JPH01291483A - Uniaxial mode semiconductor laser - Google Patents

Uniaxial mode semiconductor laser

Info

Publication number
JPH01291483A
JPH01291483A JP63123099A JP12309988A JPH01291483A JP H01291483 A JPH01291483 A JP H01291483A JP 63123099 A JP63123099 A JP 63123099A JP 12309988 A JP12309988 A JP 12309988A JP H01291483 A JPH01291483 A JP H01291483A
Authority
JP
Japan
Prior art keywords
mode
region
layer
oscillation
electrode
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
JP63123099A
Other languages
Japanese (ja)
Inventor
Sadao Fujita
定男 藤田
Masayuki Yamaguchi
山口 昌幸
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.)
NEC Corp
Original Assignee
NEC Corp
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 NEC Corp filed Critical NEC Corp
Priority to JP63123099A priority Critical patent/JPH01291483A/en
Publication of JPH01291483A publication Critical patent/JPH01291483A/en
Pending legal-status Critical Current

Links

Classifications

    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01SDEVICES 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
    • H01S5/00Semiconductor lasers

Abstract

PURPOSE:To assure stable uniaxial mode oscillation without causing oscillation of a TM mode even with anti-reflecting coating by forming a metal film on part of an optical waveguide including an active layer in the vicinity of the wavelength. CONSTITUTION:After a first order diffraction grating 12 including a phase shift region 10 is formed on an n type InP board 13, on which there are successively grown a guide layer 14, an active layer 1, a cladding layer 2, and a cap layer 3. In a mode filter region 9 for restricting a TM mode, the cap layer 3 and part of the cladding layer 2 are etched a and after a SiO2 film 4 is formed on the region 9, a first electrode 5 is attached to the region 9. The region further has an anti-reflecting coating film 8 on both ends. In the mode filter region 9, since the electrode 5 is located in the close vicinity of the active layer 1, the TM mode with an electric component perpendicular to the electrode 5 among modes propagating in the optical waveguide 7 is attenuated. Further, since a TE mode is parallel to the electrode 5, it can propagate through the optical waveguide 7 substantially without any attenuation. Thus, the TE mode has very high gain and hence an optical output 11 assures stable uniaxial TE mode oscillation.

Description

【発明の詳細な説明】 (産業上の利用分野) 本発明は、光通信システムに用いる単一軸モード半導体
レーザに関する。
DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a single-axis mode semiconductor laser for use in optical communication systems.

(従来の技術) 素子内部に回折格子が埋め込まれ、その回折格子の反射
を利用してレーザ発振する分布帰還型半導体レーザ(D
FB−LD)は、光ファイバの波長分散の影響を殆んど
受けず、長距離大容量の光通信用光源として有望視され
ている。
(Prior art) A distributed feedback semiconductor laser (D
FB-LD) is almost unaffected by the wavelength dispersion of optical fibers and is seen as a promising light source for long-distance, large-capacity optical communications.

このようなりFB−LDの例としては、山口らによる1
、55μm帯λ/8シフト型DFB−DC−PBHLD
(昭和62年度電子情報通信学会総合全国大会861)
の報告がある。
An example of such an FB-LD is the one by Yamaguchi et al.
, 55 μm band λ/8 shift type DFB-DC-PBHLD
(IEICE General Conference 861, 1986)
There are reports of.

この報告例では、DFB−LDの回折格子の一部分に位
相シフト量がλ/8である位相シフト領域を設けること
により、回折格子で決定される発振モードの選択性を高
めるとともに、DFB−LDの出射側の両端面に無反射
コーティングを施し、ファプリ・ペローモードの抑制を
行って安定に単一軸モード発振するDFB−LDを実現
している。
In this example report, by providing a phase shift region with a phase shift amount of λ/8 in a part of the diffraction grating of the DFB-LD, the selectivity of the oscillation mode determined by the diffraction grating is increased, and the Anti-reflection coating is applied to both end faces on the emission side to suppress the Fabry-Perot mode and realize a DFB-LD that stably oscillates in a single axis mode.

(発明が解決しようとする課題) しかしながら、前述の様な構成のDFB−LDでは両端
面の無反射コーティングにより、基本モードとは異なる
新たな不要モードの発生が起こりやすくなる。この新た
な不要モードは、DFB−LD本来の基本モードである
TEモードと偏波方向が90°異なる1Mモードと呼ば
れるものである。
(Problem to be Solved by the Invention) However, in the DFB-LD configured as described above, the anti-reflection coating on both end faces tends to cause generation of a new unnecessary mode different from the fundamental mode. This new unnecessary mode is called 1M mode, which has a polarization direction different by 90 degrees from the TE mode, which is the original fundamental mode of DFB-LD.

ここでTEモードは、その主電界成分の方向が活性層に
平行に偏波したモードであり、1Mモードはその主電界
成分の方向が、活性層に垂直に偏波したモードである。
Here, the TE mode is a mode in which the direction of its main electric field component is polarized parallel to the active layer, and the 1M mode is a mode in which the direction of its main electric field component is polarized perpendicular to the active layer.

へき開面を反射鏡とした半導体レーザでは、1Mモード
の端面反射率がTEモードより小さいから、1Mモード
は発振しなかったが、前述のDFB−LDでは無反射コ
ーティングにより、端面反射率が小さくなり、1Mモー
ドとTEモードの反射率が等しくなってくるから1Mモ
ードの発振が生じやすくなる。DFB−LDが1Mモー
ドで発振すると、2軸モ一ド発撮となるから、単一モー
ドファイバを用いた長距離光フアイバ伝送では、波長分
散、モード分配雑音が生じ、符号誤りの無い伝送が不可
能となることさえある。
In a semiconductor laser using the cleavage plane as a reflector, the end face reflectance of the 1M mode is smaller than that of the TE mode, so the 1M mode does not oscillate.However, in the DFB-LD described above, the end face reflectance is reduced due to the anti-reflection coating. , since the reflectances of the 1M mode and the TE mode become equal, oscillation of the 1M mode becomes more likely to occur. When the DFB-LD oscillates in the 1M mode, it becomes a biaxial mode oscillation, so in long-distance optical fiber transmission using a single mode fiber, chromatic dispersion and mode distribution noise occur, making transmission without code errors difficult. It may even be impossible.

上述のλ/8シフト型DFB−DC−PBHLDではフ
ァプリ・ペローモードの抑制を目的に両端面に無反射コ
ーティングを施こしているから、TMモモ−発振が起こ
りやすくなってきている。
In the above-mentioned λ/8 shift type DFB-DC-PBHLD, anti-reflection coating is applied to both end faces for the purpose of suppressing the Fabry-Perot mode, so TM momo oscillation is more likely to occur.

すなわち、従来のDFB−LDでは安定な単一軸モード
発掘全実現するために1フアプリ・ペローモードの抑制
を目的に両端面の無反射コーティングを施すと、別の不
要モードである1Mモードの発振が起りやすくなると云
う欠点があった。
In other words, in the conventional DFB-LD, when anti-reflection coating is applied to both end faces with the aim of suppressing the 1Fuply-Perot mode in order to fully discover and realize a stable single-axis mode, the oscillation of the 1M mode, which is another unnecessary mode, is suppressed. The drawback was that it was more likely to occur.

そこで、本発明の目的は、ファプリ・ペローモード抑制
のために無反射コーティングを行なっても、1Mモード
の発振が起こらず、安定な単一軸モード発振が可能な単
一軸モード半導体レーザを提供することにある。
SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a single-axis mode semiconductor laser that does not cause 1M mode oscillation even when an anti-reflection coating is applied to suppress the Fabry-Perot mode, and is capable of stable single-axis mode oscillation. It is in.

(課題を解決するだめの手段) 本発明は、活性層の近傍に回折格子を設けてなり、この
回折格子による反射を利用して単一軸モードで発振する
半導体レーザであって、前記活性層を含んだ光導波路の
近傍の一部分に、前記半導体レーザの不要モード成分の
減衰を行う金属膜を形成したことを特徴としている。
(Means for Solving the Problems) The present invention provides a semiconductor laser which includes a diffraction grating in the vicinity of an active layer and which oscillates in a single axis mode by utilizing reflection from the diffraction grating. The present invention is characterized in that a metal film is formed in a portion near the included optical waveguide to attenuate unnecessary mode components of the semiconductor laser.

(作用) DFB−Li)に於いて、ファブリ・ペローモード及び
1Mモードの発振を抑制するには、両端面に無反射コー
ティングを施し、ファブリ・ベローモードを抑制すると
ともに、DFB−LD内に、1Mモードを減衰させ、T
Eモードには減衰を殆んど与えないモードフィルタを取
り付ければよい。
(Function) In order to suppress the Fabry-Perot mode and 1M mode oscillation in the DFB-Li), anti-reflection coating is applied to both end faces to suppress the Fabry-Bello mode, and in the DFB-LD, Attenuate the 1M mode and T
A mode filter that provides almost no attenuation may be attached to the E mode.

この場合、モードフィルタによ、9.1Mモードは減衰
し、TEモードに比べ1Mモードの半導体レーザ内の利
得が低下するから、1Mモードの発振が起こらなくなる
In this case, the 9.1M mode is attenuated by the mode filter, and the gain in the semiconductor laser for the 1M mode is lower than that for the TE mode, so that oscillation in the 1M mode no longer occurs.

一方、上述のモードフィルタは、DFB−LDの活性層
の近くに金叫膜を形成する事によシ実現できる。例えば
、活性層の上部に薄い8i02膜を介して金属膜を形成
すると、電界成分が金属膜に対して垂直方向となる1M
モードは減衰を受ける。
On the other hand, the above mode filter can be realized by forming a gold film near the active layer of the DFB-LD. For example, if a metal film is formed on top of the active layer through a thin 8i02 film, the electric field component will be perpendicular to the metal film.
The modes undergo attenuation.

一方、電界成分が金属膜に平行なTEモードは減衰を受
けない。
On the other hand, the TE mode in which the electric field component is parallel to the metal film is not attenuated.

この様なモードフィルタ領域を半導体レーザ内の一部に
設ける事により、TMモモ−発振を抑制した安定な単一
軸モード半導体レーザを実現することができる。
By providing such a mode filter region in a part of the semiconductor laser, it is possible to realize a stable single-axis mode semiconductor laser in which TM momo oscillation is suppressed.

(実施例) 次に、本発明について図面を参照して説明する。(Example) Next, the present invention will be explained with reference to the drawings.

第1図は本発明の第1の実施例である波長1.3μmの
DFB−LDの断面図である。
FIG. 1 is a cross-sectional view of a DFB-LD with a wavelength of 1.3 μm, which is a first embodiment of the present invention.

第1図のDFB−LDはλ/8シフトの位相シフト領域
10を施した1、3μm帯λ/8シフト型DFB−LD
である。このDFB−LDはn型のInP基板13上に
位相シフト領域10を含んだ1次の回折格子12を形成
した後、厚さ0.1μmのInGaAsPのガイド層1
4.厚さ0.1μm波長組成1.3/jmのInGaA
sP活性層1.厚さ3μmのp型InPのクラッド層2
、厚さ0.5/jmのp+型InGaAsPのキャップ
層3を順次に成長させたものである。
The DFB-LD in Fig. 1 is a 1.3 μm band λ/8 shift type DFB-LD with a λ/8 shift phase shift region 10.
It is. In this DFB-LD, a first-order diffraction grating 12 including a phase shift region 10 is formed on an n-type InP substrate 13, and then a guide layer 1 of InGaAsP with a thickness of 0.1 μm is formed.
4. InGaA with a thickness of 0.1 μm and a wavelength composition of 1.3/jm
sP active layer 1. P-type InP cladding layer 2 with a thickness of 3 μm
, a cap layer 3 of p+ type InGaAsP having a thickness of 0.5/jm is grown in sequence.

一方、1Mモードの抑制を行うモードフィルタ領域9は
、キャップ層3及びクラッド層2の一部をエツチングし
て、クラッド層2を500OA残した上部に厚さ300
0Aの8i02膜4を形成した上に、第1の電極5を取
りつけた構造である。まだ第1図1))DPB−LDに
於いて全長を300μm。
On the other hand, the mode filter region 9 for suppressing the 1M mode is formed by etching a part of the cap layer 3 and the cladding layer 2, leaving the cladding layer 2 with a thickness of 300 OA on the upper part.
It has a structure in which a 8i02 film 4 of 0A is formed and a first electrode 5 is attached thereto. The total length in the DPB-LD is still 300 μm (see Figure 1).

モードフィルタ領域9の長さを100μmとした後、両
端面に反射率1チ以上の無反射コート膜8を設けた。
After setting the length of the mode filter region 9 to 100 μm, a non-reflection coating film 8 having a reflectance of 1 inch or more was provided on both end faces.

以上の構成のDFB−LDに於いて、モードフィルタ領
域9では、電極5が活性層1に極めて近いから、活性層
1とガイド層14で形成される光導波路7内を伝搬する
モードのうち、電界成分が電極5と垂直な1Mモードは
減衰を受ける。一方、TEモードは電界成分が電rj5
と平行であるから、モードフィルタ領域9では殆んど減
衰せずに伝搬する。そこで、光導波路7では、TEモー
ドの利得が十分に高く、光出力11はTEモードによる
安定な単一軸モード発振となる。
In the DFB-LD having the above configuration, in the mode filter region 9, since the electrode 5 is extremely close to the active layer 1, among the modes propagating in the optical waveguide 7 formed by the active layer 1 and the guide layer 14, The 1M mode in which the electric field component is perpendicular to the electrode 5 is attenuated. On the other hand, in TE mode, the electric field component is electric rj5
Since it is parallel to , it propagates in the mode filter region 9 with almost no attenuation. Therefore, in the optical waveguide 7, the gain in the TE mode is sufficiently high, and the optical output 11 becomes stable single-axis mode oscillation in the TE mode.

実際にこのDFB−LDのTEモードと1Mモードの発
振強度比(TEモードに対する1Mモードの抑圧比)を
測定してみたところ、無変調時でTMモード抑圧比45
dB、伝送速度S:4Gb/sの変調時で40dBと良
好な1Mモードの抑制を確認できた。
When we actually measured the oscillation intensity ratio between TE mode and 1M mode (suppression ratio of 1M mode to TE mode) of this DFB-LD, we found that the TM mode suppression ratio was 45 when no modulation was performed.
dB, transmission speed S: 40 dB at modulation of 4 Gb/s, good suppression of 1M mode was confirmed.

またこのDFB−LDの単一軸モード発振歩留りを調べ
た結果、半導体レーザのヒートシンク等への融着の際に
活性層にストレスが生じても、1Mモードが抑圧される
ため、モードフィルタ領域9を有したDFB−LDでは
、従来のモードフィルタ領域9の無いDI;’B−LD
に比べ歩留りが1.5倍向上した。
Furthermore, as a result of investigating the single-axis mode oscillation yield of this DFB-LD, even if stress is generated in the active layer when the semiconductor laser is fused to a heat sink, etc., the 1M mode is suppressed. In the DFB-LD with the conventional mode filter region 9,
The yield was improved by 1.5 times.

さらに本実施例のDFB−LDを用いて、伝送速度2.
4Gb/sで70kmの単一モードファイバ伝送を行な
ったところ、1Mモードの発振による波形劣化及びモー
ド分配雑音が生じる事なく、符号誤り率1O−It以下
の安定な伝送を実現することができた。
Furthermore, using the DFB-LD of this embodiment, the transmission rate is 2.
When performing single mode fiber transmission over 70km at 4Gb/s, stable transmission with a bit error rate of 1O-It or less was achieved without waveform deterioration or mode distribution noise due to 1M mode oscillation. .

第2図は、本発明の第2の実施例であるDFB−LDの
断面図である。構造的には、第1の実施例のDFB−L
Dと類似しているが、本実施例では、半導体レーザの光
強度分布が最大となる半導体レーザの中央部にモードフ
ィルタ領域9を設け、第1の実施例より1Mモードの抑
圧を大きくした構造としている。また、モードフィルタ
領域9では、クラッド層2の厚みを500OAまでエツ
チングした後に電極5を形成した。
FIG. 2 is a sectional view of a DFB-LD which is a second embodiment of the present invention. Structurally, the DFB-L of the first embodiment
Although similar to D, this embodiment has a structure in which a mode filter region 9 is provided in the center of the semiconductor laser where the light intensity distribution of the semiconductor laser is maximum, and the 1M mode is suppressed more than in the first embodiment. It is said that Further, in the mode filter region 9, the electrode 5 was formed after etching the cladding layer 2 to a thickness of 500 OA.

本実施例のDFB−LDは波長1.3μmで単一軸モー
ド発振するように各層の組成1回折格子12の周期を設
定し、DFB−LDのモードフィルタ領域及びDFB−
LDの全長をそれぞれ100μm。
In the DFB-LD of this example, the period of the composition 1 diffraction grating 12 of each layer is set so as to oscillate in a single axis mode at a wavelength of 1.3 μm, and the mode filter area of the DFB-LD and the DFB-
The total length of each LD is 100 μm.

400μmとした。It was set to 400 μm.

以上の構成のDFB−LDを動作させ、光出力11のT
Eモードに対するTMモード抑圧比を測定したところ、
無変調時でTMモード抑圧比48dB、伝送速度]JG
b/sの変調時でもTMモード抑圧比45dBと良好な
単一軸モード発振を確認した。
The DFB-LD with the above configuration is operated, and the optical output is 11 T.
When we measured the TM mode suppression ratio for E mode, we found that
TM mode suppression ratio 48dB without modulation, transmission speed] JG
Even during b/s modulation, we confirmed a TM mode suppression ratio of 45 dB and good single-axis mode oscillation.

さらに、伝送速度1.2Gb/sで8kmの単一モー−
ドファイバ伝送実験を行なった際にも、TMモード発振
による波形劣化及びモード分配雑音の影響が生じること
なく、符号誤り率IQ−11以下の良好な伝送を実現で
きた。
In addition, a single mode transmission speed of 8 km at a transmission rate of 1.2 Gb/s is possible.
Even when conducting fiber-optic transmission experiments, good transmission with a bit error rate of IQ-11 or less was achieved without waveform deterioration due to TM mode oscillation and without the effects of mode distribution noise.

尚、本発明には、以上の実施例で示した他にも様々な変
形例が考えられる。
It should be noted that various modifications of the present invention are possible in addition to those shown in the above embodiments.

例えば、各実施例では、モードフィルタ領域の構造を金
属膜を電極とし、光導波路の上に形成したが、金属膜は
光導波路の下または上に一部分だけ埋めこんだ構成とし
てもよい。
For example, in each embodiment, the structure of the mode filter region is formed on the optical waveguide using a metal film as an electrode, but the metal film may be partially buried below or above the optical waveguide.

また、本実施例の単一軸モード半導体レーザは波長L3
μmの場合について説明したが、他の波長例えば波長1
.55μm帯に適用しても同様の効果が得られる。
Furthermore, the single-axis mode semiconductor laser of this example has a wavelength of L3.
Although we have explained the case of μm, other wavelengths such as wavelength 1
.. Similar effects can be obtained even when applied to the 55 μm band.

さらに、本発明の実施例では、回折格子を活性層の下の
ガイド層とInP基板の境界に形成したが、回折格子を
形成する位置はこの場所に限らず、例えば、活性層の上
にガイド層を形成し、ガイド層とクラット層の境界に回
折格子を形成してもよい。
Furthermore, in the embodiments of the present invention, the diffraction grating was formed at the boundary between the guide layer below the active layer and the InP substrate, but the position where the diffraction grating is formed is not limited to this location. A diffraction grating may be formed at the boundary between the guide layer and the crat layer.

さらに半導体レーザ内におけるモードフィルタ領域の数
は1つに限らず複数用いてもよい。
Further, the number of mode filter regions in the semiconductor laser is not limited to one, and a plurality of mode filter regions may be used.

(発明の効果) 以上に説明したように、本発明によれば、無反射コーテ
ィングにより半導体レーザの7アプリ・ペローモードを
抑圧した状態でさらに1Mモードの発振を抑制し、回折
格子だけで決るTEモードのみで安定な発振を行う単一
軸モード半導体レーザが実現できる。
(Effects of the Invention) As explained above, according to the present invention, the oscillation of the 1M mode is further suppressed while the 7-appli-Perot mode of the semiconductor laser is suppressed by the anti-reflection coating, and the TE determined only by the diffraction grating is A single-axis mode semiconductor laser that oscillates stably only in one mode can be realized.

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

第1図は本発明の第1の実施例を示す断面図、第2図は
本発明の第2の実施例を示す断面図である0 1・・・・・・活性層、2・・・・・・クラッド層、3
・・・・・・キャップ層、4・・・・・・SiO□膜、
5,6・・・・・・電極、7・・・・・・光導波路、8
・・・・・・無反射コート膜、9・・・・・・モードフ
ィルタ領域、10・・・・・・位相シフト領域、11・
・・・・・光出力、12・・・・・・回折格子、13・
・・・−・InP基板、14・・・・・・ガイド層。 代理人 弁理士  本 庄 伸 介 ノ/ 1−m=−5舌往4         9−−−モート
74ルタ布呉ν!2−  フラ、1′層       
  10− イ1相シ2ト乍眞仄3−−−七ヤ゛ツブ4
            N−m−光f42114−5
iO2様     12− ω坊持手第1図
FIG. 1 is a sectional view showing a first embodiment of the present invention, and FIG. 2 is a sectional view showing a second embodiment of the present invention. ...Clad layer, 3
...Cap layer, 4...SiO□ film,
5, 6... Electrode, 7... Optical waveguide, 8
..... Anti-reflection coating film, 9 ..... Mode filter region, 10 ..... Phase shift region, 11.
.....light output, 12.....diffraction grating, 13.
. . . InP substrate, 14 . . . Guide layer. Agent Patent Attorney Shinsuke Honjo / 1-m=-5tongue 4 9--Mort 74 Ruta Fugo ν! 2- Fura, 1' layer
10- A 1 phase 2 to 3 - 7 phase 4
N-m-light f42114-5
Mr. iO2 12- ω-handle diagram 1

Claims (1)

【特許請求の範囲】[Claims] 活性層の近傍に回折格子を設けてなり、この回折格子に
よる反射を利用して単一軸モードで発振する半導体レー
ザに於いて、前記活性層を含んだ光導波路の近傍の一部
分に、前記半導体レーザの不要モード成分の減衰を行う
金属膜を形成したことを特徴とする単一軸モード半導体
レーザ。
In a semiconductor laser that includes a diffraction grating in the vicinity of an active layer and oscillates in a single-axis mode using reflection from the diffraction grating, the semiconductor laser is provided in a part of the optical waveguide that includes the active layer. A single-axis mode semiconductor laser characterized by forming a metal film that attenuates unnecessary mode components.
JP63123099A 1988-05-19 1988-05-19 Uniaxial mode semiconductor laser Pending JPH01291483A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP63123099A JPH01291483A (en) 1988-05-19 1988-05-19 Uniaxial mode semiconductor laser

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP63123099A JPH01291483A (en) 1988-05-19 1988-05-19 Uniaxial mode semiconductor laser

Publications (1)

Publication Number Publication Date
JPH01291483A true JPH01291483A (en) 1989-11-24

Family

ID=14852176

Family Applications (1)

Application Number Title Priority Date Filing Date
JP63123099A Pending JPH01291483A (en) 1988-05-19 1988-05-19 Uniaxial mode semiconductor laser

Country Status (1)

Country Link
JP (1) JPH01291483A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5790581A (en) * 1994-02-18 1998-08-04 Canon Kabushiki Kaisha Oscillation polarization mode selective semiconductor laser, light transmitter and optical communication system using the laser

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5790581A (en) * 1994-02-18 1998-08-04 Canon Kabushiki Kaisha Oscillation polarization mode selective semiconductor laser, light transmitter and optical communication system using the laser

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