JPH0247887A - Coupling distribution feedback type semiconductor laser - Google Patents
Coupling distribution feedback type semiconductor laserInfo
- Publication number
- JPH0247887A JPH0247887A JP63199357A JP19935788A JPH0247887A JP H0247887 A JPH0247887 A JP H0247887A JP 63199357 A JP63199357 A JP 63199357A JP 19935788 A JP19935788 A JP 19935788A JP H0247887 A JPH0247887 A JP H0247887A
- Authority
- JP
- Japan
- Prior art keywords
- mode
- semiconductor laser
- phase shift
- lambda
- specified
- 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.)
- Granted
Links
- 239000004065 semiconductor Substances 0.000 title claims description 14
- 230000008878 coupling Effects 0.000 title abstract 3
- 238000010168 coupling process Methods 0.000 title abstract 3
- 238000005859 coupling reaction Methods 0.000 title abstract 3
- 230000010363 phase shift Effects 0.000 claims abstract description 27
- 238000005253 cladding Methods 0.000 abstract description 6
- 230000010355 oscillation Effects 0.000 abstract description 6
- 229910000980 Aluminium gallium arsenide Inorganic materials 0.000 abstract description 3
- 229910001218 Gallium arsenide Inorganic materials 0.000 abstract description 3
- 229910000530 Gallium indium arsenide Inorganic materials 0.000 abstract description 3
- 238000000034 method Methods 0.000 abstract 1
- 238000010586 diagram Methods 0.000 description 6
- 230000003287 optical effect Effects 0.000 description 4
- 239000006185 dispersion Substances 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 230000003595 spectral effect Effects 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000001427 coherent effect Effects 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 230000005428 wave function 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
-
- 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
- H01S5/124—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 incorporating phase shifts
- H01S5/1246—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 incorporating phase shifts plurality of phase shifts
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明は、発振周波数が安定しており、スペクトル幅の
狭い半導体レーザに関するものである。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor laser having a stable oscillation frequency and a narrow spectrum width.
発振周波数が安定している結合分布帰還型半導体レーザ
（ＤＦＢレーザ）の従来例の主要部を第６図に示す。こ
の第６図に示す構造では、スペクトル幅を狭くするため
に共振器長を長くすると、中心付近の光強度が高くなり
すぎて、空間的ホールバーニングを生じモードが不安定
になる。これを改善するためには、第７図に示す結合位
相シフト分布帰還（ＤＦＢ）構造が有効である。FIG. 6 shows the main parts of a conventional example of a coupled distributed feedback semiconductor laser (DFB laser) whose oscillation frequency is stable. In the structure shown in FIG. 6, if the resonator length is increased in order to narrow the spectral width, the light intensity near the center becomes too high, causing spatial hole burning and making the mode unstable. In order to improve this, a combined phase shift distributed feedback (DFB) structure shown in FIG. 7 is effective.
しかしながら、前記の従来構造では、発振周波数とフラ
ッグ周波数との差δがＯのモードは、最低次モードとな
らず、δ≠０である２つのモードが最低次モードとなる
ため、この最低次モードを抑圧する方法でレーザ動作さ
せなければならないという問題があった。However, in the conventional structure described above, the mode in which the difference δ between the oscillation frequency and the flag frequency is O is not the lowest-order mode, but the two modes in which δ≠0 are the lowest-order modes. The problem is that the laser must be operated in a way that suppresses the
更に、これを改善するために、第８図のように３箇所の
位相シフト量φをλ／４からずらせる構造が提案されて
いる。ここで、λはレーザ光の波長である。しかし、こ
の第８図に示す構造では、δが０にならないため発振周
波数がサンプルごとにバラツクという問題があった。Furthermore, in order to improve this problem, a structure has been proposed in which the phase shift amount φ at three locations is shifted from λ/4 as shown in FIG. Here, λ is the wavelength of the laser beam. However, in the structure shown in FIG. 8, there was a problem in that the oscillation frequency varied from sample to sample because δ did not become 0.
なお、第６図〜第８図において、１１．１３は例えばＩ
ｎＰ、 ＡｌＧａＡｓ等からなるクラッド層、１２は例
えばＩｎＧａＡｓ、 ＧａＡｓ等からなる活性層である
。In addition, in FIGS. 6 to 8, 11.13 is, for example, I
The cladding layer 12 is made of nP, AlGaAs, etc., and the active layer 12 is made of InGaAs, GaAs, etc., for example.
本発明は、前記問題点を解決するためになされたもので
ある。The present invention has been made to solve the above problems.
本発明の目的は、δ＝０のモードが最低次で存在し、か
つモード分布が平担になる結合分布帰還型半導体レーザ
を提供することにある。An object of the present invention is to provide a coupled distributed feedback semiconductor laser in which the mode of δ=0 exists at the lowest order and the mode distribution is flat.
本発明の前記ならびにその他の目的と新規な特徴は、本
明細書の記述及び添付図面によって明らかになるであろ
う。The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.
前記目的を達成するために、本発明は、３箇所の位相シ
フト部位を有する結合分布帰還型半導体レーザであって
、真中の位相シフト量がλ／４であり、両側の位相シフ
トが０、−１，１を除く−１と１の間のパラメータｑに
対してλ（１＋ｑ）／４及びλ（１−ｑ）／４であり、
かつこの３箇所の位相シフトにより４分割された各部分
の長さが端から順にＬ（１＋ｄ）／４．Ｌ（１−ｄ）／
４．Ｌ（１−ｄ）／４．Ｌ（１＋ｄ）／４であり、但し
λはレーザ光の波長、Ｌは半導体レーザの全長、ｄは−
１と１を除く−１と１の間の数であることを最も主要な
特徴とする。In order to achieve the above object, the present invention provides a coupled distributed feedback semiconductor laser having three phase shift sites, in which the phase shift amount at the center is λ/4, and the phase shifts at both sides are 0, -. λ(1+q)/4 and λ(1-q)/4 for a parameter q between −1 and 1 excluding 1 and 1,
The length of each portion divided into four by the phase shift at these three locations is L(1+d)/4. L(1-d)/
4. L(1-d)/4. L(1+d)/4, where λ is the wavelength of the laser beam, L is the total length of the semiconductor laser, and d is -
The most important feature is that it is a number between -1 and 1, excluding 1 and 1.
前述の手段によれば、３箇所ある位相シフトをφ□＝λ
（１＋ｑ）／４．φ２＝λ／４．φ、＝λ（１ｑ）／４
、但し−１＜ｑ＜０、Ｏ＜ｑ＜１とし。According to the above-mentioned means, the phase shift at three locations is φ□=λ
(1+q)/4. φ2=λ/4. φ,=λ(1q)/4
, where -1<q<0 and O<q<1.
この位相シフトで４分割された各部分の長さＱ１ｔρＺ
＋ ｆ１３＋ ρ、をそれぞれΩ□−１！４＝Ｌ（１＋
ｄ）／４．Ω、＝１２３＝Ｌ（１−ｄ）／４とし、但し
−１くｄく１と設定することにより、前述のδ＝０のモ
ードが最低次で存在し、かつモード分布が平担になる結
合分布帰還型半導体レーザを提供することができる。The length of each part divided into four by this phase shift Q1tρZ
+ f13+ ρ, respectively Ω□-1!4=L(1+
d)/4. Ω, = 123 = L (1 - d) / 4, but by setting -1 × d × 1, the mode of δ = 0 mentioned above exists at the lowest order, and the mode distribution becomes flat. A coupled distributed feedback semiconductor laser can be provided.
すなわち、従来の構造はφ、＝φ２＝φ３であり、前述
のｑ＝Ｑの場合のみがこれと重複するが、本発明ではｑ
≠０が特徴である。That is, the conventional structure is φ, = φ2 = φ3, and only the case of q=Q described above overlaps with this, but in the present invention, q
≠0 is a characteristic.
（発明の実施例〕
以下、本発明の一実施例を図面を用いて具体的に説明す
る。(Embodiment of the Invention) An embodiment of the present invention will be specifically described below with reference to the drawings.
第１図は、本・発明の一実施例の結合分布帰還型半導体
レーザの概略構成を説明するための要部断面図である。FIG. 1 is a sectional view of a main part for explaining the schematic structure of a coupled distributed feedback semiconductor laser according to an embodiment of the present invention.
本実施例の結合分布帰還型半導体レーザは、第１図に示
すように、例えばＩｎＰ、 ＡｌＧａＡｓ等からなるク
ラッド層１とクラッド層３の間に２例えばＩｎＧａＡｓ
、 ＧａＡｓ等からなる活性層２が設けられている。As shown in FIG. 1, the coupled distributed feedback semiconductor laser of this embodiment has two layers of, for example, InGaAs, between a cladding layer 1 and a cladding layer 3 made of, for example, InP, AlGaAs, etc.
An active layer 2 made of , GaAs, or the like is provided.
そして、位相シフト量がφ１＝λ（１＋ｑ）／４゜φ２
＝λ／４．φ３＝λ（１−ｑ）／４である光位相シフト
部分３箇所を有し、これに分割された４つの部分の長が
Ｌ（１＋ｄ）／４．Ｌ（１−ｄ）／４゜Ｌ（１−ｄ）／
４．Ｌ（１＋ｄ）／４であるような結合分布帰還構造に
なっている。Then, the phase shift amount is φ1=λ(1+q)/4°φ2
=λ/4. It has three optical phase shift parts where φ3=λ(1-q)/4, and the lengths of the four divided parts are L(1+d)/4. L(1-d)/4゜L(1-d)/
4. The coupled distributed feedback structure is L(1+d)/4.
一般に、位相シフト部分を有する結合分布帰還（ＤＦＢ
）構造のモードは、次の結合モード方程式（１）、（２
）を解くことで決定される。Generally, coupled distributed feedback (DFB) with a phase-shifted part
) structure is expressed by the following coupled mode equations (1) and (2
) is determined by solving.
−ｄＲ／ｄＺ＋（α−ｊδ）Ｒ＝ｊｘＳ・・・・・（１
）ｄ Ｓ／ｄ Ｚ＋（α−ｊδ）Ｓ＝ｊにＲ・・・・・
（２）ここで、Ｒ，Ｓは右進行、左進行の光の波動関数
、には光帰還の強さを表わすパラメータであり。-dR/dZ+(α-jδ)R=jxS・・・(1
)d S/d Z+(α-jδ)S=j to R...
(2) Here, R and S are wave functions of light traveling to the right and to the left, and are parameters representing the strength of optical feedback.
結合分布帰還構造の溝の深さに比例する量である。It is an amount proportional to the depth of the groove of the coupled distributed feedback structure.
しきい値ゲインαとδは、式（１）及び式（２）を境界
条件のもとで解くことで求まる。The threshold gains α and δ are determined by solving equations (1) and (2) under boundary conditions.
φ、＝φ２＝φ３＝λ１５．に＝２．５の場合のαとδ
の関係（分数姿数）の計算結果を第２図に示す。φ,=φ2=φ3=λ15. α and δ when = 2.5
The calculation results of the relationship (fraction figure number) are shown in Figure 2.
この場合、最低次（αが最小）のモードはδ≠０となる
。同様な計算を他の様々な構造で行った結果、第１図の
構造の場合δ＝０にモードが存在することを発明者は見
出した。In this case, the mode of the lowest order (α is the minimum) is δ≠0. As a result of performing similar calculations on various other structures, the inventor found that in the structure shown in FIG. 1, a mode exists at δ=0.
第１図の構造の範囲で、δ＝０のモードのαとそれ以外
のモードの内の最低次モードとの差Δαを計算した結果
を第３図の点線で等高線として示した。Δα＜Ｏ（斜線
領域）は、δ＝Ｏのモードが最低次にならない領域であ
る。Within the structure of FIG. 1, the difference Δα between α of the mode with δ=0 and the lowest order mode among the other modes is calculated, and the results are shown as contour lines using dotted lines in FIG. Δα<O (shaded region) is a region where the mode of δ=O does not become the lowest order.
結合分布帰還構造ではモード分布が平担になるため、長
井振器構造でも安定になる。モード分布の平担さは次の
関数Ｆで定義できる。Since the mode distribution becomes flat in the coupled distributed feedback structure, even the Nagai shaker structure is stable. The flatness of the mode distribution can be defined by the following function F.
Ｆ＝（、、’ （Ｉ（Ｚ）−■、）”ｄｚ−・−−−
−−（３）但し、強度Ｉ（Ｚ）＝ＩＲ＋”＋１Ｓ１２で
あり、Ｉ。は強度ｒ （ｚ）の平均値である。にを最適
にした時のモード分布の平担さの関数Ｆのｄ及びｑ依存
性の等高線を第３図の実線に示した。最も平担になるの
はｑ＝０．４．ｄ＝０の構造であり、単一位相シフトの
場合に比べＦは約１／６になる。この構造のモード分布
及び分散関数を第４図及び第５図に示した。この構造で
レーザ動作をさせた時のスペクトル幅は、長井振器効果
により単一位相シフトの場合と比較して１１５になる。F=(,,' (I(Z)−■,)”dz−・−−
--(3) However, the intensity I(Z)=IR+''+1S12, where I is the average value of the intensity r(z). Contour lines of d and q dependence are shown as solid lines in Figure 3. The structure with q = 0.4 and d = 0 is the most flat, and F is approximately 1 compared to the case of a single phase shift. /6. The mode distribution and dispersion function of this structure are shown in Figures 4 and 5. When operating a laser with this structure, the spectral width is as follows in the case of a single phase shift due to the Nagai Oscillator effect. It becomes 115 compared to .
以上の説明かられかるように、本実施例によれば、結合
分布帰還構造を用い、モード分布が平担で長井振器化に
対し安定なレーザを実現する際、第１図に示すような対
称性を有する構造にしているため、δ＝Ｏのモードで発
振するようにできる利点がある。これは、このレーザを
コヒーレント光伝送システムや光センサシステムなどに
用いる際、発振周波数のバラつきが小さくなりシステム
全体の安定性が増加する利点がある。As can be seen from the above description, according to this embodiment, when realizing a laser with a flat mode distribution and stable against Nagai oscillator conversion using a coupled distributed feedback structure, as shown in FIG. Since it has a symmetrical structure, it has the advantage of being able to oscillate in the δ=O mode. This has the advantage that when this laser is used in a coherent optical transmission system, an optical sensor system, etc., variations in the oscillation frequency are reduced and the stability of the entire system is increased.
以上、本発明を実施例にもとづき具体的に説明したが、
本発明は、前記実施例に限定されるものではなく、その
要旨を逸脱しない範囲において種々変更可能であること
は言うまでもない。The present invention has been specifically explained above based on examples, but
It goes without saying that the present invention is not limited to the embodiments described above, and can be modified in various ways without departing from the spirit thereof.
以上、説明したように、本発明によれば、３箇所の位相
シフト部位を有する結合分布帰還型半導体レーザであっ
て、真中の位相シフト量をλ／４にし、両側の位置シフ
トが０、−１，１を除く−１と１の間のパラメータｑに
対してλ（１＋ｑ）／４及びλ（１−ｑ）／４にし、か
っこの３箇所の位置シフトにより４分割された各部分の
長さが端から順にＬ（１＋ｄ）／４．Ｌ（１−ｄ）／４
．Ｌ（１−ｄ）／４．Ｌ（１＋ｄ）／４にすることによ
り。As described above, according to the present invention, there is provided a coupled distributed feedback semiconductor laser having three phase shift sites, in which the phase shift amount at the center is set to λ/4, and the position shifts at both sides are 0, -. For the parameter q between -1 and 1 excluding 1 and 1, set it to λ (1 + q) / 4 and λ (1 - q) / 4, and calculate the length of each part divided into 4 by shifting the position of the parentheses in 3 places. Starting from the end, L(1+d)/4. L(1-d)/4
．． L(1-d)/4. By setting L(1+d)/4.
δ＝０のモードが最低次で存在し、かつモード分布が平
担になる結合分布帰還型半導体レーザを提供することが
できる。It is possible to provide a coupled distributed feedback semiconductor laser in which the mode of δ=0 exists at the lowest order and the mode distribution is flat.
第１図は、本発明の一実施例の結合分布帰還型半導体レ
ーザの概略構成を説明するための要部断面図、
第２図は、結合位相シフトＤＦＢ構造を４等分割してい
る３箇所の位相シフト量が等しくλ／５でにが２．５で
ある構造の分散関数の図、第３図は、本発明の構造にお
いて構造パラメータｄ、ｑを変化させた時のΔα（点線
）及びＦ（実線）の計算値の等高線図、
第４図及び第５図は、本発明の構造でｄ＝０゜ｑ＝０．
４の構造のレーザについてのモード分布及び分散関数の
図。
第６図は、従来構造である単一位相シフトＤＦＢ構造図
、
第７図は、他の従来構造の結合位相シフトＤＦＢ構造図
、
第８図は、他の従来構造の結合位相シフトＤＦＢ構造図
である。
図中、１，３・・・クラッド層、２・・・活性層。
第１図
２・・・滝牲１
３・・・クラ斗１FIG. 1 is a cross-sectional view of the main parts for explaining the schematic configuration of a coupled distributed feedback semiconductor laser according to an embodiment of the present invention. FIG. 2 shows three points where the coupled phase shift DFB structure is equally divided into four parts. Figure 3 is a diagram of the dispersion function of a structure in which the phase shift amounts of are equal to λ/5 and 2.5, and Δα (dotted line) and Δα (dotted line) and The contour diagrams of the calculated values of F (solid line), FIGS. 4 and 5, show the structure of the present invention when d=0゜q=0.
FIG. 4 is a diagram of the mode distribution and dispersion function for the laser with structure No. 4. Fig. 6 is a structural diagram of a single phase shift DFB with a conventional structure. Fig. 7 is a structural diagram of a combined phase shift DFB with another conventional structure. Fig. 8 is a structural diagram of a combined phase shift DFB with another conventional structure. It is. In the figure, 1, 3... cladding layer, 2... active layer. Figure 1 2...Takisuke 1 3...Kurato 1
Claims (1)
半導体レーザであって、真中の位相シフト量がλ／４で
あり、両側の位相シフトが０、−１、１を除く−１と１
の間のパラメータｑに対してλ（１＋ｑ）／４及びλ（
１−ｑ）／４であり、かつこの３箇所の位相シフトによ
り４分割された各部分の長さが端から順にＬ（１＋ｄ）
／４、Ｌ（１−ｄ）／４、Ｌ（１−ｄ）／４、Ｌ（１＋
ｄ）／４であり、但しλはレーザ光の波長、Ｌは半導体
レーザの全長、ｄは−１と１を除く−１と１の間の数で
あることを特徴とする結合分布帰還型半導体レーザ。(1) A coupled distributed feedback semiconductor laser having three phase shift parts, in which the phase shift amount in the middle is λ/4, and the phase shifts on both sides are 0, -1, -1 and 1 excluding 1.
λ(1+q)/4 and λ(
1-q)/4, and the length of each portion divided into four by these three phase shifts is L(1+d) in order from the end.
/4, L(1-d)/4, L(1-d)/4, L(1+
d)/4, where λ is the wavelength of the laser beam, L is the total length of the semiconductor laser, and d is a number between -1 and 1 excluding -1 and 1. laser.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63199357A JPH0247887A (en) | 1988-08-10 | 1988-08-10 | Coupling distribution feedback type semiconductor laser |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63199357A JPH0247887A (en) | 1988-08-10 | 1988-08-10 | Coupling distribution feedback type semiconductor laser |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0247887A true JPH0247887A (en) | 1990-02-16 |
| JPH0514436B2 JPH0514436B2 (en) | 1993-02-25 |
Family
ID=16406417
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP63199357A Granted JPH0247887A (en) | 1988-08-10 | 1988-08-10 | Coupling distribution feedback type semiconductor laser |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0247887A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6330268B1 (en) | 1998-08-27 | 2001-12-11 | Nec Corporation | Distributed feedback semiconductor laser |
| US6574261B2 (en) | 1998-08-27 | 2003-06-03 | Nec Corporation | Distributed feedback semiconductor laser |
| WO2004069524A1 (en) * | 2003-01-27 | 2004-08-19 | Nike, Inc. | Method for flange bonding |
-
1988
- 1988-08-10 JP JP63199357A patent/JPH0247887A/en active Granted
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6330268B1 (en) | 1998-08-27 | 2001-12-11 | Nec Corporation | Distributed feedback semiconductor laser |
| US6574261B2 (en) | 1998-08-27 | 2003-06-03 | Nec Corporation | Distributed feedback semiconductor laser |
| WO2004069524A1 (en) * | 2003-01-27 | 2004-08-19 | Nike, Inc. | Method for flange bonding |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0514436B2 (en) | 1993-02-25 |
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