JPS59225584A - Distribution feedback type semiconductor laser element - Google Patents

Distribution feedback type semiconductor laser element

Info

Publication number
JPS59225584A
JPS59225584A JP58101134A JP10113483A JPS59225584A JP S59225584 A JPS59225584 A JP S59225584A JP 58101134 A JP58101134 A JP 58101134A JP 10113483 A JP10113483 A JP 10113483A JP S59225584 A JPS59225584 A JP S59225584A
Authority
JP
Japan
Prior art keywords
layer
gratings
semiconductor laser
refractive index
laser
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
Application number
JP58101134A
Other languages
Japanese (ja)
Inventor
Tomoaki Uno
智昭 宇野
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Panasonic Holdings Corp
Original Assignee
Matsushita Electric Industrial Co Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Matsushita Electric Industrial Co Ltd filed Critical Matsushita Electric Industrial Co Ltd
Priority to JP58101134A priority Critical patent/JPS59225584A/en
Publication of JPS59225584A publication Critical patent/JPS59225584A/en
Pending legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S5/00—Semiconductor lasers
    • H01S5/10—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
    • 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

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  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Optics & Photonics (AREA)
  • Semiconductor Lasers (AREA)

Abstract

PURPOSE:To reduce the laser oscillated threshold value simultaneously improving the externally differentiated quantum efficiency by a method wherein gratings made of a material with refractive index different from that of a compound semiconductor layer is formed in the compound semiconductor layer. CONSTITUTION:A clad layer 25, an active layer 24 and a guidewave channel layer 23 are successively crystal-grown on a substrate 26 and then gratings 28a, 28b of SiO2 are formed by means of patterning process using two flux interference or electronic beam exposure. Next another clad layer 22 and a contact layer 21 are successively crystalized by means of liquid epitaxial process. Then an electrode 20 and another electrode 27 are respectively formed of Au/Zn and Au/Sn alloy. The optical resonance may occur between the gratings 28a and 28b increasing the feedback efficiency remarkably up to 20 times compared with the conventional efficiency. Resultantly the laser threshold value may be reduced improving the externally differentiated quantum efficiency remarkably.

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素子の改良に関する。[Detailed description of the invention] Industrial applications The present invention relates to improvements in distributed feedback semiconductor laser devices.

従来例の構成とその問題点 近年、分布帰還型半導体レーザとしてＤＦＢ（Ｄｉｓｔ
ｒｉｂｎｔｅｄ　Ｆｅｅｄ　ＢａｃＫ）構造またはＤＢ
Ｒ（Ｄｉｇｔｒｉｂｎｔｅｄ　Ｂｒａｇｇ　Ｒｅｆｌｅ
ｃｉｏｎ　）構造を有する素子が単一の波長で安定に発
振するという点から注目されている。Conventional structure and its problems In recent years, DFB (Dist
ribnted Feed BacK) structure or DB
R
Elements having a structure such as Cion) are attracting attention because they stably oscillate at a single wavelength.

以下図面を参照しながら、上述したような従来の分布帰
還型半導体レーザについて説明する。第１図にＤＢＲ構
造を有するたとえば１．３１ｔｍ発振波長の分布帰還型
半導体レーザ素子の従来例を断面図により示す。−断面
はレーザ共振方向のものである。図中において、１ｏは
電極、１１はＰ型層ｎＧａＡｓＰコｙタイト層、１２は
Ｐ型ＩｎＰクラッド層、１３はｎ型ＩｎＧａＡｓＰ導波
路層、１４はｎ型ＩｎＧａＡｓＰ活性層、１５はｎ型Ｉ
ｎＰクラッド層、１６はｎ＋型ＩｎＰ基板、１７は電極
、１８ａ、１８ｂ３ はともにｎ型層ｎＧａＡｓＰ導波路首従、刻まれたグレ
イティング、１９ａ、１９ｂはともにレーザ光の出射方
向である。レーザ発振は、グレイティング１８ａとグレ
イティング１８ｂの間で起るが、その発振の容易さはグ
レイティング１８ａおよび１８ｂの帰還効率によって決
まっている。帰還効率は、レーザを構成する結晶材料が
決まれば近似的にグレイティング部の屈折率変化量Δｎ
に比例する。ところが従来のＩ　ｎ　Ｐ／　Ｉ　ｎ　Ｇ
　ａ　Ａ　ｓ　Ｐ系のレーザではＩｎ　−（ＩｎＧａＡ
ｓＰの屈折率−ＩｎＰの屈折率）となり、この値はたと
えば１．３１１ｍの波長の光に対してはΔｎミ０．１と
非常に小さかった。この結果レーザ発振は起りにくくな
り、レーザ発振しきい値が高くなると共に外部微分量子
効率は小さくなっていた。これは他の分布帰還型半導体
レーザについても同様である。また他の結晶月相を用い
た分布帰還型半導体レーザ素子についても同様である。The conventional distributed feedback semiconductor laser as described above will be described below with reference to the drawings. FIG. 1 shows a sectional view of a conventional distributed feedback semiconductor laser device having a DBR structure and having an oscillation wavelength of, for example, 1.31 tm. -The cross section is in the direction of laser resonance. In the figure, 1o is an electrode, 11 is a P-type nGaAsP coy-tight layer, 12 is a P-type InP cladding layer, 13 is an n-type InGaAsP waveguide layer, 14 is an n-type InGaAsP active layer, and 15 is an n-type I
An nP cladding layer, 16 is an n+ type InP substrate, 17 is an electrode, 18a and 18b3 are both n-type layer nGaAsP waveguide heads, carved gratings, and 19a and 19b are both laser beam emission directions. Laser oscillation occurs between grating 18a and grating 18b, and the ease of oscillation is determined by the feedback efficiency of gratings 18a and 18b. Feedback efficiency can be calculated approximately by the amount of refractive index change Δn of the grating section, once the crystal material constituting the laser is determined.
is proportional to. However, the conventional I nP/I nG
In a A s P laser, In - (InGaA
The refractive index of sP - the refractive index of InP), and this value was very small, for example, Δn 0.1 for light with a wavelength of 1.311 m. As a result, laser oscillation becomes less likely to occur, the laser oscillation threshold becomes higher, and the external differential quantum efficiency becomes smaller. This also applies to other distributed feedback semiconductor lasers. The same applies to distributed feedback semiconductor laser devices using other crystal moon phases.

発明の目的 本発明は、分布帰還型半導体レーザにおける光の分布帰
還効率を高くすることによって、レーザ発振しきい値を
低くすると共に外部微分量子効率の大きなレーザ素子を
得ることを目的としている。OBJECTS OF THE INVENTION An object of the present invention is to lower the laser oscillation threshold and obtain a laser element with high external differential quantum efficiency by increasing the distributed feedback efficiency of light in a distributed feedback semiconductor laser.

発明の構成 本発明は、分布帰還型半導体レーザ素子において、基板
上に化合物半導体層よりなるクラッド層、活性層を形成
し、前記化合物半導体層中に前記化合物半導体層と異な
る屈折率を有する桐料よりなるグレーティングを形成す
ることにより、光の分布帰還効率を高くし、素子の特性
を改善したものである。Structure of the Invention The present invention provides a distributed feedback semiconductor laser device in which a cladding layer and an active layer made of a compound semiconductor layer are formed on a substrate, and a paulownia material having a refractive index different from that of the compound semiconductor layer is formed in the compound semiconductor layer. By forming a grating of more than 100 nm, the distributed feedback efficiency of light is increased and the characteristics of the element are improved.

実施例の説明 本発明の一実施例を図面を用いて説明する。第２図は実
施例のＤＢＲ構造を有する１、３７１ｍ波長で発振する
分布帰還型半導体レーザ素子の断面図である。断面はレ
ーザ共振方向のものである。図中において、２ｏは電極
、２１けＰ型１ｎＧａＡｓＰコンタクト層、２２はＰ型
ＩｎＰクラッド層、２３はｎ型ＩｎＧａＡｓＰ導波路層
、２４はｎ型ＩｎＧａＡｓＰ活性層、２５はｎ型ＩｎＰ
クラッド層、２６はｎ４−型ＩｎＰ　基板、２７は電極
、２８ａ　、２ｓｂはともにＳｉＯ２によって形成され
たグレイティング、２９ａ　、２９ｂはともにレーザ光
の出射方向である。DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. FIG. 2 is a sectional view of a distributed feedback semiconductor laser device having a DBR structure according to an embodiment and oscillating at a wavelength of 1,371 m. The cross section is in the laser resonance direction. In the figure, 2o is an electrode, 21 is a P-type 1nGaAsP contact layer, 22 is a P-type InP cladding layer, 23 is an n-type InGaAsP waveguide layer, 24 is an n-type InGaAsP active layer, and 25 is an n-type InP
A cladding layer 26 is an n4-type InP substrate, 27 is an electrode, 28a and 2sb are both gratings formed of SiO2, and 29a and 29b are both laser beam emission directions.

素子の作製は、結晶法として既知の液相エピタキシャル
法を用いた。基板２６上にクラッド層２６および活性層
２４および導波路層２３の結晶成長を順次行った後に、
既知の２光束干渉法あるいは電子ビーム露光法を用いた
パターン加工によって８１０２のグレイティング２８ａ
、２８ｂを形成する。The device was manufactured using a liquid phase epitaxial method known as a crystal method. After crystal growth of the cladding layer 26, active layer 24, and waveguide layer 23 is performed sequentially on the substrate 26,
The grating 28a of 8102 is formed by pattern processing using the known two-beam interference method or electron beam exposure method.
, 28b.

次に前述の液相エピタキシャル法により、クラッド層２
２、コンタクト層２１を順次結晶する。Next, the cladding layer 2 is formed by the liquid phase epitaxial method described above.
2. Sequentially crystallize the contact layer 21.

しかる後に電極２ｏを八ｕ　／Ｚ　ｎ合金により、’ｉ
、ｔｊ極２７をＡ　ｕ／Ｓ　ｎ合金により形成する。主
要各部の屈折率は、１．３７１ｍの光に対して、クラッ
ド層２２ではＮ＝３．４、導波路層２３ではＮ＝３．５
、活性層２４でｉｊＮ：３．５、クラッド層２５ではＮ
＝３．４．５ｉ０２で形成されたグレイティング２８ａ
、２８ｂではＮ＝１．ｓである。また主要各部の寸法は
、クラッド層２２は厚さが２μｍ、導波路層２３は厚さ
が０．２１ｉｍ　、活性層２４は厚さが０．２１ｔｍ　
、クラッド層２６は厚さが２μｍ５ＳＩＯ２で形成され
たグレイティング２ａａ、２ｓｂは厚さが０．２μｍ１
一本の線幅が０．２μｍ１周期が０．４μｍである。After that, the electrode 2o is made of 8u/Zn alloy.
, tj poles 27 are formed of an A u/S n alloy. The refractive index of each main part is N=3.4 for the cladding layer 22 and N=3.5 for the waveguide layer 23 for light of 1.371 m.
, ijN: 3.5 in the active layer 24, N in the cladding layer 25
Grating 28a formed by =3.4.5i02
, 28b, N=1. It is s. The dimensions of the main parts are as follows: the cladding layer 22 has a thickness of 2 μm, the waveguide layer 23 has a thickness of 0.21 mm, and the active layer 24 has a thickness of 0.21 tm.
, the cladding layer 26 has a thickness of 2 μm, and the gratings 2aa and 2sb formed of SIO2 have a thickness of 0.2 μm1.
The width of one line is 0.2 μm and one period is 0.4 μm.

光の共振はグレイティング２８ａとグレイティング２８
ｂの間で起る。光の帰還効率の大きさは、前述したよう
に、レーザを構成する結晶材料が決まれば近似的にグレ
イティング部の屈折率変化量Δｎに比例して変化する。Light resonance occurs between grating 28a and grating 28
Occurs between b. As described above, once the crystal material constituting the laser is determined, the magnitude of the light feedback efficiency changes approximately in proportion to the amount of change in the refractive index Δn of the grating portion.

そこで次に第１図に示す従来例と、第２図に示す本発明
の実施例とにおけるグレイティング部の屈折率変化量を
第３図ａ、ｂ、ｃに示す。第３図ａは従来例のグレイテ
ィング部分、第３図ｂ　ｒ、１本発明の実施例のグレイ
ティング部分、第３図Ｃは第３図ａおよび第３図すにお
けるＡ　−Ａ’、Ｂ−Ｂ’の線分に沿った屈折率の変化
をグラフにしだものである。第３図Ｃのグラフ中で、破
線はＡ−Ａ’の線分に沿った屈折率、実線はＢ　−Ｂ’
の線分に沿った屈折率を示している。なお既説明の部分
には同一の番号を附す。Therefore, the amount of change in the refractive index of the grating portion in the conventional example shown in FIG. 1 and the embodiment of the present invention shown in FIG. 2 is shown in FIGS. 3a, b, and c. FIG. 3a shows the grating part of the conventional example, FIG. 3b r, 1 the grating part of the embodiment of the present invention, and FIG. This is a graph showing the change in refractive index along the line segment -B'. In the graph of FIG. 3C, the dashed line is the refractive index along the line segment A-A', and the solid line is the refractive index along the line segment B-B'.
It shows the refractive index along the line segment. The same numbers are given to the parts that have already been explained.

第３図Ｃより明らかなように、本実施例における屈折率
変化量Δｎｂ　は従来例における屈折率変化量Δｎａ　
よりも２０倍程度大きいことがわかる。As is clear from FIG. 3C, the amount of change in refractive index Δnb in this embodiment is the amount of change in refractive index Δna in the conventional example.
It can be seen that it is about 20 times larger than .

よって本実施例の帰還効率は従来例のもの、と比べて２
０倍程度大きくなり、結果的にレーザしきい値が低下し
、外部微分量子効率も大幅に改善される。Therefore, the feedback efficiency of this embodiment is 2% compared to that of the conventional example.
As a result, the laser threshold value is lowered and the external differential quantum efficiency is also significantly improved.

なお本実施例では、ＤＢＲ構造を有する分布帰還型半導
体レーザのみについて述べたが、ＤＦＢ構造を有するも
のについても同様の効果が得られる。丑だ結晶月別とし
ては、ＩｎＰ／ＩｎＧａＡｓＰ系以外のものについて系
間外の効果が得られる。丑だ本実施例では、グレイティ
ングの形成材料としてＳ　ｉＯ２を用いたが、グレイテ
ィングの材料としては、分布帰還型半導体レーザ構造に
おける基板。In this embodiment, only a distributed feedback semiconductor laser having a DBR structure has been described, but similar effects can be obtained with a semiconductor laser having a DFB structure. As for the monthly usage of Ushida crystals, inter-system and extra-system effects can be obtained for systems other than the InP/InGaAsP system. In this example, SiO2 was used as the material for forming the grating, but the material for the grating could be a substrate in a distributed feedback semiconductor laser structure.

クラッド層、活性層あるいは導波路層の屈折率と異なる
ものであれば良い。グレイティングを形成する位置は、
活性層とクラッド層の間であれば良く、導波路層はなく
ても良い。Any material may be used as long as it has a refractive index different from that of the cladding layer, active layer, or waveguide layer. The position where the grating is formed is
It may be between the active layer and the cladding layer, and the waveguide layer may not be present.

発明の効果 この発明は、以上説明したような構造で、分布帰還型レ
ーザ素子の発振しきい値電流値を減小させることができ
るとともに、外部量子効率を高くすることができ、その
実用的効果は大なるものがある。Effects of the Invention The present invention has a structure as described above, which can reduce the oscillation threshold current value of a distributed feedback laser device and increase the external quantum efficiency. There is something big about it.

【図面の簡単な説明】[Brief explanation of drawings]

第１図は従来のＤＢＲ構造を有する分布帰還型半導体レ
ーザ素子の断面図、第２図は本発明の実施例におけるＤ
ＢＲ構造を有する分布帰還型半導体レーザ素子の断面図
、第３図ａ、ｂはそれぞれ従来例、本発明実施例におけ
るグレイティング部の断面図、第３図Ｃは従来例、本発
明の屈折率変化の様子を示す図である。 ２２・・−クラッド層、２３・・　導波路層、２４・・
・・活性層、２８ａ、２８ｂ・−・・５１０２グレイテ
イング。 代理人の氏名　弁理士　中　尾　敏　男　ほか１名第１
図 １’／ 第２図 第３図 ｆ８ａ、ｆ８ｂ イｆ−ＬFIG. 1 is a sectional view of a distributed feedback semiconductor laser device having a conventional DBR structure, and FIG. 2 is a cross-sectional view of a DBR structure according to an embodiment of the present invention.
A cross-sectional view of a distributed feedback semiconductor laser device having a BR structure, FIGS. 3a and 3b are cross-sectional views of grating portions in a conventional example and an embodiment of the present invention, respectively. FIG. 3C is a conventional example and a refractive index of the present invention. It is a figure showing the state of change. 22...-cladding layer, 23... waveguide layer, 24...
...Active layer, 28a, 28b...5102 grating. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 1' / Figure 2 Figure 3 f8a, f8b if-L

Claims (1)

【特許請求の範囲】 基板上に化合物半導体層よりなるクラッド層。 活性層を形成し、前記化合物半導体層中に前記化合物半
導体層と異なる屈折率を有する材料よりなるグレーティ
ングを形成してなることを特徴とする分布帰還型半導体
レーザ素子。[Claims] A cladding layer made of a compound semiconductor layer on a substrate. 1. A distributed feedback semiconductor laser device comprising an active layer and a grating made of a material having a refractive index different from that of the compound semiconductor layer in the compound semiconductor layer.
JP58101134A 1983-06-06 1983-06-06 Distribution feedback type semiconductor laser element Pending JPS59225584A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP58101134A JPS59225584A (en) 1983-06-06 1983-06-06 Distribution feedback type semiconductor laser element

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP58101134A JPS59225584A (en) 1983-06-06 1983-06-06 Distribution feedback type semiconductor laser element

Publications (1)

Publication Number Publication Date
JPS59225584A true JPS59225584A (en) 1984-12-18

Family

ID=14292603

Family Applications (1)

Application Number Title Priority Date Filing Date
JP58101134A Pending JPS59225584A (en) 1983-06-06 1983-06-06 Distribution feedback type semiconductor laser element

Country Status (1)

Country Link
JP (1) JPS59225584A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0227373A2 (en) * 1985-12-16 1987-07-01 Hitachi, Ltd. Process for fabricating a semiconductor structure
US4941148A (en) * 1986-11-12 1990-07-10 Sharp Kabushiki Kaisha Semiconductor laser element with a single longitudinal oscillation mode

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0227373A2 (en) * 1985-12-16 1987-07-01 Hitachi, Ltd. Process for fabricating a semiconductor structure
US4941148A (en) * 1986-11-12 1990-07-10 Sharp Kabushiki Kaisha Semiconductor laser element with a single longitudinal oscillation mode

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