JP2600490B2 - Distributed feedback semiconductor laser - Google Patents
Distributed feedback semiconductor laserInfo
- Publication number
- JP2600490B2 JP2600490B2 JP5001501A JP150193A JP2600490B2 JP 2600490 B2 JP2600490 B2 JP 2600490B2 JP 5001501 A JP5001501 A JP 5001501A JP 150193 A JP150193 A JP 150193A JP 2600490 B2 JP2600490 B2 JP 2600490B2
- Authority
- JP
- Japan
- Prior art keywords
- reflectance
- diffraction grating
- distributed feedback
- semiconductor laser
- active layer
- 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
Description
【０００１】[0001]
【産業上の利用分野】本発明は、分布帰還型半導体レー
ザに関し、特に相互変調歪特性に優れるアナログ変調用
分布帰還型半導体レーザに関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distributed feedback semiconductor laser, and more particularly to a distributed feedback semiconductor laser for analog modulation having excellent intermodulation distortion characteristics.
【０００２】[0002]
【従来の技術】サブキャリア多重光伝送方式などに用い
られるアナログ変調用光源には、高効率で相互変調歪の
小さい分布帰還型半導体（ＤＦＢ）レーザが要求されて
いる。例えば移動通信システム用では３次相互変調歪
（３ｒｄ ｉｎｔｅｒｍｏｄｕｌａｔｉｏｎ ｄｉｓｔ
ｏｒｔｉｏｎ；ＩＭＤ3 ）が充分に小さい素子が要求さ
れている。2. Description of the Related Art A distributed feedback semiconductor (DFB) laser with high efficiency and small intermodulation distortion is required for a light source for analog modulation used in a subcarrier multiplexing optical transmission system or the like. For example, for a mobile communication system, third-order intermodulation distortion (3rd intermodulation dist)
An element having a sufficiently small orientation (IMD 3 ) is required.
【０００３】ＤＦＢレーザの相互変調歪はレーザの電流
−光出力（Ｉ−Ｌ）特性の線形性に大きく関係し、Ｉ−
Ｌ特性の線形性を改善するためには結合係数や端面反射
率を最適化する必要がある。[0003] The intermodulation distortion of a DFB laser is greatly related to the linearity of the current-optical output (IL) characteristic of the laser.
In order to improve the linearity of the L characteristic, it is necessary to optimize the coupling coefficient and the end face reflectivity.
【０００４】ＤＦＢレーザの最適化設計には従来様々な
検討がなされている。例えば、特開平２−９０６８８号
公報，特開平２−２００８７号公報ではκＬや端面反射
率を最適化した位相シフトＤＦＢレーザが提案されてい
る。また、特開平１−１５５６７７号公報ではκＬと端
面反射率を最適化した均一な回折格子を持つＤＦＢレー
ザが提案されている。Various studies have been made on the optimization design of the DFB laser. For example, JP-A-2-90688 and JP-A-2-20087 propose a phase shift DFB laser in which κL and end face reflectivity are optimized. Also, Japanese Patent Application Laid-Open No. 1-155677 proposes a DFB laser having a uniform diffraction grating in which κL and end face reflectance are optimized.
【０００５】[0005]
【発明が解決しようとする課題】しかし、従来のＤＦＢ
レーザはアナログ変調を目的としたものではなく、相互
変調歪特性については何ら保障されていなかった。However, the conventional DFB
The laser was not intended for analog modulation, and no intermodulation distortion characteristics were guaranteed.
【０００６】本発明の目的は、ＤＦＢレーザのアナログ
変調歪特性と単一モード性を含めた歩留りおよび効率を
改善し、低価格の低歪アナログ変調用ＤＦＢレーザを実
現することにある。An object of the present invention is to improve the yield and efficiency including the analog modulation distortion characteristic and the single mode property of a DFB laser, and to realize a low-cost low distortion analog modulation DFB laser.
【０００７】[0007]
【課題を解決するための手段】本願発明の分布帰還型半
導体レーザは共振器方向に均一な回折格子と活性層を有
し、前面の反射率が１％以下でかつ、活性層と回折格子
との結合係数κと共振器長Ｌの積が０．４≦κＬ≦１．
０であることを特徴とする。 According to the present invention, a distributed feedback type half is provided.
Conductor lasers have a uniform diffraction grating and active layer in the cavity direction.
And the active layer and the diffraction grating have a reflectance of 1% or less on the front surface.
The product of the coupling coefficient κ and the cavity length L is 0.4 ≦ κL ≦ 1.
It is characterized by being 0.
【０００８】または、共振器方向に均一な回折格子と活
性層を有し、前面の反射率が１％以下でかつ、活性層と
回折格子との結合係数κと共振器長Ｌの積が０．５≦κ
Ｌ≦０．７であることを特徴とする。 Alternatively , a diffraction grating and an active element which are uniform in the resonator direction can be used.
Having a reflective layer having a front surface reflectance of 1% or less and an active layer.
The product of the coupling coefficient κ with the diffraction grating and the resonator length L is 0.5 ≦ κ
It is characterized in that L ≦ 0.7.
【０００９】または上記の分布帰還型半導体レーザにお
いて後面の反射率が５０％以上であることを特徴とす
る。または後面の反射率が９０％以上であることを特徴
とする。 Alternatively, the distributed feedback semiconductor laser described above
And the reflectance of the rear surface is 50% or more.
You. Alternatively, the rear surface has a reflectance of 90% or more.
And
【００１０】または、共振器方向に均一な回折格子と活
性層を有し、前面の反射率が５％未満であり、後面の反
射率が５０％以上であり、かつ活性層と回折格子との結
合係数κと共振器長Ｌの積が０．４≦κＬ≦１．０であ
ることを特徴とする。 [0010] Alternatively, a diffraction grating and an active element that are uniform in the resonator direction can be used.
With a reflective layer having a front surface reflectance of less than 5% and a rear surface
The emissivity is 50% or more, and the connection between the active layer and the diffraction grating is
The product of the integration coefficient κ and the resonator length L is 0.4 ≦ κL ≦ 1.0
It is characterized by that.
【００１１】または、共振器方向に均一な回折格子と活
性層を有し、前面の反射率が５％未満であり、後面の反
射率が５０％以上であり、かつ活性層と回折格子との結
合係数κと共振器長Ｌの積が０．５≦κＬ≦０．７であ
ることを特徴とする。 Alternatively , a diffraction grating and an active element which are uniform in the resonator direction can be used.
Having a reflective layer having a front surface reflectance of less than 5% and a rear surface having a reflectance of less than 5%.
The emissivity is 50% or more, and the connection between the active layer and the diffraction grating is
The product of the integration coefficient κ and the resonator length L is 0.5 ≦ κL ≦ 0.7
It is characterized by that.
【００１２】[0012]
【作用】図１，図２，図３を用いて本発明の原理を説明
する。The principle of the present invention will be described with reference to FIGS.
【００１３】図１は端面反射率が前面で１％、後面で７
５％の均一な回折格子を持つＤＦＢレーザについて、結
合係数と共振器長の積κＬに対する歩留りを計算した結
果である。ここでは、規格化反射鏡損失が０．０５以上
で、平均光出力８ｍＷ、変調度２０％でＩＭＤ3 ≦−８
０ｄＢｃを満足する素子の割合を歩留りとしている。こ
れは共振器方向の電界強度分布を考慮したＩ−Ｌ特性を
求め、その線形性から歪率を計算した結果に基づいてい
る。これからκＬが０．４〜１．０の範囲で歩留りが５
％より高くなり、０．５〜０．７の範囲で歩留りが１０
％より高くなることが分かる。FIG. 1 shows that the end face reflectivity is 1% on the front face and 7% on the back face.
This is the result of calculating the yield with respect to the product κL of the coupling coefficient and the cavity length for a DFB laser having a uniform diffraction grating of 5%. Here, IMD 3 ≦ −8 at a normalized reflector loss of 0.05 or more, an average optical output of 8 mW, and a modulation factor of 20%.
The ratio of the element satisfying 0 dBc is defined as the yield. This is based on the result of obtaining the IL characteristic in consideration of the electric field strength distribution in the resonator direction and calculating the distortion factor from the linearity. From now on, the yield is 5 when κL is in the range of 0.4 to 1.0.
%, And the yield is 10 in the range of 0.5 to 0.7.
%.
【００１４】図２は歩留りの前面および後面の端面反射
率依存性を同じ方法で計算した結果である。図２（ａ）
はκＬ＝０．７で後面反射率が７５％の場合についての
歩留りの前面反射率依存性を示したものである。これか
ら前面反射率を５％未満にすることにより歩留りを少な
くとも１０％以上にできる。また、前面反射率が３％付
近で歩留りの極小値が存在するが、前面反射率を１％以
下にすることで歩留りは少なくとも１２％以上にするこ
とが可能となる。図２（ｂ）はκＬ＝０．７で前面後面
反射率が１％の場合についての歩留りの後面反射率依存
性である。これから後面反射率が約５０％以上で歩留り
が１０％より高くなることが分かる。FIG. 2 shows the results of calculating the dependence of the yield on the front and rear end faces by the same method. FIG. 2 (a)
Shows the dependency of the yield on the front surface reflectance when κL = 0.7 and the rear surface reflectance is 75%. From this, the yield can be made at least 10% or more by setting the front surface reflectance to less than 5%. Further, although the yield has a local minimum value when the front surface reflectance is around 3%, the yield can be made at least 12% or more by setting the front surface reflectance to 1% or less. FIG. 2B shows the dependency of the yield on the rear surface reflectance when κL = 0.7 and the front rear surface reflectance is 1%. From this, it can be seen that the yield is higher than 10% when the rear surface reflectance is about 50% or more.
【００１５】図３は、比較的高い歩留りの得られるκＬ
＝０．７の場合について各反射率における平均的な効率
を、前面反射率１％、後面反射率７５％の場合の平均効
率で規格化して示したものである。図３（ａ）より前面
反射率については反射率が１％以下では効率はほぼ一定
で、１％を越えると効率が徐々に低下することが分か
る。また図３（ｂ）より後面反射率が高くなるに伴い効
率は直線的に上昇することが分かる。したがって、後面
反射率を９０％以上にすることによりさらに効率が改善
され、反射率１００％の時に効率は最大となる。なお、
後面からの光出力モニターを必要とする場合は、反射率
を９８％以下に留める必要がある。FIG. 3 shows κL at which a relatively high yield can be obtained.
The average efficiency at each reflectance in the case of = 0.7 is normalized by the average efficiency at the front reflectance of 1% and the rear reflectance of 75%. From FIG. 3 (a), it can be seen that the efficiency is almost constant when the reflectance is 1% or less, and the efficiency gradually decreases when the reflectance exceeds 1%. FIG. 3B shows that the efficiency increases linearly as the rear surface reflectance increases. Therefore, the efficiency is further improved by setting the rear surface reflectance to 90% or more, and the efficiency becomes maximum when the reflectance is 100%. In addition,
If a light output monitor from the rear side is required, the reflectance must be kept at 98% or less.
【００１６】[0016]
【実施例】以下に、本発明の１．３μｍ帯ＤＦＢレーザ
における実施例を図面を用いて説明する。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a 1.3 μm band DFB laser according to the present invention will be described below with reference to the drawings.
【００１７】図４に本発明のＤＦＢレーザの製造工程を
示す。図４（ａ）のように、光干渉露光法によりｎ型Ｉ
ｎＰ基板１０上に周期２０２５オングストローム，深さ
２５０オングストロームの回折格子１１を形成する。こ
の回折格子上に、図４（ｂ）のように、ｎ−ＩｎＧａＡ
ｓＰ光ガイド層１２を１０００オングストローム、多重
量子井戸（ＭＱＷ）活性層１３、ｐ−ＩｎＰクラッド層
１４を約０．５μｍの膜厚でＭＯＶＰＥ法により形成す
る。FIG. 4 shows a manufacturing process of the DFB laser of the present invention. As shown in FIG. 4A, the n-type I
A diffraction grating 11 having a period of 2025 Å and a depth of 250 Å is formed on the nP substrate 10. On this diffraction grating, as shown in FIG.
The sP light guide layer 12 is formed to a thickness of 1000 angstroms, the multiple quantum well (MQW) active layer 13 and the p-InP cladding layer 14 are formed to a thickness of about 0.5 μm by MOVPE.
【００１８】ＭＱＷ活性層について図５を用いて説明す
る。図５は、本発明のＭＱＷのバンド構造の一例を示し
たものである。このバンド構造は、井戸層３０が１．４
μｍ波長組成，厚さ５７オングストロームで、障壁層３
１が１．１３μｍ波長組成，厚さ１００オングストロー
ムで、これを５周期繰り返し、両側に１．１３μｍ波長
組成のＳＣＨ層３２，３３を、ｐ層側，ｎ層側にそれぞ
れ６００オングストローム，３００オングストロームの
厚さで設けた構造である。The MQW active layer will be described with reference to FIG. FIG. 5 shows an example of the MQW band structure of the present invention. In this band structure, the well layer 30 has a thickness of 1.4.
μm wavelength composition, thickness of 57 Å, barrier layer 3
1 is a 1.13 μm wavelength composition and a thickness of 100 angstroms, and this is repeated for 5 periods, and SCH layers 32 and 33 of a 1.13 μm wavelength composition are provided on both sides, and 600 angstroms and 300 angstroms of a p layer side and an n layer side are respectively provided. This is a structure provided with a thickness.
【００１９】これらの層の形成後、ポジ型ホトレジスト
を塗布し、露光，エッチングにより図４（ｃ）のように
ストライプを形成する。After these layers are formed, a positive photoresist is applied, and a stripe is formed by exposure and etching as shown in FIG.
【００２０】この後、ＬＰＥ法によりｐ−ＩｎＰ電流ブ
ロック層１５、ｎ−ＩｎＰ電流ブロック層１６、ｐ−Ｉ
ｎＰクラッド層１７、波長１，４μｍ組成のｐ−ＩｎＧ
ａＡｓＰキャップ層１８を形成する。次いで電極１９，
２０を蒸着し、劈開し、端面にＳｉＮ膜による反射率１
％と７５％のコーティングを施し、チップに切り出す。Thereafter, the p-InP current blocking layer 15, the n-InP current blocking layer 16, the p-I
nP cladding layer 17, p-InG having a composition of wavelength 1,4 μm
An aAsP cap layer 18 is formed. Then the electrodes 19,
20 was deposited and cleaved, and the end face had a reflectance of 1 with a SiN film.
% And 75% coating and cut into chips.
【００２１】この素子は１．３１μｍで発振し、効率を
測定した結果、約０．４Ｗ／Ａであり、非常に良好であ
った。またκＬは測定の結果、約０．９であった。試作
した素子をモジュール化し、２信号で３次相互変調歪を
測定した結果、平均ファイバー出力４ｍＷ、変調度２０
％でＩＭＤ3 ＜−８５ｄＢｃと非常に良好な歪特性を得
ることができた。This device oscillated at 1.31 μm, and the efficiency was measured. As a result, it was about 0.4 W / A, which was very good. As a result of measurement, κL was about 0.9. As a result of modularizing the prototype device and measuring the third-order intermodulation distortion with two signals, the average fiber output was 4 mW and the modulation factor was 20
%, A very good distortion characteristic of IMD 3 <−85 dBc was obtained.
【００２２】この場合、ＩＭＤ3 ＜−８５ｄＢｃを満足
する素子は全体の約４％程度であった。したがって、歩
留りを向上させるために回折格子の深さを２００オング
ストロームとして、同様に素子を作製したところ、κＬ
は約０．７となり、歩留りは約１２％となった。さら
に、前面の反射率を０．１％としたところ歩留りはさら
に向上し約１６％となった。また、後面反射率を９０％
にすると、効率が約０．４３Ｗ／Ａとなった。In this case, about 4% of the devices satisfy IMD 3 <−85 dBc. Therefore, in order to improve the yield, the depth of the diffraction grating was set to 200 angstroms, and the device was similarly manufactured.
Was about 0.7, and the yield was about 12%. Further, when the reflectance on the front surface was set to 0.1%, the yield was further improved to about 16%. Also, the rear surface reflectance is 90%.
Then, the efficiency was about 0.43 W / A.
【００２３】なお、本実施例では多重量子井戸活性層を
用いたが、バルク活性層を用いた場合にでも同様の効果
が得られることは容易に推測される。Although the multiple quantum well active layer is used in this embodiment, it is easily presumed that the same effect can be obtained even when a bulk active layer is used.
【００２４】[0024]
【発明の効果】本発明によるＤＦＢレーザによれば、高
効率でＩ−Ｌ特性の直線性のよい低歪アナログ光伝送用
ＤＦＢレーザを高歩留りで得ることが可能となる。According to the DFB laser of the present invention, it is possible to obtain a high-efficiency DFB laser for low distortion analog optical transmission having high linearity and IL characteristics at a high yield.
【図１】本発明の原理を示す図である。FIG. 1 is a diagram showing the principle of the present invention.
【図２】本発明の原理を示す図である。FIG. 2 is a diagram illustrating the principle of the present invention.
【図３】本発明の原理を示す図である。FIG. 3 is a diagram showing the principle of the present invention.
【図４】本発明の製造工程を説明するための図である。FIG. 4 is a view for explaining a manufacturing process of the present invention.
【図５】本発明の一実施例を説明するための図である。FIG. 5 is a diagram for explaining one embodiment of the present invention.
１０ ｎ型ＩｎＰ基板 １１ 回折格子 １２ ｎ−ＩｎＧａＡｓＰ光ガイド層 １３ 多重量子井戸（ＭＱＷ）活性層 １４ ｐ−ＩｎＰクラッド層 １５ ｐ−ＩｎＰ電流ブロック層 １６ ｎ−ＩｎＰ電流ブロック層 １７ ｐ−ＩｎＰクラッド層 １８ ｐ−ＩｎＧａＡｓＰキャップ層 １９，２０ 電極 ３０ 井戸層 ３１ 障壁層 ３２，３３ ＳＣＨ層 Reference Signs List 10 n-type InP substrate 11 diffraction grating 12 n-InGaAsP optical guide layer 13 multiple quantum well (MQW) active layer 14 p-InP cladding layer 15 p-InP current blocking layer 16 n-InP current blocking layer 17 p-InP cladding layer 18 p-InGaAsP cap layer 19, 20 electrode 30 well layer 31 barrier layer 32, 33 SCH layer
Claims (6)
し、前面の反射率が１％以下でかつ、活性層と回折格子
との結合係数κと共振器長Ｌの積が０．４≦κＬ≦１．
０であることを特徴とする分布帰還型半導体レーザ。 An active layer having a uniform diffraction grating in the direction of the resonator is provided.
And the active layer and the diffraction grating have a reflectance of 1% or less on the front surface.
The product of the coupling coefficient κ and the cavity length L is 0.4 ≦ κL ≦ 1.
0. A distributed feedback semiconductor laser characterized by being zero.
し、前面の反射率が１％以下でかつ、活性層と回折格子And the active layer and the diffraction grating have a reflectance of 1% or less on the front surface.
との結合係数κと共振器長Ｌの積が０．５≦κＬ≦０．The product of the coupling coefficient κ and the cavity length L is 0.5 ≦ κL ≦ 0.
７であることを特徴とする分布帰還型半導体レーザ。7. A distributed feedback semiconductor laser, wherein
型半導体レーザにおいて、後面の反射率が５０％以上で
あることを特徴とする分布帰還型半導体レーザ。 3. The distributed feedback according to claim 1,
Type semiconductor laser with a rear surface reflectance of 50% or more
A distributed feedback semiconductor laser characterized by the following.
型半導体レーザにおいて、後面の反射率が９０％以上で
あることを特徴とする分布帰還型半導体レーザ。 4. The distributed feedback according to claim 1,
Type semiconductor laser with a back surface reflectance of 90% or more
A distributed feedback semiconductor laser characterized by the following.
し、前面の反射率が５％未満であり、後面の反射率が５
０％以上であり、かつ活性層と回折格子との結合係数κ
と共振器長Ｌの積が０．４≦κＬ≦１．０であることを
特徴とする分布帰還型半導体レーザ。 5. A semiconductor device having a uniform diffraction grating and an active layer in the resonator direction.
The reflectance of the front surface is less than 5%, and the reflectance of the rear surface is less than 5%.
0% or more, and the coupling coefficient κ between the active layer and the diffraction grating
And the resonator length L is 0.4 ≦ κL ≦ 1.0.
Characteristic distributed feedback semiconductor laser.
し、前面の反射率が５％未満であり、後面の反射率が５
０％以上であり、かつ活性層と回折格子との結合係数κ
と共振器長Ｌの積が０．５≦κＬ≦０．７であることを
特徴とする分布帰還型半導体レーザ。 6. It has a uniform diffraction grating and an active layer in the resonator direction.
The reflectance of the front surface is less than 5%, and the reflectance of the rear surface is less than 5%.
0% or more, and the coupling coefficient κ between the active layer and the diffraction grating
And the product of the resonator length L is 0.5 ≦ κL ≦ 0.7.
Characteristic distributed feedback semiconductor laser.
Priority Applications (8)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5001501A JP2600490B2 (en) | 1993-01-08 | 1993-01-08 | Distributed feedback semiconductor laser |
| CA002210008A CA2210008C (en) | 1993-01-08 | 1994-01-07 | Laser diode element with excellent intermodulation distortion characteristic |
| EP96115482A EP0753914B1 (en) | 1993-01-08 | 1994-01-07 | Laser diode element with excellent intermodulation distortion characteristic |
| US08/178,859 US5469459A (en) | 1993-01-08 | 1994-01-07 | Laser diode element with excellent intermodulation distortion characteristic |
| EP94100190A EP0606092A3 (en) | 1993-01-08 | 1994-01-07 | Laser diode element. |
| CA002113027A CA2113027C (en) | 1993-01-08 | 1994-01-07 | Laser diode element with excellent intermodulation distortion characteristic |
| DE69425835T DE69425835T2 (en) | 1993-01-08 | 1994-01-07 | Laser diode element with excellent intermodulation distortion characteristics |
| US08/463,635 US5568505A (en) | 1993-01-08 | 1995-06-06 | Laser diode element with excellent intermodulation distortion characteristic |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5001501A JP2600490B2 (en) | 1993-01-08 | 1993-01-08 | Distributed feedback semiconductor laser |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH06204607A JPH06204607A (en) | 1994-07-22 |
| JP2600490B2 true JP2600490B2 (en) | 1997-04-16 |
Family
ID=11503218
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP5001501A Expired - Lifetime JP2600490B2 (en) | 1993-01-08 | 1993-01-08 | Distributed feedback semiconductor laser |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2600490B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6788725B2 (en) | 2001-11-14 | 2004-09-07 | Mitsubishi Denki Kabushiki Kaisha | Semiconductor laser device |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH01155677A (en) * | 1987-12-11 | 1989-06-19 | Toshiba Corp | Distributed feedback type semiconductor laser element |
| JPH0220087A (en) * | 1988-07-08 | 1990-01-23 | Toshiba Corp | Distributed feedback type semiconductor laser element |
| JPH03283483A (en) * | 1990-03-29 | 1991-12-13 | Mitsubishi Electric Corp | Semiconductor laser device |
| JP2751558B2 (en) * | 1990-04-13 | 1998-05-18 | 日本電気株式会社 | Integrated optical semiconductor device and driving method thereof |
-
1993
- 1993-01-08 JP JP5001501A patent/JP2600490B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH06204607A (en) | 1994-07-22 |
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