JPH0614577B2 - Semiconductor laser - Google Patents
Semiconductor laserInfo
- Publication number
- JPH0614577B2 JPH0614577B2 JP1176071A JP17607189A JPH0614577B2 JP H0614577 B2 JPH0614577 B2 JP H0614577B2 JP 1176071 A JP1176071 A JP 1176071A JP 17607189 A JP17607189 A JP 17607189A JP H0614577 B2 JPH0614577 B2 JP H0614577B2
- Authority
- JP
- Japan
- Prior art keywords
- diffraction grating
- semiconductor laser
- guide layer
- layer
- light guide
- 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 - Fee Related
Links
- 239000004065 semiconductor Substances 0.000 title claims description 31
- 230000003287 optical effect Effects 0.000 claims description 15
- 239000000758 substrate Substances 0.000 claims description 8
- 230000008878 coupling Effects 0.000 description 12
- 238000010168 coupling process Methods 0.000 description 12
- 238000005859 coupling reaction Methods 0.000 description 12
- 238000005530 etching Methods 0.000 description 7
- 238000004519 manufacturing process Methods 0.000 description 6
- 238000000034 method Methods 0.000 description 6
- 238000010894 electron beam technology Methods 0.000 description 5
- 230000000694 effects Effects 0.000 description 4
- 238000005253 cladding Methods 0.000 description 3
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- 230000004888 barrier function Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000001000 micrograph Methods 0.000 description 2
- 229910001218 Gallium arsenide Inorganic materials 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000000295 emission spectrum Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000005424 photoluminescence Methods 0.000 description 1
- 230000003595 spectral effect Effects 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/10—Construction or shape of the optical resonator, e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region
- H01S5/12—Construction or shape of the optical resonator, e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region the resonator having a periodic structure, e.g. in distributed feedback [DFB] lasers
- H01S5/1237—Lateral grating, i.e. grating only adjacent ridge or mesa
Landscapes
- Semiconductor Lasers (AREA)
Description
【発明の詳細な説明】 〔産業上の利用分野〕 本発明は発光スペクトル線幅が狭く単一縦モードで動作
する半導体レーザに関する。特に、光ガイド層に回折格
子が設けられた分布帰還形半導体レーザおよび分布ブラ
ッグ反射形半導体レーザに関する。The present invention relates to a semiconductor laser having a narrow emission spectrum line width and operating in a single longitudinal mode. In particular, the present invention relates to a distributed feedback semiconductor laser and a distributed Bragg reflection semiconductor laser in which a diffraction grating is provided in an optical guide layer.
本発明は、分布帰還形または分布ブラッグ反射形の半導
体レーザにおいて、 光ガイド層の一部にのみ選択的に回折格子を設けた構造
とすることにより、 回折格子の面積を製造時に設定してその回折格子とレー
ザ光との結合係数を制御するものである。The present invention, in a distributed feedback or distributed Bragg reflection type semiconductor laser, has a structure in which a diffraction grating is selectively provided only in a part of an optical guide layer. It controls the coupling coefficient between the diffraction grating and the laser light.
分布帰還形半導体レーザおよび分布ブラッグ反射形半導
体レーザは、回折格子により特定波長の光が帰還または
反射することを利用したレーザであり、スペクトル線幅
が狭く、単一縦モードで発振する特徴がある。このよう
な半導体レーザが高い出力時にも安定に単一縦モードで
動作させるには、回折格子とレーザ光との結合係数κＬ
が最適となるように製造する必要がある。ここで、Ｌは
半導体レーザの共振器長である。通常、分布帰還形半導
体レーザではκＬ＝１〜２が適当とされている。The distributed feedback type semiconductor laser and the distributed Bragg reflection type semiconductor laser are lasers that utilize the fact that light of a specific wavelength is fed back or reflected by a diffraction grating, and has a narrow spectral line width and oscillates in a single longitudinal mode. . In order to stably operate such a semiconductor laser in a single longitudinal mode even at a high output, the coupling coefficient κL between the diffraction grating and the laser beam is
Must be manufactured to be optimal. Here, L is the cavity length of the semiconductor laser. Normally, κL = 1 to 2 is suitable for a distributed feedback semiconductor laser.
所望の結合係数κＬを得るために、従来は、エッチング
時間により回折格子の深さを制御していた。すなわち、
大きな結合係数κＬを得るには、回折格子形成時のエッ
チング時間を長くして深くエッチングし、小さい結合係
数κＬを得るにはエッチング時間を短くしていた。In order to obtain a desired coupling coefficient κL, conventionally, the depth of the diffraction grating was controlled by the etching time. That is,
In order to obtain a large coupling coefficient κL, the etching time at the time of forming the diffraction grating is lengthened and deeply etched, and to obtain a small coupling coefficient κL, the etching time is shortened.
また、タケモト他、「1.3μｍデストリビューテド・フ
ィードバック・レーザ・ダイオード・ウィズ・グレーテ
ィング・アキュラトリイ・コントロールド・バイ・ニュ
ー・ファブリケーション・テクニーク」、エレクトロニ
クス・レターズ、第25巻第３号、第 220頁から第 221
頁、1989年２月２日(A.Takemoto, Y.Ohkura, T.Kawama,
T.Kimura,N.Yoshida, S.Kakimoto, W.Susaki,”１．３
μｍ Distributed Feedback Laser Diode with Gratin
g Accurately Controlled by New Fabrication Techniq
ue”，Electronics Letters 2nd February1989 Vol.25
No.3)には、回折格子の深さを光ガイド層の厚さにより
決定する方法が示されている。In addition, Takemoto et al., “1.3 μm Detributed Feedback Laser Diode with Grating Accurately Controlled by New Fabrication Technik”, Electronics Letters, Vol. 25, No. 3, No. 220 pages 221
Page, February 2, 1989 (A. Takemoto, Y. Ohkura, T. Kawama,
T.Kimura, N.Yoshida, S.Kakimoto, W.Susaki, ”1.3
μm Distributed Feedback Laser Diode with Gratin
g Accurately Controlled by New Fabrication Techniq
ue ”, Electronics Letters 2nd February1989 Vol.25
No. 3) shows a method of determining the depth of the diffraction grating by the thickness of the light guide layer.
この方法では、活性層の上にバリア層を成長させ、その
上に光ガイド層を成長させる。次に、この光ガイド層に
回折格子を形成するのであるが、そのとき、回折格子の
溝の部分が光ガイド層を貫通してバリア層に達する程度
にエッチングを施す。この後にクラッド層を成長させ、
光ガイド層の残った部分を埋め込む。これにより、回折
格子の深さが光ガイド層の厚さにより決定される。In this method, a barrier layer is grown on the active layer and a light guide layer is grown on it. Next, a diffraction grating is formed in this light guide layer, and at that time, etching is performed to such an extent that the groove portion of the diffraction grating penetrates the light guide layer and reaches the barrier layer. After this, grow the cladding layer,
The remaining part of the light guide layer is embedded. Thereby, the depth of the diffraction grating is determined by the thickness of the light guide layer.
しかし、結合係数κＬを回折格子の深さにより制御しよ
うとすると、その精度は数nmとなる。このような精度を
エッチングにより得るためには、例えば４：１：90の硫
酸過水を用いる場合に、エッチング時間を秒単位に制御
しなければならない。このような制御は実用上は困難で
ある。However, if the coupling coefficient κL is controlled by the depth of the diffraction grating, the accuracy will be several nm. In order to obtain such accuracy by etching, the etching time must be controlled in seconds when using sulfuric acid / hydrogen peroxide mixture of 4: 1: 90, for example. Such control is practically difficult.
また、同一基板からκの値が異なる半導体レーザを製造
することも困難である。これは、素子構造を最適化する
うえで障害となる。It is also difficult to manufacture semiconductor lasers having different κ values from the same substrate. This is an obstacle to optimizing the device structure.
タケモト他の方法は回折格子の深さ精度を改善するもの
であり、回折格子の深さが光ガイド層の厚さに等しいた
め、深さ精度を光ガイド層の成長精度で決定できる。し
かし、この方法でも、同一基板からκの値が異なる半導
体レーザを製造することは困難である。The method of Takemoto et al. Improves the depth accuracy of the diffraction grating. Since the depth of the diffraction grating is equal to the thickness of the light guide layer, the depth accuracy can be determined by the growth accuracy of the light guide layer. However, even with this method, it is difficult to manufacture semiconductor lasers having different κ values from the same substrate.
本発明は、以上の問題点を解決し、結合係数を自由に設
定できる構造の分布帰還形および分布ブラッグ反射形半
導体レーザを提供することを目的とする。It is an object of the present invention to solve the above problems and provide a distributed feedback type and distributed Bragg reflection type semiconductor laser having a structure in which the coupling coefficient can be freely set.
本発明の半導体レーザは、半導体基板上に形成された光
導波路を備え、この光導波路の共振器方向に沿って光ガ
イド層が設けられ、この光ガイド層には回折格子が形成
された半導体レーザにおいて、回折格子は、ガイド層に
共振器方向の平坦な領域を残しながら、共振器方向と直
交する方向の一部の領域に選択的に形成されたことを特
徴とする。A semiconductor laser of the present invention includes an optical waveguide formed on a semiconductor substrate, an optical guide layer is provided along the resonator direction of the optical waveguide, and the optical guide layer is provided with a diffraction grating. In the above, the diffraction grating is selectively formed in a part of a region in the direction orthogonal to the cavity direction while leaving a flat region in the cavity direction in the guide layer.
回折格子を活性層に沿って設けた場合にはこの半導体レ
ーザは分布帰還形となり、活性層からの出射光を伝搬す
る光導波路に設けた場合には、分布ブラッグ反射形とな
る。When the diffraction grating is provided along the active layer, this semiconductor laser is of the distributed feedback type, and when it is provided in the optical waveguide that propagates the light emitted from the active layer, it is of the distributed Bragg reflection type.
回折格子の面積の大小により、レーザ光と回折格子との
間の結合係数κＬの大きさを制御する。電子ビーム露光
法を用いれば、必要部分にのみ回折格子を形成すること
が十分に可能である。The magnitude of the coupling coefficient κL between the laser beam and the diffraction grating is controlled by the size of the area of the diffraction grating. If the electron beam exposure method is used, it is possible to form the diffraction grating only in a necessary portion.
第１図は本発明実施例半導体レーザの斜視図を示す。 FIG. 1 shows a perspective view of a semiconductor laser according to an embodiment of the present invention.
本実施例はリブ形の分布帰還形半導体レーザに本発明を
実施した例であり、半導体基板１上に形成された下部ク
ラッド層２、活性層３および光ガイド層４を含む光導波
路と、光ガイド層４に形成された回折格子５とを備え
る。The present embodiment is an example in which the present invention is applied to a rib type distributed feedback semiconductor laser, and includes an optical waveguide including a lower cladding layer 2, an active layer 3 and an optical guide layer 4 formed on a semiconductor substrate 1, and an optical waveguide. And a diffraction grating 5 formed on the guide layer 4.
光ガイド層４の上には、上部クラッド層、キャップ層、
絶縁層、電極などが設けられるが、第１図ではこの部分
を省略した。On the light guide layer 4, an upper clad layer, a cap layer,
An insulating layer, electrodes, etc. are provided, but these parts are omitted in FIG.
ここで本実施例の特徴とするところは、回折格子５が光
ガイド層４の一部に選択的に形成され、この光ガイド層
４の回折格子５が形成されない残りの部分は平坦な形状
に形成されたことにある。The feature of this embodiment is that the diffraction grating 5 is selectively formed on a part of the light guide layer 4, and the remaining part of the light guide layer 4 where the diffraction grating 5 is not formed is flat. It has been formed.
第２図はこの半導体レーザの製造方法を示す。FIG. 2 shows a method of manufacturing this semiconductor laser.
まず、第２図(a)に示すように、基板１上に下部クラッ
ド層２、活性層３および光ガイド層４を成長させる。First, as shown in FIG. 2 (a), the lower cladding layer 2, the active layer 3 and the light guide layer 4 are grown on the substrate 1.
次に、第２図(b)に示すように、光ガイド層４上に電子
ビームレジスト21を塗布し、リブ形導波路を形成する部
分に沿って、共振器方向に、電子ビーム露光法により回
折格子パターン22を露光する。回折格子パターン22の露
光に続いて、その外側の部分23を露光する。Next, as shown in FIG. 2 (b), an electron beam resist 21 is applied on the optical guide layer 4, and along the portion forming the rib waveguide, in the cavity direction, by the electron beam exposure method. The diffraction grating pattern 22 is exposed. Following the exposure of the diffraction grating pattern 22, the outer portion 23 is exposed.
これを現像し、ウェットエッチングする。これにより回
折格子５が形成されるとともに、外側の部分が除去され
てリブ形導波路が形成される。この状態を第２図(c)に
示す。リブ形導波路の上面には、二列の回折格子５と、
この回折格子５に挟まれた平坦部24とが設けられる。エ
ッチングの深さについては、数nmに制御する必要はな
く、20〜30nmでよい。This is developed and wet-etched. As a result, the diffraction grating 5 is formed and the outer portion is removed to form a rib-shaped waveguide. This state is shown in FIG. 2 (c). Two rows of diffraction gratings 5 are provided on the upper surface of the rib-shaped waveguide,
A flat portion 24 sandwiched between the diffraction gratings 5 is provided. The etching depth does not have to be controlled to a few nm and may be 20 to 30 nm.
これに続いて、上部クラッド層、キャップ層、絶縁層、
電極などを設ける。Following this, the upper clad layer, cap layer, insulating layer,
Provide electrodes, etc.
第３図は一部に回折格子が形成されたリブ形導波路の走
査顕微鏡写真を示す。中央の黒い帯状の部分はレジスト
であり、このレジストに覆われた部分が平坦部および回
折格子の山部となる。黒い帯状の部分の両側は、回折格
子の谷部とリブ形導波路の両側の部分とがエッチングさ
れ、GaAsウェハが露出している。FIG. 3 shows a scanning micrograph of a rib waveguide in which a diffraction grating is partially formed. The black band-shaped part in the center is the resist, and the part covered with this resist becomes the flat part and the peak part of the diffraction grating. On both sides of the black band-shaped portion, the valley portion of the diffraction grating and the portions on both sides of the rib-shaped waveguide are etched to expose the GaAs wafer.
第４図は回折格子の幅ｌとκとの関係を示す。FIG. 4 shows the relationship between the diffraction grating width 1 and κ.
ここで、回折格子５の位置および形状はリブ形導波路に
対して対称であり、回折格子５の深さは25nmで三角形、
リブ形導波路の幅（２×回折格子の幅ｌ＋平坦部24の
幅）は４μｍとした。また、平坦部24における光ガイド
層の厚さは50nmとした。このとき、κの値は２cm-1〜10
0 cm-1の範囲で変化している。すなわち、Ｌ＝１mmの半
導体レーザであれば、結合係数κＬを0.1 から10まで変
化させることができる。Here, the position and shape of the diffraction grating 5 are symmetrical with respect to the rib-shaped waveguide, and the depth of the diffraction grating 5 is 25 nm and is triangular,
The width of the rib-shaped waveguide (2 × width of diffraction grating 1 + width of flat portion 24) was 4 μm. Further, the thickness of the light guide layer in the flat portion 24 was set to 50 nm. At this time, the value of κ is 2 cm -1 to 10
It varies in the range of 0 cm -1 . That is, if the semiconductor laser has L = 1 mm, the coupling coefficient κL can be changed from 0.1 to 10.
以上の実施例において、回折格子５はリブ形導波路に対
して対称である必要はなく、二つの回折格子５の幅ｌは
異なっていてもよい。In the above embodiments, the diffraction grating 5 does not have to be symmetrical with respect to the rib waveguide, and the two diffraction gratings 5 may have different widths l.
以上の説明では分布帰還形半導体レーザを例に説明した
が、分布ブラッグ反射形半導体レーザの場合にも本発明
を同様に実施できる。Although the distributed feedback semiconductor laser has been described as an example in the above description, the present invention can be similarly implemented in the case of the distributed Bragg reflection semiconductor laser.
以上説明したように、本発明の半導体レーザは、分布帰
還形半導体レーザや分布ブラッグ反射形半導体レーザの
結合係数の値を自由に設定できるので、どのような共振
器長のものに対しても最適な結合係数を設定することが
できる効果がある。As described above, the semiconductor laser of the present invention can freely set the value of the coupling coefficient of the distributed Bragg reflector semiconductor laser or the distributed Bragg reflector semiconductor laser, so that it is suitable for any resonator length. There is an effect that various coupling coefficients can be set.
また、各層をエピタキシャル成長させた後に、その層の
膜厚およびフォトルミネッセンス波長を測定してから、
κおよびブラッグ波長を適切に調整できる効果がある。
すなわち、エピタキシャル成長の後で、その成長結果に
適したようにκおよびブラッグ波長を調整できる。Also, after epitaxially growing each layer, after measuring the film thickness and photoluminescence wavelength of the layer,
There is an effect that the κ and the Bragg wavelength can be appropriately adjusted.
That is, after the epitaxial growth, κ and the Bragg wavelength can be adjusted to suit the growth result.
さらに、同一基板上にκの異なるものを形成することが
でき、種々の結合係数κＬをもつ半導体レーザを同時に
製造でき、素子構造の最適化に効果がある。Furthermore, different κ can be formed on the same substrate, and semiconductor lasers having various coupling coefficients κL can be simultaneously manufactured, which is effective for optimizing the device structure.
また、導波路全域に回折格子を形成する必要がないの
で、電子ビーム露光の時間を短縮できる効果がある。Moreover, since it is not necessary to form a diffraction grating over the entire area of the waveguide, there is an effect that the electron beam exposure time can be shortened.
第１図は本発明実施例半導体レーザの斜視図。 第２図は製造方法を示す図。 第３図は一部に回折格子が形成されたリブ形導波路の結
晶構造を示す走査顕微鏡写真。 第４図は回折格子の幅ｌとκとの関係を示す図。 １……基板、２……下部クラッド層、３……活性層、４
……光ガイド層、５……回折格子、21……電子ビームレ
ジスト、22……回折格子パターン、23……外側の部分、
24……平坦部。FIG. 1 is a perspective view of a semiconductor laser according to an embodiment of the present invention. FIG. 2 is a diagram showing a manufacturing method. FIG. 3 is a scanning micrograph showing a crystal structure of a rib waveguide in which a diffraction grating is partially formed. FIG. 4 is a diagram showing the relationship between the diffraction grating width 1 and κ. 1 ... Substrate, 2 ... Lower clad layer, 3 ... Active layer, 4
...... Light guide layer, 5 …… Diffraction grating, 21 …… Electron beam resist, 22 …… Diffraction grating pattern, 23 …… Outer part,
24 …… Flat part.
Claims (1)
え、この光導波路の共振器方向に沿って光ガイド層が設
けられ、 この光ガイド層には回折格子が形成された 半導体レーザにおいて、 上記回折格子は、上記ガイド層に上記共振器方向の平坦
な領域を残しながら、上記共振器方向と直交する方向の
一部の領域に選択的に形成された ことを特徴とする半導体レーザ。1. A semiconductor laser comprising an optical waveguide formed on a semiconductor substrate, an optical guide layer being provided along a resonator direction of the optical waveguide, and a diffraction grating being formed in the optical guide layer, The semiconductor laser, wherein the diffraction grating is selectively formed in a part of a region in a direction orthogonal to the resonator direction while leaving a flat region in the guide layer in the resonator direction.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1176071A JPH0614577B2 (en) | 1989-07-07 | 1989-07-07 | Semiconductor laser |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1176071A JPH0614577B2 (en) | 1989-07-07 | 1989-07-07 | Semiconductor laser |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0340481A JPH0340481A (en) | 1991-02-21 |
| JPH0614577B2 true JPH0614577B2 (en) | 1994-02-23 |
Family
ID=16007212
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1176071A Expired - Fee Related JPH0614577B2 (en) | 1989-07-07 | 1989-07-07 | Semiconductor laser |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0614577B2 (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP5143985B2 (en) * | 2001-08-10 | 2013-02-13 | 古河電気工業株式会社 | Distributed feedback laser diode |
| GB0201031D0 (en) * | 2002-01-17 | 2002-03-06 | Bookham Technology Plc | Method of producing a rib waveguide |
| WO2004019080A2 (en) * | 2002-08-26 | 2004-03-04 | University Of Delaware | Method for fabricating optical devices in photonic crystal structures |
| FR2910643B1 (en) * | 2006-12-22 | 2009-06-12 | Alcatel Lucent Sa | OPTOELECTRONIC COMPONENT HAVING A TRANSFORMED STRUCTURE DIFFRACTION NETWORK |
| JP6275841B2 (en) * | 2013-12-27 | 2018-02-07 | インテル・コーポレーション | Asymmetric optical waveguide grating resonator and DBR laser |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6297390A (en) * | 1985-10-23 | 1987-05-06 | Sharp Corp | Semiconductor laser element |
-
1989
- 1989-07-07 JP JP1176071A patent/JPH0614577B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0340481A (en) | 1991-02-21 |
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