JP2841570B2 - External cavity semiconductor laser and optical transmission device using the same - Google Patents
External cavity semiconductor laser and optical transmission device using the sameInfo
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- JP2841570B2 JP2841570B2 JP1288338A JP28833889A JP2841570B2 JP 2841570 B2 JP2841570 B2 JP 2841570B2 JP 1288338 A JP1288338 A JP 1288338A JP 28833889 A JP28833889 A JP 28833889A JP 2841570 B2 JP2841570 B2 JP 2841570B2
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Description
【発明の詳細な説明】 産業上の利用分野 本発明は半導体レーザ光を用いて情報・記号を伝送を
行う光通信分野に係わるものであり、特に一つの半導体
レーザで複数の波長を発振させる半導体レーザ装置とこ
れを用いた光伝送装置に関するものである。Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the field of optical communication in which information and symbols are transmitted using semiconductor laser light, and more particularly to a semiconductor that oscillates a plurality of wavelengths with one semiconductor laser. The present invention relates to a laser device and an optical transmission device using the same.
従来の技術 発振波長がたとえば半導体レーザに注入される電流等
により制御可能で、しかも安定に単一波長で単一縦モー
ド発振する半導体レーザは、光通信分野においては単に
一つのレーザ光源を用いるだけで複数の受信局に異なる
独立した情報を伝送することが可能となり開発が要求さ
れている。2. Description of the Related Art A semiconductor laser whose oscillation wavelength can be controlled by, for example, a current injected into the semiconductor laser and stably oscillates at a single wavelength in a single longitudinal mode requires only one laser light source in the optical communication field. Thus, different independent information can be transmitted to a plurality of receiving stations, and development is required.
従来、注入電流によって発振波長が変化する半導体レ
ーザとして活性層に量子井戸構造を用いその発振波長が
注入電流に応じて第一の量子準位から第二の量子準位に
対応する波長に変化することを応用した半導体レーザが
提案されている。注入電流に応じて前記の第一の量子準
位から第二の量子準位に対応する波長に変化するメカニ
ズムは注入電流の増加に伴うレーザキャビティイ内の光
のロスの変化に起因するものと考えられている。Conventionally, a quantum well structure is used as an active layer as a semiconductor laser whose oscillation wavelength changes according to an injection current, and the oscillation wavelength changes from a first quantum level to a wavelength corresponding to a second quantum level according to the injection current. Semiconductor lasers that take advantage of this have been proposed. The mechanism of changing the wavelength from the first quantum level to the wavelength corresponding to the second quantum level in accordance with the injection current is caused by a change in light loss in the laser cavity with an increase in the injection current. It is considered.
発明が解決しようとする課題 ところがこれらのレーザは発振波長が量子井戸構造に
よって決定されるために波長の制御のためには単分子オ
ーダーでの膜厚制御が必要であり、実際には特定の発振
波長で発振させるべく発振波長の制御を充分に行うこと
が困難であった。また三波長以上の特定の波長で発振さ
せることは極めて困難であった。さらにこのレーザを実
現するためには分子線エピタキシャル成長装置等の高価
な装置が必要であった。Problems to be Solved by the Invention However, in these lasers, since the oscillation wavelength is determined by the quantum well structure, it is necessary to control the film thickness on the order of a single molecule in order to control the wavelength. It has been difficult to sufficiently control the oscillation wavelength so as to oscillate at the wavelength. Also, it was extremely difficult to oscillate at three or more specific wavelengths. Further, to realize this laser, an expensive apparatus such as a molecular beam epitaxial growth apparatus was required.
本発明は以上に示したような従来のように量子井戸構
造の二波長発振の半導体レーザの課題を克服するもので
あり、量子井戸構造を用いなくても複数の波長で、しか
も特定の波長で発振させることが可能なレーザを提供す
るものである。また本発明は三波長以上の複数の発振波
長で発振しうる新たな半導体レーザ装置を実現するもの
である。The present invention overcomes the problems of the conventional two-wavelength oscillation semiconductor laser having a quantum well structure as described above, and can be used at a plurality of wavelengths without using a quantum well structure, and at a specific wavelength. It is intended to provide a laser which can be oscillated. The present invention also provides a new semiconductor laser device that can oscillate at a plurality of oscillation wavelengths of three or more.
課題を解決するための手段 本発明は、 （１）半導体レーザの活性層の片方の端面から放射する
発散性の放射光のうちの複数の特定の波長の光だけを前
記半導体レーザの活性層の片端面に直接集光して光帰還
を行なう機能を有し、かつ平面基板上に形成された反射
型の光回折素子で構成された外部共振器鏡と、前記特定
の波長で発振する半導体レーザを含んで形成された外部
共振器型の半導体レーザを提供する。Means for Solving the Problems The present invention provides: (1) Only light having a plurality of specific wavelengths out of divergent radiated light radiated from one end face of an active layer of a semiconductor laser; An external resonator mirror having a function of directly condensing light on one end face to perform optical feedback, and comprising a reflection type optical diffraction element formed on a flat substrate, and a semiconductor laser oscillating at the specific wavelength And a semiconductor laser of an external resonator type formed including:
（２）また、上記レーザにおいて、外部共振器鏡を構成
している複数の特定の波長を帰還する反射型の光回折素
子が、曲がりと周期の連続的に変化する構造を有する複
数種の回折格子でなり、かつそれぞれの回折格子の形状
が円もしくは楕円の２次曲線群の一部で表わされる構成
を提供する。(2) In the above laser, the reflection type optical diffraction element that feeds back a plurality of specific wavelengths constituting the external resonator mirror has a plurality of diffraction types having a structure in which the bending and the period change continuously. A configuration is provided in which each diffraction grating is a grating and the shape of each diffraction grating is represented by a part of a group of circular or elliptic quadratic curves.
（３）また、上記各回折格子を形成する格子の形状に次
式で表わされる円群の一部である構成を提供する。(3) Further, a configuration is provided in which the shape of the grating forming each diffraction grating is part of a circle group represented by the following equation.
x2＋（ｙ−ｆ・sinθ）２＝（ｍλi/2＋ｆ）２−（ｆ・cosθ）２ ここでx,yは光回折素子の形成される平面基板上の直
交座標であり、ｆは活性層端面と前記座標系の原点との
設定距離、θは前記活性層端面と前記原点を結ぶ軸と回
折格子の形成された平面基板のｙ軸とのなす角、λｉは
半導体レーザに帰還される特定の複数の波長、ｉ及びｍ
は整数である。x 2 + (y−f · sin θ) 2 = (mλ i / 2 + f) 2 − (f · cos θ) 2 where x and y are orthogonal coordinates on a flat substrate on which the optical diffraction element is formed, and f is set distance of the active layer end face and the origin of the coordinate system, theta is the angle between the y-axis of the plane substrate formed with the diffraction grating and the axis connecting the origin and the active layer end face, lambda i is fed back to the semiconductor laser Specific plurality of wavelengths, i and m
Is an integer.
（４）さらにまた、上記各回折格子を形成する格子の形
状が次式で表わされる楕円群の一部であることを特徴と
する構成を提供する。(4) Further, there is provided a configuration characterized in that the shape of the grating forming each diffraction grating is a part of an ellipse group represented by the following equation.
x2/｛（ｍλi/2＋ｆ）２−（ｆ・cosθ）２｝ ＋｛ｙ−（Δｆ＋ｆ）sinθ｝2/｛（ｍλi/2 ＋（Δｆ＋ｆ））２−（（Δｆ＋ｆ）cosθ）２｝＝１ ここでx,yは光回折素子の形成される平面基板上の直交
座標であり、ｆは活性層端面と前記座標系の原点との設
定距離、θは前記活性層端面と前記原点を結ぶ軸と回折
格子の形成された平面基板のｙ軸とのなす角、λｉは半
導体レーザに帰還される特定の複数の波長、ｉ及びｍは
整数である。またΔｆは非点隔差であり、前記活性層端
面から前記座標系のｘ方向に広がるレーザ光の発散中心
点と前記活性層端面から前記座標系のｙ方向に広がるレ
ーザ光の発散中心点との距離を示す。x 2 / ｛(mλ i / 2 + f) 2- (f · cos θ) 2 ｝ + ｛y- (Δf + f) sin θ｝ 2 / ｛(mλ i / 2 + (Δf + f)) 2 -((Δf + f) cos θ) 2 ｝ = 1 Here, x and y are orthogonal coordinates on the plane substrate on which the optical diffraction element is formed, f is a set distance between the end face of the active layer and the origin of the coordinate system, and θ is the end face of the active layer and the origin. Λ i is a specific plurality of wavelengths fed back to the semiconductor laser, and i and m are integers. Δf is the astigmatic difference, and is the difference between the divergence center point of the laser light spreading in the x direction of the coordinate system from the end face of the active layer and the divergence center point of the laser light spreading in the y direction of the coordinate system from the end face of the active layer. Indicates the distance.
（５）また、上記レーザにおいて、半導体レーザ活性層
の片端面から放射する発散性の放射光のうちの特定の波
長の光が、前記外部共振器により活性層片端面に集光し
て光帰還される際、前記特定の波長に対して、半導体レ
ーザ自体の共振器により発振し得る前記特定の波長に対
して隣接した発振波長の光が前記活性層の外部に集光さ
れる構成を提供する。(5) In the above laser, light of a specific wavelength out of divergent radiation emitted from one end face of the semiconductor laser active layer is condensed on one end face of the active layer by the external resonator, and optical feedback is performed. In this case, a configuration is provided in which, for the specific wavelength, light having an oscillation wavelength adjacent to the specific wavelength, which can be oscillated by the resonator of the semiconductor laser itself, is collected outside the active layer. .
（６）また、上記レーザにおいて、外部共振器鏡を構成
する回折格子が、電子計算機制御の電子ビーム露光法に
より形成され、光が放射されかつ外部共振器鏡により光
が集光される片端面に無反射膜が形成されている構成を
提供する。(6) In the above laser, a diffraction grating constituting an external resonator mirror is formed by an electron beam exposure method controlled by an electronic computer, and one end face on which light is emitted and light is condensed by the external resonator mirror. To provide a configuration in which an anti-reflection film is formed.
（７）そして、本発明は複数の波長で発振可能な外部、
共振器型の半導体レーザを用いた光伝送装置を提供す
る。(7) The present invention provides an external device capable of oscillating at a plurality of wavelengths,
Provided is an optical transmission device using a resonator type semiconductor laser.
作用 本発明は、半導体レーザ活性層の端面から放射する発
散性の放射光のうちの設計で決定し得る特定の複数波長
の光だけを、曲がりと周期の連続的に変化する構造を有
する反射型の複数の回折格子を用いることにより、集光
性の光ビームに変換して前記活性層の端面に直接集光し
て光帰還を行なうことが可能となることを応用するもの
であり、従来の外部共振器型レーザの様にレーザと外部
共振器鏡の間にコリメーションレンズが介在しないので
素子の小型化が実現でき、従って光帰還の光路中に収差
が発生することが防げ、その結果設計で決定される複数
の波長で発振し得る外部共振器型半導体レーザが実現さ
れるもである。The present invention is directed to a reflective type having a structure in which only a plurality of specific wavelengths of divergent radiation emitted from the end face of the semiconductor laser active layer, which can be determined by design, have a continuously changing curve and period. By using a plurality of diffraction gratings, it is possible to convert the light beam into a converging light beam and directly converge the light on the end face of the active layer to perform optical feedback. Since no collimation lens is interposed between the laser and the external cavity mirror as in the external cavity laser, the element can be miniaturized, and therefore, aberrations can be prevented from occurring in the optical path of the optical feedback. An external cavity semiconductor laser capable of oscillating at a plurality of determined wavelengths is realized.
実施例 本発明の外部共振器型の半導体レーザの一例として二
波長発振の半導体レーザの概略図を第１図に示す。１は
GaAs基板を用いてAlGaAsを活性層とする発振波長0.8μ
ｍ帯のファブリーペロー型半導体レーザ、２は半導体レ
ーザの放射光の光軸に対して傾斜して配置された外部共
振器鏡基板であり、その基板の表面には反射型の回折格
子3a及び3bが形成されている。半導体レーザの片端面４
から放射された発散性の光は、回折格子3a及び3bに達す
る。この回折格子の光回折現象に伴う光分散効果により
波長選択された特定の二波長の光（λ１＝0.800μｍ及
びλ２＝0.805μｍ）のみが半導体レーザの方向に反射
され、半導体レーザの片端面４に集光され半導体レーザ
の活性層５に光帰還される。ここで波長選択される特定
の波長は回折格子の形状及び基板の傾斜角で決定され、
前期の特定の波長以外の波長の光は回折素子の波長分散
効果により異なる方向に分散して集光され活性層に光帰
還されることはない。また活性層の片端面には反射防止
膜６が形成されており、片端面４ともう一方の端面７で
形成される半導体レーザ自体のファブリーペロー共振器
による発振は抑圧されている。Embodiment FIG. 1 is a schematic view of a two-wavelength oscillation semiconductor laser as an example of an external resonator type semiconductor laser of the present invention. 1 is
Oscillation wavelength 0.8μ with AlGaAs as active layer using GaAs substrate
An m-band Fabry-Perot type semiconductor laser, 2 is an external resonator mirror substrate which is arranged to be inclined with respect to the optical axis of the radiation light of the semiconductor laser, and the surface of the substrate has reflection type diffraction gratings 3a and 3b. Are formed. One end face 4 of semiconductor laser
The divergent light emitted from reaches the diffraction gratings 3a and 3b. Only two specific wavelengths of light (λ1 = 0.800 μm and λ2 = 0.805 μm) whose wavelength has been selected by the light dispersion effect accompanying the light diffraction phenomenon of this diffraction grating are reflected in the direction of the semiconductor laser, and the one end face 4 of the semiconductor laser 4 And is fed back to the active layer 5 of the semiconductor laser. The specific wavelength selected here is determined by the shape of the diffraction grating and the tilt angle of the substrate,
Light having a wavelength other than the specific wavelength in the previous period is dispersed in different directions due to the wavelength dispersion effect of the diffractive element and collected, and is not fed back to the active layer. An antireflection film 6 is formed on one end face of the active layer, and the oscillation of the semiconductor laser itself formed by one end face 4 and the other end face 7 by the Fabry-Perot resonator is suppressed.
また、半導体レーザ１自体のファブリーペローモード
により発振し得る隣接した副モードの波長の光は活性層
５の上部もしくは下部約２μｍの位置に集光されるよう
に設計されている。The light of the wavelength of the adjacent sub-mode which can oscillate in the Fabry-Perot mode of the semiconductor laser 1 itself is designed to be focused on the upper or lower part of the active layer 5 at a position of about 2 μm.
第２図を用いて、本発明に用いた外部共振器鏡の設計
原理を示す。回折素子の形成される平面基板上にx,yの
直交座標系を仮定し、光の発散点及び集光点となる活性
層端面Ｐが前記座標の原点から垂直方向に対しｙ軸方向
にθの角をなす線上に存在し、しかも原点からｆの距離
に設定されていると仮定する。Ｐから放射され回折格子
の一点Ｇに到達し、反射されて再度Ｐに戻る光の位相が
揃うように回折格子の形状が設定されているとき、この
回折格子は外部共振器鏡としてはたらくことになる。即
ち点Ｇ（X,Y）を回折格子の等位相点と考えると、回折
格子の形状は次式で与えられる。FIG. 2 shows the design principle of the external resonator mirror used in the present invention. Assuming an orthogonal coordinate system of x and y on the plane substrate on which the diffraction element is formed, the active layer end face P which is a divergence point and a condensing point of light is θ from the origin of the coordinates in the y-axis direction with respect to the vertical direction. It is assumed that they are present on a line forming the corner of and the distance is set to f from the origin. When the shape of the diffraction grating is set so that the light emitted from P reaches one point G of the diffraction grating, is reflected and returns to P again, the phase of the diffraction grating is set to be such that the diffraction grating functions as an external resonator mirror. Become. That is, when the point G (X, Y) is considered as an equal phase point of the diffraction grating, the shape of the diffraction grating is given by the following equation.
2PG＝ｍλｉ＋（定数） （第一式） ここで、λｉは半導体レーザの複数の設定発振波長、
ｍは整数である。2PG = mλ i + (constant) (first formula) where λ i is a plurality of set oscillation wavelengths of the semiconductor laser,
m is an integer.
原点における前記定数を０ときめると、回折格子の形
状をx,y座標で示すと 次式で表される。When the constant at the origin is set to 0, the shape of the diffraction grating is represented by the following equation when represented by x and y coordinates.
x2＋（ｙ−ｆ・sinθ）２＝（ｍλi/2＋ｆ）２−（ｆ・cosθ）２ （第二式） 従って回折格子の形状は点（0,f・sinθ）を中心とし
半径がｍの関数となる円群である。x 2 + (y−f · sin θ) 2 = (mλ i / 2 + f) 2 − (f · cos θ) 2 (Equation 2) Accordingly, the shape of the diffraction grating has a center point (0, f · sin θ) and a radius of It is a group of circles that is a function of m.
第３図に、本発明の実施例に用いた外部共振器鏡の概
略を示す。（Ａ）は外部共振器鏡の断面を示す。Si基板
２の上に形成された約0.6μｍの電子線レジスト32に、
前記の第２式で表される曲線状にを電子ビームを照射
し、現像液に浸すことにより前記電子ビームの照射され
た部分を除去し凹凸構造が形成されている。この凹凸構
造の電子ビーム線レジストの表面に金の薄膜33を形成
し、高い反射率の回折格子が形成されている。（Ｂ）は
電子ビームで形成された二種類の回折格子の形状の概略
を示す。それぞれの回折格子の形成されている領域の大
きさは0.05x0.1cm2である。回折格子の凹部の形状は第
２式で表され、設定パラメータとして ｆ＝2mm、θ＝48.2゜、λ１＝0.8μｍ、λ２＝0.84μｍ とした。FIG. 3 schematically shows an external resonator mirror used in the embodiment of the present invention. (A) shows a cross section of the external resonator mirror. The electron beam resist 32 of about 0.6 μm formed on the Si substrate 2
An electron beam is irradiated on the curved line represented by the above-mentioned formula (2), and the part irradiated with the electron beam is removed by immersing in a developing solution to form an uneven structure. A gold thin film 33 is formed on the surface of the electron beam resist having the concavo-convex structure, and a diffraction grating having a high reflectance is formed. (B) schematically shows the shapes of two types of diffraction gratings formed by an electron beam. The size of the area where each diffraction grating is formed is 0.05 × 0.1 cm 2 . The shape of the concave portion of the diffraction grating is represented by the following equation (2), and f = 2 mm, θ = 48.2 °, λ 1 = 0.8 μm, and λ 2 = 0.84 μm as setting parameters.
上記の様に形成した回折格子を外部共振器鏡として第
１図に示した外部共振器型半導体レーザを構成した結
果、約0.8μｍと0.84μｍの二波長で発振し得る半導体
レーザが実現できた。しかも注入電流がしきい値電流近
傍では0.8μｍでほぼ単一縦モード発振し、注入電流の
増加と共に0.84μｍの発振強度が増加し、しきい値の約
1.5倍の注入電流においては0.84μｍの単一縦モードが
実現された。しかも更に注入電流を増加させてもこの発
振波長はほとんど変化せず単一縦モードが維持されてい
た。Using the diffraction grating formed as described above as an external resonator mirror to form the external resonator type semiconductor laser shown in FIG. 1, a semiconductor laser capable of oscillating at two wavelengths of about 0.8 μm and 0.84 μm was realized. . Furthermore, near the threshold current, the injection current oscillates almost in a single longitudinal mode at 0.8 μm, and as the injection current increases, the oscillation intensity of 0.84 μm increases.
At 1.5 times the injection current, a single longitudinal mode of 0.84 μm was realized. Moreover, even if the injection current is further increased, the oscillation wavelength hardly changes, and the single longitudinal mode is maintained.
また発振波長は半導体レーザ基板と外部共振器鏡との
なす角を変化させることにより0.8μｍ及び0.84μｍを
中心に約0.02μｍの波長範囲において連続的に制御する
ことが可能であった。The oscillation wavelength could be continuously controlled in a wavelength range of about 0.02 μm centering on 0.8 μm and 0.84 μm by changing the angle between the semiconductor laser substrate and the external resonator mirror.
以上の実施例に於いては、外部共振器鏡を形成する回
折格子の形状が円群の一部である場合をしめしたが、使
用する半導体レーザが例えばゲインガイド型の半導体レ
ーザであり非点隔差が存在する場合にも適用することが
可能である。In the above embodiment, the case where the shape of the diffraction grating forming the external resonator mirror is a part of a circle group is shown. However, the semiconductor laser to be used is, for example, a gain guide type semiconductor laser and the astigmatism. The present invention can be applied to a case where a difference exists.
半導体レーザの放射ビームに非点隔差Δｆが存在する
ときには、第２図と同様に前記座標の原点から垂直方向
に対しｙ軸方向にθの角をなす線上にｘ方向に対する発
散点P1とｙ方向に対する発散点P2を仮定し、原点からそ
れぞれｆ及びｆ＋Δｆの距離に設定されていると仮定す
ると、同様に回折格子の形状は次式で与えられる。When the astigmatic difference Δf exists in the radiation beam of the semiconductor laser, the divergence point P1 with respect to the x direction and the divergence point P1 with respect to the x direction on a line forming an angle of θ in the y axis direction with respect to the vertical direction from the origin of the coordinates as in FIG. Assuming that the divergence point P2 is set at distances f and f + Δf from the origin, the shape of the diffraction grating is similarly given by the following equation.
x2/｛（ｍλi/2＋ｆ）２−（ｆ・cosθ）２｝ ＋｛ｙ−（Δｆ＋ｆ）sinθ｝2/｛（ｍλi/2 ＋（Δｆ＋ｆ））２−（（Δｆ＋ｆ）cosθ）２｝＝１ （第三式） ここで、λｉは半導体レーザの複数の設定発振波長で
λ１＝0.8μｍ、λ２＝0.84μｍ、ｍは整数である。x 2 / ｛(mλ i / 2 + f) 2- (f · cos θ) 2 ｝ + ｛y- (Δf + f) sin θ｝ 2 / ｛(mλ i / 2 + (Δf + f)) 2 -((Δf + f) cos θ) 2 } = 1 (third type), where the lambda i .lambda.1 = 0.8 [mu] m at a plurality of setting the oscillation wavelength of the semiconductor laser, .lambda.2 = 0.84 .mu.m, m is an integer.
第三式で表される楕円形状の二種類の回折格子の形成
された基板を外部共振器鏡として第１図に示した外部共
振器型半導体レーザを構成した結果、約0.8μｍと0.84
μｍの二波長で発振し得る半導体レーザが実現できた。
しかも注入電流がしきい値電流近傍では0.8μｍでほぼ
単一縦モード発振し、注入電流の増加と共に0.84μｍの
発振強度が増加し、しきい値の約1.5倍の注入電流にお
いては0.84μｍの単一縦モードが実現された。しかも更
に注入電流を増加させてもこの発振波長はほとんど変化
せず単一縦モードが維持されていた。As a result of configuring the external cavity semiconductor laser shown in FIG. 1 as an external cavity mirror using the substrate on which the two types of elliptical diffraction gratings represented by the third formula are formed, the results are about 0.8 μm and 0.84 μm.
A semiconductor laser capable of oscillating at two wavelengths of μm has been realized.
In addition, near the threshold current, the injection current oscillates almost in a single longitudinal mode at 0.8 μm at 0.8 μm, and the oscillation intensity of 0.84 μm increases with the increase of the injection current. Single longitudinal mode was realized. Moreover, even if the injection current is further increased, the oscillation wavelength hardly changes, and the single longitudinal mode is maintained.
以上は二種類の回折格子を基板の異なる領域に形成し
た場合を示したが、同一の領域に二種類の回折格子を形
成しても差し支えない。Although the case where two types of diffraction gratings are formed in different regions of the substrate has been described above, two types of diffraction gratings may be formed in the same region.
以上の実施例では半導体レーザとしてガリウム砒素基
板を用い活性層としてアルミニウム・ガリウム・砒素を
用いた0.8μｍ帯のものを用いたが、アルミニウム・ガ
リウム・インジウム・りんを活性層として用いた0.6μ
ｍ帯、あるいはインジウム・りん基板を用いインジウム
・ガリウム・砒素・りんを活性層として用いた1.3μ
ｍ、あるいは1.5μｍ帯の半導体レーザを用いても全く
同様の効果が得られることは自明である。In the above embodiment, a gallium arsenide substrate was used as the semiconductor laser and a 0.8 μm band using aluminum, gallium, and arsenic was used as the active layer, but a 0.6 μm band using aluminum, gallium, indium, and phosphorus as the active layer was used.
1.3μ using m-band or indium / gallium / arsenic / phosphorus as active layer using indium / phosphorus substrate
It is obvious that exactly the same effect can be obtained even if a semiconductor laser in the m or 1.5 μm band is used.
また以上は二波長で発振するレーザの実施例を示した
が必ずしもこれに限らず三波長以上の複数の発振波長で
発振し得る半導体レーザを実現することが可能である。Although the embodiment of the laser oscillating at two wavelengths has been described above, the present invention is not limited to this, and a semiconductor laser capable of oscillating at a plurality of oscillation wavelengths of three wavelengths or more can be realized.
次に本発明の外部共振器型半導体レーザを用いた光伝
送装置の一例を示す。１は本発明に用いる前述の半導体
レーザで注入電流に応じてλ１（0.83μｍ）とλ２（0.
84μｍ）の波長で発振する。そして42は結合レンズ、43
は光ファイバー、44は光分波器でλ１とλ２の光を分離
して受光素子45と受光素子46で検出される。従って一定
の信号電流を与えておき、すでに説明した原理に基ずき
バイアス電流を変化させることにより波長が変化し、信
号の受信局を変えることが可能となる。Next, an example of an optical transmission device using the external cavity semiconductor laser of the present invention will be described. 1 lambda 1 in accordance with the injection current in the aforementioned semiconductor laser for use in the present invention (0.83 .mu.m) and lambda 2 (0.
It oscillates at a wavelength of 84 μm). And 42 is a coupling lens, 43
Is an optical fiber, and 44 is an optical demultiplexer, which separates the lights of λ 1 and λ 2 and detects them by the light receiving elements 45 and 46. Therefore, by giving a constant signal current and changing the bias current based on the principle already described, the wavelength changes, and it becomes possible to change the signal receiving station.
また以上の実施例においては二波長で発振するレーザ
を用いたがが必ずしもこれに限らず三波長以上の複数の
発振波長で発振し得る半導体レーザを用いることにより
単一のレーザ光源で複数の受信局に信号を分離して伝送
することが可能である。In the above embodiment, a laser oscillating at two wavelengths is used. However, the present invention is not limited to this. By using a semiconductor laser capable of oscillating at a plurality of oscillation wavelengths of three or more wavelengths, a single laser It is possible to separate and transmit the signal to the station.
発明の効果 以上のように本発明は従来の半導体レーザの課題を克
服し、容易に複数の波長で発振可能な半導体レーザとそ
れを応用した光伝送装置を実現するものであり、大きな
価値を有するものである。また本発明の光伝送装置は従
来のように複数の半導体レーザを使用する必要がなくシ
ステムの簡易化が図れ、産業上多大な価値を有する。As described above, the present invention overcomes the problems of the conventional semiconductor laser and realizes a semiconductor laser that can easily oscillate at a plurality of wavelengths and an optical transmission device using the same, and has great value. Things. Further, the optical transmission device of the present invention does not require the use of a plurality of semiconductor lasers as in the related art, simplifies the system, and has great industrial value.
第１図は本発明の一実施例の二波長発振の外部共振器型
半導体レーザの概略図、第２図は本発明に用いた外部共
振器鏡を構成する回折素子の原理及び形状を説明する
図、第３図（Ａ），（Ｂ）は本発明の実施例に用いた外
部共振器鏡の概略断面図、平面図、第４図は本発明の他
の実施例の二波長発振の外部共振器型半導体レーザを用
いた光伝送装置の概略図である。 １……半導体レーザ、２……外部共振器鏡基板、3a,3b
……回折格子、４……端面、６……反射防止膜。FIG. 1 is a schematic view of a two-wavelength oscillation external resonator type semiconductor laser according to one embodiment of the present invention, and FIG. 2 explains the principle and shape of a diffraction element constituting an external resonator mirror used in the present invention. FIGS. 3 (A) and 3 (B) are schematic sectional views and plan views of an external resonator mirror used in an embodiment of the present invention, and FIG. 4 is an external view of a two-wavelength oscillation according to another embodiment of the present invention. FIG. 2 is a schematic diagram of an optical transmission device using a resonator type semiconductor laser. 1 ... semiconductor laser, 2 ... external resonator mirror substrate, 3a, 3b
...... Diffraction grating, 4 ... End face, 6 ... Anti-reflection film.
フロントページの続き (56)参考文献 特開 平１−230279（ＪＰ，Ａ) 特開 平２−209784（ＪＰ，Ａ) 特開 昭51−93694（ＪＰ，Ａ) 特開 昭61−181183（ＪＰ，Ａ) (58)調査した分野(Int.Cl.6，ＤＢ名) H01S 3/18 H04B 9/00 ＪＩＣＳＴファイル（ＪＯＩＳ)Continuation of the front page (56) References JP-A-1-230279 (JP, A) JP-A-2-209784 (JP, A) JP-A-51-93694 (JP, A) JP-A-61-181183 (JP, A) , A) (58) Fields investigated (Int. Cl. 6 , DB name) H01S 3/18 H04B 9/00 JICST file (JOIS)
Claims (8)
射型の光回折素子で構成され、半導体レーザの活性層の
端面から放射する発散性の放射光のうちの少なくとも二
波長以上の複数の特定の波長の光を前記半導体レーザの
活性層の端面に直接集光して光帰還を行う機能を有する
外部共振器鏡と、前記特定の波長で発振する半導体レー
ザを含んで形成されたことを特徴とする外部共振器型半
導体レーザ。1. A semiconductor device comprising a plurality of different types of reflection type optical diffraction elements formed on a plane substrate, wherein at least two or more wavelengths of divergent radiation emitted from an end face of an active layer of a semiconductor laser are provided. An external resonator mirror having a function of directly condensing light of a specific wavelength on an end face of an active layer of the semiconductor laser and performing optical feedback, and a semiconductor laser oscillating at the specific wavelength. An external cavity type semiconductor laser characterized by the above-mentioned.
波長を帰還する反射型の光回折素子が、曲がりと周期の
連続的に変化する構造を有する複数種の回折格子でな
り、かつそれぞれの回折格子の形状が円もしくは楕円の
２次曲線群の一部で表わされることを特徴とする特許請
求の範囲第１項記載の外部共振器型半導体レーザ。2. A reflection type optical diffraction element which feeds back a plurality of specific wavelengths constituting an external resonator mirror comprises a plurality of types of diffraction gratings having a structure in which a bending and a period change continuously. 2. The external resonator type semiconductor laser according to claim 1, wherein the shape of each diffraction grating is represented by a part of a circle or an elliptic quadratic curve group.
表わされる円群の一部であることを特徴とする特許請求
の範囲第２項記載の外部共振器型半導体レーザ。 x2＋（ｙ−ｆ・sinθ）２＝（ｍλi/2＋ｆ）２−（ｆ・cosθ）２ ここでx,yは光回折素子の形成される平面基板上の直交
座標であり、ｆは活性層端面と前記直交座標の原点との
設定距離、θは前記活性層端面と前記原点を結ぶ軸と回
折格子の形成された平面基板のｙ軸とのなす角、λｉは
半導体レーザに帰還される特定の複数の波長、ｉ及びｍ
は整数である。3. The external cavity semiconductor laser according to claim 2, wherein the shape of each of the diffraction gratings is part of a circle group represented by the following equation. x 2 + (y−f · sin θ) 2 = (mλ i / 2 + f) 2 − (f · cos θ) 2 where x and y are orthogonal coordinates on a flat substrate on which the optical diffraction element is formed, and f is The set distance between the end face of the active layer and the origin of the orthogonal coordinates, θ is the angle formed between the axis connecting the end face of the active layer and the origin and the y-axis of the plane substrate on which the diffraction grating is formed, and λ i is fed back to the semiconductor laser. Specific plurality of wavelengths, i and m
Is an integer.
表わされる楕円群の一部であることを特徴とする特許請
求の範囲第２項記載の外部共振器型半導体レーザ。 x2/｛（ｍλi/2＋ｆ）２−（ｆ・cosθ）２｝ ＋｛ｙ−（Δｆ＋ｆ）sinθ｝2/｛（ｍλi/2 ＋（Δｆ＋ｆ）２−（（Δｆ＋ｆ）cosθ）２｝＝１ ここでx,yは光回折素子の形成される平面基板上の直交
座標であり、ｆは活性層端面と前記直交座標の原点との
設定距離、θは前記活性層端面と前記原点を結ぶ軸と回
折格子の形成された平面基板のｙ軸とのなす角、λｉは
半導体レーザに帰還される特定の複数の波長、ｉ及びｍ
は整数である。またΔｆは非点隔差であり、前記活性層
端面から前記座標系のｘ方向に広がるレーザ光の発散中
心点と前記活性層端面から前記座標系のｙ方向に広がる
レーザ光の発散中心点との距離を示す。4. The external cavity type semiconductor laser according to claim 2, wherein the shape of the grating forming each diffraction grating is part of an ellipse group represented by the following equation. x 2 / ｛(mλ i / 2 + f) 2 − (f · cos θ) 2 ｛+ {y− (Δf + f) sin θ｝ 2 / {(mλ i / 2 + (Δf + f) 2 − ((Δf + f) cos θ) 2 } = 1 Here, x and y are orthogonal coordinates on the plane substrate on which the optical diffraction element is formed, f is a set distance between the active layer end face and the origin of the orthogonal coordinates, and θ is the active layer end face and the origin. The angle between the connecting axis and the y-axis of the plane substrate on which the diffraction grating is formed, λ i is a plurality of specific wavelengths fed back to the semiconductor laser, i and m
Is an integer. Δf is the astigmatic difference, and is the difference between the divergence center point of the laser light spreading in the x direction of the coordinate system from the end face of the active layer and the divergence center point of the laser light spreading in the y direction of the coordinate system from the end face of the active layer. Indicates the distance.
発散性の放射光のうちの特定の波長の光が、外部共振器
により活性層片端面に集光して光帰還される際、前記特
定の波長に対して、半導体レーザ自体の共振器により発
振し得る前記特定の波長に対して隣接した発振波長の光
が活性層の外部に集光されることを特徴とする特許請求
の範囲第１項記載の外部共振器型半導体レーザ。5. When light of a specific wavelength out of divergent radiation emitted from one end face of the semiconductor laser active layer is condensed on one end face of the active layer by an external resonator and returned as light, The light of an oscillation wavelength adjacent to the specific wavelength which can be oscillated by the resonator of the semiconductor laser itself for a specific wavelength is collected outside the active layer. 2. The external cavity semiconductor laser according to claim 1.
計算機制御の電子ビーム露光法により形成されているこ
とを特徴とする特許請求の範囲第１項記載の外部共振器
型半導体レーザ。6. The external cavity semiconductor laser according to claim 1, wherein the diffraction grating constituting the external cavity mirror is formed by an electron beam exposure method controlled by a computer.
外部共振器鏡により光が集光される片端面に無反射膜が
形成されていることを特徴とする特許請求の範囲第１項
記載の外部共振器型半導体レーザ。7. The semiconductor laser according to claim 1, wherein an anti-reflection film is formed on one end surface of the semiconductor laser where light is emitted and light is collected by an external resonator mirror. External cavity type semiconductor laser.
射型の光回折素子で構成され、半導体レーザの活性層の
端面から放射する発散性の放射光のうちの少なくとも二
波長以上の複数の特定の波長の光を前記半導体レーザの
活性層の端面に直接集光して光帰還を行う機能を有する
外部共振器鏡と、注入電流を変えることにより前記複数
の特定の波長で発振する半導体レーザを含んで形成され
た外部共振器型半導体レーザを用いた光伝送装置。8. A divergent radiated light radiated from an end face of an active layer of a semiconductor laser, comprising a plurality of different types of reflection type light diffraction elements formed on a plane substrate, and a plurality of divergent radiated lights of at least two wavelengths. An external resonator mirror having a function of directly condensing light of a specific wavelength on an end face of an active layer of the semiconductor laser to perform optical feedback, and a semiconductor oscillating at the plurality of specific wavelengths by changing an injection current. An optical transmission device using an external cavity type semiconductor laser including a laser.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1288338A JP2841570B2 (en) | 1989-11-06 | 1989-11-06 | External cavity semiconductor laser and optical transmission device using the same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1288338A JP2841570B2 (en) | 1989-11-06 | 1989-11-06 | External cavity semiconductor laser and optical transmission device using the same |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH03148891A JPH03148891A (en) | 1991-06-25 |
| JP2841570B2 true JP2841570B2 (en) | 1998-12-24 |
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| WO2012087282A1 (en) * | 2010-12-20 | 2012-06-28 | Hewlett-Packard Development Company, Lp | Vertical-cavity surface-emitting laser system and method for fabricating the same |
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| JPH01230279A (en) * | 1988-03-10 | 1989-09-13 | Hikari Gijutsu Kenkyu Kaihatsu Kk | Semiconductor laser device |
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