WO2014189015A1 - 量子カスケードレーザ - Google Patents
量子カスケードレーザ Download PDFInfo
- Publication number
- WO2014189015A1 WO2014189015A1 PCT/JP2014/063241 JP2014063241W WO2014189015A1 WO 2014189015 A1 WO2014189015 A1 WO 2014189015A1 JP 2014063241 W JP2014063241 W JP 2014063241W WO 2014189015 A1 WO2014189015 A1 WO 2014189015A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- light
- emission
- level
- frequency
- active layer
- Prior art date
Links
Images
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
- H01S5/30—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
- H01S5/3401—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 having no PN junction, e.g. unipolar lasers, intersubband lasers, quantum cascade lasers
- H01S5/3402—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 having no PN junction, e.g. unipolar lasers, intersubband lasers, quantum cascade lasers intersubband lasers, e.g. transitions within the conduction or valence bands
-
- 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
- H01S5/06—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium
- H01S5/0604—Arrangements for controlling the laser output parameters, e.g. by operating on the active medium comprising a non-linear region, e.g. generating harmonics of the laser frequency
-
- 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
- H01S5/1092—Multi-wavelength lasing
- H01S5/1096—Multi-wavelength lasing in a single cavity
-
- 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
- H01S2302/00—Amplification / lasing wavelength
- H01S2302/02—THz - lasers, i.e. lasers with emission in the wavelength range of typically 0.1 mm to 1 mm
-
- 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
- H01S5/02—Structural details or components not essential to laser action
- H01S5/0206—Substrates, e.g. growth, shape, material, removal or bonding
- H01S5/0208—Semi-insulating substrates
-
- 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
- H01S5/305—Structure or shape of the active region; Materials used for the active region characterised by the doping materials used in the laser structure
- H01S5/3086—Structure or shape of the active region; Materials used for the active region characterised by the doping materials used in the laser structure doping of the active layer
- H01S5/309—Structure or shape of the active region; Materials used for the active region characterised by the doping materials used in the laser structure doping of the active layer doping of barrier layers that confine charge carriers in the laser structure, e.g. the barriers in a quantum well structure
Definitions
- the present invention relates to a quantum cascade laser using intersubband transition in a quantum well structure.
- Light in the mid-infrared wavelength region (for example, wavelength 5 to 30 ⁇ m) is an important wavelength region in the spectroscopic analysis field.
- quantum cascade lasers (QCL) have attracted attention as high-performance semiconductor light sources in such a wavelength region (see, for example, Patent Documents 2 to 6 and Non-Patent Documents 5 to 7).
- Quantum cascade lasers are monopolar laser elements that use a level structure with subbands formed in a semiconductor quantum well structure and generate light by electronic transition between subbands.
- High-efficiency and high-power operation can be realized by cascading the quantum well light-emitting layers serving as active regions in multiple stages.
- the cascade coupling of the quantum well light-emitting layers is realized by alternately stacking the quantum well light-emitting layers and the injection layers using an electron injection layer for injecting electrons into the emission upper level.
- terahertz terahertz
- the terahertz band is a so-called far infrared region of about 100 ⁇ m in terms of wavelength, and is a region corresponding to the boundary between radio waves and light.
- Terahertz light terahertz wave
- terahertz wave is characterized by the combination of radio wave transparency and light straightness, so that it can be used as an unprecedented sensing method in various fields such as medical organisms, security, communications, and space observation. Has been.
- a maximum operating temperature of up to 200K has been reported at an oscillation frequency of 2.85 THz when configured with cascade coupling of triple quantum well structures.
- Non-patent Document 3 Appl. Phys. Lett. Vol.99 (2011) 131106-1-131106- 3
- Non-Patent Document 4 Appl. Phys. Lett. Vol. 101 (2012) pp. 251121-1-251121-4.
- the optical output of the current DFG-THZ-QCL is several tens of ⁇ W level at room temperature, and power consumption is large, so that it is difficult to oscillate at high duty cycle. Therefore, further improvement in characteristics is also demanded for such QCL.
- the present invention has been made to solve the above problems, and an object of the present invention is to provide a quantum cascade laser capable of suitably generating long-wavelength light such as the above-described terahertz light.
- a quantum cascade laser includes (1) a semiconductor substrate, and (2) a first unit stacked body that is provided on the semiconductor substrate and includes a quantum well light emitting layer and an injection layer.
- a first active layer having a cascade structure in which quantum well light-emitting layers and injection layers are alternately stacked by being stacked in multiple stages; and (3) provided in series with respect to the first active layer on a semiconductor substrate.
- a second active layer having a cascade structure in which the quantum well light-emitting layers and the injection layers are alternately stacked by stacking the second unit stacked body including the quantum well light-emitting layers and the injection layers in multiple stages.
- the first unit stacked body of the first active layer has a light emitting upper level and a light emitting lower level in the subband level structure, and the first unit stacked body has a first light emission transition between the subbands of electrons. produced configured to be able to light with the frequency ⁇ 1, (5) the The second unit stacked body of the active layer has, in its subband level structure, a first emission upper level, a second emission upper level having energy higher than the first emission upper level, and a plurality of emission lower levels. And (6) light of the first frequency ⁇ 1 generated in the first active layer, and configured to be capable of generating at least light of the second frequency ⁇ 2 by light emission transition between the subbands of electrons. A light having a difference frequency ⁇ between the first frequency ⁇ 1 and the second frequency ⁇ 2 is generated by generating a difference frequency using light having the second frequency ⁇ 2 generated in the second active layer.
- the quantum cascade laser as described above is constituted by a first unit laminated body, a first frequency and a first active layer for generating light of omega 1 (angular frequency, simply referred to as frequency or less), it is constituted by a second unit laminated body
- two types of active layers including a second active layer that generates light having the second frequency ⁇ 2 are provided in series on the semiconductor substrate.
- light can be generated.
- the first and second emission upper levels in the subband level structure of the second unit stack constituting the second active layer among the first and second active layers It has a structure having a plurality of lower emission levels.
- a DAU / MS (dual-upper-state to multiple lower state) structure it is necessary to generate a difference frequency by appropriately setting the level interval of each level in the level structure related to light emission.
- the value of the second-order nonlinear susceptibility ⁇ (2) can be increased. As a result, it is possible to suitably generate long-wavelength light such as terahertz light with high efficiency by differential frequency generation.
- the quantum cascade laser of the present invention is constituted by a first unit laminated body, a first active layer for generating a first frequency omega 1 of the light, it is constituted by the second unit laminated body, a second frequency omega
- a second active layer that generates light of 2 is provided in series on the semiconductor substrate, and generates light of the difference frequency ⁇ by the difference frequency generation by the light of the first frequency ⁇ 1 and the light of the second frequency ⁇ 2 ;
- the second unit stack constituting the second active layer has a structure having first and second emission upper levels and a plurality of emission lower levels in the subband level structure. It is possible to suitably generate long wavelength light such as high efficiency.
- FIG. 1 is a diagram schematically showing a basic configuration of a quantum cascade laser.
- FIG. 2 is a diagram showing a subband level structure in the first active layer of the quantum cascade laser.
- FIG. 3 is a diagram showing a subband level structure in the second active layer of the quantum cascade laser.
- FIG. 4 is a diagram illustrating an example of the configuration of the quantum cascade laser.
- FIG. 5 is a diagram illustrating an example of the configuration of the unit laminate structure constituting the first active layer.
- FIG. 6 is a chart showing an example of the structure of the unit laminate for one period in the first active layer.
- FIG. 7 is a diagram illustrating an example of the configuration of the unit laminate structure constituting the second active layer.
- FIG. 1 is a diagram schematically showing a basic configuration of a quantum cascade laser.
- FIG. 2 is a diagram showing a subband level structure in the first active layer of the quantum cascade laser.
- FIG. 3 is a diagram showing a subband level structure in
- FIG. 8 is a chart showing an example of the structure of the unit laminate structure for one period in the second active layer.
- FIG. 9 is a graph showing an emission spectrum obtained in the second active layer.
- FIG. 10 is a graph showing the electric field strength dependence of the second-order nonlinear susceptibility.
- FIGS. 11A and 11B are graphs showing the dependence of the second-order nonlinear susceptibility on the energy of light at the second frequency ⁇ 2 .
- FIG. 12 is a graph showing current-light output characteristics of the quantum cascade laser.
- FIG. 13 is a graph showing the relationship between the two-wavelength mid-infrared light output and the terahertz light output.
- FIG. 1 is a diagram schematically showing a basic configuration of a quantum cascade laser according to the present invention.
- the quantum cascade laser 1A of the present embodiment is a monopolar type laser element that generates light by utilizing electronic transition between subbands in a semiconductor quantum well structure.
- the quantum cascade laser 1A includes a semiconductor substrate 10, a first active layer 15 formed on the semiconductor substrate 10, and a second active layer 25 formed in series with respect to the first active layer 15 on the semiconductor substrate 10.
- a light having a difference frequency ⁇
- between ⁇ 1 and the second frequency ⁇ 2 is generated.
- the light having a frequency ⁇ generated here is, for example, light having a long wavelength such as terahertz light.
- the first active layer 15 has a cascade structure in which quantum well light-emitting layers used for light generation and electron injection layers used for injection of electrons into the light-emitting layers are alternately stacked in multiple stages.
- a semiconductor multilayer structure composed of a quantum well light-emitting layer and an injection layer is used as a first unit multilayer body 16 for one cycle, and the first unit multilayer body 16 is stacked in multiple stages to have a cascade structure.
- a first active layer 15 is configured.
- the number of first unit stacks 16 is appropriately set, and is about several hundreds, for example.
- the second active layer 25 has a cascade structure in which quantum well light-emitting layers used for light generation and electron injection layers used for injection of electrons into the light-emitting layers are alternately stacked in multiple stages.
- a semiconductor multilayer structure composed of a quantum well light emitting layer and an injection layer and different from the first unit multilayer body 16 is used as a second unit multilayer body 26 for one cycle, and the second unit multilayer body 26 is stacked in multiple stages.
- the second active layer 25 having a cascade structure is configured.
- the number of stacked second unit stacked bodies 26 is appropriately set, and is about several hundreds, for example.
- the first active layer 15 is formed on the semiconductor substrate 10 directly or via another semiconductor layer.
- the second active layer 25 is directly formed on the first active layer 15 in the configuration example shown in FIG.
- another semiconductor layer for example, a buffer layer
- the stacking order of the first and second active layers 15 and 25 from the semiconductor substrate 10 side may be reversed.
- a configuration example of the level structure in the first and second active layers 15 and 25 will be described.
- FIG. 2 is a diagram showing a subband level structure in the first active layer of the quantum cascade laser shown in FIG.
- the first active layer 15 in the present embodiment has an SPC (single phonon resonance-continuum) structure (see Patent Document 4: Japanese Patent Laid-Open No. 2008-177366), and is configured to be able to generate light having the first frequency ⁇ 1. Has been.
- SPC single phonon resonance-continuum
- each of the plurality of unit laminate bodies 16 included in the first active layer 15 includes a quantum well light emitting layer 17 and an electron injection layer 18.
- the light emitting layer 17 and the injection layer 18 are formed to have a predetermined quantum well structure including a quantum well layer and a quantum barrier layer, respectively.
- the subband level structure which is an energy level structure by a quantum well structure is formed.
- the first unit stacked body 16 in the present embodiment has an emission upper level L up , an emission lower level L low, and an emission lower level L low in the subband level structure.
- a relaxation miniband MB that functions as a relaxation level L r including a plurality of levels having low energy.
- the relaxation miniband MB is set so that the energy difference between the emission lower level L low and the miniband MB becomes the energy of longitudinal optical (LO) phonon.
- an injection barrier for electrons injected from the injection layer 18a to the light emitting layer 17 between the light emitting layer 17 and the injection layer 18a in the previous unit laminated body. barrier) layer.
- an extraction barrier layer for electrons from the light emitting layer 17 to the injection layer 18 is provided between the light emitting layer 17 and the injection layer 18.
- the electrons that have transitioned to the lower emission level L low are relaxed at a high speed to the relaxation miniband MB by LO phonon scattering, and further relaxed at a high speed within the miniband MB.
- laser oscillation is performed between the upper level L up and the lower level L low by extracting electrons from the emission lower level L low at high speed via LO phonon scattering and relaxation in the miniband.
- a population inversion for realization is formed.
- the relaxation miniband MB is preferably formed to have a band structure in which the miniband in the light emitting layer 17 and the miniband in the injection layer 18 are combined as shown in FIG.
- electrons relaxed from the emission lower level L low to the mini-band MB are emitted from the relaxation mini-band MB via the extraction barrier and the injection layer 18 to the emission upper level in the subsequent emission layer 17b. It is injected in cascade to the position L up .
- FIG. 3 is a diagram showing a subband level structure in the second active layer of the quantum cascade laser shown in FIG.
- the second active layer 25 in this embodiment has a DAU / MS (dual-upper-state to multiple lower state) structure
- Patent Document 5 Japanese Patent Application Laid-Open No. 2011-035139
- Patent Document 6 Japanese Patent Application Laid-Open No. 2011-243781.
- the light having the first frequency ⁇ 1 and the light having the second frequency ⁇ 2 can be generated.
- each of the plurality of unit laminated bodies 26 included in the second active layer 25 includes a quantum well light emitting layer 27 and an electron injection layer 28.
- the light emitting layer 27 and the injection layer 28 are formed to have a predetermined quantum well structure including a quantum well layer and a quantum barrier layer, respectively.
- a subband level structure which is an energy level structure based on a quantum well structure, is formed in the second unit stacked body 26.
- a second emission upper level (level 5) L up2 L 5 having an energy higher than the emission level, a plurality of emission lower levels, and a relaxation level L r having an energy lower than the emission lower level.
- the first emission lower level (level 1) L low1 L 1 and the first emission.
- the second emission lower level (level 2) L low2 L 2 having higher energy than the lower level, and the third emission lower level (level 3) having higher energy than the second emission lower level.
- L low3 L 3
- an injection barrier for electrons injected from the injection layer 28a to the light emitting layer 27 between the light emitting layer 27 and the injection layer 28a in the preceding unit laminated body. barrier) layer.
- an extraction barrier layer for electrons from the light emitting layer 27 to the injection layer 28 is also provided between the light emitting layer 27 and the injection layer 28 as necessary.
- FIG. 3 exemplifies a configuration in which only a thin barrier layer that allows a sufficient wave function to leak out is provided between the light emitting layer 27 and the injection layer 28.
- Second emission upper level L up1 electrons injected into the L up2, the first, second, and transition into the respective third emission lower level L low1, L low2, L low3 , this time .
- Light having an energy corresponding to the energy difference between the subband levels of the emission upper level and the lower level is generated and emitted.
- the light having the energy E 1 at the first frequency ⁇ 1 and the second frequency ⁇ light energy E 2 is generated and released at 2.
- the electrons that have transitioned to the emission lower levels L low1 , L low2 , and L low3 are relaxed to the relaxation level L r .
- the relaxation level L r used for the relaxation of electrons only one level is schematically shown in FIG. 3, but the relaxation level is constituted by a plurality of levels or minibands. Also good.
- electrons are relaxed from the emission lower level to the relaxation level L r, through the injection layer 28, relaxation level from L r, emission upper level L in the rear stage of the light emitting layer 27b up1, L up2 Are injected in cascade.
- cascade light generation occurs in the active layer 25. That is, by stacking a large number of light emitting layers 27 and injection layers 28 alternately, electrons move one after the other in a cascade manner in the stacked body 26, and at the time of light emission transition between subbands in each stacked body 26. Light having a frequency ⁇ 1 and light having a second frequency ⁇ 2 are generated.
- the first and second frequencies ⁇ 1 are obtained by the above-described level structure in the second unit stacked body 26 constituting the active layer 25. , ⁇ 2, the second-order nonlinear susceptibility ⁇ (2) necessary for generating the difference frequency is increased.
- the laser 1A in which the first and second active layers 15 and 25 are stacked the light having the first frequency ⁇ 1 generated in the first active layer 15 and the first and second light generated in the second active layer 25 are obtained. Due to the difference frequency generation by the light having the second frequencies ⁇ 1 and ⁇ 2 , light having the difference frequency ⁇ such as THz light is generated.
- the distribution by the diffraction grating for selectively oscillating the light of the second frequency ⁇ 2 in the semiconductor stacked structure in the quantum cascade laser 1A shown in FIG. 1 with respect to the light generated in the second active layer 25 It is also possible to provide a feedback type oscillation mechanism. In this case, by the difference frequency generation by the light of the first frequency ⁇ 1 generated in the first active layer 15 and the light of the second frequency ⁇ 2 generated in the second active layer 25 and selected by the diffraction grating structure, Light having a difference frequency ⁇ is generated.
- the quantum cascade laser 1A includes a first active layer 15 configured to generate light having a first frequency ⁇ 1 and a second unit stacked body 26.
- two types of active layers including the second active layer 25 that generates at least light having the second frequency ⁇ 2 are provided in series on the semiconductor substrate 10.
- light having a long wavelength such as terahertz light is generated as light of the difference frequency ⁇ .
- the first and second light emission in the subband level structure of the second unit stacked body 26 constituting the second active layer 25 among the first and second active layers 15 and 25 has a configuration having upper levels L up1 and L up2 and a plurality of lower emission levels (in the configuration of FIG. 3, first to third emission lower levels L low1 , L low2 and L low3 ).
- L up1 and L up2 and a plurality of lower emission levels
- the DAU / MS structure by appropriately setting the level interval of each level in the level structure related to light emission, the light of the first frequency ⁇ 1 and the light of the second frequency ⁇ 2 are used.
- the value of the second-order nonlinear susceptibility ⁇ (2) necessary for generating the difference frequency can be increased.
- the second unit stacked body 26 of the second active layer 25 can generate light having the first frequency ⁇ 1 in addition to the light having the second frequency ⁇ 2 in the subband level structure. It is preferable that it is comprised. According to such a configuration, the second-order nonlinear susceptibility ⁇ (2) for generating the difference frequency by the light of the first frequency ⁇ 1 and the light of the second frequency ⁇ 2 is sufficiently increased, and the difference frequency ⁇ Can be generated with high efficiency.
- a mechanism for selecting light having the second frequency ⁇ 2 with respect to the light generated in the second active layer 25, for example, a distributed feedback oscillation mechanism using a diffraction grating is provided.
- a distributed feedback (DFB) type oscillation mechanism by providing such a distributed feedback (DFB) type oscillation mechanism, light having a difference frequency ⁇ is generated in the second active layer 25 having the DAU / MS structure.
- the light having the second frequency ⁇ 2 used in the above can be suitably and selectively generated.
- the second active layer 25, if it is not necessary to selectively generate a second frequency omega 2 of the light may not be provided.
- the second unit stacked body 26 of the second active layer 25 has its subband level as shown in FIG.
- the level structure as a plurality of emission lower levels, a first emission lower level L low1 , a second emission lower level L low2 having higher energy than the first emission lower level, and a second emission lower level
- a configuration having a third emission lower level L low3 having a high energy can be obtained.
- the second unit stacked body 26 of the second active layer 25 has an energy difference ⁇ E 21 between the first emission lower level and the second emission lower level, the second emission lower level, and the third emission lower level.
- the energy difference ⁇ E 32 from the level and the energy difference ⁇ E 54 between the first emission upper level and the second emission upper level are configured to substantially coincide with the light energy E having the difference frequency ⁇ . It is preferable.
- the second-order nonlinear susceptibility ⁇ (2) for generating the light of the difference frequency ⁇ by the difference frequency generation is sufficiently large. Thus, the efficiency of difference frequency generation can be improved.
- the second unit stacked body 26 of the second active layer 25 has the subband level structure in which the first emission upper level is changed to the first emission lower level.
- the light emission transition energy ⁇ E 41 and the light emission transition energy ⁇ E 52 from the second light emission upper level to the second light emission lower level are respectively one light of the first frequency ⁇ 1 and the second frequency ⁇ 2.
- the light of the first frequency ⁇ 1 substantially coincides with the energy of the light emission transition ⁇ E 42 from the first light emission upper level to the second light emission lower level, and the second light emission upper level.
- both the supply of light having the second frequency ⁇ 2 and the generation of light having the difference frequency ⁇ by the DFG can be suitably realized in the second active layer 25.
- the plurality of lower emission levels in the second unit stack 26 of the second active layer 25 is not limited to the configuration having the three lower emission levels as described above, but the first and second emission upper levels. On the other hand, for example, it may be configured to have two or four or more emission lower levels. Even with such a configuration, the efficiency of difference frequency generation can be improved by making the energy difference between adjacent emission lower levels substantially coincide with the energy of light having the difference frequency ⁇ .
- the level structure in the first active layer 15 that supplies the light of the first frequency ⁇ 1 , the first unit stacked body 16 of the first active layer 15 has its structure as shown in FIG.
- an electron having a relaxation miniband MB including a plurality of levels having energy lower than the emission lower level L low and having undergone an emission transition from the emission upper level to the emission lower level is , It can be configured to relax from the lower emission level to the relaxation miniband by LO phonon scattering.
- light with the first frequency ⁇ 1 can be suitably generated with high efficiency.
- the subband level structure in the first active layer 15 is not limited to the SPC structure described above as long as it can suitably generate light having the first frequency ⁇ 1 , and various level structures are used. good.
- terahertz (THz) light by difference frequency generation (DFG) in the quantum cascade laser 1A of the above embodiment will be further described.
- DFG-THZ-QCL in order to realize generation of THz waves by DFG, pump light of two different frequencies ⁇ 1 and ⁇ 2 (for example, mid-infrared light), and a high second order with respect to those pump lights An active layer having a nonlinear susceptibility ⁇ (2) is required.
- the first active layer 15 that generates light having the first frequency ⁇ 1 and the second active layer 25 that generates light having the second frequency ⁇ 2 are combined. Such a condition is realized by adopting a DAU / MS structure in the second active layer 25.
- the DAU / MS structure whose specific example is shown in FIG. 3 has an extremely wide gain curve by utilizing the intersubband transition from the first and second emission upper levels to the plurality of emission lower levels. At the same time, it is a level structure in which good laser characteristics can be obtained by forming an inversion distribution with high efficiency.
- the upper level, the lower level number, the energy of each level, the energy interval between levels, etc. are appropriately designed to double the conventional level.
- the above-described large second-order nonlinear susceptibility ⁇ (2) and thereby high-efficiency DFG can be realized.
- the power W ( ⁇ ) of the light of the difference frequency ⁇ generated by the DFG is the power of the mid-infrared pump light of the first and second frequencies.
- W ( ⁇ 1 ), W ( ⁇ 2 ), and the coherence length l coh are proportional to the square, and the nonlinear susceptibility ⁇ (2) is proportional to the dipole moment z nm of the transition.
- e is the electric charge
- Ne is the number of inversion distributions
- ⁇ nm is the half width of light emission.
- Equation (2) is, chi for the difference frequency ⁇ generated against Delta] E 21 indicates (2)
- Equation (3) is, chi for the difference frequency ⁇ generated against Delta] E 32
- Equation (4) shows ⁇ (2) for the difference frequency ⁇ generated for ⁇ E 54 .
- the second-order nonlinear susceptibility ⁇ (2) is expressed by the sum of products of dipole moments in the corresponding transition.
- the light emission transitions 4 ⁇ 1, 5 ⁇ 2 are set to the same first frequency ⁇ 1 transition, and the light emission transitions 4 ⁇ 2, 5 ⁇ 3 are set to the same second frequency. it can be a transition of ⁇ 2.
- the difference frequency ⁇ between the frequencies ⁇ 1 and ⁇ 2 corresponds to the frequency of the THz light to be generated, and the three level intervals of ⁇ E 54 , ⁇ E 32 , and ⁇ E 21 shown in FIG. These level intervals contribute to the second-order nonlinear susceptibility ⁇ (2) . Therefore, according to the configuration of the above embodiment, the susceptibility ⁇ (2) is more than twice as large as that of the conventional structure in which only one level interval contributes to the susceptibility ⁇ (2) . It is possible.
- FIG. 4 is a diagram illustrating an example of a specific configuration of the quantum cascade laser.
- FIG. 5 is a diagram showing an example of the configuration of the first unit stacked body constituting the first active layer in the quantum cascade laser shown in FIG. 4, and FIG. 6 shows one cycle of the first active layer. It is a chart which shows an example of the structure of the 1st unit layered product.
- FIG. 7 is a diagram showing an example of the configuration of the second unit stacked body constituting the second active layer in the quantum cascade laser shown in FIG. 4, and FIG. 8 shows one cycle of the second active layer. It is a chart which shows an example of the structure of the 2nd unit layered product.
- FIG. 5 shows the quantum well structure and the subband level structure of a part of the multistage repetitive structure of the light emitting layer 17 and the injection layer 18 in the first active layer 15.
- FIG. 7 shows the quantum well structure and the subband level structure of a part of the multistage repetitive structure of the second active layer 25 by the light emitting layer 27 and the injection layer 28.
- . 4 to 8 can be formed by crystal growth by, for example, molecular beam epitaxy (MBE) method or metal organic vapor phase epitaxy (MOVPE) method.
- MBE molecular beam epitaxy
- MOVPE metal organic vapor phase epitaxy
- a semi-insulating InP single crystal substrate 50 is used as the semiconductor substrate 10. Crystal growth can be consistently grown, for example, by the MOVPE method. Then, on this InP substrate 50, in order from the substrate side, the 300 nm-thick InGaAs lower core layer 51, the first active layer 15 in which the first unit stacked body 16 is stacked in multiple stages, and the second unit stacked body 26 in multiple stages.
- an element structure of the quantum cascade laser 1B of DFG-THz-QCL is formed.
- a diffraction grating structure 55 that is a wavelength selection mechanism is formed at a predetermined position in the upper core layer 52. In this laminated structure, the core layer, the cladding layer, and the contact layer excluding the active layer are lattice-matched to the InP substrate.
- first, design frequencies ⁇ , ⁇ 1 and ⁇ 2 are determined.
- the selection of (wavelength) is very important.
- the SPC structure shown in FIG. 2 is used as the cascade structure of the first active layer 15 that generates light having the first frequency ⁇ 1 .
- the SPC structure does not have a large non-linear susceptibility ⁇ (2) due to the structural feature that light emission transitions from one upper level to one lower level, and is not a structure suitable for DFG. By using it, it becomes easy to perform high-performance oscillation at a high temperature above room temperature, which is extremely suitable as a structure for generating pump light having the first frequency ⁇ 1 .
- MIR mid-infrared
- the active layer 15 is configured by stacking the first unit stacked body 16 including the light emitting layer 17 and the injection layer 18 in 20 cycles.
- the unit stacked body 16 for one period includes 11 quantum well layers 161 to 164 and 181 to 187, and 11 quantum barrier layers 171 to 174 and 191 to 197 alternately. It is configured as a stacked quantum well structure.
- the quantum well layer is composed of In 0.56 Ga 0.44 As layer.
- the quantum barrier layer is composed of an In 0.48 Al 0.52 As layer.
- the light emitting layer 17 and the injection layer 18 have a laminated portion including four well layers 161 to 164 and barrier layers 171 to 174 in the laminated structure shown in FIG. , which mainly functions as the light emitting layer 17. Further, a laminated portion composed of seven well layers 181 to 187 and barrier layers 191 to 197 is a portion mainly functioning as the injection layer 18.
- FIG. 6 shows an example of a specific structure of the first unit stacked body 16 for one period in the first active layer 15.
- the first unit stacked body 16 includes a plurality of light emitting upper levels L up , lower light emitting levels L low , and relaxation levels L r in the subband level structure shown in FIG. And a mini-band MB including the first level ⁇ 1 , and configured to be able to generate light having the first frequency ⁇ 1 .
- the thicknesses of the quantum well layer and the barrier layer in the light emitting layer 17 and the injection layer 18 are designed based on quantum mechanics.
- the active layer 25 is configured by laminating a second unit laminated body 26 including a light emitting layer 27 and an injection layer 28 in 30 cycles.
- the unit stacked body 26 for one period includes 11 quantum well layers 261 to 264 and 281 to 287, and 11 quantum barrier layers 271 to 274 and 291 to 297 alternately. It is configured as a stacked quantum well structure.
- the quantum well layer is composed of an In 0.56 Ga 0.44 As layer.
- the quantum barrier layer is composed of an In 0.48 Al 0.52 As layer.
- the light emitting layer 27 and the injection layer 28 have a laminated portion including four well layers 261 to 264 and barrier layers 271 to 274 in the laminated structure shown in FIG. , which mainly functions as the light emitting layer 27. Further, a laminated portion composed of seven well layers 281 to 287 and barrier layers 291 to 297 is a portion mainly functioning as the injection layer 28. Further, among the semiconductor layers of the light emitting layer 27, the first quantum barrier layer 271 is located between the previous injection layer and the light emitting layer 27, and electrons from the previous injection layer to the light emitting layer 27. It is an injection barrier layer against the above.
- the extraction barrier layer for electrons from the light emitting layer 27 to the injection layer 28 located between the light emitting layer 27 and the injection layer 28 effectively functions as an extraction barrier.
- the barrier layer 291 is formally defined as an extraction barrier layer, and the light emitting layer 27 and the injection layer 28 are functionally divided before and after the barrier layer 291.
- FIG. 8 shows an example of a specific structure of the second unit stacked body 26 for one period in the second active layer 25.
- the second unit stacked body 26 has the first and second emission upper levels L up1 (L 4 ), L up2 (L 5 ), the first in the subband level structure shown in FIG.
- Each of the two frequencies ⁇ 1 and ⁇ 2 can be generated.
- the thicknesses of the quantum well layer and the barrier layer in the light emitting layer 27 and the injection layer 28 are designed based on quantum mechanics.
- Z 52 1.33 nm
- z 51 0.62 nm
- z 43 1.4 nm
- z 42 1.36 nm
- z 41 0.735 nm
- z 32 8.848 nm
- z 31 0.7 nm
- z 21 9.99 nm.
- FIG. 9 is a graph showing an emission spectrum obtained in the second active layer.
- the horizontal axis indicates the emission energy (meV) or wavelength ( ⁇ m), and the vertical axis indicates the emission intensity (au).
- graph A1 shows the emission spectrum of transition 5 ⁇ 1
- graph A2 shows the emission spectrum of transition 4 ⁇ 1
- graph A3 shows the emission spectrum of transition 5 ⁇ 2
- graph A4 Shows the emission spectrum of transition 4 ⁇ 2
- graph A5 shows the emission spectrum of transition 5 ⁇ 3
- graph A6 shows the emission spectrum of transition 4 ⁇ 3.
- the transition 4 ⁇ 1, 5 ⁇ 2 corresponds to the first frequency omega 1
- the transition 4 ⁇ 2,5 ⁇ 3 corresponds to the second frequency omega 2.
- a graph A0 shows a total emission spectrum obtained by adding the emission intensity at each transition shown in the graphs A1 to A6.
- the emission from the second active layer 25 having the DAU / MS structure has a very wide emission spectrum, and the overall emission frequency is the first and second frequencies ⁇ . 1 and an intermediate frequency between ⁇ 2 .
- the second light is selectively oscillated. Therefore, in the configuration example shown in FIG. 4, the light of the second frequency ⁇ 2 is forcibly selected as a feedback mechanism for selecting the wavelength of the oscillation light in the second active layer 25 in the upper core layer 52.
- a diffraction grating structure 55 to be oscillated is formed, thereby constituting a distributed feedback (DFB) type oscillation mechanism.
- DFB distributed feedback
- the diffraction grating structure 55 to select the second frequency omega 2 of the light can be used a configuration in which a diffraction grating pitch 1650nm inside waveguide.
- the second frequency ⁇ 2 selected by the diffraction grating structure 55 determines the frequency ⁇ of THz light generated by the DFG together with the first frequency ⁇ 1 , the pitch in the diffraction grating structure 55, The setting of the selected frequency is important.
- the energy of light selected by the diffraction grating structure 55 is preferably set in a range of about ⁇ 5% with respect to the energy ⁇ E 42 of the transition 4 ⁇ 2. This is because the half-value width of electroluminescence of a single intersubband transition at room temperature is about 10% of the center wavelength.
- the second active layer 25 generates THz waves by generating a difference frequency using a high-order second-order nonlinear susceptibility ⁇ (2) in addition to supplying light of the second frequency ⁇ 2 . It has a function.
- FIG. 10 is a graph showing the electric field strength dependence of the second-order nonlinear susceptibility ⁇ (2) in the second active layer 25.
- the horizontal axis represents the electric field strength (kV / cm)
- the vertical axis represents the second-order nonlinear susceptibility ⁇ (2) (pm / V).
- FIG. 10 is a graph showing the electric field strength dependence of the second-order nonlinear susceptibility ⁇ (2) in the second active layer 25.
- the horizontal axis represents the electric field strength (kV / cm)
- the vertical axis represents the second-order nonlinear susceptibility ⁇ (2) (pm / V).
- graph B1 shows the nonlinear susceptibility due to level 2-1
- graph B2 shows the nonlinear susceptibility due to level 3-2
- graph B3 shows the nonlinear susceptibility due to level 5-4. Shows the rate.
- Graph B0 shows the overall nonlinear susceptibility by adding the susceptibility at each level shown in graphs B1 to B3.
- a large susceptibility ⁇ (2) is obtained within each level interval in the vicinity of the operating electric field. It turns out that it functions effectively.
- the coupling coefficient ⁇ with the light fed back by the diffraction grating is It is preferable to adjust the value so that only the light oscillated by the second active layer 25 among the first and second active layers 15 and 25 functions.
- the oscillation of the light of the first frequency ⁇ 1 deviated from the feedback by the diffraction grating is affected by the diffraction grating. Therefore, the above conditions are easily achieved.
- FIG. 11 is a graph showing the dependence of the second-order nonlinear susceptibility ⁇ (2) in the second active layer 25 on the light energy at the second frequency ⁇ 2 .
- the horizontal axis indicates the light energy E 2 (eV) at the second frequency ⁇ 2
- the vertical axis indicates the second-order nonlinear susceptibility ⁇ (2) (pm / V). Yes.
- the horizontal axis represents the difference E 1 ⁇ E 2 (meV) between the light energy at the first frequency ⁇ 1 and the light energy at the second frequency ⁇ 2
- the vertical axis represents The second-order nonlinear susceptibility ⁇ (2) (pm / V) is shown.
- graphs C1 and D1 show the nonlinear susceptibility due to level 2-1
- graphs C2 and D2 show the nonlinear susceptibility due to level 3-2
- C3 and D3 indicate the nonlinear susceptibility by level 5-4
- Graphs C0 and D0 indicate the overall nonlinear susceptibility by adding the susceptibility at each level shown in graphs C1 to C3 and D1 to D3.
- E 2 of the second frequency omega 2 of the light it can be seen that the value of the susceptibility chi (2) and deviates from the peak is greatly reduced.
- the configuration in which the light of the second frequency ⁇ 2 is selected by the diffraction grating structure 55 is illustrated.
- the first and second It is also possible to adopt a configuration in which a DFB operation is performed on both lights having frequencies ⁇ 1 and ⁇ 2 .
- Such a configuration can be realized, for example, by setting the pitch of the diffraction grating to 1410 nm and 1650 nm for the first and second frequencies ⁇ 1 and ⁇ 2 , respectively.
- FIG. 12 and FIG. 13 show the element characteristics at room temperature of the quantum cascade laser when the laser is configured as a laser element having a cavity length of 3 mm and a ridge width of 25 ⁇ m processed in the ridge waveguide structure in the specific configuration example described above. It explains using.
- FIG. 12 is a graph showing the current-light output characteristics for the mid-infrared (MIR) light and terahertz (THz) light of the quantum cascade laser.
- the horizontal axis represents current (A) or current density (kA / cm 2 ), and the vertical axis represents peak power (mW) of MIR light or peak power ( ⁇ W) of THz light.
- graph G1 shows the current dependence of the peak power of the first wavelength lambda 1 of the MIR light
- graph G2 shows the current dependence of the peak power of the second wavelength lambda 2 of the MIR light Yes
- Graph G3 shows the current dependence of the peak power of THz light generated by the difference frequency generation.
- the first, second wavelength lambda 1, lambda 2 of the MIR light, respectively, the threshold current density of 4.7kA / cm 2, 6kA / cm 2 was confirmed.
- the output of THz light a peak power of about 13 ⁇ W was obtained.
- FIG. 13 is a graph showing the relationship between two-wavelength mid-infrared (MIR) light output and terahertz (THz) light output.
- the horizontal axis indicates the amount (W 1 ⁇ W 2 ) ⁇ 10 3 (W 2 ) related to the peak power of MIR light having two wavelengths ⁇ 1 and ⁇ 2
- the vertical axis indicates the peak power ( ⁇ W) of THz light. Is shown.
- the quantum cascade laser according to the present invention is not limited to the above-described embodiments and configuration examples, and various modifications are possible.
- an InP substrate is used as a semiconductor substrate, and the first and second active layers are composed of InGaAs / InAlAs.
- emission transition by intersubband transition in a quantum well structure is possible.
- various configurations may be used.
- various material systems such as GaAs / AlGaAs, InAs / AlSb, GaN / AlGaN, and SiGe / Si can be used in addition to the above InGaAs / InAlAs.
- Various methods may be used for the semiconductor crystal growth method.
- the first active layer and the second active layer are configured by the strain compensation structure.
- an active layer may be configured to lattice match with the InP substrate. good.
- various structures may be used for the stacked structure in the active layer of the quantum cascade laser and the semiconductor stacked structure as the entire laser element.
- the quantum cascade laser may be configured to include a semiconductor substrate and the first and second active layers having the above-described configuration provided on the semiconductor substrate.
- the unit laminated body of the first active layer has a light emission upper level and a light emission lower level in its subband level structure, and the light having the first frequency ⁇ 1 is generated by the intersubband light emission transition.
- the unit stacked body of the second active layer may have a first emission upper level, a second emission upper level, and a plurality of emission in the subband level structure. It has only to be configured to have at least a lower level and be capable of generating at least light having the second frequency ⁇ 2 by light emission transition between subbands of electrons.
- a semiconductor substrate and (2) a first unit stacked body that is provided on the semiconductor substrate and includes a quantum well light-emitting layer and an injection layer are stacked in multiple stages.
- the first unit stacked body has a light emission upper level and a light emission lower level in its subband level structure, and can generate light having a first frequency ⁇ 1 by an intersubband light emission transition.
- the subband level structure includes a first emission upper level, a second emission upper level having higher energy than the first emission upper level, and a plurality of emission lower levels, at least be capable of generating up the second frequency omega 2 of the light by intersubband radiative transition, first generated in the first frequency omega 1 of the light, and a second active layer which is generated in the first active layer (6) by difference frequency generation using two frequency omega 2 of the light, using the configuration to generate a first frequency omega 1 and the light of the second frequency omega 2 of the difference frequency omega.
- the second unit stacked body of the second active layer is configured to be able to generate light of the first frequency ⁇ 1 in addition to light of the second frequency ⁇ 2 in the subband level structure. It is preferable that According to such a configuration, the second-order nonlinear susceptibility ⁇ (2) for generating the difference frequency by the light of the first frequency ⁇ 1 and the light of the second frequency ⁇ 2 is sufficiently increased, and the difference frequency ⁇ Can be generated with high efficiency.
- a distributed feedback oscillation mechanism using a diffraction grating is provided for selecting light having the second frequency ⁇ 2 with respect to light generated in the second active layer.
- a distributed feedback (DFB) type oscillation mechanism in the resonator structure of the quantum cascade laser, in the second active layer, the second frequency ⁇ 2 used to generate light of the difference frequency ⁇ . It is possible to selectively generate the light.
- the second unit stack of the second active layer has the first emission as a plurality of lower emission levels in the subband level structure.
- a configuration having a lower level, a second emission lower level having higher energy than the first emission lower level, and a third emission lower level having energy higher than the second emission lower level. Can do.
- the second unit stack of the second active layer has an energy difference between the first emission lower level and the second emission lower level, and the second emission lower level and the third emission lower level.
- the energy difference and the energy difference between the first light emission upper level and the second light emission upper level are preferably configured so as to substantially match the energy of the light having the difference frequency ⁇ .
- the second-order nonlinear susceptibility ⁇ (2) for generating the light of the difference frequency ⁇ by the difference frequency generation is sufficiently large. Can be set.
- the second unit stack of the second active layer has the luminescence transition from the first emission upper level to the first emission lower level in the subband level structure.
- the energy and the energy of the light emission transition from the second light emission upper level to the second light emission lower level substantially coincide with the energy of one light of the first frequency ⁇ 1 and the second frequency ⁇ 2 , respectively.
- the energy of the light emission transition from the light emission upper level to the second light emission lower level and the energy of the light emission transition from the second light emission upper level to the third light emission lower level are respectively the first frequency ⁇ 1 and the second frequency. it is preferably configured to substantially match the energy of the omega 2 of the other light.
- the first unit stacked body of the first active layer has a plurality of levels having energy lower than the emission lower level in the subband level structure. Electrons that have a relaxation miniband that includes a level and have undergone an emission transition from the upper emission level to the lower emission level can be relaxed from the lower emission level to the relaxation miniband by longitudinal optical phonon scattering. it can. According to such an SPC (single phonon resonance-continuum) structure, light with the first frequency ⁇ 1 can be suitably generated with high efficiency.
- the present invention can be used as a quantum cascade laser capable of suitably generating long-wavelength light such as terahertz light.
Landscapes
- Physics & Mathematics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Optics & Photonics (AREA)
- Nonlinear Science (AREA)
- Semiconductor Lasers (AREA)
Abstract
Description
50…InP基板、51…InGaAs下部コア層、52…InGaAs上部コア層、53…InPクラッド層、54…InGaAsコンタクト層、55…回折格子構造、
Lup…発光上準位、Lup1…第1発光上準位、Lup2…第2発光上準位、Llow…発光下準位、Llow1…第1発光下準位、Llow2…第2発光下準位、Llow3…第3発光下準位、Lr…緩和準位、MB…緩和ミニバンド。
Claims (5)
- 半導体基板と、
前記半導体基板上に設けられ、量子井戸発光層及び注入層からなる第1単位積層体が多段に積層されることで前記量子井戸発光層と前記注入層とが交互に積層されたカスケード構造が形成された第1活性層と、
前記半導体基板上に前記第1活性層に対して直列に設けられ、量子井戸発光層及び注入層からなる第2単位積層体が多段に積層されることで前記量子井戸発光層と前記注入層とが交互に積層されたカスケード構造が形成された第2活性層とを備え、
前記第1活性層の前記第1単位積層体は、そのサブバンド準位構造において、発光上準位と、発光下準位とを有し、電子のサブバンド間発光遷移によって第1周波数ω1の光を生成可能に構成され、
前記第2活性層の前記第2単位積層体は、そのサブバンド準位構造において、第1発光上準位と、前記第1発光上準位よりも高いエネルギーを有する第2発光上準位と、複数の発光下準位とを有し、電子のサブバンド間発光遷移によって第2周波数ω2の光を少なくとも生成可能に構成され、
前記第1活性層で生成される前記第1周波数ω1の光、及び前記第2活性層で生成される前記第2周波数ω2の光による差周波発生によって、前記第1周波数ω1及び前記第2周波数ω2の差周波数ωの光を生成することを特徴とする量子カスケードレーザ。 - 前記第2活性層の前記第2単位積層体は、そのサブバンド準位構造において、前記第2周波数ω2の光に加えて、前記第1周波数ω1の光を生成可能に構成されるとともに、
前記第2活性層で生成される光に対し、前記第2周波数ω2の光を選択するための回折格子による分布帰還型の発振機構が設けられていることを特徴とする請求項1記載の量子カスケードレーザ。 - 前記第2活性層の前記第2単位積層体は、そのサブバンド準位構造において、前記複数の発光下準位として、第1発光下準位と、前記第1発光下準位よりも高いエネルギーを有する第2発光下準位と、前記第2発光下準位よりも高いエネルギーを有する第3発光下準位とを有し、
前記第1発光下準位と前記第2発光下準位とのエネルギー差、前記第2発光下準位と前記第3発光下準位とのエネルギー差、及び前記第1発光上準位と前記第2発光上準位とのエネルギー差が、それぞれ前記差周波数ωの光のエネルギーと略一致するように構成されていることを特徴とする請求項1または2記載の量子カスケードレーザ。 - 前記第2活性層の前記第2単位積層体は、そのサブバンド準位構造において、
前記第1発光上準位から前記第1発光下準位への発光遷移のエネルギー、及び前記第2発光上準位から前記第2発光下準位への発光遷移のエネルギーが、それぞれ前記第1周波数ω1及び前記第2周波数ω2の一方の光のエネルギーと略一致するとともに、
前記第1発光上準位から前記第2発光下準位への発光遷移のエネルギー、及び前記第2発光上準位から前記第3発光下準位への発光遷移のエネルギーが、それぞれ前記第1周波数ω1及び前記第2周波数ω2の他方の光のエネルギーと略一致するように構成されていることを特徴とする請求項3記載の量子カスケードレーザ。 - 前記第1活性層の前記第1単位積層体は、そのサブバンド準位構造において、前記発光下準位よりも低いエネルギーを有する複数の準位を含む緩和ミニバンドを有し、前記発光上準位から前記発光下準位への発光遷移を経た電子は、縦光学フォノン散乱によって前記発光下準位から前記緩和ミニバンドへと緩和することを特徴とする請求項1~4のいずれか一項記載の量子カスケードレーザ。
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2015518240A JP6276758B2 (ja) | 2013-05-23 | 2014-05-19 | 量子カスケードレーザ |
US14/888,999 US9484715B2 (en) | 2013-05-23 | 2014-05-19 | Quantum-cascade laser |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2013109164 | 2013-05-23 | ||
JP2013-109164 | 2013-05-23 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2014189015A1 true WO2014189015A1 (ja) | 2014-11-27 |
Family
ID=51933568
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/JP2014/063241 WO2014189015A1 (ja) | 2013-05-23 | 2014-05-19 | 量子カスケードレーザ |
Country Status (3)
Country | Link |
---|---|
US (1) | US9484715B2 (ja) |
JP (1) | JP6276758B2 (ja) |
WO (1) | WO2014189015A1 (ja) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN108336643A (zh) * | 2018-01-31 | 2018-07-27 | 中国科学院上海微系统与信息技术研究所 | 有源区结构及具有宽带增益的太赫兹量子级联激光器 |
JP2019192822A (ja) * | 2018-04-26 | 2019-10-31 | 住友電気工業株式会社 | 量子カスケードレーザ |
JP2020123662A (ja) * | 2019-01-30 | 2020-08-13 | 住友電気工業株式会社 | 量子カスケードレーザ |
Families Citing this family (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2011243781A (ja) * | 2010-05-19 | 2011-12-01 | Hamamatsu Photonics Kk | 量子カスケードレーザ |
US10340662B2 (en) * | 2014-06-04 | 2019-07-02 | Sharp Kabushiki Kaisha | Quantum cascade laser |
JP6371332B2 (ja) * | 2016-05-20 | 2018-08-08 | シャープ株式会社 | 量子カスケードレーザ |
JP7475924B2 (ja) * | 2020-03-30 | 2024-04-30 | 浜松ホトニクス株式会社 | 量子カスケードレーザ |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2008177366A (ja) * | 2007-01-18 | 2008-07-31 | Hamamatsu Photonics Kk | 量子カスケードレーザ |
US20090213890A1 (en) * | 2008-02-27 | 2009-08-27 | Patel C Kumar N | Quantum cascade laser |
JP2010521815A (ja) * | 2007-03-16 | 2010-06-24 | プレジデント アンド フェローズ オブ ハーバード カレッジ | テラヘルツ放射の発生方法および装置 |
WO2013061656A1 (ja) * | 2011-10-28 | 2013-05-02 | 浜松ホトニクス株式会社 | 量子カスケードレーザの製造方法 |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5509025A (en) | 1994-04-04 | 1996-04-16 | At&T Corp. | Unipolar semiconductor laser |
JP2010278326A (ja) | 2009-05-29 | 2010-12-09 | Hamamatsu Photonics Kk | 量子カスケードレーザ |
JP5523759B2 (ja) | 2009-07-31 | 2014-06-18 | 浜松ホトニクス株式会社 | 量子カスケードレーザ |
JP2011243781A (ja) | 2010-05-19 | 2011-12-01 | Hamamatsu Photonics Kk | 量子カスケードレーザ |
-
2014
- 2014-05-19 WO PCT/JP2014/063241 patent/WO2014189015A1/ja active Application Filing
- 2014-05-19 US US14/888,999 patent/US9484715B2/en active Active
- 2014-05-19 JP JP2015518240A patent/JP6276758B2/ja active Active
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2008177366A (ja) * | 2007-01-18 | 2008-07-31 | Hamamatsu Photonics Kk | 量子カスケードレーザ |
JP2010521815A (ja) * | 2007-03-16 | 2010-06-24 | プレジデント アンド フェローズ オブ ハーバード カレッジ | テラヘルツ放射の発生方法および装置 |
US20090213890A1 (en) * | 2008-02-27 | 2009-08-27 | Patel C Kumar N | Quantum cascade laser |
WO2013061656A1 (ja) * | 2011-10-28 | 2013-05-02 | 浜松ホトニクス株式会社 | 量子カスケードレーザの製造方法 |
Non-Patent Citations (3)
Title |
---|
KARUN VIJAYRAGHAVAN ET AL.: "Terahertz sources based on Cerenkov difference-frequency generation in quantum cascade lasers", APPLIED PHYSICS LETTERS, vol. 100, June 2012 (2012-06-01), pages 251104-1 - 251104-4 * |
MIKHAIL A. BELKIN ET AL.: "High- Temperature Operation of Terahertz Quantum Cascade Laser Sources", IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS, vol. 15, no. 3, May 2009 (2009-05-01), pages 952 - 967 * |
Q.Y. LU ET AL.: "Room temperature single-mode terahertz sources based on intracavity difference-frequency generation in quantum cascade lasers", APPLIED PHYSICS LETTERS, vol. 99, September 2011 (2011-09-01), pages 131106-1 - 131106-3 * |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN108336643A (zh) * | 2018-01-31 | 2018-07-27 | 中国科学院上海微系统与信息技术研究所 | 有源区结构及具有宽带增益的太赫兹量子级联激光器 |
CN108336643B (zh) * | 2018-01-31 | 2020-06-09 | 中国科学院上海微系统与信息技术研究所 | 有源区结构及具有宽带增益的太赫兹量子级联激光器 |
JP2019192822A (ja) * | 2018-04-26 | 2019-10-31 | 住友電気工業株式会社 | 量子カスケードレーザ |
JP7028049B2 (ja) | 2018-04-26 | 2022-03-02 | 住友電気工業株式会社 | 量子カスケードレーザ |
JP2020123662A (ja) * | 2019-01-30 | 2020-08-13 | 住友電気工業株式会社 | 量子カスケードレーザ |
Also Published As
Publication number | Publication date |
---|---|
US9484715B2 (en) | 2016-11-01 |
US20160087408A1 (en) | 2016-03-24 |
JPWO2014189015A1 (ja) | 2017-02-23 |
JP6276758B2 (ja) | 2018-02-07 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
JP6276758B2 (ja) | 量子カスケードレーザ | |
Strauf et al. | Self-tuned quantum dot gain in photonic crystal lasers | |
JP5641667B2 (ja) | 量子カスケードレーザ | |
US7843981B2 (en) | Quantum cascade laser | |
JP5523759B2 (ja) | 量子カスケードレーザ | |
JP5248881B2 (ja) | 量子カスケードレーザ | |
US8514903B2 (en) | Quantum cascade laser | |
JP2010278326A (ja) | 量子カスケードレーザ | |
US8699538B2 (en) | Quantum cascade laser | |
JP5941655B2 (ja) | 量子カスケードレーザ | |
US8330140B2 (en) | Semiconductor light emitting device | |
Cao | Research progress in terahertz quantum cascade lasers | |
WO2010082405A1 (ja) | 量子カスケードレーザ | |
JP2011151249A (ja) | 量子カスケードレーザ | |
Xie et al. | Nonlinear quantum cascade lasers: Toward broad tunability and short-wavelength operation | |
JP2009239093A (ja) | 量子カスケードレーザ | |
Liu et al. | Carrier dynamics investigation in a quantum cascade laser using Mid-IR femtosecond pulses | |
Xie et al. | In-plane integration of quantum cascade lasers with resonant intersubband nonlinearities | |
Kumar et al. | Terahertz Quantum Cascaded Laser Based on LO‐phonon Scattering Using GaAs/Al x Ga 1− x As (x= 0.15) Material System | |
Belenky et al. | Electrically tunable mid-infrared single-mode high-speed semiconductor laser | |
Belyanin et al. | Two-color heterolasers as parametric generators of infrared radiation | |
GB2473491A (en) | THz Radiation Medium |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
121 | Ep: the epo has been informed by wipo that ep was designated in this application |
Ref document number: 14800895 Country of ref document: EP Kind code of ref document: A1 |
|
ENP | Entry into the national phase |
Ref document number: 2015518240 Country of ref document: JP Kind code of ref document: A |
|
WWE | Wipo information: entry into national phase |
Ref document number: 14888999 Country of ref document: US |
|
NENP | Non-entry into the national phase |
Ref country code: DE |
|
122 | Ep: pct application non-entry in european phase |
Ref document number: 14800895 Country of ref document: EP Kind code of ref document: A1 |