JP2666297B2 - Tunable semiconductor laser - Google Patents

Tunable semiconductor laser

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Publication number
JP2666297B2
JP2666297B2 JP62228910A JP22891087A JP2666297B2 JP 2666297 B2 JP2666297 B2 JP 2666297B2 JP 62228910 A JP62228910 A JP 62228910A JP 22891087 A JP22891087 A JP 22891087A JP 2666297 B2 JP2666297 B2 JP 2666297B2
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JP
Japan
Prior art keywords
semiconductor laser
layer
refractive index
thickness
waveguide
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
Application number
JP62228910A
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Japanese (ja)
Other versions
JPS6472583A (en
Inventor
光博 矢野
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Fujitsu Ltd
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Fujitsu Ltd
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Publication of JPS6472583A publication Critical patent/JPS6472583A/en
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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
    • H01S5/06255—Controlling the frequency of the radiation
    • H01S5/06256—Controlling the frequency of the radiation with DBR-structure
    • 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
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
    • H01S3/105—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating by controlling the mutual position or the reflecting properties of the reflectors of the cavity, e.g. by controlling the cavity length
    • H01S3/1055—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating by controlling the mutual position or the reflecting properties of the reflectors of the cavity, e.g. by controlling the cavity length one of the reflectors being constituted by a diffraction grating

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Optics & Photonics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Semiconductor Lasers (AREA)

Description

【発明の詳細な説明】 〔概要〕 光共振器の導波路の屈折率を電圧制御で変化させる機
能を備えた半導体レーザに係り、 屈折率可変範囲をより大とすることを目的として、 屈折率可変である前記導波路は、母体結晶層と該母体
結晶よりエネルギギャップの小なる単結晶層から構成さ
れる超格子構造であり、前記エネルギギャップの小なる
単結晶各層の厚みは、中心から隔たるに従い順次その厚
さを増すように形成されている。各層の厚さは、例え
ば、厚みがW0である中心層から数えて第ｎ番目に位置す
る２つの結晶層の厚みを（１＋αn2）W0とする。 〔産業上の利用分野〕 本発明は光通信などに利用される発光波長可変の半導
体レーザに関わり、特に超格子の屈折率制御構造部を有
する半導体レーザに関わる。 近年、光通信技術は急速な発展を見せているが、特に
コヒーレント光を用いる通信技術が注目を集めている。
これは、従来の光通信が光のオン／オフのみをコード化
に利用するものであるのに対し、光を短波長の電磁波と
して扱い、より長波長の電磁波いわゆる電波と同じよう
に、その位相、周波数などを制御することにより、FM、
PM、FSK、PSKなどの変調をかけて情報伝達を行うもので
ある。 それによって、より多量の情報を伝達し或いは伝達距
離を延長することが可能になるが、このような方式に使
用される半導体レーザにはより厳しい仕様や新しい機能
が要求されることになる。即ち、単一モードの発振を行
うことは当然として、その周波数変動幅が極めて小であ
る半導体レーザが求められると共に、他方では波長チュ
ーニングの可能な半導体レーザも必要となっている。 本発明は後者の波長チューニング可能な半導体レー
ザ、即ち発光波長可変半導体レーザに関わるものであ
る。 〔従来技術と発明が解決しようとする問題点〕 半導体レーザの発光波長を変化させるには、レーザ共
振器の長さや屈折率を変える、動作温度を変える等の手
段があるが、最も現実的と見られているのは屈折率を電
気的に変化させる方法である。 これは、屈折率がηであるレーザ共振器に閉じ込めら
れた光の波長Λと外部空間に放出される光の波長λとの
間には、λ＝ηΛなる関係があることから、実効的には
固定であるΛに対しηを変化させることでλを変えるこ
とが出来るという事情に基づいている。 また、電圧の印加によって屈折率が変化するのは、屈
折率が単位体積内の双極子モーメントの総和に比例する
ことから、電圧印加で電気双極子が傾いて双極子モーメ
ントが増し、屈折率が大になると説明される。従って、
レーザ共振器に双極子モーメントの変化量の大きい材料
或いは構造を採用することにより、半導体レーザの波長
可変量を大とすることが出来る。 本発明の発明者は、超格子構造の量子井戸部分には双
極子が局在し、電圧印加による屈折率変化が大である点
に着目し、超格子構造の波長制御構造部を有する半導体
レーザ或いは屈折率制御に著効のある超格子構造を発明
し、特願昭62−149140,同62−149141,同62−149142とし
て特許出願している。 超格子構造を構成するバンドキャップの狭い結晶層
は、その実空間の厚みが小であるほど屈折率の変化は大
となるが、現実の半導体レーザに於ける導波路に光が分
布する幅は、量子井戸の幅よりも２桁程度大であるため
光に対する相互作用が弱く、目的とする波長変化を十分
に得ることが出来ない。従来技術ではこの点が未解決で
あり、上記先行出願発明もまた、満足し得る解決策をも
たらすものにはなっていない。 〔問題点を解決するための手段〕 発光波長の変化量は、光導波路における光の強度分布
と屈折率変化の重ね合わせ積分量として表されるが、本
発明は、この重ね合わせ積分量を実効的に最大にする超
格子構造を用いることによって大幅に波長を変化せしめ
得る半導体レーザを実現したものであって、本発明の半
導体レーザは、 半導体単結晶内に光共振器が設けられ、屈折率可変で
ある前記導波路は、母体結晶層と該母体結晶よりエネル
ギギャップの小なる単結晶層から構成される超格子構造
であり、前記エネルギギャップの小なる単結晶層各層の
厚みは、中心から隔たるに従い順次その厚さを増すよう
に形成されて成ることを特徴としている。 〔作 用〕 双極子の密度は量子井戸を形成する狭バンドギャップ
層の実空間の厚みに反比例する。即ち、狭バンドギャッ
プ層の実空間の厚みが小であるほど屈折率変化は大であ
り、厚いと屈折率変化は小である。従って本発明の如
く、光の強度分布が最大である中心部では狭バンドギャ
ップ層を最も薄く、即ち屈折率変化を最大にし、光の強
度が弱まる部分で狭バンドギャップ層を厚くすれば、光
の強度分布と屈折率変化の重ね合わせ積分量を効果的に
大とすることが出来る。 従って、本発明の実施態様の如き半導体レーザでは、
発光波長の変化幅が大きなものとなる。 〔実施例〕 第１図は本発明の実施例の半導体レーザの導波路部分
構造を模式的に示す模式的斜視図及び断面図である。同
図（ａ）に示される半導体レーザを図中に記入された切
断面によるＸ−Ｘ断面が同図（ｂ）である。斜視図では
BH型レーザが例示されているが、本発明は光閉じ込めの
構造によって限定されるものではなく、公知の他の型の
レーザにも適用できる。 図に於いて、１はｎ−InP、2aはｎ−InGaAsPのクラッ
ド層、2bは同じ材料からなる回折格子、3aはInGaAsPの
活性層、3bはInP中に設けられたInGaAsPの超格子層、４
はｐ−InP層,5aはレーザ発振用電流注入電極、5bは屈折
率制御用電極である。なお、上記４元系結晶の組成は通
常の半導体レーザに於けると同様で、例えばクラッド層
のバンドギャップはλ＝1.3μｍ、活性層はλ＝1.55μ
ｍである。また、超格子層3bはλ＝1.5μｍのInGaAsPの
複数の層と障壁層であるInPの複数の層から成ってい
る。 実施例の半導体レーザは、図から明らかなように、左
方の部分が電流注入領域で、通常の半導体レーザと同じ
構造、右方の部分が回折格子を備えた屈折率制御領域で
ある。 半導体レーザの構造と発振の原理は周知の事柄である
から詳しい説明は省略するが、本発明の半導体レーザに
於いても、活性層3aへの電流注入と劈開面間の定在波共
振による誘導放出すなわちレーザ発振が起こる。 一方、屈折率制御領域の構造では、分布ブラッグ反射
を利用して発光波長を制御する回折格子は周知である
が、共振器の導波路の構造が超格子となっており、量子
井戸を形成するInGaAsP層と障壁層であるInP層から構成
されている。InGaAsP層の組成は既述した通りである。 該超格子部分の導電型は、その上端面あるいは下端面
のいずれかにｐ−ｎ接合が存在し、そこに逆バイアスが
印加されるものであるから、全ての層が、ｐ型/n型のい
ずれか同じ導電型であればよいことになる。 而して、本発明の重要点は、該超格子構造の各InGaAs
P層の厚みは第２図に示されるように、中心から隔たる
につれて次第にその厚みを増すという特徴を有すること
である。該図の横軸は第１図の高さ方向に対応する実空
間の距離を示し、縦軸は電子のエネルギレベルを示す。
低レベルの部分がInGaAsP層であり、該部分に量子井戸
が形成される。 第２図に示された厚さ分布は、本発明における最も好
ましい態様であって、中心に位置するInGaAsP層の厚み
をW0とすると、中心層から数えて第ｎ番目になる２つの
InGaAsP層の厚みは（１＋αn2）W0として規定されてい
る。InP部分の厚みｔは一定である。 導波路内の光の強度分布はマックスウエルの方程式に
従う分布を示すから、屈折率の変化も同様の分布をとる
ようにすれば、両者の重ね合わせ積分値は最大となるの
であるが、既に述べたように、屈折率変化は低エネルギ
レベル層の厚さに反比例するから、この厚さを放物線分
布とすることで、重ね合わせ積分値を最大とすることが
出来る。即ち、上記の式に従う厚さ分布が最も望ましい
ことになる。 光導波路の厚さは限られた範囲の値をとり、本発明で
はそれを何層かの超格子構造に分割することになる。そ
の場合光強度分布に精密に一致させるためには細かく分
割することが望ましいが、層間距離ｔをあまり小さくす
ると量子井戸間の相互干渉のため屈折率変化が抑制され
るので、分割する層数には自ずから限界がある。分割数
はまた、工程上の制約も受ける。上式のαは分割層数と
光導波路の厚さを整合させるための定数である。 例えば、ｔの値を量子井戸間の相互干渉の無い値であ
る100Åに選び、層数ｎを10とした場合、InGaAsP層の厚
みが最外層で中心層の４倍になるようにするには、α＝
3/100とすれば良いことになる。 上記実施例の構造の半導体レーザは、公知のプロセス
技術によって形成可能であるが、図示の導波路部分は、
例えば次のようにして形成することが出来る。 まず、ｎ−InP単結晶層１に回折格子の溝を掘り、MOC
VD等の方法によってｎ−InGaAsP層をエピタキシャル成
長させて層2a,2bを形成する。この時、回折格子の溝は
埋められて成長面は平坦になる。その上にInGaAsP活性
層3aを成長させる。 次いで、屈折率制御領域の活性層を選択的に除去し、
同領域にMBE等の手段によって超格子層を選択的に成長
させる。更に、両領域上にｐ−InPをエピタキシャル成
長させる。 〔発明の効果〕 以上説明したように本発明の半導体レーザでは、導波
路の光強度分布に合わせた屈折率変化を実現するもので
あり、特に上記実施例の場合は重ね合わせ積分値がほゞ
最大なるので、コヒーレント光通信に適した発光波長可
変半導体レーザが得られる。 該実施例以外の層厚分布でも、中心から隔たるにつれ
て厚みを大にすれば、重ね合わせ積分値は大となり、同
様の目的が達成される。DETAILED DESCRIPTION OF THE INVENTION [Summary] The present invention relates to a semiconductor laser having a function of changing the refractive index of a waveguide of an optical resonator by voltage control. The tunable waveguide has a superlattice structure composed of a host crystal layer and a single crystal layer having a smaller energy gap than the host crystal. The thickness of each single crystal layer having a smaller energy gap is separated from the center. It is formed so that its thickness is gradually increased as it is pulled. The thickness of each layer has a thickness of, for example, W 0 and is counted from the center layer to the thickness of the two crystal layers positioned in the n-th (1 + αn 2) and W 0. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser having a variable emission wavelength used for optical communication and the like, and more particularly to a semiconductor laser having a superlattice refractive index control structure. 2. Description of the Related Art In recent years, optical communication technology has been rapidly developing, and communication technology using coherent light has received attention.
This is because conventional optical communication uses only on / off of light for encoding, but treats light as a short-wavelength electromagnetic wave and, like a longer-wavelength electromagnetic wave, a so-called radio wave, its phase FM, by controlling the frequency, etc.
It transmits information by modulating PM, FSK, PSK, etc. As a result, a larger amount of information can be transmitted or the transmission distance can be extended, but stricter specifications and new functions are required for the semiconductor laser used in such a method. That is, it is natural that a semiconductor laser having an extremely small frequency variation width is required, as well as a single mode oscillation. On the other hand, a semiconductor laser capable of wavelength tuning is also required. The present invention relates to the latter wavelength tunable semiconductor laser, that is, a tunable semiconductor laser. [Problems to be solved by the prior art and the invention] To change the emission wavelength of the semiconductor laser, there are means such as changing the length and refractive index of the laser resonator, changing the operating temperature, etc. What is seen is a method of electrically changing the refractive index. This is because there is a relationship of λ = ηΛ between the wavelength Λ of the light confined in the laser resonator having the refractive index η and the wavelength λ of the light emitted to the external space. Is based on the fact that λ can be changed by changing η with respect to Λ which is fixed. In addition, the refractive index changes with the application of a voltage because the refractive index is proportional to the sum of the dipole moments in a unit volume. Explained to be big. Therefore,
By adopting a material or a structure having a large change amount of the dipole moment for the laser resonator, the wavelength variable amount of the semiconductor laser can be increased. The inventor of the present invention focused on the fact that dipoles are localized in the quantum well portion of the superlattice structure and the refractive index change due to voltage application is large, and a semiconductor laser having a wavelength control structure portion of the superlattice structure Alternatively, a superlattice structure effective for controlling the refractive index was invented, and patent applications were filed as Japanese Patent Application Nos. 62-149140, 62-149141, and 62-149142. In a crystal layer having a narrow bandgap constituting a superlattice structure, the change in the refractive index increases as the thickness of the real space decreases, but the width of light distribution in a waveguide in an actual semiconductor laser is Since the width is about two orders of magnitude larger than the width of the quantum well, the interaction with light is weak, and a desired wavelength change cannot be obtained sufficiently. This point has not been solved in the prior art, and the above-mentioned prior invention does not provide a satisfactory solution. [Means for Solving the Problems] The amount of change in the emission wavelength is expressed as a superposition integral amount of the light intensity distribution and the refractive index change in the optical waveguide. The present invention has realized a semiconductor laser whose wavelength can be largely changed by using a superlattice structure that maximizes the wavelength. The semiconductor laser of the present invention has an optical resonator provided in a semiconductor single crystal and has a refractive index. The variable waveguide has a superlattice structure composed of a base crystal layer and a single crystal layer having a smaller energy gap than the base crystal, and the thickness of each single crystal layer having a smaller energy gap is from the center. It is characterized in that it is formed so as to increase its thickness as the distance increases. [Operation] The dipole density is inversely proportional to the real space thickness of the narrow bandgap layer forming the quantum well. That is, the smaller the thickness of the real space of the narrow band gap layer is, the larger the change in the refractive index is, and the larger the thickness is, the smaller the change in the refractive index is. Therefore, as in the present invention, if the narrow band gap layer is the thinnest at the center where the light intensity distribution is maximum, that is, the refractive index change is maximized, and the narrow band gap layer is thickened at the portion where the light intensity is weakened, Can be effectively increased by integrating the intensity distribution and the refractive index change. Therefore, in the semiconductor laser according to the embodiment of the present invention,
The change width of the emission wavelength becomes large. Embodiment FIG. 1 is a schematic perspective view and a sectional view schematically showing a waveguide partial structure of a semiconductor laser according to an embodiment of the present invention. FIG. 2B is a sectional view taken along line XX of the semiconductor laser shown in FIG. In the perspective view
Although a BH type laser is illustrated, the present invention is not limited by the structure of the optical confinement, and can be applied to other known types of lasers. In the figure, 1 is n-InP, 2a is a cladding layer of n-InGaAsP, 2b is a diffraction grating made of the same material, 3a is an active layer of InGaAsP, 3b is a superlattice layer of InGaAsP provided in InP, 4
Denotes a p-InP layer, 5a denotes a laser injection current injection electrode, and 5b denotes a refractive index control electrode. The composition of the quaternary crystal is the same as that in a normal semiconductor laser. For example, the band gap of the cladding layer is λ = 1.3 μm, and the active layer is λ = 1.55 μm.
m. The superlattice layer 3b is composed of a plurality of layers of InGaAsP having λ = 1.5 μm and a plurality of layers of InP which is a barrier layer. As is clear from the drawing, the semiconductor laser of the embodiment has a current injection region on the left side, the same structure as a normal semiconductor laser, and a refractive index control region provided with a diffraction grating on the right side. Since the structure and oscillation principle of the semiconductor laser are well known, detailed description is omitted. However, in the semiconductor laser of the present invention, current injection into the active layer 3a and induction by standing wave resonance between the cleavage planes are also performed. Emission, or lasing, occurs. On the other hand, in the structure of the refractive index control region, a diffraction grating that controls the emission wavelength using distributed Bragg reflection is well known, but the structure of the waveguide of the resonator is a superlattice and forms a quantum well. It is composed of an InGaAsP layer and an InP layer serving as a barrier layer. The composition of the InGaAsP layer is as described above. The conductivity type of the superlattice portion is such that a pn junction exists on either the upper end surface or the lower end surface thereof and a reverse bias is applied thereto, so that all layers are p-type / n-type. It is only necessary to use the same conductivity type. Therefore, the important point of the present invention is that each InGaAs of the superlattice structure is used.
As shown in FIG. 2, the thickness of the P layer is such that it gradually increases as the distance from the center increases. The horizontal axis of the figure indicates the distance in the real space corresponding to the height direction of FIG. 1, and the vertical axis indicates the energy level of electrons.
The low level portion is the InGaAsP layer, and a quantum well is formed in this portion. The thickness distribution shown in FIG. 2 is the most preferable embodiment in the present invention, and when the thickness of the center InGaAsP layer is W 0 , the two n-th layers counted from the center layer
The thickness of the InGaAsP layer is defined as (1 + αn 2 ) W 0 . The thickness t of the InP portion is constant. Since the light intensity distribution in the waveguide shows a distribution according to Maxwell's equation, if the change in the refractive index also takes the same distribution, the superposition integral value of the two will be the maximum, but as described above. As described above, since the change in the refractive index is inversely proportional to the thickness of the low energy level layer, by making this thickness a parabolic distribution, the superposition integral value can be maximized. That is, the thickness distribution according to the above equation is most desirable. The thickness of the optical waveguide takes a value in a limited range, and in the present invention, it is divided into several layers of a superlattice structure. In that case, it is desirable to divide finely in order to precisely match the light intensity distribution. However, if the interlayer distance t is too small, a change in the refractive index is suppressed due to mutual interference between quantum wells. Has its own limitations. The number of divisions is also subject to process constraints. Α in the above equation is a constant for matching the number of divided layers with the thickness of the optical waveguide. For example, if the value of t is selected to be 100 °, which is a value with no mutual interference between quantum wells, and the number of layers n is set to 10, the thickness of the InGaAsP layer is four times as large as the center layer in the outermost layer. , Α =
It should be 3/100. The semiconductor laser having the structure of the above embodiment can be formed by a known process technology.
For example, it can be formed as follows. First, a groove of a diffraction grating is dug in the n-InP single crystal layer 1, and the MOC
The layers 2a and 2b are formed by epitaxially growing an n-InGaAsP layer by a method such as VD. At this time, the grooves of the diffraction grating are filled and the growth surface becomes flat. An InGaAsP active layer 3a is grown thereon. Next, the active layer in the refractive index control region is selectively removed,
A superlattice layer is selectively grown in the same region by means such as MBE. Further, p-InP is epitaxially grown on both regions. [Effects of the Invention] As described above, the semiconductor laser of the present invention realizes a change in the refractive index in accordance with the light intensity distribution of the waveguide. In particular, in the case of the above-described embodiment, the superposition integral value is almost zero. Since the maximum value is obtained, an emission wavelength variable semiconductor laser suitable for coherent optical communication can be obtained. In the layer thickness distributions other than those of the embodiment, if the thickness increases as the distance from the center increases, the superposition integral value increases, and the same object is achieved.

【図面の簡単な説明】 第１図は本発明の半導体レーザの模式的斜視図及び断面
図、 第２図は導波路の超格子構造の構成を模式的に示す図で
あって、図に於いて １はｎ−InP、 2aはクラッド層、 2bは回折格子、 3aは活性層、 3bは超格子層、 ４はｐ−InP層、 5aは電流注入電極、 5bは屈折率制御電極 である。BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic perspective view and a cross-sectional view of a semiconductor laser of the present invention, and FIG. 2 is a view schematically showing a configuration of a superlattice structure of a waveguide. 1 is n-InP, 2a is a cladding layer, 2b is a diffraction grating, 3a is an active layer, 3b is a superlattice layer, 4 is a p-InP layer, 5a is a current injection electrode, and 5b is a refractive index control electrode.

Claims (1)

(57)【特許請求の範囲】 １．半導体単結晶内に光共振器が設けられ、該光共振器
の導波路の一部分に電圧を印加することによって該導波
路の屈折率を変化せしめるごとく構成された半導体レー
ザであって、屈折率可変である前記導波路は、母体結晶
層と該母体結晶よりエネルギギャップの小なる単結晶層
から構成される超格子構造であり、前記エネルギギャッ
プの小なる単結晶層各層の厚みは、中心から隔たるに従
い順次その値を増すように形成されて成ることを特徴と
する波長可変型半導体レーザ。(57) [Claims] An optical resonator is provided in a semiconductor single crystal, and a semiconductor laser configured to change a refractive index of the waveguide by applying a voltage to a part of the waveguide of the optical resonator. Is a superlattice structure composed of a base crystal layer and a single crystal layer having a smaller energy gap than the base crystal, and the thickness of each of the single crystal layers having a smaller energy gap is spaced from the center. A wavelength tunable semiconductor laser formed so as to increase its value sequentially as it goes.
JP62228910A 1987-09-11 1987-09-11 Tunable semiconductor laser Expired - Lifetime JP2666297B2 (en)

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Publication number Priority date Publication date Assignee Title
JP2671334B2 (en) * 1987-12-10 1997-10-29 ソニー株式会社 Electrode structure of semiconductor laser
JPH01175784A (en) * 1987-12-29 1989-07-12 Matsushita Electric Ind Co Ltd Optical integrated circuit

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS561589A (en) * 1979-06-18 1981-01-09 Furukawa Electric Co Ltd:The Method of controlling laser oscillation output
JPS6142189A (en) * 1984-08-02 1986-02-28 Matsushita Electric Ind Co Ltd Semiconductor laser
JPS6154690A (en) * 1984-08-24 1986-03-18 Nec Corp Semiconductor laser device
JPS61116896A (en) * 1984-11-13 1986-06-04 Sharp Corp Semiconductor laser device
JPS62183587A (en) * 1986-02-07 1987-08-11 Fujitsu Ltd Semiconductor laser

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS561589A (en) * 1979-06-18 1981-01-09 Furukawa Electric Co Ltd:The Method of controlling laser oscillation output
JPS6142189A (en) * 1984-08-02 1986-02-28 Matsushita Electric Ind Co Ltd Semiconductor laser
JPS6154690A (en) * 1984-08-24 1986-03-18 Nec Corp Semiconductor laser device
JPS61116896A (en) * 1984-11-13 1986-06-04 Sharp Corp Semiconductor laser device
JPS62183587A (en) * 1986-02-07 1987-08-11 Fujitsu Ltd Semiconductor laser

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