JP2879083B2 - DFB semiconductor laser - Google Patents
DFB semiconductor laserInfo
- Publication number
- JP2879083B2 JP2879083B2 JP2024867A JP2486790A JP2879083B2 JP 2879083 B2 JP2879083 B2 JP 2879083B2 JP 2024867 A JP2024867 A JP 2024867A JP 2486790 A JP2486790 A JP 2486790A JP 2879083 B2 JP2879083 B2 JP 2879083B2
- Authority
- JP
- Japan
- Prior art keywords
- layer
- ingaasp
- diffraction grating
- semiconductor laser
- band gap
- 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
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
- H01S5/06—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
- H01S5/06258—Controlling the frequency of the radiation with DFB-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
- H01S5/00—Semiconductor lasers
- H01S5/20—Structure or shape of the semiconductor body to guide the optical wave ; Confining structures perpendicular to the optical axis, e.g. index or gain guiding, stripe geometry, broad area lasers, gain tailoring, transverse or lateral reflectors, special cladding structures, MQW barrier reflection layers
- H01S5/2004—Confining in the direction perpendicular to the layer structure
Landscapes
- Physics & Mathematics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Optics & Photonics (AREA)
- Semiconductor Lasers (AREA)
Description
【発明の詳細な説明】 〔産業上の利用分野〕 本発明は、コヒーレント光通信の光源として開発が期
待される狭線幅DFB（Distributed Feed−Back: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 narrow linewidth DFB (Distributed Feed-Back) semiconductor laser expected to be developed as a light source for coherent optical communication.
特に、長共振器DFB半導体レーザの製作に必要な低結
合係数の回折格子を再現性良く製作するための層構造を
有するDFB半導体レーザに関する。In particular, the present invention relates to a DFB semiconductor laser having a layer structure for manufacturing a diffraction grating having a low coupling coefficient required for manufacturing a long cavity DFB semiconductor laser with good reproducibility.
第３図は従来の技術のDFB半導体レーザの模式的断面
構造図を示す。第３図において、１はｎ−InP基板、２
はｎ−InPクラッド層、４はｕ−InGaAsP活性層、５はｐ
−InGaAsPガイド層、６はｐ−InPクラッド層、７はｐ−
InGaAsPコンタクト層、８はｎ−電極、９はｐ−電極、1
0は光のパワー分布、11は回折格子を示す。FIG. 3 is a schematic sectional structural view of a DFB semiconductor laser according to the prior art. In FIG. 3, 1 is an n-InP substrate, 2
Is an n-InP cladding layer, 4 is a u-InGaAsP active layer, 5 is p
-InGaAsP guide layer, 6 is p-InP cladding layer, 7 is p-
InGaAsP contact layer, 8 is n-electrode, 9 is p-electrode, 1
0 indicates a light power distribution, and 11 indicates a diffraction grating.
従来の多電極あるいは単電極DFB半導体レーザの層構
造は、例えば、第３図に図示するように、ｎ−InP基板
１と、ｎ−InPクラッド層２と、発光波長1.55μｍのア
ンドープのｕ−InGaAsP活性層４と、回折格子11を有す
る発光波長1.3μｍのｐ−InGaAsPガイド層５と、ｐ−In
Pクラッド層６と、ｐ−InGaAsPコンタクト層７とからな
るような層構造であった。このため、光のパワー分布10
が、回折格子11を有するｐ−InGaAsPガイド層５の側に
引き寄せられ、またｐ−InGaAsPガイド層５とｎ−InPク
ラッド層２及びｐ−InPクラッド層６との屈折率差が比
較的大であったため、結合係数κの比較的大きなDFB半
導体レーザしか製作できなかった。For example, as shown in FIG. 3, the layer structure of a conventional multi-electrode or single-electrode DFB semiconductor laser includes an n-InP substrate 1, an n-InP cladding layer 2, an undoped u-layer having an emission wavelength of 1.55 μm. An InGaAsP active layer 4, a p-InGaAsP guide layer 5 having a diffraction grating 11 and an emission wavelength of 1.3 μm,
The layered structure was composed of a P cladding layer 6 and a p-InGaAsP contact layer 7. Therefore, the light power distribution 10
Is attracted toward the p-InGaAsP guide layer 5 having the diffraction grating 11, and the refractive index difference between the p-InGaAsP guide layer 5 and the n-InP clad layer 2 and the p-InP clad layer 6 is relatively large. Therefore, only a DFB semiconductor laser having a relatively large coupling coefficient κ could be manufactured.
しかし最近の研究の進展により、狭線幅DFB半導体レ
ーザの製作に共振器長を長くすることが有効であるとの
知見が得られ、S.Ogitaらにより、“DEPENDENCE OF SPE
CTRAL LINE WIDTH ON CAVITY LENGTH AND COUPLING COE
FFICIENT IN DFBLASER"と題する論文がElectron.Lett.2
4（1988）pp.613において発表された。しかし、共振器
長Ｌを長くすると、κＬが大きくなり、回折格子と光の
結合が大きくなりすぎて、外部に取り出す光が、小にな
るばかりでなく、ストライプに沿った光密度の不均一性
も大になり、ホールバーニング（hole burning）が起り
やすくなり、かえって、線幅は、広がってしまうという
問題点があった。However, recent research has shown that increasing the cavity length is effective in fabricating narrow-linewidth DFB semiconductor lasers, and S. Ogita et al.
CTRAL LINE WIDTH ON CAVITY LENGTH AND COUPLING COE
FFICIENT IN DFBLASER "is published in Electron.Lett.2
4 (1988) pp.613. However, when the cavity length L is increased, κL becomes large, and the coupling between the diffraction grating and the light becomes too large, so that not only the light extracted to the outside becomes small, but also the light density non-uniformity along the stripe. The problem is that hole burning is more likely to occur, and the line width is rather widened.
この問題点の解決法として、結合係数κが小なるDFB
半導体レーザが求められる。結合係数κを小さくするた
めには、回折格子の深さを小さくすれば良いが、単純に
回折格子の深さを小さくすることは、エッチングの不均
一、及び結晶成長中のマストランスポート（mass−tran
sport）による回折格子の変形或いは消失が起り、面内
均一性の良い浅い回折格子を有するDFB半導体レーザの
製作は困難であった。As a solution to this problem, DFB with a small coupling coefficient κ
A semiconductor laser is required. In order to reduce the coupling coefficient κ, the depth of the diffraction grating may be reduced. However, simply reducing the depth of the diffraction grating may cause non-uniform etching and mass transport (mass transport) during crystal growth. −tran
sport) caused the deformation or disappearance of the diffraction grating, and it was difficult to manufacture a DFB semiconductor laser having a shallow diffraction grating with good in-plane uniformity.
更に従来技術の問題点を具体的に述べると、従来の層
構造のDFB半導体レーザは、ｕ−InGaAsP活性層４に隣接
する回折格子を有するｐ−InGaAsPガイド層５が一つで
あり、かつ回折格子を有するＰ−InGaAsPガイド層５と
ｐ−InP及びｎ−InPクラッド層（6,2n）との屈折率差が
比較的大であったため、光と回折格子の結合が大きくな
るという欠点があった。結合係数κの小なるDFB半導体
レーザを実現するためには、極く浅い回折格子を形成し
なければならず、エッチングの不均一、或いは、結晶成
長中のマストランスポートによる回折格子の変形、消失
により、回折格子の面内均一性を保つのが困難であっ
た。More specifically, the problems of the prior art are described in detail. A DFB semiconductor laser having a conventional layer structure has a single p-InGaAsP guide layer 5 having a diffraction grating adjacent to the u-InGaAsP active layer 4 and has a diffraction structure. Since the refractive index difference between the P-InGaAsP guide layer 5 having the grating and the p-InP and n-InP cladding layers (6.2n) is relatively large, there is a disadvantage that the coupling between the light and the diffraction grating increases. Was. In order to realize a DFB semiconductor laser with a small coupling coefficient κ, an extremely shallow diffraction grating must be formed, resulting in uneven etching or deformation or disappearance of the diffraction grating due to mass transport during crystal growth. Therefore, it was difficult to maintain the in-plane uniformity of the diffraction grating.
本発明の目的は、かかる低結合係数のDFB半導体レー
ザの製作の困難さを解決し、長共振器DFB半導体レーザ
において、適正なκＬの値を持つ、結合係数κの小なる
長共振器DFB半導体レーザを提供することにある。An object of the present invention is to solve the difficulty in manufacturing such a low-coupling-coefficient DFB semiconductor laser. In a long-cavity DFB semiconductor laser, a long-cavity DFB semiconductor having an appropriate value of κL and a small coupling coefficient κ is provided. It is to provide a laser.
本発明のDFB半導体レーザは、回折格子（11,110）を
有する第１のガイド層（5,30）を従来より低屈折率に
し、クラッド層（6,2,20,60）との屈折率差を小さく
し、かつ、活性層（4,40）の、回折格子（11,110）を有
する第１のガイド層（5,30）の反対側に、第２のガイド
層（3,50）を設け、光のパワー分布（10）を第２のガイ
ド層（3,50）側に引き寄せ、回折格子（11,110）を有す
る第１のガイド層（5,30）から光のパワー分布（10）を
引き離し、回折格子（11,110）と光結合を小ならしめ
て、結合係数κの小なるDFB半導体レーザ（第１図及び
第２図）を実現することを最も主要な特徴とする。In the DFB semiconductor laser of the present invention, the refractive index of the first guide layer (5, 30) having the diffraction grating (11, 110) is made lower than that of the conventional one, and the refractive index difference from the cladding layer (6, 2, 20, 60) is reduced. A second guide layer (3,50) is provided on the opposite side of the active layer (4,40) from the first guide layer (5,30) having the diffraction grating (11,110). Is attracted to the second guide layer (3,50) side, the light power distribution (10) is separated from the first guide layer (5,30) having the diffraction grating (11,110), and diffraction is performed. The main feature of the present invention is to realize a DFB semiconductor laser (FIGS. 1 and 2) having a small coupling coefficient κ by reducing the optical coupling with the grating (11, 110).
即ち、回折格子（11,110）の深さが普通程度の深さで
あっても、回折格子（11,110）と光の結合を小さくし、
結合係数κの小なるDFB半導体レーザを製作でき、回折
格子（11,110）がある程度深ければ、エッチングの不均
一、成長中のマストランスポートによる回折格子（11,1
10）の変形が起っても、回折格子（11,110）の面内均一
性の制御は、比較的容易になる利点がある。That is, even if the depth of the diffraction grating (11,110) is a normal depth, the coupling between the diffraction grating (11,110) and light is reduced,
A DFB semiconductor laser with a small coupling coefficient κ can be manufactured, and if the diffraction grating (11,110) is deep to some extent, the etching becomes uneven and the diffraction grating (11,1
Even if the deformation of 10) occurs, there is an advantage that control of the in-plane uniformity of the diffraction grating (11, 110) becomes relatively easy.
従って、本発明の構成は下記に示す通りである。即
ち、第１導電型のInP基板（１）と、 第１導電型でバンドギャップ幅EcのInPクラッド層
（２）と、 第１導電型でバンドギャップ幅Eg2の第２のInGaAsPガ
イド層（３）と、 第１導電型或いは第２導電型或いはアンドープでバン
ドギャップ幅EaのInGaAsP活性層（４）と、 回折格子（11）を有し第２導電型でバンドギャップ幅
Eg1の第１のInGaAsPガイド層（５）と、 第２導電型でバンドギャップ幅EcのInPクラッド層
（６）と、 第２導電型のInGaAsPコンタクト層（７）とがそれぞ
れ順次積層されていて、かつ、 前記バンドギャップ幅Ea、Eg1、Eg2及びEcの間には、
Ea＜Eg2＜Eg1＜Ecの関係が成り立つことを特徴とするDF
B半導体レーザ（第１図）としての構成を有する。Therefore, the configuration of the present invention is as shown below. That is, a first conductivity type InP substrate (1), a first conductivity type InP cladding layer (2) having a band gap width Ec, and a first conductivity type InP cladding layer (2) having a band gap width Eg 2 . 3), an InGaAsP active layer (4) of a first conductivity type or a second conductivity type or an undoped band gap width Ea, and a diffraction grating (11) having a band gap width of a second conductivity type.
A first InGaAsP guide layer (5) of Eg1, a second conductivity type InP clad layer (6) having a band gap width Ec, and a second conductivity type InGaAsP contact layer (7) are sequentially laminated. And, between the band gap widths Ea, Eg 1 , Eg 2 and Ec,
DF characterized by the relationship of Ea <Eg 2 <Eg 1 <Ec
It has a configuration as a B semiconductor laser (FIG. 1).
或いはまた、第１導電型のInP基板（１）と、 第１導電型でバンドギャップ幅EcのInPクラッド層（2
0）と、 第１導電型で回折格子（110）を有しバンドギャップ
幅Eg1の第１のInGaAsPガイド層（30）と、 第１導電型或いは第２導電型或いはアンドープでバンド
ギャップ幅EaのInGaAsP活性層（40）と、 第２導電型でバンドギャップ幅Eg2の第２のInGaAsPガ
イド層（50）と、 第２導電型でバンドギャップ幅EcのInPクラッド層（6
0）と、 第２導電型のInGaAsPコンタクト層（７）とがそれぞ
れ順次積層されていて、かつ、 前記バンドギャップ幅Ea、Eg1、Eg2及びEcの間には、
Ea＜Eg2＜Eg1＜Ecの関係が成り立つことを特徴とするDF
B半導体レーザ（第２図）としての構成を有する。Alternatively, a first conductivity type InP substrate (1) and a first conductivity type InP cladding layer (2) having a band gap width Ec.
0), the first InGaAsP guide layer bandgap width Eg 1 has a diffraction grating in the first conductivity type (110) and (30), the band gap width Ea in the first conductivity type or a second conductive type or an undoped the InGaAsP active layer (40), and second InGaAsP guide layer bandgap width Eg 2 in the second conductivity type (50), InP cladding layer bandgap width Ec second conductivity type (6
0) and a second conductivity type InGaAsP contact layer (7) are sequentially stacked, and the band gap widths Ea, Eg 1 , Eg 2 and Ec are:
DF characterized by the relationship of Ea <Eg 2 <Eg 1 <Ec
It has a configuration as a B semiconductor laser (FIG. 2).
或いはまた、活性層（4,40）には、InP結晶に格子整
合する発光波長1.55μｍの組成のInGaAsP層を使用し、
回折格子（11,110）を有する第１のガイド層（5,30）に
は、InP結晶に格子整合する発光波長1.1μｍの組成のIn
GaAsP層を使用し、回折格子（11,110）の無い第２のガ
イド層（3,50）には、InP結晶に格子整合する発光波長
1.3μｍの組成のInGaAsP層を使用し、活性層（4,40）の
厚さｄ、回折格子（11,110）を有するガイド層（5,30）
の厚さt1、回折格子（11,110）のないガイド層（3,50）
の厚さt2を足し合せた厚みｄ＋t1＋t2が、0.25μｍ≦ｄ
＋t1＋t2≦0.4μｍの範囲にあることを特徴とするDFB半
導体レーザ（第１図，第２図）として構成を有する。Alternatively, for the active layer (4, 40), an InGaAsP layer having a composition with an emission wavelength of 1.55 μm lattice-matched to the InP crystal is used,
The first guide layer (5, 30) having the diffraction grating (11, 110) has an In composition having an emission wavelength of 1.1 μm that is lattice-matched to the InP crystal.
The second guide layer (3,50) using a GaAsP layer and having no diffraction grating (11,110) has an emission wavelength lattice-matched to the InP crystal.
A guide layer (5, 30) using an InGaAsP layer having a composition of 1.3 μm, a thickness d of the active layer (4, 40), and a diffraction grating (11, 110).
Thickness t 1 , guide layer (3,50) without diffraction grating (11,110)
The thickness d + t 1 + t 2 obtained by adding the thickness t 2 is 0.25 μm ≦ d
It has a configuration as a DFB semiconductor laser (FIGS. 1 and 2), which is in the range of + t 1 + t 2 ≦ 0.4 μm.
或いはまた、ストライプ状の電流注入領域を除いて、
ストライプの外側は、高抵抗の半絶縁性のsi（semi−in
sulating）−InPによって埋込まれているか、ｐ−ｎ接
合の逆バイアスを利用したｐ型とｎ型のInP電流阻止層
によって埋込まれていることを特徴とするDFB半導体レ
ーザとしての構成を有するものである。Alternatively, except for the stripe-shaped current injection region,
The outside of the stripe is a high-resistance semi-insulating si (semi-in
a DFB semiconductor laser characterized by being buried by -InP or buried by p-type and n-type InP current blocking layers utilizing reverse bias of a pn junction. Things.
（実施例１） 第１図は、本発明の第１の実施例としてのDFB半導体
レーザの模式的断面構造図である。第１図において、１
はｎ−InP基板、２はｎ−InPクラッド層、３は発光波長
λ＝1.3μｍの組成のｎ−InGaAsPガイド層、４は発光波
長1.55μｍの組成のアンドープのｕ−InGaAsP活性層、
５は回折格子11を有する発光波長1.1μｍの組成のｐ−I
nGaAsPガイド層、６はｐ−InPクラッド層、７はｐ−InG
aAsPコンタクト層、８はｎ−電極、９はｐ−電極、10は
光のパワー分布、11は回折格子、12は電極分離溝であ
る。第１図に図示された本発明の第１の実施例において
はこのような層構造になっていることから、光のパワー
分布10は回折格子11のあるｐ−InGaAsPガイド層５の側
から、反対の、回折格子11のないｎ−InGaAsPガイド層
３の側（発光波長λ＝1.3μｍの組成のｎ−InGaAsPガイ
ド層３）へ引き寄せられ、かつ回折格子11を有するＰ−
InGaAsPガイド層５（発光波長λ＝1.1μｍの組成）とｐ
−InPクラッド層６との屈折率差は小さくなり、回折格
子11と光の結合は小になり、結合係数κの小なる長共振
器DFB半導体レーザが実現できる。Embodiment 1 FIG. 1 is a schematic cross-sectional structure diagram of a DFB semiconductor laser as a first embodiment of the present invention. In FIG. 1, 1
Is an n-InP substrate, 2 is an n-InP cladding layer, 3 is an n-InGaAsP guide layer having a composition having an emission wavelength of λ = 1.3 μm, 4 is an undoped u-InGaAsP active layer having a composition having an emission wavelength of 1.55 μm,
5 is a p-I composition having a diffraction grating 11 and an emission wavelength of 1.1 μm.
nGaAsP guide layer, 6 is p-InP cladding layer, 7 is p-InG
aAsP contact layer, 8 is an n-electrode, 9 is a p-electrode, 10 is a light power distribution, 11 is a diffraction grating, and 12 is an electrode separation groove. In the first embodiment of the present invention shown in FIG. 1 having such a layer structure, the light power distribution 10 is changed from the side of the p-InGaAsP guide layer 5 where the diffraction grating 11 is located. On the other hand, the P- layer which is attracted to the side of the n-InGaAsP guide layer 3 without the diffraction grating 11 (the n-InGaAsP guide layer 3 having the composition of the emission wavelength λ = 1.3 μm) and has the diffraction grating 11
InGaAsP guide layer 5 (composition with emission wavelength λ = 1.1 μm) and p
-The difference in the refractive index from the InP cladding layer 6 is reduced, the coupling between the diffraction grating 11 and the light is reduced, and a long cavity DFB semiconductor laser having a small coupling coefficient κ can be realized.
結合係数κは、ｐ−InPクラッド層６と回折格子11を
有するｐ−InGaAsPガイド層５の屈折率の２乗の差に比
例することが知られており、回折格子11を有するｐ−In
GaAsPガイド層５の組成を発光波長λ＝1.3μｍの組成の
ｎ−InGaAsP層３から発光波長λ−1.1μｍの組成のｐ−
InGaAsP層５に変えることにより、約1/2に低減できる。
また光のパワー分布10のシフトの効果も加わるから、同
じ形状の回折格子11に対して、結合係数κは、約1/2か
ら1/3にすることができる。なお、発光波長λ＝1.55μ
ｍの組成のｕ−InGaAsP活性層４の厚さｄと発光波長λ
＝1.1μｍの組成の、回折格子11を有するｐ−InGaAsPガ
イド層５の厚さt1、及び発光波長λ＝1.3μｍの組成
の、回折格子11の無いｎ−InGaAsPガイド層３の厚さt2
の足し合せた厚さｄ＋t1＋t2が、0.25μｍ≦ｄ＋t1＋t2
≦0.4μｍの範囲にしておけば、DFB半導体レーザのしき
い値電流Ithに比例することが知られている量d/Γ（Γ
は活性層の光の閉じ込め係数）を充分小さくでき、低し
きい値電流のDFB半導体レーザが実現される。It is known that the coupling coefficient κ is proportional to the difference between the square of the refractive index of the p-InP cladding layer 6 and the refractive index of the p-InGaAsP guide layer 5 having the diffraction grating 11.
The composition of the GaAsP guide layer 5 is changed from the n-InGaAsP layer 3 having the composition of the emission wavelength λ = 1.3 μm to the p- composition of the composition of the emission wavelength λ-1.1 μm.
By changing to the InGaAsP layer 5, it can be reduced to about 1/2.
In addition, since the effect of shifting the light power distribution 10 is added, the coupling coefficient κ can be reduced from about か ら to 3 for the diffraction grating 11 having the same shape. The emission wavelength λ = 1.55μ
The thickness d of the u-InGaAsP active layer 4 having a composition of m and the emission wavelength λ
= 1.1 μm, the thickness t 1 of the p-InGaAsP guide layer 5 having the diffraction grating 11, and the thickness t 1 of the n-InGaAsP guide layer 3 without the diffraction grating 11 having the composition of the emission wavelength λ = 1.3 μm Two
Thickness d + t 1 + t 2 is 0.25 μm ≦ d + t 1 + t 2
If it is within a range of ≦ 0.4 μm, the amount d / Γ (Γ) which is known to be proportional to the threshold current I th of the DFB semiconductor laser
Can sufficiently reduce the light confinement coefficient of the active layer, and a DFB semiconductor laser with a low threshold current can be realized.
（実施例２） 第２図は本発明の第２の実施例としてのDFB半導体レ
ーザの模式的断面構造図である。第２図において、１は
ｎ−InP基板、20はｎ−InPクラッド層、30は回折格子11
0を有する発光波長λ＝1.1μｍの組成のｎ−InGaAsPガ
イド層、40は発光波長λ＝1.55μｍの組成のアンドープ
のｕ−InGaAsP活性層、50は発光波長λ＝1.3μｍの組成
のｐ−InGaAsPガイド層、60はｐ−InPクラッド層、７は
ｐ−InGaAsPコンタクト層、８はｎ−電極、９はｐ−電
極、10は光のパワー分布、110は回折格子、12は電極分
離溝である。Embodiment 2 FIG. 2 is a schematic sectional structural view of a DFB semiconductor laser as a second embodiment of the present invention. In FIG. 2, 1 is an n-InP substrate, 20 is an n-InP cladding layer, and 30 is a diffraction grating 11.
N-InGaAsP guide layer having a composition of emission wavelength λ = 1.1 μm having 0; 40, an undoped u-InGaAsP active layer having a composition of emission wavelength λ = 1.55 μm; InGaAsP guide layer, 60 is p-InP clad layer, 7 is p-InGaAsP contact layer, 8 is n-electrode, 9 is p-electrode, 10 is light power distribution, 110 is diffraction grating, and 12 is electrode separation groove. is there.
第２図に図示された本発明による第２の実施例として
のDFB半導体レーザにおいては、回折格子110がｎ−InP
基板１の側にあるため、ｎ−InP基板１に直接回折格子1
10を形成できるという特徴がある。ｎ−InPクラッド層2
0とｎ−InP基板１の導電型及びバンドギャップ幅は同一
であるため、ｎ−InP基板１側のｎ−InPクラッド層20は
省略することもできる。即ち、縦方向の層構造は１回の
結晶成長にて形成できる点が特徴となる。第１図に図示
した第１の実施例では結晶成長を２回に分けて行なわな
ければならない。In the DFB semiconductor laser according to the second embodiment of the present invention shown in FIG. 2, the diffraction grating 110 has an n-InP
Since it is on the substrate 1 side, the diffraction grating 1 is directly connected to the n-InP substrate 1.
There is a feature that 10 can be formed. n-InP cladding layer 2
Since the conductivity type and the band gap width of 0 and the n-InP substrate 1 are the same, the n-InP cladding layer 20 on the n-InP substrate 1 side can be omitted. That is, the feature is that the vertical layer structure can be formed by one crystal growth. In the first embodiment shown in FIG. 1, crystal growth must be performed in two steps.
以上説明したように、本発明のDFB半導体レーザによ
れば、回折格子を有する第１のガイド層を従来より低屈
折率にし、クラッド層との屈折差を小さくし、かつ活性
層の回折格子を有する第１のガイド層の反対側に、第２
のガイド層を設けて、光のパワー分布を第２のガイド層
側に引き寄せ、回折格子と光の結合を小ならしめて、回
折格子の深さがある程度深くても、結合係数κを小さく
することができるという利点がある。As described above, according to the DFB semiconductor laser of the present invention, the refractive index of the first guide layer having the diffraction grating is made lower than that of the conventional guide layer, the refractive index difference with the cladding layer is reduced, and the diffraction grating of the active layer is formed. On the opposite side of the first guide layer having
To guide the light power distribution to the second guide layer side, to reduce the coupling between the diffraction grating and the light, and to reduce the coupling coefficient κ even if the diffraction grating is deep to some extent. There is an advantage that can be.
結合係数κを小さくする方法は、回折格子を極く浅く
する方法もあるが、回折格子を単純に浅くしただけで
は、エッチングの不均一、及び結晶成長中のマストラン
スポートによる回折格子の変形、消失が起り、面内均一
性の良い、浅い回折格子の形成は困難であったのに対し
て、本発明のDFB半導体レーザによれば、回折格子をあ
る程度深く形成することによって、エッチングの不均
一、結晶成長中のマストランスポートによる回折格子の
変形が起っても、回折格子の面内均一性が保たれ、均一
性の良い、低結合係数の長共振器DFB半導体レーザが製
作できるという効果がある。As a method of reducing the coupling coefficient κ, there is also a method of making the diffraction grating extremely shallow.However, if the diffraction grating is simply made shallow, unevenness of etching, deformation of the diffraction grating due to mass transport during crystal growth, Although the disappearance occurred and it was difficult to form a shallow diffraction grating with good in-plane uniformity, according to the DFB semiconductor laser of the present invention, unevenness of etching was achieved by forming the diffraction grating to a certain depth. Even if the diffraction grating is deformed by mass transport during crystal growth, the in-plane uniformity of the diffraction grating is maintained, and a long cavity DFB semiconductor laser with good uniformity and low coupling coefficient can be manufactured. There is.
第１図は本発明の第１の実施例としてのDFB半導体レー
ザの模式的断面構造図、 第２図は本発明の第２の実施例としてのDFB半導体レー
ザの模式的断面構造図、 第３図は従来のDFB半導体レーザの模式的構造断面図で
ある。 １…ｎ−InP基板 2,20…ｎ−InPクラッド層 3,30…ｎ−InGaAsPガイド層 4,40…ｕ−InGaAsP活性層 5,50…ｐ−InGaAsPガイド層 6,60…ｐ−InPクラッド層 ７…ｐ−InGaAsPコンタクト層 ８…ｎ−電極 ９…ｐ−電極 10…光のパワー分布 11,110…回折格子 12…電極分離溝FIG. 1 is a schematic sectional view of a DFB semiconductor laser according to a first embodiment of the present invention. FIG. 2 is a schematic sectional view of a DFB semiconductor laser according to a second embodiment of the present invention. The figure is a schematic sectional view of a conventional DFB semiconductor laser. DESCRIPTION OF SYMBOLS 1 ... n-InP substrate 2,20 ... n-InP cladding layer 3,30 ... n-InGaAsP guide layer 4,40 ... u-InGaAsP active layer 5,50 ... p-InGaAsP guide layer 6,60 ... p-InP cladding Layer 7: p-InGaAsP contact layer 8: n-electrode 9: p-electrode 10: light power distribution 11, 110: diffraction grating 12: electrode separation groove
Claims (3)
ド層と、 第１導電型或いは第２導電型或いはアンドープでバンド
ギャップ幅EaのInGaAsP活性層と、 回折格子を有し第２導電型でバンドギャップ幅Eg1の第
１のInGaAsPガイド層と、 第２導電型でバンドギャップ幅EcのInPクラッド層と、 第２導電型のInGaAsPコンタクト層とがそれぞれ順次積
層されていて、かつ、 前記バンドギャップ幅Ea、Eg1、Eg2及びEcの間には、Ea
＜Eg2＜Eg1＜Ecの関係が成り立つことを特徴とするDFB
半導体レーザ。An InP substrate of a first conductivity type, an InP cladding layer of a first conductivity type having a band gap width Ec, a second InGaAsP guide layer of a first conductivity type having a band gap width Eg 2 , An InGaAsP active layer of conductive type or second conductive type or undoped with a band gap width Ea; a first InGaAsP guide layer having a diffraction grating of a second conductive type and band gap width of Eg 1 ; An InP cladding layer having a gap width Ec and an InGaAsP contact layer of the second conductivity type are sequentially laminated, and Ea, Eg 1 , Eg 2 and Ec are located between the band gap widths Ea, Eg 1 , Eg 2 and Ec.
DFB characterized by the relationship <Eg 2 <Eg 1 <Ec
Semiconductor laser.
１のInGaAsPガイド層と、 第１導電型或いは第２導電型或いはアンドープでバンド
ギャップ幅EaのInGaAsP活性層と、 第２導電型でバンドギャップ幅Eg2の第２のInGaAsPガイ
ド層と、 第２導電型でバンドギャップ幅EcのInPクラッド層と、 第２導電型のInGaAsPコンタクト層とがそれぞれ順次積
層されていて、かつ、 前記バンドギャップ幅Ea、Eg1、Eg2及びEcの間には、Ea
＜Eg2＜Eg1＜Ecの関係が成り立つことを特徴とするDFB
半導体レーザ。Wherein the InP substrate of a first conductivity type, and the InP cladding layer bandgap width Ec in the first conductivity type, the band gap Eg 1 has a diffraction grating in the first conductivity type first InGaAsP guide A first conductive type or a second conductive type or an undoped InGaAsP active layer having a band gap width Ea; a second conductive type having a band gap width Eg 2 of a second InGaAsP guide layer; An InP cladding layer having a gap width Ec and an InGaAsP contact layer of the second conductivity type are sequentially laminated, and Ea, Eg 1 , Eg 2 and Ec are located between the band gap widths Ea, Eg 1 , Eg 2 and Ec.
DFB characterized by the relationship <Eg 2 <Eg 1 <Ec
Semiconductor laser.
波長1.55μｍの組成のInGaAsP層を使用し、回折格子を
有する第１のガイド層には、InP結晶に格子整合する発
光波長1.1μｍの組成のInGaAsP層を使用し、回折格子の
無い第２のガイド層には、InP結晶に格子整合する発光
波長1.3μｍの組成のInGaAsP層を使用し、活性層の厚さ
ｄ、回折格子を有するガイド層の厚さt1、回折格子のな
いガイド層の厚さt2を足し合せた厚みｄ＋t1＋t2が、0.
25μｍ≦ｄ＋t1＋t2≦0.4μｍの範囲にあることを特徴
とする前記請求項１或いは請求項２の内、いずれか１項
記載のDFB半導体レーザ。3. The active layer uses an InGaAsP layer having a composition of an emission wavelength of 1.55 μm lattice-matched to the InP crystal, and the first guide layer having a diffraction grating has an emission wavelength of 1.1. An InGaAsP layer having a composition of 1.3 μm was used for the second guide layer having no diffraction grating, and an InGaAsP layer having a composition of an emission wavelength of 1.3 μm lattice-matched to the InP crystal was used. The thickness d + t 1 + t 2 obtained by adding the thickness t 1 of the guide layer having the following formula and the thickness t 2 of the guide layer having no diffraction grating is equal to 0.
3. The DFB semiconductor laser according to claim 1, wherein the DFB semiconductor laser is in a range of 25 μm ≦ d + t 1 + t 2 ≦ 0.4 μm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2024867A JP2879083B2 (en) | 1990-02-02 | 1990-02-02 | DFB semiconductor laser |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2024867A JP2879083B2 (en) | 1990-02-02 | 1990-02-02 | DFB semiconductor laser |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH03229481A JPH03229481A (en) | 1991-10-11 |
| JP2879083B2 true JP2879083B2 (en) | 1999-04-05 |
Family
ID=12150163
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2024867A Expired - Lifetime JP2879083B2 (en) | 1990-02-02 | 1990-02-02 | DFB semiconductor laser |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2879083B2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5272714A (en) * | 1991-12-12 | 1993-12-21 | Wisconsin Alumni Research Foundation | Distributed phase shift semiconductor laser |
| EP1283571B1 (en) * | 2001-08-06 | 2015-01-14 | nanoplus GmbH Nanosystems and Technologies | Laser with weakly coupled grating |
-
1990
- 1990-02-02 JP JP2024867A patent/JP2879083B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH03229481A (en) | 1991-10-11 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP4643794B2 (en) | Semiconductor light emitting device | |
| JP3481458B2 (en) | Semiconductor laser | |
| US7463663B2 (en) | Semiconductor laser diode and integrated semiconductor optical waveguide device | |
| JP2004179274A (en) | Optical semiconductor device | |
| US4622674A (en) | Single longitudinal mode semiconductor laser | |
| JP2870632B2 (en) | Semiconductor optical integrated circuit and method of manufacturing the same | |
| JP2982422B2 (en) | Semiconductor laser and method of manufacturing the same | |
| US5764682A (en) | Distributed feedback semiconductor laser and method for fabricating the same | |
| US5805627A (en) | Laser diode and optical communications system using such laser diode | |
| JPH065975A (en) | Semiconductor laser | |
| US5321716A (en) | Distributed Feedback semiconductor laser with controlled phase shift | |
| US5579155A (en) | Semiconductor optical amplifier | |
| JP2879083B2 (en) | DFB semiconductor laser | |
| US6552358B2 (en) | High power single mode laser and method of fabrication | |
| KR19990037200A (en) | Semiconductor laser and manufacturing method | |
| JP2656248B2 (en) | Semiconductor laser | |
| US20090267195A1 (en) | Semiconductor element and method for manufacturing semiconductor element | |
| JP2000244059A (en) | Semiconductor laser device | |
| JP2770722B2 (en) | Manufacturing method of tunable semiconductor laser | |
| JP2606838B2 (en) | Distributed feedback semiconductor laser | |
| JPH0555702A (en) | Variable wavelength type semiconductor laser device | |
| JP2010165869A (en) | Semiconductor laser element | |
| JPH09232666A (en) | Semiconductor laser and optical transmission module for parallel transmission | |
| JPS641072B2 (en) | ||
| JP2924433B2 (en) | Semiconductor laser and method of manufacturing the same |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20090129 Year of fee payment: 10 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20090129 Year of fee payment: 10 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20100129 Year of fee payment: 11 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20110129 Year of fee payment: 12 |
|
| EXPY | Cancellation because of completion of term | ||
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20110129 Year of fee payment: 12 |