JP2008530814A - Quantum well laser diode with broadband gain - Google Patents

Quantum well laser diode with broadband gain Download PDF

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JP2008530814A
JP2008530814A JP2007556067A JP2007556067A JP2008530814A JP 2008530814 A JP2008530814 A JP 2008530814A JP 2007556067 A JP2007556067 A JP 2007556067A JP 2007556067 A JP2007556067 A JP 2007556067A JP 2008530814 A JP2008530814 A JP 2008530814A
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quantum well
laser diode
active layer
diffraction grating
multiple quantum
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グ、ボン−ゾ
キム、ヨン−カン
ホ、クァン−ス
ソン、ハン−ウク
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LS Cable and Systems Ltd
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    • 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
    • H01S5/30—Structure or shape of the active region; Materials used for the active region
    • H01S5/34—Structure or shape of the active region; Materials used for the active region comprising quantum well or superlattice structures, e.g. single quantum well [SQW] lasers, multiple quantum well [MQW] lasers or graded index separate confinement heterostructure [GRINSCH] lasers
    • H01S5/343—Structure or shape of the active region; Materials used for the active region comprising quantum well or superlattice structures, e.g. single quantum well [SQW] lasers, multiple quantum well [MQW] lasers or graded index separate confinement heterostructure [GRINSCH] lasers in AIIIBV compounds, e.g. AlGaAs-laser, InP-based laser
    • H01S5/34346—Structure or shape of the active region; Materials used for the active region comprising quantum well or superlattice structures, e.g. single quantum well [SQW] lasers, multiple quantum well [MQW] lasers or graded index separate confinement heterostructure [GRINSCH] lasers in AIIIBV compounds, e.g. AlGaAs-laser, InP-based laser characterised by the materials of the barrier layers
    • H01S5/3438—Structure or shape of the active region; Materials used for the active region comprising quantum well or superlattice structures, e.g. single quantum well [SQW] lasers, multiple quantum well [MQW] lasers or graded index separate confinement heterostructure [GRINSCH] lasers in AIIIBV compounds, e.g. AlGaAs-laser, InP-based laser characterised by the materials of the barrier layers based on In(Al)P
    • 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
    • H01S5/30—Structure or shape of the active region; Materials used for the active region
    • H01S5/34—Structure or shape of the active region; Materials used for the active region comprising quantum well or superlattice structures, e.g. single quantum well [SQW] lasers, multiple quantum well [MQW] lasers or graded index separate confinement heterostructure [GRINSCH] lasers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y20/00—Nanooptics, e.g. quantum optics or photonic crystals
    • 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
    • H01S5/22—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 having a ridge or stripe structure
    • H01S5/227—Buried mesa structure ; Striped active layer
    • 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
    • H01S5/22—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 having a ridge or stripe structure
    • H01S5/227—Buried mesa structure ; Striped active layer
    • H01S5/2275—Buried mesa structure ; Striped active layer mesa created by etching

Abstract

本発明は、注入された電流を光に変換する、多重量子井戸構造を備えた活性層と、当該活性層を挟んで形成される化合物半導体のＰＮ接合構造と、電流の注入のための電極とを含む量子井戸レーザーダイオードにおいて、当該活性層の多重量子井戸は、量子井戸の厚さが均一でない構造を有することを特徴とする量子井戸レーザーダイオードを提供する。
【選択図】図４The present invention relates to an active layer having a multiple quantum well structure that converts injected current into light, a PN junction structure of a compound semiconductor formed with the active layer interposed therebetween, an electrode for current injection, In the quantum well laser diode, the multiple quantum well of the active layer has a structure in which the thickness of the quantum well is not uniform.
[Selection] Figure 4

Description

本発明は、レーザーダイオード（Ｌａｓｅｒ Ｄｉｏｄｅ；ＬＤ）に関するものであって、より詳しくは、広帯域利得（Ｗｉｄｅｂａｎｄ Ｇａｉｎ）を提供する多重量子井戸（Ｍｕｔｉｐｌｅ Ｑｕａｎｔｕｍ Ｗｅｌｌ；ＭＱＷ）構造を備えたレーザーダイオードに関する。   The present invention relates to a laser diode (LD), and more particularly, to a laser diode having a multiple quantum well (MQW) structure that provides a wideband gain.

半導体レーザーダイオードの中で、特に、非冷却型分布帰還型レーザーダイオード（Ｕｎｃｏｏｌｅｄ ＤＦＢ ＬＤ）は、通常埋め立てられた活性層と平坦な表面を有するＰＢＨ（Ｐｌａｎａｒ Ｂｕｒｉｅｄ Ｈｅｔｅｒｏｓｔｒｕｃｔｕｒｅ）構造から成る。   Among semiconductor laser diodes, in particular, an uncooled distributed feedback laser diode (Uncooled DFB LD) has a PBH (Planar Buried Heterostructure) structure having a normally buried active layer and a flat surface.

図１を参照すれば、一般的な分布帰還型レーザーダイオードは、ベースになるＩｎＰ基板１０と、注入された電流を光に変換させる活性層１３と、光がよく拘束されるよう当該活性層１３の両側に備えられるＩｎＧａＡｓＰ物質の光拘束層１２、１４と、シングルモード波長を作るように当該ＩｎＰ基板１０と当該活性層１３との間に備えられる回折格子１１と、当該光拘束層１４の上に行きながら順次備えられるｐ−ＩｎＰクラッド層１５、ＩｎＧａＡｓ層１６、ＩｎＰ層１７とを含む。   Referring to FIG. 1, a general distributed feedback laser diode includes a base InP substrate 10, an active layer 13 that converts injected current into light, and the active layer 13 so that light is well constrained. Optical constraining layers 12 and 14 of InGaAsP material provided on both sides of the substrate, a diffraction grating 11 provided between the InP substrate 10 and the active layer 13 so as to produce a single mode wavelength, and the optical constraining layer 14 The p-InP clad layer 15, the InGaAs layer 16, and the InP layer 17 are sequentially provided while going to the center.

特に、前記活性層１３は、光が生成される部分であって、最近ではレーザーダイオードの性能を向上させるために量子井戸１３ａと障壁層１３ｂが反復的に形成された多重量子井戸構造が備えられることが一般的である。   In particular, the active layer 13 is a portion where light is generated, and recently, in order to improve the performance of the laser diode, a multiple quantum well structure in which a quantum well 13a and a barrier layer 13b are repeatedly formed is provided. It is common.

従来のレーザーダイオードに備えられる多重量子井戸は、一様に量子井戸の厚さが互いに同一の構造を有するが、図２に示すように、それぞれの量子井戸の厚さが同一の場合、全ての量子井戸の伝導帯域に拘束される電子のエネルギー状態が類似であり、また価電子帯域にある正孔のエネルギー状態が全て類似な値を有するため、伝導帯域の電子が価電子帯域の正孔と結合して作り出すエネルギー（Ｅｇ）が全て類似な波長領域に存在するようになる（図３の利得プロファイルを参照）。   The multiple quantum wells provided in the conventional laser diode have a structure in which the thicknesses of the quantum wells are uniformly the same as each other, but as shown in FIG. Since the energy states of the electrons constrained by the conduction band of the quantum well are similar, and the energy states of the holes in the valence band all have similar values, the electrons in the conduction band are different from the holes in the valence band. All of the energy (Eg) produced by combining exists in a similar wavelength region (see the gain profile in FIG. 3).

一方、レーザーダイオードの動作を見れば、順方向電圧を印加する初期にはレーザーダイオードがＬＥＤのように作動することになるが、これは低電圧領域で活性層のキャリアが反転分布（Ｐｏｐｕｌａｔｉｏｎ ｉｎｖｅｒｓｉｏｎ）になるほど十分ではなく自然放出（Ｓｐｏｎｔａｎｅｏｕｓ ｅｍｉｓｓｉｏｎ）が優勢だからである。電圧が増加するにつれて活性層内で反転分布が起き、誘導放出（Ｓｔｉｍｕｌａｔｅｄ ｅｍｉｓｓｉｏｎ）が優勢になる閾値電圧（Ｔｈｒｅｓｈｏｌｄ ｖｏｌｔａｇｅ）地点においては、レーザーダイオード内における光の損失と光増幅による利得とがバランスを取るようになり、閾値電流（Ｔｈｒｅｓｈｏｌｄ ｃｕｒｒｅｎｔ）が流れるときにＬＥＤ動作からレーザー発振への変化が起きるようになる。閾値電流以上の注入電流からは誘導放出によりレーザーダイオードから干渉性（Ｃｏｈｅｒｅｎｔ）の光が出るようになり、このときに、波長スペクトルはファブリ−ペロー（Ｆａｂｒｙ−Ｐｅｒｏｔ）モードを満足する共振条件と、多重量子井戸構造によって決められる利得スペクトルプロファイルによって多重モード（Ｍｕｌｔｉｐｌｅ ｍｏｄｅ）の波長を含むようになる。   On the other hand, in the operation of the laser diode, the laser diode operates like an LED in the initial period of applying the forward voltage. This is because the carriers in the active layer are inversion distribution (Population inversion) in the low voltage region. This is because the spontaneous emission is dominant. As the voltage increases, an inversion distribution occurs in the active layer, and at the threshold voltage point where stimulated emission becomes dominant, the loss of light in the laser diode and the gain due to optical amplification balance. Thus, when a threshold current flows, a change from LED operation to laser oscillation occurs. Coherent light is emitted from the laser diode by stimulated emission from an injection current that is equal to or higher than the threshold current, and at this time, the resonance condition that the wavelength spectrum satisfies the Fabry-Perot mode, The gain spectrum profile determined by the multiple quantum well structure includes multiple mode wavelengths.

分布帰還型レーザーダイオード（ＤＦＢ ＬＤ）は、ファブリ−ペローレーザーダイオードの活性層の近くに回折格子を備えた構造を有するものであって、回折格子のピッチ（Ｐｉｔｃｈ）に応じて反射指数（Ｒｅｆｌｅｃｔｉｖｅ ｉｎｄｅｘ）が変わるようになり、利得スペクトルで回折格子の周期に合う特定のブラッグ波長（Ｂｒａｇｇ ｗａｖｅｌｅｎｇｔｈ）のみを選択的に出力する。すなわち、数個のファブリ−ペローモードの中で一つのモードのみを選択的に取ってシングルモード波長スペクトル（ＤＦＢモード）を可能にさせる。   A distributed feedback laser diode (DFB LD) has a structure having a diffraction grating near the active layer of a Fabry-Perot laser diode, and has a reflection index (Reflective index) according to the pitch of the diffraction grating. ) Is changed, and only a specific Bragg wavelength (Bragg wavelength) matching the period of the diffraction grating in the gain spectrum is selectively output. That is, only one mode is selectively selected from several Fabry-Perot modes to enable a single mode wavelength spectrum (DFB mode).

一般に、ＤＦＢモードと利得ピーク（ファブリ−ペローモード）の温度係数は、それぞれ約０.１ｎｍ／℃と０.４ｎｍ/℃の値を有する。このような温度係数の差により温度変化に応じたＤＦＢモードの動作範囲がたびたび制約を受ける。通常、利得ピークは温度が変わるときＤＦＢモードより３倍〜５倍速く動くため、もしＤＦＢモードと利得ピークが一致すれば、より低い、またはより高い温度でＤＦＢモードが利得ピークから分離され、ひどい場合、ＤＦＢモードと利得ピークが結合できないため、ファブリ−ペローモードが発振するようになる。ＤＦＢモードの温度動作範囲は結合係数の関数であり、結合係数が増加するにつれて増加する。大きい結合係数は閾値電流密度を低く維持しＤＦＢモードの動作温度範囲を広くする長所があるが、非線形的な電流−光出力特性を示すかキンク（Ｋｉｎｋ）特性を示すため、結合係数を大きくすることができない。従って、−４０〜８５℃程度の温度範囲でＤＦＢ発振が可能な非冷却分布帰還型レーザーダイオードを製作するため、従来には結合係数を適当な値で維持した状態で利得ピークとＤＦＢモード発振波長間の間隔、すなわち離調（Ｄｅｔｕｎｉｎｇ）を適当に調節してＤＦＢモード発振の温度範囲を調節する方式が用いられた。   In general, the temperature coefficients of the DFB mode and the gain peak (Fabry-Perot mode) have values of about 0.1 nm / ° C. and 0.4 nm / ° C., respectively. Due to the difference in temperature coefficient, the operation range of the DFB mode corresponding to the temperature change is often restricted. Normally, the gain peak moves 3 to 5 times faster than the DFB mode when the temperature changes, so if the DFB mode and the gain peak match, the DFB mode is separated from the gain peak at a lower or higher temperature and is terrible. In this case, since the DFB mode and the gain peak cannot be coupled, the Fabry-Perot mode oscillates. The temperature operating range of the DFB mode is a function of the coupling coefficient and increases as the coupling coefficient increases. A large coupling coefficient has the advantage of maintaining a low threshold current density and widening the operating temperature range of the DFB mode. However, the coupling coefficient is increased because it exhibits a nonlinear current-light output characteristic or a kink characteristic. I can't. Therefore, in order to manufacture an uncooled distributed feedback laser diode capable of DFB oscillation in the temperature range of about -40 to 85 ° C., conventionally, the gain peak and the DFB mode oscillation wavelength are maintained with the coupling coefficient maintained at an appropriate value. A method of adjusting the temperature range of the DFB mode oscillation by appropriately adjusting the interval, that is, detuning was used.

しかし、従来の非冷却型分布帰還型レーザーダイオードは多重量子井戸を成す量子井戸の厚さが全て均一な構造を有することから、−３ｄＢにおける利得ピークの幅（利得ピークの１／２になる地点の幅）が狭いので全体温度範囲（−４０〜８５℃）を満足する値に対して離調地点を取っても離調値の許容範囲が小さくなる。また、半導体基板に多重量子井戸を生成させるときウエハー全体の利得ピーク均一度も厳格に管理しなければならないという問題がある。   However, since the conventional uncooled distributed feedback laser diode has a structure in which the thicknesses of the quantum wells forming the multiple quantum well are all uniform, the gain peak width at -3 dB (a point where the gain peak is ½) Therefore, even if a detuning point is taken with respect to a value satisfying the entire temperature range (−40 to 85 ° C.), the allowable range of the detuning value becomes small. In addition, there is a problem that the uniformity of the gain peak of the entire wafer must be strictly managed when generating multiple quantum wells on a semiconductor substrate.

本発明は、上述のような点を考慮して創案されたものであって、使用温度範囲をより広げるように広帯域利得を有する、多重量子井戸構造を備えたレーザーダイオードを提供することにその目的がある。   The present invention was devised in view of the above points, and an object of the present invention is to provide a laser diode having a multiple quantum well structure having a broadband gain so as to further widen the operating temperature range. There is.

上述のような目的を果たすため、本発明は、注入された電流を光に変換する、多重量子井戸構造を備えた活性層と、当該活性層を挟んで形成される化合物半導体のＰＮ接合構造と、電流を注入するための電極とを含む量子井戸レーザーダイオードにおいて、当該活性層の多重量子井戸は、量子井戸の厚さが均一でない構造を有することを特徴とする。   In order to achieve the above-described object, the present invention provides an active layer having a multiple quantum well structure that converts injected current into light, and a PN junction structure of a compound semiconductor formed with the active layer interposed therebetween. In the quantum well laser diode including an electrode for injecting current, the multiple quantum well of the active layer has a structure in which the thickness of the quantum well is not uniform.

前記多重量子井戸は、量子井戸の厚さがそれぞれ異なるように構成してもよい。   The multiple quantum wells may be configured such that the quantum wells have different thicknesses.

代案として、前記多重量子井戸は、同じ厚さを有する量子井戸のグループを含み、当該グループごとに異なる厚さを有する構造から成り立たせてもよい。   As an alternative, the multiple quantum well may include a group of quantum wells having the same thickness, and a structure having a different thickness for each group.

本発明には、ベースになるＩｎＰ基板と、当該基板と前記活性層との間に介在される、当該活性層で生成された光をシングルモード波長にする回折格子がさらに含まれる。   The present invention further includes a base InP substrate and a diffraction grating that is interposed between the substrate and the active layer and converts light generated in the active layer to a single mode wavelength.

前記回折格子としては、指数結合（Ｉｎｄｅｘ ｃｏｕｐｌｅｄ）型、利得結合（Ｇａｉｎ ｃｏｕｐｌｅｄ）型、損失結合（Ｌｏｓｓ ｃｏｕｐｌｅｄ）型または複合結合（Ｃｏｍｐｌｅｘ ｃｏｕｐｌｅｄ）型が採用されることが望ましい。   As the diffraction grating, it is preferable to employ an index coupled type, a gain coupled type, a loss coupled type, or a complex coupled type.

前記回折格子により作られるシングルモード波長は、可視光領域から赤外線領域までの範囲に含まれる。   The single mode wavelength produced by the diffraction grating is included in the range from the visible light region to the infrared region.

本発明に備えられる導波構造としては、隆起（Ｒｉｄｇｅ）型または埋立ヘテロ構造（Ｂｕｒｉｅｄ Ｈｅｔｅｒｏｓｔｒｕｃｔｕｒｅ）が採用されることが望ましい。   As the waveguide structure provided in the present invention, it is desirable to adopt a ridge type or buried heterostructure.

前記多重量子井戸またはその障壁層には、ストレイン（Ｓｔｒａｉｎ）が印加されることが望ましい。   Preferably, a strain is applied to the multiple quantum well or its barrier layer.

以下、添付した図面を参照しながら本発明の望ましい実施例を詳しく説明する。これに先立って、本明細書及び請求範囲に使われた用語や単語は一般的及び辞書的な意味に限定して解釈されてはいけず、発明者は自らの発明を最善の方法で説明するために用語の概念を適切に定義することができるという原則に則して、本発明の技術的思想に符合する意味と概念とに解釈されなければならない。従って、本明細書に記載された実施例は本発明の最も望ましい一実施例に過ぎず、本発明の技術的思想の全てを代弁するものではないため、本出願時点においてこれらに代替できる多様な均等物と変形例があり得ることを理解しなければならない。   Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms and words used in this specification and claims should not be construed as limited to general and lexical meaning, and the inventor will best explain his invention. Therefore, in accordance with the principle that the concept of a term can be appropriately defined, it should be interpreted as a meaning and a concept consistent with the technical idea of the present invention. Therefore, the embodiment described in the present specification is only the most preferred embodiment of the present invention, and does not represent all the technical ideas of the present invention. It should be understood that there can be equivalents and variations.

図４は、本発明の望ましい実施例による量子井戸レーザーダイオードの構成を示す切開斜視図である。
図４を参照すれば、本発明の望ましい実施例による量子井戸レーザーダイオードは、化合物半導体のＰＮ接合構造の間に備えられる多重量子井戸構造を備えた活性層１０２と、電流を注入するための電極１０１ａ、１０１ｂとを含み、当該多重量子井戸を成す量子井戸の厚さが均一でない構造を有する。このようなレーザーダイオードに備えられる導波構造としては、公知の隆起型あるいは埋立ヘテロ構造の採用が望ましい。 FIG. 4 is a cut perspective view illustrating a configuration of a quantum well laser diode according to a preferred embodiment of the present invention.
Referring to FIG. 4, a quantum well laser diode according to a preferred embodiment of the present invention includes an active layer 102 having a multiple quantum well structure provided between compound semiconductor PN junction structures, and an electrode for injecting current. 101a and 101b, and the quantum wells constituting the multiple quantum well have a non-uniform thickness. As the waveguide structure provided in such a laser diode, it is desirable to adopt a known raised type or buried heterostructure.

より具体的に、本発明の望ましい実施例によるレーザーダイオードは、ＩｎＰ基板１００の上で活性層１０２が１〜１.５μｍ程度の幅を有するメサ（Ｍｅｓａ）模様にエッチングされて形成され、エッチングされた活性層１０２の両側にｐ−ＩｎＰ層とｎ−ＩｎＰ層の電流遮断層１０３が生成され、さらに活性層１０２の上側にｐ−ＩｎＰクラッド層１０４が生成された構造を有する。ここで、電流遮断層１０３は、注入された電流が活性層１０２以外の領域に漏洩されるのを防ぐ作用をする。   More specifically, the laser diode according to the preferred embodiment of the present invention is formed by etching the active layer 102 on the InP substrate 100 into a mesa pattern having a width of about 1 to 1.5 μm. In addition, a current blocking layer 103 of a p-InP layer and an n-InP layer is generated on both sides of the active layer 102, and a p-InP cladding layer 104 is generated on the upper side of the active layer 102. Here, the current blocking layer 103 functions to prevent the injected current from leaking to a region other than the active layer 102.

望ましくは、前記ＩｎＰ基板１００と活性層１０２との間にはシングルモード波長を作るための回折格子１０８が備えられることである。このような回折格子１０８は、公知されている指数結合型、利得結合型、損失結合型または複合結合型が用いられることが望ましい。同時に、当該回折格子１０８により作られるシングルモード波長は、可視光領域から赤外線領域までの範囲に含まれることが望ましい。   Preferably, a diffraction grating 108 for generating a single mode wavelength is provided between the InP substrate 100 and the active layer 102. As such a diffraction grating 108, a known exponential coupling type, gain coupling type, loss coupling type, or composite coupling type is preferably used. At the same time, it is desirable that the single mode wavelength generated by the diffraction grating 108 be included in the range from the visible light region to the infrared region.

本発明の望ましい実施例によるレーザーダイオードには、寄生静電容量の減少のために略Ｕ字状でｐ−ＩｎＰ層１０４と電流遮断層１０３をエッチングして形成されたＵ−チャンネル１０７が用意される。   A laser diode according to a preferred embodiment of the present invention is provided with a U-channel 107 formed by etching the p-InP layer 104 and the current blocking layer 103 in a substantially U shape to reduce parasitic capacitance. The

また、前記Ｕ−チャンネル１０７上には、ＩｎＧａＡｓ層１０５及び絶縁層１０６が蒸着された後、Ｕ−チャンネル１０７の内側部分の絶縁層１０６が選択的に除去され、その除去された部分には上記ＩｎＰ基板１００下面のｎ型電極１０１ａに対応するｐ型電極１０１ｂが所定のパターンに形成される。   In addition, after the InGaAs layer 105 and the insulating layer 106 are deposited on the U-channel 107, the insulating layer 106 inside the U-channel 107 is selectively removed. A p-type electrode 101b corresponding to the n-type electrode 101a on the lower surface of the InP substrate 100 is formed in a predetermined pattern.

上述のように、多層で構成された後、レーザーダイオードの長さに合わせてウエハー切断工程を経て形成されるファセット（Ｆａｃｅｔ）の表側は無反射膜（図示しない）がコートされ、裏側は高反射膜１０９がコートされて光出力効率をより高めるようになる。   As described above, after being composed of multiple layers, the front side of the facet formed through the wafer cutting process according to the length of the laser diode is coated with a non-reflective film (not shown), and the back side is highly reflective. The film 109 is coated to further increase the light output efficiency.

特に、活性層１０２は、電極１０１ａ、１０１ｂを通じて注入される電流を光に変換させるものであって、多重量子井戸構造を備える。ここで、多重量子井戸構造は、厚さがそれぞれ異なる量子井戸を含んで構成される。代案として、多重量子井戸構造は、同じ厚さを有する量子井戸のグループを含み、各グループごとに異なる厚さを有するように構成してもよい。   In particular, the active layer 102 converts a current injected through the electrodes 101a and 101b into light, and has a multiple quantum well structure. Here, the multiple quantum well structure includes quantum wells having different thicknesses. Alternatively, the multiple quantum well structure may include groups of quantum wells having the same thickness, with each group having a different thickness.

前記多重量子井戸は、量子井戸と障壁層が反復的に形成された構造を有するが、レーザーダイオードの特性を調節するように各量子井戸や障壁層にはストレインが印加されてもよい。   The multiple quantum well has a structure in which a quantum well and a barrier layer are repeatedly formed. However, a strain may be applied to each quantum well or barrier layer so as to adjust the characteristics of the laser diode.

図５に示すように、量子井戸の厚さが互いに異なるように形成されれば、伝導帯域にある量子井戸のエネルギー状態が多様に分布し、同じく価電子帯域の正孔のエネルギー状態が全て異なる値を有するようになる。従って、伝導帯域の電子が価電子帯域の正孔と結合して作り出すエネルギー（Ｅｇ）が広い波長領域に渡って存在することになるので、図６に示すように、波長による利得プロファイルが、図３を参照して説明した従来技術に比べて相対的に広い利得幅を有するようになる。   As shown in FIG. 5, if the quantum wells are formed to have different thicknesses, the energy states of the quantum wells in the conduction band are distributed in various ways, and the energy states of the holes in the valence band are all different. Has a value. Therefore, energy (Eg) generated by combining electrons in the conduction band with holes in the valence band exists over a wide wavelength region. Therefore, as shown in FIG. As compared with the prior art described with reference to FIG. 3, the gain width is relatively wide.

一方、従来技術により量子井戸の厚さを均一にして非冷却型分布帰還型レーザーダイオードを製作する場合には、図７に示すような、利得ピーク及びブラッグ波長の変化特性が現れる。すなわち、常温Ｔ２で、利得ピーク（中央プロファイルを参照）とＤＦＢモードブラッグ波長（Ａ）を一致させたとき、低温Ｔ１（左側プロファイルを参照）や高温Ｔ３（右側プロファイルを参照）で利得ピークの移動速度がブラッグ波長（Ｔ１はＢ、Ｔ３はＣを参照）の移動速度より速いので、低温Ｔ１や高温Ｔ３におけるブラッグ波長の利得値がＤＦＢ閾値利得値（基準線Ｉを参照）より小さくてＤＦＢ発振にならず、低温や高温の利得プロファイルのピーク地点におけるファブリ−ペロー波長が発振するようになる。   On the other hand, when an uncooled distributed feedback laser diode is manufactured with the quantum well thickness made uniform according to the prior art, gain peak and Bragg wavelength change characteristics appear as shown in FIG. That is, when the gain peak (refer to the center profile) and the DFB mode Bragg wavelength (A) are matched at room temperature T2, the gain peak shifts at low temperature T1 (refer to the left profile) or high temperature T3 (refer to the right profile). Since the speed is faster than the moving speed of the Bragg wavelength (see B for T1 and C for T3), the gain value of the Bragg wavelength at the low temperature T1 and the high temperature T3 is smaller than the DFB threshold gain value (see the reference line I) and DFB oscillation However, the Fabry-Perot wavelength at the peak point of the low-temperature or high-temperature gain profile oscillates.

一方、本発明によって多重量子井戸の厚さを図５のように形成すれば、利得幅が相対的に広いので非冷却型分布帰還レーザーダイオードを製作する場合には、図８に示すような、利得ピーク及びブラッグ波長の変化特性が現れる。すなわち、常温Ｔ２で利得ピーク（中央プロファイルを参照）とブラッグ波長（Ａ）を一致させたとき、低温Ｔ１や高温Ｔ３における利得ピーク（Ｔ１は左側、Ｔ３は右側プロファイルを参照）の移動速度がブラッグ波長（Ｔ１はＢ、Ｔ３はＣを参照）の移動速度より速いが、利得プロファイルの幅が広いので低温Ｔ１や高温Ｔ３におけるブラッグ波長の利得値がＤＦＢ閾値利得値（基準線Ｉを参照）より充分大きくてＤＦＢ発振が起きファブリ−ペロー波長が発振しない。   On the other hand, if the thickness of the multiple quantum well is formed as shown in FIG. 5 according to the present invention, the gain width is relatively wide. Therefore, when an uncooled distributed feedback laser diode is manufactured, as shown in FIG. Gain peak and Bragg wavelength change characteristics appear. That is, when the gain peak (refer to the central profile) and the Bragg wavelength (A) coincide with each other at room temperature T2, the moving speed of the gain peak at low temperature T1 or high temperature T3 (refer to the left profile for T1 and the right profile for T3) is Bragg. Faster than the moving speed of the wavelength (T1 for B, T3 for C), but the gain profile is wide, so the Bragg wavelength gain value at low temperature T1 or high temperature T3 is higher than the DFB threshold gain value (see reference line I) DFB oscillation occurs and the Fabry-Perot wavelength does not oscillate.

したがって、量子井戸を除いた全ての構成が同一の条件であれば、本発明で用いる多重量子井戸を用いる場合、従来技術に比べてより広い温度領域でＤＦＢモード発振が可能である。   Therefore, if all the configurations except for the quantum well are the same, when the multiple quantum well used in the present invention is used, DFB mode oscillation is possible in a wider temperature region than in the conventional technique.

本発明において、量子井戸を製作する工程そのものは従来の半導体工程技術を用いることができる。   In the present invention, a conventional semiconductor process technology can be used for the process of manufacturing the quantum well.

以上のように、本発明は、限定された実施例と図面とによって説明されたが、本発明はこれによって限定されず、本発明が属する技術分野において通常の知識を持つ者により本発明の技術思想と特許請求範囲の均等範囲内で多様な修正及び変形が可能なのは言うまでもない。   As described above, the present invention has been described with reference to the limited embodiments and drawings. However, the present invention is not limited thereto, and the technology of the present invention can be obtained by those having ordinary knowledge in the technical field to which the present invention belongs. It goes without saying that various modifications and variations can be made within the scope of the idea and the scope of claims.

本発明による分布帰還レーザーダイオードは、従来に比べて幅の広い利得プロファイルを有するようになるので、広い使用温度範囲に渡ってＤＦＢ発振が可能である。   Since the distributed feedback laser diode according to the present invention has a wider gain profile than the conventional one, DFB oscillation is possible over a wide operating temperature range.

また、不均一な多重量子井戸構造を用いるので、製造の際ウエハー全体の利得ピーク均一度を厳格に管理する必要がないという長所もある。   Further, since a non-uniform multiple quantum well structure is used, there is an advantage that it is not necessary to strictly control the gain peak uniformity of the entire wafer during manufacturing.

本明細書に添付される下記の図面は本発明の望ましい実施例を例示するものであって、発明の詳細な説明とともに本発明の技術思想をさらに理解させる役割を果たすものであるため、本発明はそのような図面に記載された事項にのみ限定されて解釈されてはいけない。   The following drawings attached to the present specification illustrate preferred embodiments of the present invention and serve to further understand the technical idea of the present invention together with the detailed description of the invention. Should not be construed as being limited to the matter described in such drawings.

従来技術による分布帰還型レーザーダイオードの構成図である。It is a block diagram of the distributed feedback type laser diode by a prior art. 従来技術による分布帰還型レーザーダイオードの多重量子井戸構造図である。1 is a multiple quantum well structure diagram of a distributed feedback laser diode according to the prior art. FIG. 従来技術による分布帰還型レーザーダイオードの利得プロファイル（Ｐｒｏｆｉｌｅ）である。It is a gain profile (Profile) of the distributed feedback type laser diode by a prior art. 本発明の望ましい実施例によるレーザーダイオードの構成を示す切開斜視図である。1 is a cut perspective view showing a configuration of a laser diode according to a preferred embodiment of the present invention. 図４の多重量子井戸構造図である。It is a multiple quantum well structure figure of FIG. 本発明の望ましい実施例によるレーザーダイオードの利得プロファイルである。3 is a gain profile of a laser diode according to a preferred embodiment of the present invention. 従来技術による分布帰還型レーザーダイオードの温度変化に応じた利得ピークとブラッグ（Ｂｒａｇｇ）波長の変化を示すグラフである。6 is a graph showing a change in gain peak and Bragg wavelength according to a temperature change of a distributed feedback laser diode according to the prior art. 本発明による分布帰還型レーザーダイオードの温度変化に応じた利得ピークとブラッグ波長の変化を示すグラフである。6 is a graph showing changes in gain peak and Bragg wavelength according to temperature changes of the distributed feedback laser diode according to the present invention.

Claims (8)

注入された電流を光に変換する、多重量子井戸構造を備えた活性層と、この活性層を挟んで形成される化合物半導体のＰＮ接合構造と、電流を注入するための電極とを含む量子井戸レーザーダイオードにおいて、
当該活性層の多重量子井戸は、量子井戸の厚さが均一でない構造を有することを特徴とする量子井戸レーザーダイオード。 A quantum well including an active layer having a multiple quantum well structure that converts injected current into light, a PN junction structure of a compound semiconductor formed across the active layer, and an electrode for injecting current In laser diode,
The quantum well laser diode, wherein the multiple quantum well of the active layer has a structure in which the thickness of the quantum well is not uniform. 前記多重量子井戸は、量子井戸の厚さがそれぞれ異なることを特徴とする請求項１に記載の量子井戸レーザーダイオード。 The quantum well laser diode according to claim 1, wherein the multiple quantum wells have different quantum well thicknesses. 前記多重量子井戸は、同じ厚さを有する量子井戸のグループを含み、当該グループごとに異なる厚さを有することを特徴とする請求項１に記載の量子井戸レーザーダイオード。 The quantum well laser diode according to claim 1, wherein the multiple quantum well includes a group of quantum wells having the same thickness, and the group has a different thickness. ベースになるＩｎＰ基板が備えられ、
前記基板と前記活性層との間に介在されて前記活性層で生成された光をシングルモード波長にする回折格子をさらに含むことを特徴とする請求項１に記載の量子井戸レーザーダイオード。 A base InP substrate is provided,
The quantum well laser diode according to claim 1, further comprising a diffraction grating interposed between the substrate and the active layer so that light generated in the active layer has a single mode wavelength. 前記回折格子として、指数結合型回折格子、利得結合型回折格子、損失結合型回折格子及び複合結合型回折格子のうちから選択された何れか一つが備えられたことを特徴とする請求項４に記載の量子井戸レーザーダイオード。 5. The diffraction grating according to claim 4, further comprising any one selected from an exponential coupled diffraction grating, a gain coupled diffraction grating, a loss coupled diffraction grating, and a composite coupled diffraction grating. The quantum well laser diode described. 前記回折格子により作られるシングルモード波長は、可視光領域から赤外線領域までの範囲に含まれることを特徴とする請求項４に記載の量子井戸レーザーダイオード。 5. The quantum well laser diode according to claim 4, wherein the single mode wavelength produced by the diffraction grating is included in a range from a visible light region to an infrared region. 光導波構造として、隆起型または埋立ヘテロ構造が用いられたことを特徴とする請求項１に記載の量子井戸レーザーダイオード。 2. The quantum well laser diode according to claim 1, wherein a raised type or a buried heterostructure is used as the optical waveguide structure. 前記多重量子井戸またはその障壁層にストレインが印加されたことを特徴とする請求項１に記載の量子井戸レーザーダイオード。 2. The quantum well laser diode according to claim 1, wherein a strain is applied to the multiple quantum well or a barrier layer thereof.
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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH02170589A (en) * 1988-12-23 1990-07-02 Hitachi Ltd Semiconductor element, wavelength variable semiconductor laser and semiconductor phase modulator
JPH07221403A (en) * 1994-02-03 1995-08-18 Mitsubishi Electric Corp Variable wave-length semiconductor laser
JPH07249829A (en) * 1994-03-10 1995-09-26 Hitachi Ltd Distributed feedback semiconductor laser
JPH09283837A (en) * 1996-04-09 1997-10-31 Matsushita Electric Ind Co Ltd Distributed semiconductor feed back laser device

Family Cites Families (4)

* Cited by examiner, † Cited by third party
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US5483547A (en) 1994-05-10 1996-01-09 Northern Telecom Limited Semiconductor laser structure for improved stability of the threshold current with respect to changes in the ambient temperature
JP3249999B2 (en) * 1995-03-13 2002-01-28 日本電信電話株式会社 Semiconductor laser device
GB2363901A (en) * 2000-06-20 2002-01-09 Mitel Semiconductor Ab An optical emission device having quantum wells

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH02170589A (en) * 1988-12-23 1990-07-02 Hitachi Ltd Semiconductor element, wavelength variable semiconductor laser and semiconductor phase modulator
JPH07221403A (en) * 1994-02-03 1995-08-18 Mitsubishi Electric Corp Variable wave-length semiconductor laser
JPH07249829A (en) * 1994-03-10 1995-09-26 Hitachi Ltd Distributed feedback semiconductor laser
JPH09283837A (en) * 1996-04-09 1997-10-31 Matsushita Electric Ind Co Ltd Distributed semiconductor feed back laser device

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