WO2016147450A1 - 量子カスケードレーザ - Google Patents
量子カスケードレーザ Download PDFInfo
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- H01S5/34313—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 with a well layer having only As as V-compound, e.g. AlGaAs, InGaAs
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- 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
- H01S5/34366—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 InGa(Al)AS
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- H01S5/2205—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 comprising special burying or current confinement layers
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Definitions
- Embodiments of the present invention relate to a quantum cascade laser.
- Quantum cascade laser Quantum Cascade Laser
- a semiconductor is small, highly convenient, and enables high-precision measurement.
- the quantum cascade laser has, for example, GaInAs and AlInAs stacked alternately and has an active layer including a quantum well layer. Then, both side surfaces of the active layer have a structure sandwiched between, for example, InP clad layers.
- the cascade-connected quantum well layers can emit infrared laser light having a wavelength of 3 to 20 ⁇ m due to intersubband transition of carriers.
- CO 2 gas contained in exhaled breath has a unique absorption spectrum due to infrared irradiation.
- the gas concentration can be known by measuring the amount of infrared absorption.
- the isotope ratio of 13 CO 2 and 12 CO 2 it is possible to diagnose the presence or absence of a human body abnormality.
- the wavelength range of the laser light emitted from the quantum cascade laser is required to be controlled to a range of 3.5 to 4.5 ⁇ m.
- a quantum cascade laser capable of high output in a wavelength band of 4.5 ⁇ m or less.
- the active layer of the quantum cascade laser has a plurality of light emitting regions and a plurality of injection regions.
- Each light emitting region has an injection barrier layer and a light emitting quantum well layer that has at least two well layers and emits infrared light by intersubband transition.
- Each injection region includes an extraction barrier layer and a relaxation quantum well layer that forms an energy level that relaxes the energy of carriers from the light emitting region.
- the well layer on the extraction barrier layer side is deeper than the second well layer on the injection barrier layer side.
- the respective light emitting regions and the respective injection regions are alternately stacked.
- FIG. 1A is a schematic perspective view in which the semiconductor laser device according to the first embodiment of the present invention is partially cut
- FIG. 1B is a schematic cross-sectional view along the line AA.
- 2A is an energy band diagram of the conduction band of a QCL quantum well structure having a lattice-matched luminescence quantum well layer
- FIG. 2B is a conduction diagram of a QCL having a luminescence quantum well layer whose lattice is not matched. It is an energy band figure of a belt. It is an energy band figure (electric field is zero) of the conduction band of QCL concerning a 1st embodiment.
- FIG. 4A is an energy band diagram of the QCL conduction band according to the second embodiment (when an electric field is applied), and FIG.
- FIG. 4B is a graph of a gain spectrum.
- FIG. 5A is an energy band diagram (when an electric field is applied) of the conduction band of the QCL according to the comparative example, and FIG. 5B is a graph of gain dependence with respect to wavelength.
- FIG. 6A is an energy band diagram of the conduction band of the QCL according to the third embodiment (when an electric field is applied), and FIG. 6B is a graph of gain dependence with respect to wavelength.
- FIG. 7A is an energy band diagram of the conduction band of the QCL according to the fourth embodiment (when an electric field is applied), and FIG. 7B is a graph of gain dependence with respect to wavelength.
- FIG. 8A is an energy band diagram of the conduction band of the QCL according to the fifth embodiment (when an electric field is applied), and FIG.
- FIG. 8B is a graph of gain dependence with respect to wavelength.
- FIG. 9A is an energy band diagram of the conduction band of the QCL according to the sixth embodiment (when an electric field is applied), and FIG. 9B is a graph of gain dependence with respect to wavelength.
- FIG. 10A is an energy band diagram of the conduction band of the QCL according to the seventh embodiment (when an electric field is applied), and FIG. 10B is a graph of gain dependence with respect to wavelength.
- FIG. 11A is a graph showing the absorption coefficients of 13 CO 2 and 12 CO 2 at wave numbers 2275 to 2325 cm ⁇ 1
- FIG. 11B is a graph showing the absorption coefficient of wave numbers 2295.7 to 2296.3 cm ⁇ 1 . .
- FIG. 1A is a schematic perspective view in which the quantum cascade laser according to the first embodiment of the present invention is partially cut
- FIG. 1B is a schematic cross-sectional view along the line AA.
- the quantum cascade laser includes at least a substrate 10, a stacked body 20 provided on the substrate 10, and a dielectric layer 40.
- the QCL may further include a first electrode 50, a second electrode 52, and an insulating film 42.
- the stacked body 20 includes a first cladding layer 22, a first guide layer 23, an active layer 24, a second guide layer 25, and a second cladding layer 28.
- the refractive index of the first cladding layer 22 and the refractive index of the second cladding layer 28 are respectively lower than the refractive indexes of the first guide layer 23, the active layer 24, and the second guide layer 25,
- the infrared laser beam 60 is appropriately confined in the stacking direction of the active layer 24.
- the stacked body 20 has a stripe shape and can be called a ridge waveguide RG.
- the two end surfaces of the ridge waveguide RG are mirror surfaces, the stimulated emission light is emitted from the light exit surface as infrared laser light 62.
- the optical axis 62 is defined as a line connecting the centers of the cross sections of the optical resonator having the mirror surface as the resonance surface. That is, the optical axis 62 coincides with the extending direction of the ridge waveguide RG.
- the width WA in the direction parallel to the first surface 24a and the second surface 24b of the active layer 24 is too wide, a high-order mode is generated in the horizontal horizontal direction, It becomes difficult to obtain an output. If the width WA of the active layer 24 is set to 5 to 20 ⁇ m, for example, the control in the horizontal and transverse mode becomes easy. Assuming that the refractive index of the dielectric layer 40 is lower than the refractive index of any layer constituting the active layer 24, the dielectric layer 40 provided so as to sandwich the side surfaces 20a and 20b of the stacked body 20 causes the optical axis to be A ridge waveguide RG can be formed along the line 62.
- FIG. 2A is an energy band diagram of a QCL quantum well structure having a lattice-matched light-emitting quantum well layer
- FIG. 2B is an energy band diagram of a QCL having a light-emitting quantum well layer whose lattice is not matched.
- QCL having a light emitting quantum well layer represented in FIG. 2 (a) has a MQW (Multi-Quatum Well) structure of three well layers, the depth D C of the potential (energy) of the well layer is the same Shall.
- Both the well layer and the barrier layer constituting the light emitting quantum well layer are lattice-matched to InP (lattice constant a0: about 5.8687 angstrom) which is a substrate.
- the well layer may be made of In 0.53 Ga 0.47 As and the barrier layer may be made of In 0.52 Al 0.48 As.
- the QCL comprises a light emitting quantum well layer represented in FIG. 2 (b), the has a deep well layer depth D D than the depth D C of the well layer represented in FIG. 2 (a).
- the lattice constant a1 is about 5.9242 angstroms.
- the barrier layer is made of In 0.362 Al 0.638 As, the lattice constant a2 is about 5.8049 angstroms.
- a compressive stress is applied to the well layer and a tensile stress is applied to the barrier layer with respect to InP serving as the substrate 10.
- the depth of the well layer is equal to the energy discontinuity ⁇ E C of the conduction band E C.
- the distortion compensation MQW represented in FIG. 2 (b) it can be larger than the depth D C of the well layers representing the depth D D of the well layer in FIG. 2 (a). Therefore, the interval between the subband levels of the well layer can be increased, and the wavelength ⁇ 1 of the infrared light due to the intersubband transition ST can be made shorter than the wavelength ⁇ 2 of the subband transition shown in FIG.
- FIG. 3 is an energy band diagram (electric field is zero) of the conduction band of the QCL according to the first embodiment.
- the first embodiment is QCL using electrons as carriers.
- the light emitting quantum well layer 86 has a plurality of well layers.
- the depth of the well layer from the injection barrier layer B1 side is represented by D1, D2, and D3.
- the depth of the well layer on the extraction barrier layer BE side is deeper than the well layer on the injection barrier layer BI side. That is, D1 ⁇ D2 or D2 ⁇ D3. Further, as shown in the figure, D1 ⁇ D2 ⁇ D3 may be satisfied.
- the wavelength of infrared light can be shortened.
- the relaxation quantum well layer 88 may be lattice-matched to the substrate 10.
- FIG. 4A is an energy band diagram of the QCL conduction band according to the second embodiment (when an electric field is applied), and FIG. 4B is a graph of a gain spectrum.
- the active layer 24 has a cascade structure in which light emitting regions and injection regions are alternately stacked.
- the electron wave function can be obtained by simulation.
- the light emitting regions 82 and 92 include an injection barrier layer BI and light emitting quantum well layers 86 and 96 that have at least two well layers and emit infrared light by intersubband transition.
- the injection regions 84 and 94 relax the energy of carriers from the extraction barrier layer BE and the light emitting regions 82 and 92, and inject energy into the next light emitting region (miniband levels Lm1, Lm2, etc.).
- the well layer on the extraction barrier layer BE side among the at least two adjacent well layers is deeper than the well layer on the injection barrier layer BI side.
- the depth of the well layer is D3 ⁇ D1 ⁇ D2.
- the depth of the well layer may gradually increase (D1 ⁇ D2 ⁇ D3).
- the energy levels become discrete and subbands (high level Lu, low level Ll) and the like are generated.
- Carriers injected from the injection barrier layer BI are effectively confined in the well layer, the carriers transition from the high level Lu to the low level Ll, and light (h ⁇ ) corresponding to (Lu ⁇ Ll) is emitted. .
- the energy L11 and L12 of the carriers injected into the injection region are relaxed to the miniband level Lm2 while passing through the relaxation quantum well layers 88 and 98.
- Table 1 represents the configuration of the QCL unit laminate according to the third embodiment.
- the numbers in the last column represent the thickness (angstrom) of each layer.
- the well layers constituting the light emitting quantum well layers 86 and 96 are all made of In 0.53 Ga 0.47 As and lattice-matched with InP (lattice constant: a0) of the substrate 10.
- the conduction band edges of the barrier layers constituting the light-emitting quantum well layers 86 and 96 are increased, and the barrier layers are increased (that is, the well layers are deepened).
- the barrier layers are increased (that is, the well layers are deepened).
- carriers are effectively confined in the well layers in the light emitting regions 82 and 92, and the light output can be increased.
- the injection barrier layer BI, the extraction barrier layer BE, and the relaxation quantum well layers 88 and 98 can be lattice-matched to InP of the substrate 10. If it does in this way, crystallinity will be maintained favorable as a whole.
- the conduction band E C In the energy band diagram when an electric field is applied, the conduction band E C is inclined. In the tilted energy band diagram, the energy E C at the conduction band edge of the barrier layer in the broken line region RB1 is locally changed by changing the composition ratio of the two barrier layers of the light emitting quantum well layers 86 and 96 to make lattice mismatch. Can be almost the same height.
- the intersubband transition mainly occurs in the second well layer (depth D1) of the light emitting quantum well layers 86 and 96.
- the vertical axis represents relative net mode gain
- the horizontal axis represents wavelength ( ⁇ m).
- the wavelength at which the net mode gain is maximized is in the vicinity of 3.7 ⁇ m and 4.3 ⁇ m. Therefore, spectroscopic measurement of 13 CO 2 and 12 CO 2 is possible.
- FIG. 5A is an energy band diagram (when electric field is applied) of the conduction band of the QCL according to the comparative example, and FIG.
- Table 2 all the quantum wells of the light emitting regions 182 and 192 and the injection regions 184 and 194 are lattice-matched to InP of the substrate 10.
- the height of the barrier layer is constant, and carriers leaking to the extraction barrier layer BE beyond the barrier layers of the light emitting quantum well layers 186 and 196 increase.
- the light confinement effect is lowered, and it is difficult to increase the transition between subbands. As a result, the light output is low.
- the wavelength at which the gain is maximized is 4.4 ⁇ m or more, which is shorter than this. Is difficult.
- FIG. 6A is an energy band diagram of the conduction band of the QCL according to the third embodiment (when an electric field is applied), and FIG. 6B is a graph of gain dependence with respect to wavelength.
- Table 3 represents the configuration of the QCL unit laminate according to the third embodiment.
- the well layers constituting the light emitting quantum well layers 86 and 96 are all made of In 0.53 Ga 0.47 As and lattice-matched with InP of the substrate 10.
- lattice constants of two adjacent layers composed of In 0.48 Al 0.52 As and In 0.46 Al 0.54 As, respectively. a2 is smaller than the lattice constant a0 of InP of the substrate 10. For this reason, as indicated by the broken line region RB2, the conduction band edges of the light emitting quantum well layers 86 and 96 are further raised as compared with the second embodiment, and the barrier layer is further increased (that is, the well layer is deepened).
- the injection barrier layer BI, the extraction barrier layer BE, and the relaxation quantum well layers 88 and 98 are lattice-matched to InP of Rob Plan 10. For this reason, the fall of crystallinity is suppressed as a whole.
- the wavelength at which the gain is maximized is in the vicinity of 3.7 ⁇ m. Therefore, spectroscopic measurement of 13 CO 2 and 12 CO 2 is possible.
- FIG. 7A is an energy band diagram of the conduction band of the QCL according to the fourth embodiment (when an electric field is applied), and FIG. 7B is a graph of gain dependence with respect to wavelength.
- Table 4 represents the configuration of the QCL unit laminate according to the fourth embodiment.
- the lattice constant a1 of the two layers having In 0.55 Ga 0.45 As and In 0.57 Ga 0.43 As is the substrate 10 It is larger than the lattice constant a0 of InP. For this reason, as represented by the broken line region RW1, the conduction band edges of the well layers of the light emitting quantum well layers 86 and 96 are lowered and the well layers are deepened.
- the conduction band edges of the light emitting quantum well layers 86 and 96 are higher than those in the second embodiment, and the barrier layer is further increased (that is, the well layer is deepened).
- the injection barrier layer BI, the extraction barrier layer BE, and the relaxation quantum well layers 88 and 98 are lattice-matched to InP of the substrate 10. For this reason, the fall of crystallinity is suppressed as a whole.
- the wavelength at which the gain is maximized is in the vicinity of 3.6 ⁇ m. Therefore, spectroscopic measurement of 13 CO 2 and 12 CO 2 is possible.
- FIG. 8A is an energy band diagram of the conduction band of the QCL according to the fifth embodiment (when an electric field is applied), and FIG. 8B is a graph of gain dependence with respect to wavelength. Moreover, (Table 5) represents the structure of the unit laminated body of QCL concerning 5th Embodiment.
- the conduction band edges of the light emitting quantum well layers 86 and 96 are higher than those of the second embodiment, and the barrier layer is further increased (that is, the well layer is deepened).
- the injection barrier layer BI, the extraction barrier layer BE, and the relaxation quantum well layers 88 and 98 are lattice-matched to InP of the substrate 10. For this reason, the fall of crystallinity is suppressed as a whole.
- the wavelength at which the gain is maximized is in the vicinity of 3.6 ⁇ m and 4.3 ⁇ m. Therefore, spectroscopic measurement of 13 CO 2 and 12 CO 2 is possible.
- FIG. 9A is a conduction band energy band diagram of QCL according to the sixth embodiment (when an electric field is applied), and FIG. 9B is a graph of gain dependence with respect to wavelength.
- Table 6 shows the structure of the QCL unit laminate according to the seventh embodiment.
- the lattice constant a2 of the two layers composed of In 0.48 Al 0.52 As and In 0.46 Al 0.54 As, respectively, is The lattice constant a0 of InP of the substrate 10 is smaller.
- the conduction band edges of the light emitting quantum well layers 86 and 96 are higher than those of the second embodiment, and the barrier layer is further increased (that is, the well layer is deepened).
- the injection barrier layer BI, the extraction barrier layer BE, and the relaxation quantum well layers 88 and 98 are lattice-matched to InP of the substrate 10. For this reason, the fall of crystallinity is suppressed as a whole.
- the wavelength at which the gain is maximized is in the vicinity of 3.55 ⁇ m. Therefore, spectroscopic measurement of 13 CO 2 and 12 CO 2 is possible.
- FIG. 10A is an energy band diagram (electric field applied state) of the conduction band of the QCL according to the seventh embodiment
- FIG. 10B is a graph of gain dependence with respect to wavelength.
- (Table 7) represents the structure of the unit laminated body of QCL concerning 7th Embodiment.
- the barrier layers constituting the light emitting quantum well layers 86 and 96 In 0.48 Al 0.52 As, In 0.46 Al 0.54 As, and In 0.48 Al 0.52 As, respectively.
- the lattice constant a2 of these three layers is smaller than the lattice constant a0 of InP of the substrate 10.
- the conduction band edges of the light emitting quantum well layers 86 and 96 are higher than those of the second embodiment, and the barrier layer is further increased (that is, the well layer is deepened).
- the injection barrier layer BI, the extraction barrier layer BE, and the relaxation quantum well layers 88 and 98 are lattice-matched to InP of the substrate 10. For this reason, the fall of crystallinity is suppressed as a whole.
- the wavelength at which the gain is maximized is in the vicinity of 3.55 ⁇ m. Therefore, spectroscopic measurement of 13 CO 2 and 12 CO 2 is possible.
- a quantum cascade laser capable of increasing the output in the wavelength band of 4.4 ⁇ m or less is provided.
- FIG. 11A is a graph showing the absorption coefficients of 13 CO 2 and 12 CO 2 at wave numbers 2275 to 2325 cm ⁇ 1
- FIG. 11B is a graph showing the absorption coefficient of wave numbers 2295.7 to 2296.3 cm ⁇ 1 .
- the CO 2 concentration is 8%
- the pressure is 0.5 atm
- the temperature is 313K.
- the isotopes of 13 CO 2 and 12 CO 2 can be used to detect H. pylori.
- a human drinks a reagent containing 13 C-urea as a labeled compound. If there is H. pylori in the stomach, it reacts with the reagent and 13 CO 2 is discharged as nausea. On the other hand, without H. pylori, 13 CO 2 is not discharged. Therefore, by measuring the isotope ratio of 13 CO 2 and 12 CO 2 , the degree of Helicobacter pylori infection can be known, and the stomach can be diagnosed with high accuracy.
- the test object is not limited to H. pylori. By measuring the concentration of CO 2 containing isotopes, the gastric emptying ability can be diagnosed in a wide range.
- FIG. 11A shows a wave number of 2275 cm ⁇ 1 (wavelength: 4.396 ⁇ m) to a wave number of 2325 cm ⁇ 1 (wavelength: 4.301 ⁇ m) is preferable.
- FIG. 11B shows a wave number range including one of the 12 CO 2 absorption lines and one of the 13 CO 2 absorption lines.
- the maximum value of the gain occurs at a wavelength of 4.4 ⁇ m or more, and it is difficult to cover a preferable wave number range.
- the maximum value of the gain can be controlled in the range of 3.55 to 4.5 ⁇ m.
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Abstract
Description
また、13CO2と12CO2の同位体比を測定すると、ヒトの身体の異常の有無を診断することが可能となる。この場合、量子カスケードレーザから放出されるレーザ光の波長範囲は、3.5~4.5μmの範囲などに制御することが要求される。
図1(a)は本発明の第1の実施形態にかかる量子カスケードレーザを部分切断した模式斜視図、図1(b)はA-A線に沿った模式断面図、である。
量子カスケードレーザ(QCL:Quantum Cascade Laser)は、基板10と、基板10の上に設けられた積層体20と、誘電体層40と、を少なくとも有する。また、QCLは、第1電極50と、第2電極52と、絶縁膜42と、をさらに有してもよい。
図2(a)に表す発光量子井戸層を有するQCLは、3つの井戸層のMQW(Multi-Quatum Well)構造を有し、井戸層のポテンシャル(エネルギー)の深さDCは、同一であるものとする。発光量子井戸層を構成する井戸層および障壁層は、ともに基板であるInP(格子定数a0:約5.8687オングストローム)に格子整合させる。たとえば、井戸層をIn0.53Ga0.47Asからなるものとし、障壁層をIn0.52Al0.48Asからなるものとすればよい。
なお、 第1の実施形態は、電子をキャリアとするQCLである。
活性層24は、発光領域と、注入領域と、が交互に積層されたカスケード構造を有する。なお、電子の波動関数は、シミュレーションにより求めることができる。
G=Γ×g-α
比較例では、(表2)に表すように、発光領域182、192および注入領域184、194のすべての量子井戸は、基板10のInPに格子整合している。このため、破線領域RBCで表すように、障壁層の高さが一定であり、発光量子井戸層186、196の障壁層を越えて抽出障壁層BEに漏れ出るキャリアが増加する。このため、光閉じ込め効果が低下し、サブバンド間遷移を高めることが困難となる。この結果、光出力は低い。
また、(表5)は、第5の実施形態にかかるQCLの単位積層体の構成を表す。
また、(表6)は、第7の実施形態にかかるQCLの単位積層体の構成を表す。
また、(表7)は、第7の実施形態にかかるQCLの単位積層体の構成を表す。
なお、CO2濃度は8%、圧力は0.5気圧、温度は313K、とする。
Claims (19)
- 注入障壁層と少なくとも2つの井戸層を有しサブバンド間遷移により赤外光を放出する発光量子井戸層とを含む複数の発光領域と、抽出障壁層と前記発光領域からのキャリアのエネルギーを緩和するエネルギー準位を形成する緩和量子井戸層とを含む複数の注入領域と、を有する活性層を備え、
それぞれの発光量子井戸層内で隣接する2つの井戸層において、前記抽出障壁層の側の井戸層は、前記注入障壁層の側の第2井戸層よりも深く、
それぞれの発光領域とそれぞれの注入領域とが交互に積層された、量子カスケードレーザ。 - 前記それぞれの発光量子井戸層において、前記抽出障壁層に向かうに従って井戸層が深くなる請求項1記載の量子カスケードレーザ。
- 前記発光領域と前記注入領域とが交互に積層される基板をさらに備えた請求項2記載の量子カスケードレーザ。
- 前記それぞれの発光量子井戸層は、前記基板の格子定数よりも小さい格子定数を有する障壁層を少なくとも1つ有する請求項3記載の量子カスケードレーザ。
- 電界が印加されて前記サブバンド間遷移を生じるとき、前記発光量子井戸層の障壁層のうち少なくとも2つの伝導帯端エネルギーは同一である請求項4記載の量子カスケードレーザ。
- 前記それぞれの発光量子井戸層は、前記基板の格子定数よりも大きい格子定数を有する井戸層を少なくとも1つ有する請求項3記載の量子カスケードレーザ。
- 前記それぞれの発光量子井戸層は、前記基板の格子定数よりも大きい格子定数を有する井戸層を少なくとも1つ有する請求項4記載の量子カスケードレーザ。
- 前記それぞれの発光量子井戸層は、前記基板の格子定数よりも大きい格子定数を有する井戸層を少なくとも1つ有する請求項5記載の量子カスケードレーザ。
- 前記それぞれの緩和量子井戸層は、前記基板の格子定数に整合した障壁層および井戸層を有する請求項3記載の量子カスケードレーザ。
- 前記それぞれの緩和量子井戸層は、同一の深さを有する複数の井戸層を含む請求項9記載の量子カスケードレーザ。
- 前記発光領域と前記注入領域とが交互に積層される基板をさらに備えた請求項1記載の量子カスケードレーザ。
- 前記それぞれの発光量子井戸層は、前記基板の格子定数よりも小さい格子定数を有する障壁層を少なくとも1つ有する請求項11記載の量子カスケードレーザ。
- 電界が印加されて前記サブバンド間遷移を生じるとき、前記発光量子井戸層の障壁層のうち少なくとも2つの伝導帯端エネルギーは同一である請求項12記載の量子カスケードレーザ。
- 前記それぞれの発光量子井戸層は、前記基板の格子定数よりも大きい格子定数を有する井戸層を少なくとも1つ有する請求項11記載の量子カスケードレーザ。
- 前記それぞれの発光量子井戸層は、前記基板の格子定数よりも大きい格子定数を有する井戸層を少なくとも1つ有する請求項12記載の量子カスケードレーザ。
- 前記それぞれの発光量子井戸層は、前記基板の格子定数よりも大きい格子定数を有する井戸層を少なくとも1つ有する請求項13記載の量子カスケードレーザ。
- 前記それぞれの緩和量子井戸層は、前記基板の格子定数に整合した障壁層および井戸層を有する請求項11記載の量子カスケードレーザ。
- 前記それぞれの緩和量子井戸層は、同一の深さを有する複数の井戸層を含む請求項17記載の量子カスケードレーザ。
- 前記基板はInPを含み、
前記複数の発光領域および前記複数の注入領域は、InGaAsを含む井戸層とInAlAsを含む障壁層とを含む多重量子井戸層をそれぞれ有する請求項1記載の量子カスケードレーザ。
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