary to use a vessel.
本発明の目的は、上述の課題を解決し、特殊な光送信
器や光変調器を用いずに利得の安定化制御が可能な半導
体光増幅器を提供することにある。An object of the present invention is to solve the above-mentioned problems and to provide a semiconductor optical amplifier capable of controlling stabilization of gain without using a special optical transmitter or optical modulator.
（課題を解決するための手段） 本発明による半導体光増幅装置は、活性層の光軸方向
に配列されていて互いに独立な複数の電流注入領域を持
つ半導体光増幅器と、前記複数の電流注入領域のうち入
力端面に近い第一の注入領域に直流電流と共に低周波の
特定周波数信号を印加する手段と、前記光増幅器の出力
光中の前記特定の周波数信号成分を検出し、その大きさ
を一定値に保つように、前記光増幅器の前記第一の注入
領域以外の電流注入領域への注入電流を制御する手段と
からなることを特徴とするものである。(Means for Solving the Problems) A semiconductor optical amplifier according to the present invention comprises a semiconductor optical amplifier arranged in the optical axis direction of an active layer and having a plurality of independent current injection regions, and the plurality of current injection regions. Means for applying a low-frequency specific frequency signal together with a direct current to the first injection region near the input end face, and detecting the specific frequency signal component in the output light of the optical amplifier, and keeping its magnitude constant Means for controlling an injection current into a current injection region other than the first injection region of the optical amplifier so as to maintain the value.
（作用） 本願と同一の出願人により先に出願されている特願昭
63−123142に述べられているように、半導体光増幅器で
は、エピタキシャル層側の電極を分離することにより、
互いに独立に電流を注入できる多電極構造を実現するこ
とが可能である。また、「電子情報通信学会論文誌」、
第E71巻、第10号、1988年、第972−974頁に述べられて
いるように、半導体光増幅器は注入電流を変調すること
により、利得をもつ光変調器として利用できる。従っ
て、多電極構造半導体光増幅器を用いた場合、入力側に
近い電極に直流バイアスと共に低周波パイロット信号を
印加し、光増幅器出力のパイロット信号成分を抽出し
て、それを一定値になるように制御することにより、利
得安定化が可能となる。この場合、パイロット信号印加
のための光変調器と光増幅器がモノリシック集積されて
いる素子を用いているから、特殊な光送信器や光変調器
を用いずに利得の安定化制御ができる半導体光増幅装置
が可能となる。(Action) A Japanese patent application filed earlier by the same applicant as the present application
As described in 63-123142, in the semiconductor optical amplifier, by separating the electrode on the epitaxial layer side,
It is possible to realize a multi-electrode structure in which currents can be injected independently of each other. In addition, the IEICE Transactions,
As described in Vol. E71, No. 10, 1988, pp. 972-974, a semiconductor optical amplifier can be used as an optical modulator having a gain by modulating an injection current. Therefore, when a multi-electrode semiconductor optical amplifier is used, a low-frequency pilot signal is applied to an electrode close to the input side together with a DC bias, and a pilot signal component of the optical amplifier output is extracted so that it becomes a constant value. By controlling, gain stabilization becomes possible. In this case, since an optical modulator and an optical amplifier for applying a pilot signal are monolithically integrated, a semiconductor optical device that can control gain stabilization without using a special optical transmitter or optical modulator. An amplification device becomes possible.
（実施例） 第１図は本発明の一実施例の半導体光増幅装置を示す
ブロック図である。本図において、半導体光増幅器20
は、光軸に沿い、かつ基盤に垂直な面における断面図で
示してある。先ず初めに、本実施例に用いる半導体光増
幅器の製作方法に付いて説明する。(Embodiment) FIG. 1 is a block diagram showing a semiconductor optical amplifier according to an embodiment of the present invention. In the figure, the semiconductor optical amplifier 20
Is shown in cross section in a plane along the optical axis and perpendicular to the substrate. First, a method for manufacturing the semiconductor optical amplifier used in this embodiment will be described.
まず気相成長法により、ｎ−InPバッファ層11、ノン
ドープのInGaAsP活性層12、ｐ−InPクラッド層13、ｐ−
InGaAsPキャップ層14を（100）ｎ−InP基板10上に連続
的に成長する。次に、ここでは図示していないが、エッ
チングと埋込の成長により特開昭58−067087号に開示さ
れているような二重のチャンネルプレーナ埋込み（DC−
PBH）構造を形成する。この半導体光増幅器において
は、利得の偏光依存性を低減するための活性層を0.2μ
ｍ、幅を１μｍとした。First, an n-InP buffer layer 11, a non-doped InGaAsP active layer 12, a p-InP cladding layer 13,
An InGaAsP cap layer 14 is continuously grown on the (100) n-InP substrate 10. Next, although not shown here, double channel planar embedding (DC-emitter) as disclosed in JP-A-58-067087 is performed by etching and embedding growth.
(PBH) structure. In this semiconductor optical amplifier, the active layer for reducing the polarization dependence of the gain is 0.2 μm.
m and the width were 1 μm.
次にｐ側にオーム性電極を前面に蒸着した後、通常の
フォトリングラフィ法及びドライエッチング法によりｐ
側電極15、ｐ−InGaAsPキャップ層14及びｐ−InPクラッ
ド層13の途中迄を光軸に垂直な方向にストライプ状に除
去する。図ではｐ側電極15のうちの信号入力側を15a、
出力側を15bとして符号を付している。次いでｎ側電極1
6を形成し、へき開により入出力端面17a、17bを形成
し、その上に無反射コート膜となるSiN膜18a,18bをプラ
ズマCVD法により形成する。ここで述べたｐ側電極と半
導体層の途中迄の除去はｐ側電極を15a,15bに分割し電
気的な分離を行うためのもので、半導体層の除去の代わ
りにイオン打込等を用いてもよい。このような構造をと
ることにより、活性層の光軸方向に、互いに独立に電流
を注入できる２つの領域を得ることができる。Next, after an ohmic electrode is vapor-deposited on the front side on the p-side, p-side is formed by a usual photolithography method and dry etching method.
A part of the side electrode 15, the p-InGaAsP cap layer 14, and the p-InP clad layer 13 is striped in a direction perpendicular to the optical axis. In the figure, the signal input side of the p-side electrode 15 is 15a,
The output side is denoted by reference numeral 15b. Then n-side electrode 1
6 is formed, and input / output end faces 17a and 17b are formed by cleavage, and SiN films 18a and 18b to be non-reflective coating films are formed thereon by a plasma CVD method. The removal of the p-side electrode and the semiconductor layer halfway as described here is for dividing the p-side electrode into 15a and 15b for electrical isolation, and using ion implantation or the like instead of removing the semiconductor layer. You may. By adopting such a structure, it is possible to obtain two regions in which currents can be injected independently of each other in the optical axis direction of the active layer.
次に本実施例の動作を説明する。光ファイバ1aにより
伝送された入力光信号19aはレンズ等の光結合手段（図
では省略）により光増幅器20のに結合される。電極15a
は、光増幅器20のｐ側電極のうち入力側に近い電極であ
る。発振器2aからの小振幅、低周波（ここでは10kHz）
パイロット信号と直流電流2bからの直流電流とが駆動回
路2cにより加え合わされ、電極15aに印可される。光増
幅器20の光出力19bは、光ファイバ1bに結合された後、
一部は光分岐３により分岐され、光検出器４により電気
信号に変換される。光検出器４の出力信号は、増幅器５
により増幅される。増幅器５の出力側には帯域フィルタ
が設けていて、この帯域フィルタにより10KHzのパイロ
ット信号周波成分が取り出される。このパイロット信号
周波数成分は、整流回路６で整流され、整流回路６の出
力の直流信号は、低域フィルタ７を通り平滑化され、差
動増幅器８の一つの入力端子8aに入力される。差動増幅
器８のもう一つの入力端子8bには、基準となる電圧が印
可される。差動増幅器８の出力は光増幅器駆動回路９で
電力を増幅される。光増幅器駆動回路９の出力は光増幅
器20のもう一つのｐ側電極15bに駆動電流として加えら
れる。このような構成により、半導体光増幅器20の光出
力19bは、光分岐３、光検出器４、増幅器５、整流回路
６、低域フィルタ７、差動増幅器８および光増幅器駆動
回路９を経て、ｐ側電極15bに帰還される。この帰還回
路により、差動増幅器８の出力が零になるように、光増
幅器駆動回路９の出力の駆動電流が制御され、ひいては
半導体光増幅器20の利得が一定に制御される。Next, the operation of this embodiment will be described. The input optical signal 19a transmitted by the optical fiber 1a is coupled to the optical amplifier 20 by optical coupling means (not shown) such as a lens. Electrode 15a
Is an electrode close to the input side of the p-side electrode of the optical amplifier 20. Small amplitude, low frequency (10 kHz here) from oscillator 2a
The pilot signal and the DC current from the DC current 2b are added by the drive circuit 2c and applied to the electrode 15a. After the optical output 19b of the optical amplifier 20 is coupled to the optical fiber 1b,
A part is split by the optical splitter 3 and converted into an electric signal by the photodetector 4. The output signal of the photodetector 4 is
Amplified by A band filter is provided on the output side of the amplifier 5, and a 10 KHz pilot signal frequency component is extracted by the band filter. This pilot signal frequency component is rectified by the rectifier circuit 6, and the DC signal output from the rectifier circuit 6 is smoothed through the low-pass filter 7 and input to one input terminal 8 a of the differential amplifier 8. A reference voltage is applied to another input terminal 8b of the differential amplifier 8. The power of the output of the differential amplifier 8 is amplified by the optical amplifier driving circuit 9. The output of the optical amplifier drive circuit 9 is applied as a drive current to another p-side electrode 15b of the optical amplifier 20. With this configuration, the optical output 19b of the semiconductor optical amplifier 20 passes through the optical branch 3, the photodetector 4, the amplifier 5, the rectifier 6, the low-pass filter 7, the differential amplifier 8, and the optical amplifier driver 9, It is fed back to the p-side electrode 15b. By this feedback circuit, the drive current of the output of the optical amplifier drive circuit 9 is controlled so that the output of the differential amplifier 8 becomes zero, and the gain of the semiconductor optical amplifier 20 is controlled to be constant.
この構成によれば、低周波信号を伝送信号に重畳する
ための特殊な光送信器や外部変調器を用いることなく光
増幅器の利得安定化制御が可能となる。光増幅器を光変
調器として用いる際には、自然放出光が問題になるが、
入力信号光強度に対して、利得の大きさ（直流バイアス
の大きさ）を最適化することによりこの問題は除くこと
が出来る。実験では電極15aへの直流注入電流30mA、パ
イロット信号振幅1mAの状態で、光増幅器20のファイバ
間利得を10dBに安定化することが確認できた。According to this configuration, the gain stabilization control of the optical amplifier can be performed without using a special optical transmitter or an external modulator for superimposing the low frequency signal on the transmission signal. When an optical amplifier is used as an optical modulator, spontaneous emission becomes a problem.
This problem can be eliminated by optimizing the magnitude of the gain (the magnitude of the DC bias) with respect to the input signal light intensity. In the experiment, it was confirmed that the gain between the fibers of the optical amplifier 20 was stabilized at 10 dB under the condition that the DC injection current to the electrode 15a was 30 mA and the pilot signal amplitude was 1 mA.
また、従来、遠隔地に置かれた光送信器でパイロット
信号を印可していたのに比べ、光増幅器20の極く近くで
パイロット信号を印加するから、遠隔地に置かれた光送
信器の状態、光送信器と光交換機の間の光ファイバ伝送
路1aの状態によらず、光増幅器20の利得の安定化制御が
容易に確実に実現できるという利点も生じる。In addition, since a pilot signal is applied very close to the optical amplifier 20 as compared with a conventional case where a pilot signal is applied by an optical transmitter located in a remote place, an optical transmitter located in a remote place is applied. Regardless of the state and the state of the optical fiber transmission line 1a between the optical transmitter and the optical switch, there is an advantage that the stabilization control of the gain of the optical amplifier 20 can be easily and reliably realized.
以上の実施例では、光増幅器出力中のパイロット信号
の強度のモニタを、光増幅器出力の一部を分岐して光電
変換することにより行ったが、雑誌「エレクトロニクス
・レターズ（Electronics Letters）」、第25巻、1989
年、235−236頁に述べられているように、光増幅器の端
子電圧変化を検知してもよい。In the above embodiment, the monitoring of the intensity of the pilot signal during the output of the optical amplifier is performed by branching a part of the output of the optical amplifier and performing photoelectric conversion. However, the magazine "Electronics Letters", Volume 25, 1989
As described on pages 235-236, a change in terminal voltage of an optical amplifier may be detected.
（発明の効果） 以上に説明したように、本発明によれば、従来の光増
幅器の利得安定化方法で必要であった低周波信号を伝送
信号に重畳するための特殊な光送信器や外部変調器を必
要とせずに利得の安定化制御が可能な半導体光増幅装置
が得られる。(Effects of the Invention) As described above, according to the present invention, a special optical transmitter or external device for superimposing a low-frequency signal on a transmission signal, which is required in a conventional method for stabilizing the gain of an optical amplifier, is provided. A semiconductor optical amplifying device capable of controlling stabilization of gain without requiring a modulator is obtained.
第１図は本発明による半導体光増幅装置の構成を示すブ
ロック図である。本図に於て、1a,1bは光ファイバ、2a
は発振器、2bは直流電源、2cは駆動回路、３は光分岐、
４は光検出器、５は増幅器、６は帯域フィルタ、７は整
流回路、８は差動増幅器、8a,8bは端子、９は駆動回
路、10は半導体基板、11,12,13、14は半導体、15a,15b,
16は電極、17a,17bは端面、18a,18bは無反射コート膜、
19a,19bは光信号である。FIG. 1 is a block diagram showing a configuration of a semiconductor optical amplifier according to the present invention. In this figure, 1a and 1b are optical fibers, 2a
Is an oscillator, 2b is a DC power supply, 2c is a drive circuit, 3 is an optical branch,
4 is a photodetector, 5 is an amplifier, 6 is a bandpass filter, 7 is a rectifier circuit, 8 is a differential amplifier, 8a and 8b are terminals, 9 is a drive circuit, 10 is a semiconductor substrate, 11, 12, 13, and 14 are Semiconductor, 15a, 15b,
16 is an electrode, 17a and 17b are end faces, 18a and 18b are non-reflective coating films,
19a and 19b are optical signals.
Claims (1)
複数の電流注入領域を持つ半導体光増幅器と、前記複数
の電流注入領域のうち入力端面に近い第一の注入領域に
直流電流と共に低周波の特定周波数信号を印加する手段
と、前記光増幅器の出力光中の前記特定周波数信号の成
分を検出し、その大きさを一定値に保つように、前記光
増幅器における前記第一の注入領域以外の電流注入領域
への注入電流を制御する手段とからなることを特徴とす
る半導体光増幅装置。1. A semiconductor optical amplifier having a plurality of independent current injection regions arranged in the direction of the optical axis of an active layer, and a first injection region of the plurality of current injection regions near an input end face together with a direct current. Means for applying a low-frequency specific frequency signal, and detecting the component of the specific frequency signal in the output light of the optical amplifier, and performing the first injection in the optical amplifier so as to maintain the magnitude thereof at a constant value. A means for controlling an injection current to a current injection region other than the region.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2238780A JP2900567B2 (en) | 1990-09-07 | 1990-09-07 | Semiconductor optical amplifier |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2238780A JP2900567B2 (en) | 1990-09-07 | 1990-09-07 | Semiconductor optical amplifier |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH04118637A JPH04118637A (en) | 1992-04-20 |
| JP2900567B2 true JP2900567B2 (en) | 1999-06-02 |
Family
ID=17035171
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2238780A Expired - Lifetime JP2900567B2 (en) | 1990-09-07 | 1990-09-07 | Semiconductor optical amplifier |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2900567B2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3821920B2 (en) | 1996-09-17 | 2006-09-13 | 富士通株式会社 | Optical communication system |
| JP2016129163A (en) | 2015-01-09 | 2016-07-14 | 三菱電機株式会社 | Laser module |
-
1990
- 1990-09-07 JP JP2238780A patent/JP2900567B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH04118637A (en) | 1992-04-20 |
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