JPS62173786A - Distributed feedback type semiconductor laser - Google Patents
Distributed feedback type semiconductor laserInfo
- Publication number
- JPS62173786A JPS62173786A JP1633786A JP1633786A JPS62173786A JP S62173786 A JPS62173786 A JP S62173786A JP 1633786 A JP1633786 A JP 1633786A JP 1633786 A JP1633786 A JP 1633786A JP S62173786 A JPS62173786 A JP S62173786A
- Authority
- JP
- Japan
- Prior art keywords
- layer
- active layer
- diffraction grating
- light
- active
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 239000004065 semiconductor Substances 0.000 title claims description 5
- 238000010521 absorption reaction Methods 0.000 claims abstract description 19
- 238000005253 cladding Methods 0.000 claims description 9
- 238000000034 method Methods 0.000 abstract description 8
- 230000010355 oscillation Effects 0.000 abstract description 8
- 229910001218 Gallium arsenide Inorganic materials 0.000 abstract description 7
- 239000000758 substrate Substances 0.000 abstract description 6
- 230000001902 propagating effect Effects 0.000 abstract 1
- 230000000737 periodic effect Effects 0.000 description 16
- 229910000980 Aluminium gallium arsenide Inorganic materials 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 230000003647 oxidation Effects 0.000 description 3
- 238000007254 oxidation reaction Methods 0.000 description 3
- 239000006096 absorbing agent Substances 0.000 description 2
- 230000008878 coupling Effects 0.000 description 2
- 238000010168 coupling process Methods 0.000 description 2
- 238000005859 coupling reaction Methods 0.000 description 2
- 230000031700 light absorption Effects 0.000 description 2
- 230000006798 recombination Effects 0.000 description 2
- 238000005215 recombination Methods 0.000 description 2
- 101150110330 CRAT gene Proteins 0.000 description 1
- 230000002902 bimodal effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000008280 blood Substances 0.000 description 1
- 210000004369 blood Anatomy 0.000 description 1
- 239000000969 carrier Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000002655 kraft paper Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000013307 optical fiber Substances 0.000 description 1
- 238000007790 scraping Methods 0.000 description 1
- 238000004904 shortening Methods 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
- H01S5/1228—DFB lasers with a complex coupled grating, e.g. gain or loss coupling
Landscapes
- Physics & Mathematics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Optics & Photonics (AREA)
- Semiconductor Lasers (AREA)
Abstract
Description
【発明の詳細な説明】 〔産業上の利用分野〕 本発明は、分布帰還型半導体レーザに関する。[Detailed description of the invention] [Industrial application field] The present invention relates to a distributed feedback semiconductor laser.
本発明は、分布帰還型半導体レーザにおいて、活性層近
傍に周期的な光の吸収層を設け、レーザ利得を周期的に
変化させ屈折率の虚数部にも周期的変調を与えることに
よって、安定な単一波長動作を行わせるようにしたもの
である。The present invention provides stable distributed feedback semiconductor lasers by providing a periodic light absorption layer near the active layer, periodically changing the laser gain, and periodically modulating the imaginary part of the refractive index. It is designed to perform single wavelength operation.
〔従来の技術ｊ
分布帰還型半導体レーザ（以下、ＤＦＢレーザと略す）
は単一波長で動作し易いことから長距離で大容量の光フ
アイバ通信に用いる光源として期待されている。しかし
、従来の回折格子の周期的な凹凸によって与えられる屈
折率の実数部のみの周期的な変化を用いたＤＦＢレーザ
は、２モ一ド発振の可能性がある。これを単一モード発
振にする為には回折格子中央部にλ／４シフトを導入す
る必要がある。[Conventional technology j Distributed feedback semiconductor laser (hereinafter abbreviated as DFB laser)
Since it is easy to operate at a single wavelength, it is expected to be used as a light source for long-distance, large-capacity optical fiber communications. However, a conventional DFB laser that uses a periodic change in only the real part of the refractive index given by the periodic irregularities of a diffraction grating has a possibility of bimodal oscillation. In order to make this a single mode oscillation, it is necessary to introduce a λ/4 shift into the center of the diffraction grating.
ところで、屈折率の虚数部にも周期的な変化を導入した
ＤＦＢレーザは、特に他の工夫無しで単−縦モード発振
となる。従来、この方法に関する提案として、一つは活
性層を周期的に分断する方法（特開昭６０−１０２７８
８号公報）、他は成長時に周期的な活性層を形成する方
法（特開昭６０−１０２７８９公報）等がある。By the way, a DFB laser in which a periodic change is also introduced in the imaginary part of the refractive index becomes single-longitudinal mode oscillation without any other special measures. Conventionally, as a proposal regarding this method, one is a method of periodically dividing the active layer (Japanese Patent Application Laid-Open No. 10278-1989).
8), and others include a method of forming periodic active layers during growth (Japanese Unexamined Patent Publication No. 102789/1989).
しかし乍ら、上述の前者の方法は活性層を周期的に分割
ないし削る工程を含む為に、非発光再結合の増加、寿命
の短命化が予想される。又、後者の方法では横モードの
安定化が困難となる。However, since the former method described above includes a step of periodically dividing or scraping the active layer, it is expected that non-radiative recombination will increase and the lifetime will be shortened. Furthermore, in the latter method, it is difficult to stabilize the transverse mode.
本発明は、上述の点に鑑み、活性１舗を傷つけづに屈折
率の虚数部に周期的変調を与えて単一波長動作するＤＦ
Ｂレーザを提供するものである。In view of the above points, the present invention provides a DF that operates at a single wavelength by periodically modulating the imaginary part of the refractive index without damaging the active part.
B laser.
本発明は、クラッド層（２１（８１、活性層（３）、活
性Ｊ偕（３）からの光を回折格子へ導くためのガイド層
（５）を積層して有するＤＦＢレーザにおいて、活性層
（３）の近傍に活性Ｊｉｆ （３１のバンドギャップと
等しいか又はこれより小さいバンドギャップを有する吸
収層（６）を設けて成るものである。The present invention provides a DFB laser having a cladding layer (21 (81), an active layer (3), and a guide layer (5) for guiding light from the active layer (3) to a diffraction grating). 3) is provided with an absorption layer (6) having a bandgap equal to or smaller than the bandgap of the active Jif (31).
吸収層（６）は活性Ｍ（３）からの光を吸収するもので
あり、光の進行方向に沿って周期的に設けられる。The absorption layer (6) absorbs the light from the active layer (3), and is provided periodically along the direction in which the light travels.
またこの吸収層（６）を含んで周期的な凹凸部ら回折格
子（７）が形成される。Further, a diffraction grating (7) is formed from periodic uneven portions including this absorption layer (6).
上述の構成によれば、周期的に存在する吸収層（６）に
よって活性層（３）からしみ出した光が吸収され、その
吸収された部分のレーザ利得が減少する。これによりＤ
ＦＢレーザの長手方向に見たレーザ利得が周期的に変化
し、屈折率の虚数部が周期的に変化する。従って、回折
格子による屈折率の実数部の周期的な変化に加えて、虚
数部も周期的に変化し、ブラック波長付近の単−縦モー
ド発振がｒ＋Ｊ能となる。According to the above configuration, the light seeping out from the active layer (3) is absorbed by the periodically existing absorption layer (6), and the laser gain of the absorbed portion is reduced. As a result, D
The laser gain seen in the longitudinal direction of the FB laser changes periodically, and the imaginary part of the refractive index changes periodically. Therefore, in addition to the periodic change in the real part of the refractive index due to the diffraction grating, the imaginary part also changes periodically, and the single-longitudinal mode oscillation near the black wavelength becomes r+J function.
この構成では活性層を傷つけることがないので、非発光
再結合の増加、寿命の短命化は回避される。With this configuration, the active layer is not damaged, so an increase in non-radiative recombination and a shortening of the lifetime can be avoided.
以Ｆ、図面を参照して本発明によるＤＦＢレーザの実施
例を説明する。Hereinafter, embodiments of the DFB laser according to the present invention will be described with reference to the drawings.
第１図は、ＧａＡｓ系のＤＦＢレーザの例である。FIG. 1 shows an example of a GaAs-based DFB laser.
７５０ｎｍ〜９００ｎｍの波長領域ではＧａＡｓ系とな
る。本例においては、ｎ−ＧａＡｓ基板（１）の上にｎ
−ＡｌＧａＡｓによるクラット層（２）及びＧａＡｓ
（又はＡＩＧａＡｓ）の活性層（３）を順次形成する。In the wavelength range of 750 nm to 900 nm, the material is GaAs-based. In this example, an n-GaAs substrate (1) is
- Crat layer (2) made of AlGaAs and GaAs
An active layer (3) of (or AIGaAs) is sequentially formed.
このクラフト層（２）及び活性層（３）は通常の構造で
あり、クラッド層（２）のへｌ比を高くとる。この活性
層（３）上にキャリアを活性層（３）に閉じ込めるため
にへｌ比がやや多めの薄いｐ−＾ｌＧａＡ３ブロック層
（４）を形成し、さらにこのブロックｒ＠（４１上に活
性層（３）からの光を後述の回折格子（７）に導くため
の例えば叶ＩｎＧａＡｓＰガイドｆ＃ （５）を形成す
る。The kraft layer (2) and the active layer (3) have a normal structure, and the cladding layer (2) has a high hel ratio. A thin p-^lGaA3 block layer (4) with a slightly higher Hel ratio is formed on this active layer (3) in order to confine carriers in the active layer (3). For example, an InGaAsP guide f# (5) is formed to guide light from the layer (3) to a diffraction grating (7) to be described later.
ガイドＩ！ （５）としてはＡｌＧａＡｓ１曲でもよい
が、ここではＡｌＧａＡｓに格子整合するｒｎＧａＡｓ
Ｐ Ｊ−を用いた。これは次のホログラフィック露光法
で回折格子を形成する際の酸化を極力抑える為に有効で
ある。Guide I! For (5), one piece of AlGaAs may be used, but here, rnGaAs which is lattice matched to AlGaAs is used.
PJ- was used. This is effective for suppressing oxidation as much as possible when forming a diffraction grating in the next holographic exposure method.
次に、活性層（３）のバンドギャップと等しいか又はこ
れより小さいバンドギャップを有する吸収層となるＧａ
Ａｓｊｆｆｌを形成した後、ホログラフィック露光法に
より回折格子（７）を形成し、同時に周期的に分入りさ
れた吸収層（６）を形成する。この回折格子（７）の形
成時に空気にさらされる血は酸化を極力抑えるためにＡ
Ｉを含んでいないツエが望ましい。この点で本例でばＧ
ａＡｓ吸収層（ム）とＩｎＧａＡｓＰガイドＰｔ ｆｆ
１ｌのみが空気にさらされるため、界面酸化の問題を減
らずことができる。吸収ＩＮ （６１のＧａＡｓ１ｔ＃
はｎタイプでもｐタイプでも良いが、本例ではｎ−Ｇａ
Ａｓ１ｍを示した。次に通常通りｐ−ＡｌＧａＡｓクラ
ッド層（８）を形成する。このクラッド層（８）の屈折
率はＩｎＧａＡｓＰの屈折率より小さくする必要がある
。次で叶ＧａＡｓギャップ層（９）を介して一方の電極
（１０）を形成し、またｎ−ＧａＡｓ基板（１）の裏面
に他方の電極（１１）を形成してＤＦＢレーザ（１２）
を構成する。Next, Ga is used as an absorption layer having a bandgap equal to or smaller than the bandgap of the active layer (3).
After forming Asjffl, a diffraction grating (7) is formed by a holographic exposure method, and at the same time an absorption layer (6) having periodic portions is formed. The blood exposed to the air during the formation of this diffraction grating (7) is A to suppress oxidation as much as possible.
A tsue that does not include I is desirable. At this point, in this example, G
aAs absorption layer (mu) and InGaAsP guide Pt ff
Since only 1 liter is exposed to air, interfacial oxidation problems are not reduced. Absorption IN (61 GaAs1t#
may be n-type or p-type, but in this example n-Ga
It showed As1m. Next, a p-AlGaAs cladding layer (8) is formed as usual. The refractive index of this cladding layer (8) needs to be smaller than the refractive index of InGaAsP. Next, one electrode (10) is formed through the GaAs gap layer (9), and the other electrode (11) is formed on the back surface of the n-GaAs substrate (1) to form a DFB laser (12).
Configure.
かかる構成によれば、活性層（３）からの光が周期的に
配列された吸収層（６）に吸収されることによって、そ
の部分でのレーザ利得が減少する。従ってＤＦＢレーザ
の長手方向に見たレーザ利得が周期的に変化し、屈折率
の虚数部が周期的に変化する。According to this configuration, light from the active layer (3) is absorbed by the periodically arranged absorption layers (6), thereby reducing the laser gain in that portion. Therefore, the laser gain seen in the longitudinal direction of the DFB laser changes periodically, and the imaginary part of the refractive index changes periodically.
従って、ＤＦＢレーザとしての光の帰還は、回折格子（
７）による屈折率の実数部の周期的変化を利用した屈折
率型カップリングに加えて、屈折率の虚数部の周期的変
化を利用した利得型カップリングとなり、ブラック波長
付近の単−縦モード発厖が１、ＩＪ能となる。Therefore, the feedback of light as a DFB laser is determined by the diffraction grating (
In addition to refractive index type coupling that utilizes periodic changes in the real part of the refractive index as described in 7), gain type coupling utilizes periodic changes in the imaginary part of the refractive index, and a single-longitudinal mode near the black wavelength is generated. The release becomes 1 and IJ ability.
ス、第１図の構成において、吸収層（６）としてｎタイ
プを用いた場合には、吸収層（６）が周期的な′市流狭
さく層として慟（。即ちガイド）＠ （５１とプロツり
屓（４）を充分薄くすると、活性層（３）に注入される
電流が周期的となり、周期的な利得分布が形成されるこ
とになり、周期的な吸収層（６）の効果を強め合うもの
である。In the configuration shown in FIG. 1, when an n-type absorber layer (6) is used, the absorber layer (6) acts as a periodic narrowing layer (that is, a guide) @ (51 and If the layer (4) is made sufficiently thin, the current injected into the active layer (3) becomes periodic, forming a periodic gain distribution, which strengthens the effect of the periodic absorption layer (6). It fits.
第２図はＩｎＰ糸のＤＦＢレーザの例である。FIG. 2 is an example of a DFB laser using InP thread.
１．３μｍ〜１．５μｍの波長領域ではＴｎＰ系となる
。In the wavelength range of 1.3 μm to 1.5 μm, it becomes TnP type.
本例においては、ｎ−ＩｎＰ基板（２１）にｎ−ｒｎＰ
クラッド層（２２）を形成し、この上に活性層（２６）
のバンドギャップと等しいか、これより小ざいバンドギ
ャップを有するｐタイプ又はｎタイプ、本例ではｐ−１
ｎＧａＡｓＰ吸収１ｍ（２３）を成長せしめ、次にホロ
グラフィック露光法で回折格子（２４）を形成する。こ
れにより吸収１５（２３）は周期的に分割される。次で
、順次、ｎ−１ｎＧａＡｓＰガイド層（２５）、ｒｎＧ
ａＡｓＰ活性層（２６）及びｐ−１ｎＰクラツド！＠
（２７）を成長し、電極（２８）及び（２９）を形成し
てＤＦＢレーザ（３０）を構成する。なお、回折格子（
２４）、吸収層（２３）は活性１’１（２Ｂ）よりｐ側
に形成してもよい。In this example, the n-InP substrate (21) is
A cladding layer (22) is formed, and an active layer (26) is formed on this.
p-type or n-type, in this example p-1, with a bandgap smaller than or equal to the bandgap of
An nGaAsP absorption layer (23) of 1 m is grown, and then a diffraction grating (24) is formed by holographic exposure. This causes the absorption 15 (23) to be divided periodically. Next, the n-1nGaAsP guide layer (25), rnG
aAsP active layer (26) and p-1nP cladding! @
(27) is grown to form electrodes (28) and (29) to constitute a DFB laser (30). In addition, the diffraction grating (
24), the absorption layer (23) may be formed on the p side from the active 1'1 (2B).
この構成の場合も、第１図で説明したと同様に周期的な
吸収層（２３）によりレーザ利得を周期的に変化させ、
屈折率の実数部に加えて、虚数部も周期的に変化し、単
−縦モード発振が可能となる。In the case of this configuration as well, the laser gain is changed periodically by the periodic absorption layer (23) in the same way as explained in FIG.
In addition to the real part of the refractive index, the imaginary part also changes periodically, allowing single-longitudinal mode oscillation.
上述せる本発明によれば、ＤＦＢレーザにおいて、活性
層近傍に活性層のバンドギャップと等しいか又はこれよ
り小さいバンドギャップを有する光の吸収層を有するこ
とにより、活性層を傷つけることなく、屈折率の虚数部
に周期豹変ＩＭを与えることができ、極めて安定な単−
縦モード発振のＤＦＢレーザを実現することができる。According to the present invention described above, in a DFB laser, by having a light absorption layer having a band gap equal to or smaller than the band gap of the active layer in the vicinity of the active layer, the refractive index can be adjusted without damaging the active layer. It is possible to give a periodic change IM to the imaginary part of
A DFB laser with longitudinal mode oscillation can be realized.
図面のＩｆｆ）車な説明
第１図は本発明によるＤＦＢレーザの一実施例を示す断
面図、第２図は本発明によるＤＦＢレーザの他の実施例
を示す断面図である。Description of Drawings FIG. 1 is a sectional view showing one embodiment of the DFB laser according to the present invention, and FIG. 2 is a sectional view showing another embodiment of the DFB laser according to the present invention.
（１）は基板、（２）はクラッド層、（３）は活性層、
（４）はブロック層、（５）はガイド層、（６）は吸収
層、（７）は回折格子、（８）はクラッド層、（１０）
、 （１１）は電極である。(1) is the substrate, (2) is the cladding layer, (3) is the active layer,
(4) is a block layer, (5) is a guide layer, (6) is an absorption layer, (7) is a diffraction grating, (8) is a cladding layer, (10)
, (11) is an electrode.
Claims (1)
なる分布帰還型半導体レーザにおいて、上記吸収層のバ
ンドギャップが上記活性層のバンドギャップと等しいか
、小さいことを特徴とする分布帰還型半導体レーザ。A distributed feedback semiconductor laser comprising a cladding layer, an active layer, a guide layer, and an absorption layer, wherein the bandgap of the absorption layer is equal to or smaller than the bandgap of the active layer. laser.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1633786A JPS62173786A (en) | 1986-01-28 | 1986-01-28 | Distributed feedback type semiconductor laser |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1633786A JPS62173786A (en) | 1986-01-28 | 1986-01-28 | Distributed feedback type semiconductor laser |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS62173786A true JPS62173786A (en) | 1987-07-30 |
Family
ID=11913600
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1633786A Pending JPS62173786A (en) | 1986-01-28 | 1986-01-28 | Distributed feedback type semiconductor laser |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS62173786A (en) |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0240984A (en) * | 1988-07-30 | 1990-02-09 | Tokyo Univ | Distributed feedback-type semiconductor laser device |
| JPH03145780A (en) * | 1989-10-31 | 1991-06-20 | Mitsubishi Electric Corp | Semiconductor laser |
| US5093835A (en) * | 1989-06-30 | 1992-03-03 | Mitsubishi Denki Kabushiki Kaisha | Semiconductor laser device |
| US5325379A (en) * | 1992-01-20 | 1994-06-28 | Siemens Aktiengesellschaft | Tunable laser diode |
| EP0614254A1 (en) * | 1993-03-01 | 1994-09-07 | Canon Kabushiki Kaisha | Gain-coupling distributed feedback semiconductor laser and method of producing the same |
| EP1162708A1 (en) * | 2000-06-06 | 2001-12-12 | The Furukawa Electric Co., Ltd. | Distributed feedback semiconductor laser device |
| KR100324203B1 (en) * | 1999-09-18 | 2002-02-16 | 오길록 | Gain-coupled distributed feedback laser diode and fabrication method for the same |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS60132380A (en) * | 1983-12-21 | 1985-07-15 | Hitachi Ltd | Distributed feedback type semiconductor laser device |
-
1986
- 1986-01-28 JP JP1633786A patent/JPS62173786A/en active Pending
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS60132380A (en) * | 1983-12-21 | 1985-07-15 | Hitachi Ltd | Distributed feedback type semiconductor laser device |
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0240984A (en) * | 1988-07-30 | 1990-02-09 | Tokyo Univ | Distributed feedback-type semiconductor laser device |
| US5093835A (en) * | 1989-06-30 | 1992-03-03 | Mitsubishi Denki Kabushiki Kaisha | Semiconductor laser device |
| US5143864A (en) * | 1989-06-30 | 1992-09-01 | Misubishi Denki Kabushiki Kaisha | Method of producing a semiconductor laser |
| JPH03145780A (en) * | 1989-10-31 | 1991-06-20 | Mitsubishi Electric Corp | Semiconductor laser |
| US5325379A (en) * | 1992-01-20 | 1994-06-28 | Siemens Aktiengesellschaft | Tunable laser diode |
| EP0614254A1 (en) * | 1993-03-01 | 1994-09-07 | Canon Kabushiki Kaisha | Gain-coupling distributed feedback semiconductor laser and method of producing the same |
| KR100324203B1 (en) * | 1999-09-18 | 2002-02-16 | 오길록 | Gain-coupled distributed feedback laser diode and fabrication method for the same |
| EP1162708A1 (en) * | 2000-06-06 | 2001-12-12 | The Furukawa Electric Co., Ltd. | Distributed feedback semiconductor laser device |
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