JPH0220087A - Distributed feedback type semiconductor laser element - Google Patents
Distributed feedback type semiconductor laser elementInfo
- Publication number
- JPH0220087A JPH0220087A JP63170467A JP17046788A JPH0220087A JP H0220087 A JPH0220087 A JP H0220087A JP 63170467 A JP63170467 A JP 63170467A JP 17046788 A JP17046788 A JP 17046788A JP H0220087 A JPH0220087 A JP H0220087A
- Authority
- JP
- Japan
- Prior art keywords
- resonator
- phase shift
- distributed feedback
- length
- kappal
- 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 17
- 230000010363 phase shift Effects 0.000 claims abstract description 17
- 230000000737 periodic effect Effects 0.000 claims abstract description 9
- 230000003287 optical effect Effects 0.000 claims description 9
- 230000008878 coupling Effects 0.000 claims description 7
- 238000010168 coupling process Methods 0.000 claims description 7
- 238000005859 coupling reaction Methods 0.000 claims description 7
- 230000010355 oscillation Effects 0.000 abstract description 14
- 238000004519 manufacturing process Methods 0.000 abstract description 10
- 238000002310 reflectometry Methods 0.000 abstract 4
- 238000010586 diagram Methods 0.000 description 4
- 239000011248 coating agent Substances 0.000 description 3
- 238000000576 coating method Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 230000008859 change Effects 0.000 description 2
- 238000004891 communication Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 230000002411 adverse Effects 0.000 description 1
- 230000002902 bimodal effect Effects 0.000 description 1
- 238000003776 cleavage reaction Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 230000005693 optoelectronics Effects 0.000 description 1
- 239000000523 sample Substances 0.000 description 1
- 230000007017 scission Effects 0.000 description 1
- 230000001052 transient 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
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】
[発明の目的]
(産業上の利用分野)
本発明は光導波路上に形成した回折格子により光フィー
ドバックをして発振動作を行う分布帰還型半導体レーザ
素子に関する。DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a distributed feedback semiconductor laser device that performs oscillation operation by performing optical feedback using a diffraction grating formed on an optical waveguide.
(従来の技術)
近年、開発が盛ん・な分布帰還型半導体レーザ素子(D
FB−1,0:Distributed Feedba
ck La5erDiode )は、その共振軸方向に
周期的な凹凸(回折格子)が形成されており、その回折
格子の周期に整合した縦モードのみを優先的に光フィー
ドバック(光帰還)を行い、単一縦モード発振(1本の
発振線)を可能としている。従って、このレーザ素子に
寄せる期待は大きく、特に長距離大容量光通信用光源と
してGa1nAsP/InP系材料を用いた分布帰還型
半導体レーザ素子が実用化されている。(Prior art) Distributed feedback semiconductor laser devices (D
FB-1,0:Distributed Feedba
The ck La5er Diode) has periodic concavities and convexities (diffraction grating) formed in the direction of its resonance axis, and performs optical feedback preferentially only for the longitudinal mode that matches the period of the diffraction grating, resulting in a single This enables longitudinal mode oscillation (one oscillation line). Therefore, expectations are high for this laser device, and distributed feedback semiconductor laser devices using Ga1nAsP/InP-based materials have been put into practical use, particularly as light sources for long-distance, high-capacity optical communications.
ところで、このような利点をもつ分布帰還型半導体レー
サ索子であるが、製造時において必然的に形成されてし
まう両端の反射端面の影響により単一縦モード性に関し
ては歩留り上の大きな制約を受ける。即ち、この反射端
面と回折格子の位相との位置関係が縦モードの発振特性
に大きな影響を与える。加えてこの両者の位置関係の制
御が技術的に困難であるため、この問題を確率的な問題
(歩留り)に帰着させてしまう。By the way, although distributed feedback semiconductor laser probes have these advantages, they are subject to significant yield constraints regarding single longitudinal mode properties due to the influence of reflective end faces at both ends that are inevitably formed during manufacturing. . That is, the positional relationship between this reflective end face and the phase of the diffraction grating has a great influence on the oscillation characteristics of the longitudinal mode. In addition, since it is technically difficult to control the positional relationship between the two, this problem is reduced to a probabilistic problem (yield).
この問題を解決するために、第6図(a)に示すように
、分布帰還型半導体レーザ素子の共振器中央部に導波光
波長λの1/4に相当する回折格子1の不連続部(λハ
位相シフト)2を設けるとともに、その両端面にARコ
ート(無反射コーティング)を施して両端面の反射率を
限りなく零に近づけた構造が提案されている。In order to solve this problem, as shown in FIG. 6(a), we created a discontinuous part ( A structure has been proposed in which the reflectance of both end surfaces is made as close to zero as possible by providing a phase shift λ (phase shift) 2 and applying an AR coating (anti-reflection coating) to both end surfaces.
また、上記位相シフト部2と等価的位相シフト(1■造
も提案されており、例えば第6図(b)に示すように、
回折格子1には不連続部を設けずに、導波路3の中央部
3aの形状を変化させるものである。このように構成す
ることにより、導波路3の位相速度が中央部3aで変化
するため、等価的に位相シフトを生しる。Furthermore, a phase shifter (1) structure equivalent to the phase shifter 2 has also been proposed; for example, as shown in FIG. 6(b),
The shape of the central portion 3a of the waveguide 3 is changed without providing a discontinuous portion in the diffraction grating 1. With this configuration, the phase velocity of the waveguide 3 changes at the central portion 3a, resulting in an equivalent phase shift.
(発明が解決しようとする課題)
しかしながら、このような位相シフト型分布帰還型レー
ザ素子においても、結合係数にと共振器長しとの積κL
(回折格子による光のフィードバック量に対応する)の
値が1.25付近にないと軸方向のホールバーニングが
発生し、単一縦モード特性を損うことが指摘されている
(斐田他、電子情報通信学会、光電子エレクトロニクス
研究会0QEft6−7 PP、49−58.1987
年)。(Problem to be Solved by the Invention) However, even in such a phase-shift distributed feedback laser device, the product κL of the coupling coefficient and the cavity length is
It has been pointed out that if the value of (corresponding to the amount of optical feedback by the diffraction grating) is not around 1.25, hole burning in the axial direction will occur and the single longitudinal mode characteristics will be impaired (Hida et al. Institute of Electronics, Information and Communication Engineers, Optoelectronic Electronics Study Group 0QEft6-7 PP, 49-58.1987
Year).
また、端面の反射率も極めて小さく抑える必要があり、
高い精度でのAI?コートの技術が要求されている。さ
らに、この反射率低減を完壁に近づけるために、導波路
を端面部で埋め込む窓構造を採用する等の工夫も必要と
されている(例えば、Utaka ct、al、PP
、23[1−245、IEEE JOUI?NAL
OFQUANTUM IELECTRONIC8VO
L、QE−20,1984)。In addition, it is necessary to keep the reflectance of the end face extremely low.
AI with high precision? Court skills are required. Furthermore, in order to bring this reflectance reduction closer to perfection, it is necessary to adopt a window structure in which the waveguide is buried at the end face (for example, Utaka CT, AL, PP
, 23 [1-245, IEEE JOUI? NAL
OFQUANTUM IELECTRONIC8VO
L, QE-20, 1984).
本発明は上述した問題点を解決するためになされたもの
で、比較的製作が容易でかつ単一縦モード特性か比較的
晶い歩留りで得られる分布帰還型半導体レーザ素子を提
供するものである。The present invention has been made to solve the above-mentioned problems, and provides a distributed feedback semiconductor laser device that is relatively easy to manufacture and has single longitudinal mode characteristics and a relatively high crystal yield. .
[発明の(l′11成コ
(課題を解決するための手段)
本発明の分布帰還型半導体レーザ素子は、共振器軸方向
に周期tM造を有する光導波路と、この周ル1描逍を有
する共振器の中央から両方向に向かって共振器長の20
%以下の距離間に形成された1個以上の位相シフト領域
またはこの位相シフト頭載に等両的に対応する導波路変
形領域とを何し、両端面の反射率が5〜15%でかつ結
合係数にと前記共振器長しとの積κL値が、0,6≦κ
LSI、0となるように構成されていることを特徴とす
るものである。[Means for Solving the Problems of the Invention] The distributed feedback semiconductor laser device of the present invention comprises an optical waveguide having a period tM structure in the direction of the cavity axis, and a shape of the circumference of the optical waveguide. 20 of the resonator length in both directions from the center of the resonator with
% or less, or a waveguide deformation region that corresponds equally to the phase shift head, and the reflectance of both end faces is 5 to 15%, and The product κL value of the coupling coefficient and the resonator length is 0,6≦κ
It is characterized in that it is configured to have an LSI of 0.
また、周期構造が、この周期構造を有する共振器の長さ
をほぼ3等分する2つの点で管内波長の1/8の位相シ
フト領域またはこの位相シフト領域に等価的に対応する
導波路変形領域を有する分布帰還型半導体レーザ素子に
おいて、結合係数にと共振器長しの積κLの値か0.5
≦κLSI、3の場合に両端面の反q・1率を5〜20
%とし、前記κLの値が1.2≦κL≦2.1の場合に
は両端面の反射率を2%以ドとして構成したことを特徴
とするものである。In addition, the periodic structure has a phase shift region of 1/8 of the channel wavelength at two points that approximately divide the length of the resonator having this periodic structure into three equal parts, or a waveguide deformation that equivalently corresponds to this phase shift region. In a distributed feedback semiconductor laser device having a region, the value of the product κL of the coupling coefficient and the cavity length is 0.5.
In the case of ≦κLSI, 3, the reflection q・1 ratio of both end faces is 5 to 20.
%, and when the value of κL is 1.2≦κL≦2.1, the reflectance of both end faces is set to 2% or less.
即ち、内部中央付近に位相シフト部を持つ回折格子およ
び導波路構造を何する分布帰還型レーザ素子において、
その回折格子の深さと共振−器長の積に比例する規格化
結合係数κLの範囲と端面の反射率の範囲を最適化する
ことにより、実現の簡単な工程で単一縦モード歩留りを
大きくすることができるものである。That is, in a distributed feedback laser device that has a diffraction grating and a waveguide structure that have a phase shift portion near the center of the interior,
By optimizing the range of the normalized coupling coefficient κL, which is proportional to the product of the depth of the diffraction grating and the resonance-length, and the range of the reflectance of the end facets, the single longitudinal mode yield can be increased with a simple implementation process. It is something that can be done.
(作 用)
本発明の特徴は、端面の反射率とκL値の最適値を決定
するに際し、レーザ素子内部の光強度分布を考慮した点
にあり、共振器軸方向におけるホールバーニングの現象
によるモードの不安定性を考慮している。従来はしきい
値の一番低い縦モト(主モード)と次にしきい値の低い
モード(副モード)とのゲイン差Δα(−α1−α0)
のみに否目し、その値が大きければ良いとされていた。(Function) The feature of the present invention is that the light intensity distribution inside the laser element is taken into consideration when determining the optimum values of the reflectance of the end face and the κL value. The instability of is taken into account. Conventionally, the gain difference Δα (-α1-α0) between the vertical mode with the lowest threshold (main mode) and the mode with the next lowest threshold (secondary mode)
It was believed that the higher the value, the better.
本発明は内部光分布にも着目してより現実に近いものと
し、従来とは異なる最適値を見出したことにその特徴が
ある。The present invention is characterized by paying attention to the internal light distribution to make it more realistic, and finding an optimum value different from the conventional one.
(実施例)
以下、本発明の実施例について図を参照すると共に、理
論と計算例を交えて詳細に説明する。(Example) Hereinafter, examples of the present invention will be described in detail with reference to the drawings and with theory and calculation examples.
第1図は分布帰還型半導体レーザ素子の発振モード特性
の一例を示す模式図である。FIG. 1 is a schematic diagram showing an example of oscillation mode characteristics of a distributed feedback semiconductor laser device.
横軸原点はブラッグ(Bragg )条件での発振を示
し、横軸は伝搬定数のブラッグ条件からのずれ(δ−β
−βo1β0はブラッグ条件での伝搬定数)と共振器り
の積でプロットしている。また、縦軸はミラー損失分に
対応するしきい値ゲインαと共振器長しとの積である。The origin of the horizontal axis shows the oscillation under the Bragg condition, and the horizontal axis shows the deviation of the propagation constant from the Bragg condition (δ−β
-βo1β0 is plotted as the product of the propagation constant under the Bragg condition) and the resonance error. Further, the vertical axis is the product of the threshold gain α corresponding to the mirror loss and the resonator length.
図中の白丸は各縦モードを示し、最低しきい値ゲインα
0を有するのが主モード(単一縦モード発振する)であ
る。The white circles in the figure indicate each longitudinal mode, and the lowest threshold gain α
0 is the main mode (single longitudinal mode oscillation).
規格化しきい値ゲイン差ΔαLは、主モードの規格化し
きい値ゲ・インαOLと次にしきい値ゲインの小さい副
モードの規格化しきい値ゲインα1Lとの差である。従
来はこの値が大きければそれだけ+11−縦モード性が
良いとされ、規格化結合係数κLが大きければ大きいほ
どΔαLが大きくなるため、κLを大きくすることが望
まれていた。The normalized threshold gain difference ΔαL is the difference between the normalized threshold gain αOL of the main mode and the normalized threshold gain α1L of the secondary mode having the next smallest threshold gain. Conventionally, it has been believed that the larger this value is, the better the +11-longitudinal mode property is, and the larger the normalized coupling coefficient κL, the larger the ΔαL, so it has been desired to increase κL.
しかしながら、前述したように、発振以後の単−縦モー
ドの安定性はΔαのみによるものではなく、その発振器
軸方向における内部光強度分布の影響を強く受けること
が指摘されており、この現象は軸方向のホールバーニン
グと呼ばれている。However, as mentioned above, it has been pointed out that the stability of the single longitudinal mode after oscillation is not only due to Δα, but is also strongly influenced by the internal light intensity distribution in the axial direction of the oscillator. This is called directional hole burning.
すなわち、共振器側方向で光強度の強い領域があると、
その領域の注、入キャリア密度は他の領域と比較して減
少する。このキャリア密度の軸方向の分布はプラズマ効
果、バンドギャップの変化を通じて軸方向の屈折率分布
を不均一なものとする。In other words, if there is a region with strong light intensity toward the cavity side,
Note that the incoming carrier density in that region decreases compared to other regions. This axial distribution of carrier density makes the axial refractive index distribution non-uniform through plasma effects and band gap changes.
分布帰還型レーザ素子の場合は等価屈折率の空間的変化
は光波の位)目が回折格子に対して場所によって相対的
に変化することを意味し、等価的な1M。In the case of a distributed feedback laser device, a spatial change in the equivalent refractive index means that the order of the light wave changes from place to place relative to the diffraction grating, which is equivalent to 1M.
相シフトを形成したことになる。このような構造上の変
化は、分布帰還型レーザ素子の発振条件の連続的な変化
を誘起する原因となる。これが軸方向ホールバーニング
と呼ばれるものである。This means that a phase shift has been formed. Such structural changes cause continuous changes in the oscillation conditions of the distributed feedback laser device. This is called axial hole burning.
この変化は、Δαが大きければΔαが零になるまで連続
的に発生し続け、外微分量子効率の変化、過渡現象波形
への悪影響等のリニアでない不都合な現象を示す。Δα
が零になれば、モードが次の縦モードにジャンプし電流
−光出力特性にも折れ曲り(キンク:Hnk )を生じ
る。If Δα is large, this change will continue to occur until Δα becomes zero, resulting in undesirable non-linear phenomena such as changes in external differential quantum efficiency and adverse effects on transient waveforms. Δα
When becomes zero, the mode jumps to the next longitudinal mode, causing a kink (Hnk) in the current-light output characteristics.
従って、Δαの小さい素子では余裕がないため、発振後
は容易にモードジャンプを起す。しかし、Δαが小さく
てもこのホールバーニングが起らなければ単一縦モード
性は保持される。逆にΔαが大きい素子でも軸方向ホー
ルバーニングによる電流−光出力特性に強い非直線性を
生じた後にモードジャンプを起して単一縦モード性が破
壊されることがある。もちろん、Δαも大きく、内部光
強度分布も平坦で軸方向ホールバーニングが起らなけれ
ば、それが最も好ましい。Therefore, an element with a small Δα has no margin, and mode jumps easily occur after oscillation. However, even if Δα is small, if this hole burning does not occur, the single longitudinal mode property is maintained. Conversely, even in an element with a large Δα, after strong nonlinearity occurs in the current-optical output characteristics due to axial hole burning, a mode jump may occur and the single longitudinal mode property may be destroyed. Of course, it is most preferable that Δα is large, the internal light intensity distribution is flat, and axial hole burning does not occur.
このように分布帰還型半導体レーザ素子のレーザ発振後
の振舞いが実験、理論の両面から解明されつつある。In this way, the behavior of distributed feedback semiconductor laser devices after laser oscillation is being clarified both experimentally and theoretically.
本発明はこのような現状を背景に、Δαも比較的大きく
、また軸方向ホールバーニングの影響も少なく、実際に
安定な単一縦モード動作を実現する分布帰還型半導体レ
ーザ素子を容易に制御できる工程で歩留り良く作製でき
る構造を提案している。Against this background, the present invention has been developed to easily control a distributed feedback semiconductor laser device that has a relatively large Δα, is less affected by axial hole burning, and actually achieves stable single longitudinal mode operation. We are proposing a structure that can be manufactured with high yield in the process.
本発明の数値的限定は以下の計算によるものであるが、
実験的にも同様の傾向が確認できる。The numerical limitations of the present invention are based on the following calculations,
A similar tendency can be confirmed experimentally as well.
即ち、規格化モードゲイン差ΔαLが0.05以上であ
り、共振器軸方向の光強度分布の最小値と最大値の比F
R−,1min 、/ I maxが0.8以上であ
る(FRの値が1に近づけば近づくほど、光分布が平坦
で軸方向ホールバーニングも小さい。例えば、へき開面
を用いた通常のファプリーペロー型レーザ素子ではFR
は約0.8強である)。That is, the normalized mode gain difference ΔαL is 0.05 or more, and the ratio F of the minimum value and maximum value of the light intensity distribution in the resonator axis direction is
R-, 1 min, / I max is 0.8 or more (the closer the FR value is to 1, the flatter the light distribution and the smaller the axial hole burning. In Perot type laser element, FR
is approximately a little over 0.8).
この二つの条件を同時に満足する分布帰還型半導体素子
は、比較的単一縦モード特性に優れているものである。A distributed feedback semiconductor device that satisfies these two conditions at the same time has relatively excellent single longitudinal mode characteristics.
尚、FRの定義を第2図に例示した。Incidentally, the definition of FR is illustrated in FIG.
上記二つの条件を満足するレーザ素子が、任意のへき開
面位相で得られる確率を、κLの直および片面の反射率
の値をパラメータとして等確率線図として表現したもの
が第3図、第4図および第5図である。この計算は結合
波動方程式を用いた分布帰還レーザの括礎理論に基づい
ている。κLの値は0.2〜2.2まで0.1刻み(2
1ポイント)、反射率は0〜100%まで0.5%刻み
(21ポイント)で変化させた。夫々のポイントは反射
端面の位相を両方で8Xs−84(通り)変化させた場
合、FR≧0.6、ΔαL≧0.05の条件を満たす素
子が得られる確率を示している(図示せず)。Figures 3 and 4 show the probability that a laser element that satisfies the above two conditions can be obtained at any cleavage plane phase using the normal and single-sided reflectance values of κL as parameters. FIG. This calculation is based on the fundamental theory of distributed feedback lasers using the coupled wave equation. The value of κL is from 0.2 to 2.2 in 0.1 increments (2
1 point), and the reflectance was changed from 0 to 100% in 0.5% increments (21 points). Each point indicates the probability of obtaining an element that satisfies the conditions of FR≧0.6 and ΔαL≧0.05 when the phases of the reflective end faces are changed by 8Xs-84 (paths) on both sides (not shown). ).
等高線はこの確率を分りやすく表記したものであり、一
種の歩留りマツプである。この図面1枚は8 X8 X
21X21−28224種類の分布帰還レーザ素子を調
べたことに対応している。Contour lines represent this probability in an easy-to-understand manner, and are a kind of yield map. This one drawing is 8 x 8 x
This corresponds to the investigation of 21X21-28224 types of distributed feedback laser elements.
図中に挿入した図は、1%以下の低反射領域を計算した
もので、0.1%刻みで計算したものである。The figure inserted in the figure shows the calculation of the low reflection area of 1% or less, calculated in 0.1% increments.
第3図は中央にλハ位相シフタをもつ分布帰還レーザの
歩留りマツプである。従来の理想的条件即ち両端面の反
射が零でκL −1,25付近で、90%以上の歩留り
が得られることが分る。しかし、この条件付近を、さら
に細かい計算によると(挿入図)、50%以上の歩留り
を得るためには反射率が0.2%以下(1,2≦κLS
I、4)の値を持つ必要があることが判明した。FIG. 3 is a yield map of a distributed feedback laser with a λ phase shifter in the center. It can be seen that a yield of 90% or more can be obtained under conventional ideal conditions, that is, zero reflection on both end faces and around κL -1.25. However, according to more detailed calculations around this condition (inset), in order to obtain a yield of 50% or more, the reflectance must be 0.2% or less (1,2≦κLS
It turns out that it is necessary to have a value of I, 4).
この両面0.2%以下の反射率を得るのは無反射(AR
)コートだけでは制御が困難であり、窓構造との併用等
工程の増加を招くものである。これに対し、
0.6≦κLSI、0.5≦R(反射率)515%の範
囲においても、比較的、製作の容易な緩い条件の範囲で
30〜50%程度の歩留りが得られる。第3図では、両
端面の反射率を同一として計算したが、両端面の反射率
が大きく異なる場合は、傾向は違うものとなるが、上記
製造条件の範囲内であれば大きな差はない。Obtaining a reflectance of 0.2% or less on both sides is achieved by anti-reflection (AR)
) It is difficult to control with just a coat, and the number of processes increases, such as when using it in combination with a window structure. On the other hand, even in the range of 0.6≦κLSI and 0.5≦R (reflectance) of 515%, a yield of about 30 to 50% can be obtained under relatively easy manufacturing conditions. In FIG. 3, the calculations were made assuming that the reflectances of both end faces are the same, but if the reflectances of both end faces are significantly different, the trends will be different, but within the range of the above manufacturing conditions, there is no big difference.
本例はこの条件に入るように分布帰還レーザの構造を決
定するものである。実際、λハシフタ付分布帰還レーザ
を試作した際に、反射率を2%程度までARコートによ
り抑えたにも拘らず、従来の予想のように高い歩留りは
得られず、軸方向ホールバーニングによる非線形な電流
−光出力特性を示し、モードかジャンプして2モ一ド発
振してしまう素子か多かった。これに対し、反射率が比
較的大きい10%程度の素子の方が単一縦モードが動的
にも安定な素子が多く得られた。In this example, the structure of the distributed feedback laser is determined to satisfy this condition. In fact, when we prototyped a distributed feedback laser with a λ-shifter, even though we suppressed the reflectance to about 2% with an AR coating, we were not able to obtain as high a yield as previously expected, and the non-linear Many of the devices showed a current-optical output characteristic, and the mode jumped, resulting in bimodal oscillation. On the other hand, more elements with a relatively large reflectance of about 10% had a single longitudinal mode that was dynamically stable.
第4図は中央部にλ/8位相シフタを有する構造に関す
る歩留りマツプであるが、このときの理想条件は両端面
の反射率が零で、κL −1,35付近に設定されるこ
とである。この構造ではこの理想条件付近の詳細な計算
によると、1.2≦κLSI、6、R≦0.4%の範囲
で50%の歩留りが得られる。この条件はλハシフト構
造の場合より緩いが、やはり相当難しい制御条件である
。この構造でも、理想条件から離れた0、6≦κLSI
、0.5≦R≦15%の範囲に比較的実現可能な30〜
50%歩留り領域が存在している。Figure 4 is a yield map for a structure with a λ/8 phase shifter in the center, and the ideal condition is that the reflectance on both end faces is zero and is set around κL -1,35. . In this structure, according to detailed calculations near the ideal conditions, a yield of 50% can be obtained in the range of 1.2≦κLSI, 6, and R≦0.4%. Although this condition is less strict than that for the λ ha shift structure, it is still a fairly difficult control condition. Even in this structure, 0, 6≦κLSI, which is far from the ideal condition,
, 30~ which is relatively achievable in the range of 0.5≦R≦15%.
A 50% yield region exists.
さて、第3図は共振器長をほぼ等分に3分割する2点に
、λ/8位相シフタが設けられている構造の歩留りマツ
プである。この場合、安定な単一縦モードが得られる条
件はかなり緩くなる。この場合は詳細な計算によると、
1.2≦κL≦2.1、R52%の広い範囲で40%の
歩留りが得られる。この範囲ではかなり実現性が高くな
る。また、先の2例と同様に0.5≦κLSI、3のと
きは両端面の反射率Rを5%≦R≦20%とすることに
より、その歩留りを30〜40%程度にできる。このよ
うにλ/8シフタを3等分点2箇所に設けることにより
、広い範囲の構造パラメータで高い単一縦モード歩留り
が可能となる。実際この構造の素子をInGaAsP/
InP系材料で試作した結果、比較的高い歩留りで安定
な単一縦モード動作か確認された。Now, FIG. 3 is a yield map of a structure in which λ/8 phase shifters are provided at two points that divide the resonator length into three approximately equal parts. In this case, the conditions for obtaining a stable single longitudinal mode are considerably relaxed. In this case, according to detailed calculations,
A yield of 40% can be obtained over a wide range of 1.2≦κL≦2.1 and R52%. Within this range, the feasibility is quite high. Further, as in the previous two examples, when 0.5≦κLSI, 3, the yield can be made approximately 30 to 40% by setting the reflectance R of both end faces to 5%≦R≦20%. By providing the λ/8 shifters at two trisecting points in this manner, a high single longitudinal mode yield can be achieved with a wide range of structural parameters. In fact, a device with this structure is InGaAsP/
As a result of trial manufacturing using InP-based materials, stable single longitudinal mode operation was confirmed with relatively high yield.
[発明の効果]
以上説明したように本発明の分布帰還型半導体レーザ素
子によれば、単一縦モード発振の得られるレーザ素子を
高歩留りで製作することが可能となる。本発明は分布帰
還型半導体レーザ素子の本質的特性に立脚したものであ
り、レーザ素子の量産化をijf能とするものである。[Effects of the Invention] As explained above, according to the distributed feedback semiconductor laser device of the present invention, it is possible to manufacture a laser device capable of single longitudinal mode oscillation at a high yield. The present invention is based on the essential characteristics of distributed feedback semiconductor laser devices, and is intended to facilitate mass production of laser devices.
従って、そのコストダウンと普及に対し大きく貢献する
ことができる。Therefore, it can greatly contribute to cost reduction and widespread use.
第1図はΔαLを説明するためのαL−δLダイアグラ
ム、第2図はFRの定義を説明するための分布帰還型半
導体レーザ素子の内部光強度分布の一例を示す図、第3
図は共振器中央にλハ位相シフタを有する場合、両方の
端面反射率(縦軸)とκLの値(横軸)を変化させたと
きΔαLの値が0.05以上でFR(内部光強度分布の
平坦性を示すパラメータ)が0.6以上である素子の得
られる歩留りを等高線表示した図、第4図は中央にλ/
8位相シフタを有する場合の同様の歩留りの等高線表示
した図、第5図は共振器を3等分する2点にλ/8位相
シフタを有する場合の歩留りの等高線表示、第6図は従
来の位相シフト構造を有する分布帰還型半導体レーザ素
子の導波路構造を示す平面および断面図である。
出願人 株式会社 東芝FIG. 1 is an αL-δL diagram for explaining ΔαL, FIG. 2 is a diagram showing an example of the internal light intensity distribution of a distributed feedback semiconductor laser device for explaining the definition of FR, and FIG.
The figure shows that when the resonator has a λ phase shifter in the center, when both end face reflectances (vertical axis) and the value of κL (horizontal axis) are changed, when the value of ΔαL is 0.05 or more, the FR (internal light intensity Figure 4 is a contour line representation of the yield obtained for devices with a parameter (parameter indicating flatness of distribution) of 0.6 or more, with λ/
A similar diagram showing contour lines of the yield in the case of having 8 phase shifters. Figure 5 shows the contour lines of the yield in the case of having λ/8 phase shifters at two points dividing the resonator into three equal parts. FIG. 2 is a plan view and a cross-sectional view showing a waveguide structure of a distributed feedback semiconductor laser device having a phase shift structure. Applicant: Toshiba Corporation
Claims (1)
の周期構造を有する共振器の中央から両方向に向かって
共振器長の20%以下の距離間に形成された1個以上の
位相シフト領域またはこの位相シフト領域に等価的に対
応する導波路変形領域とを有し、両端面の反射率が5〜
15%でかつ結合係数κと前記共振器長Lとの積κL値
が、 0.6≦κL≦1.0となるように構成されていること
を特徴とする分布帰還型半導体レーザ素子。 (2)周期構造が、この周期構造を有する共振器の長さ
をほぼ3等分する2つの点で管内波長の1/8の位相シ
フト領域またはこの位相シフト領域に等価的に対応する
導波路変形領域を有する分布帰還型半導体レーザ素子に
おいて、 結合係数κと共振器長Lの積κLの値が 0.5≦κL≦1.3の場合に両端面の反射率を5〜2
0%とし、前記κLの値が1.2≦κL≦2.1の場合
には両端面の反射率を2%以下として構成したことを特
徴とする分布帰還型半導体レーザ素子。[Claims] (1) An optical waveguide having a periodic structure in the direction of the resonator axis and an optical waveguide formed between the center of the resonator having the periodic structure and a distance of 20% or less of the resonator length in both directions. It has one or more phase shift regions or a waveguide deformation region that equivalently corresponds to the phase shift regions, and the reflectance of both end faces is 5 to 5.
15% and the product κL value of the coupling coefficient κ and the resonator length L satisfies the following: 0.6≦κL≦1.0. (2) A waveguide whose periodic structure corresponds to a phase shift region of 1/8 of the channel wavelength or equivalently corresponds to this phase shift region at two points that approximately divide the length of the resonator having this periodic structure into three equal parts. In a distributed feedback semiconductor laser device having a deformation region, when the value of the product κL of the coupling coefficient κ and the cavity length L is 0.5≦κL≦1.3, the reflectance of both end faces is set to 5 to 2.
0%, and when the value of κL is 1.2≦κL≦2.1, the reflectance of both end faces is set to 2% or less.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP63170467A JPH0220087A (en) | 1988-07-08 | 1988-07-08 | Distributed feedback type semiconductor laser element |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP63170467A JPH0220087A (en) | 1988-07-08 | 1988-07-08 | Distributed feedback type semiconductor laser element |
Publications (1)
Publication Number | Publication Date |
---|---|
JPH0220087A true JPH0220087A (en) | 1990-01-23 |
Family
ID=15905483
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP63170467A Pending JPH0220087A (en) | 1988-07-08 | 1988-07-08 | Distributed feedback type semiconductor laser element |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPH0220087A (en) |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH04229687A (en) * | 1990-06-12 | 1992-08-19 | Toshiba Corp | Semiconductor laser |
JPH06204607A (en) * | 1993-01-08 | 1994-07-22 | Nec Corp | Distributed feedback type semiconductor laser |
US5394429A (en) * | 1992-10-30 | 1995-02-28 | Nec Corporation | Distributed-feedback laser with improved analog modulation distortion characteristics and method for fabricating the same |
US5469459A (en) * | 1993-01-08 | 1995-11-21 | Nec Corporation | Laser diode element with excellent intermodulation distortion characteristic |
US6788725B2 (en) | 2001-11-14 | 2004-09-07 | Mitsubishi Denki Kabushiki Kaisha | Semiconductor laser device |
-
1988
- 1988-07-08 JP JP63170467A patent/JPH0220087A/en active Pending
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH04229687A (en) * | 1990-06-12 | 1992-08-19 | Toshiba Corp | Semiconductor laser |
US5394429A (en) * | 1992-10-30 | 1995-02-28 | Nec Corporation | Distributed-feedback laser with improved analog modulation distortion characteristics and method for fabricating the same |
JPH06204607A (en) * | 1993-01-08 | 1994-07-22 | Nec Corp | Distributed feedback type semiconductor laser |
US5469459A (en) * | 1993-01-08 | 1995-11-21 | Nec Corporation | Laser diode element with excellent intermodulation distortion characteristic |
US5568505A (en) * | 1993-01-08 | 1996-10-22 | Nec Corporation | Laser diode element with excellent intermodulation distortion characteristic |
US6788725B2 (en) | 2001-11-14 | 2004-09-07 | Mitsubishi Denki Kabushiki Kaisha | Semiconductor laser device |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
JP3643486B2 (en) | Optical functional device and optical communication system | |
JP4860628B2 (en) | Semiconductor optical device and external cavity laser equipped with semiconductor optical device | |
JPS61216383A (en) | Distributed feedback semiconductor laser | |
US8937980B2 (en) | Distributed feedback-laser diodes | |
JPH06338659A (en) | Laser element | |
JPH0220087A (en) | Distributed feedback type semiconductor laser element | |
JP5310533B2 (en) | Optical semiconductor device | |
JPH11163464A (en) | Distribution feedback type semiconductor laser | |
WO2018197015A1 (en) | Curved waveguide laser | |
JPS59163886A (en) | Coupling cavity laser | |
KR100456670B1 (en) | Distributed Bragg reflector laser diode having distributed feedback laser diode and optical spot size converter on the same substrate | |
JP2000261093A (en) | Distribution feedback type semiconductor laser | |
JPH0290688A (en) | Distributed feedback type semiconductor laser | |
WO2021148121A1 (en) | Dfb laser with angled central waveguide section | |
CN114784616A (en) | Conical semiconductor laser integrated with super lens | |
JPH01155677A (en) | Distributed feedback type semiconductor laser element | |
JPS6232680A (en) | Integrated type semiconductor laser | |
JP2002223032A (en) | Optical element and method for manufacturing it | |
JP2005117045A (en) | Fixed gain semiconductor optical amplifier | |
JPS61135184A (en) | Semiconductor laser device | |
JP3024603B2 (en) | Semiconductor laser and method of manufacturing the same | |
JP3368607B2 (en) | Distributed feedback semiconductor laser | |
JPWO2016167071A1 (en) | Grating element and external resonator type light emitting device | |
JPS61171190A (en) | Distributed reflection type laser | |
JPS62136890A (en) | Semiconductor laser device |