Abstract: A laser module LM is provided with a quantum cascade laser 1, a tubular member 5, and an infrared detector 7. The tubular member 5 has a pair of opening ends 5a, 5b and is arranged so that one opening end 5a is opposed to a face 1b opposed to an emitting end face 1a of the quantum cascade laser 1. The infrared detector 7 is arranged so as to be opposed to the other opening end 5b of the tubular member 5. Light emitted from the face (rear end face) 1b opposed to the emitting end face (front end face) 1a of the quantum cascade laser 1 is guided inside the tubular member 5 to enter the infrared detector 7, and then is detected.

Abstract: A DFB quantum cascade laser element that can reliably CW-oscillate a single-mode light even at room temperature or a temperature in proximity thereof is provided. In a quantum cascade laser element 1, a top-grating approach for which a diffraction grating 7 is formed on a laminate 3 is adopted, and thus in comparison with a buried-grating approach, deterioration in temperature characteristics of the laser element and decline in the yield and reproducibility are suppressed. In addition, since the thickness of a cladding layer 5 located between an active layer 4 and the diffraction grating 7 is within a range of 42±10% of the oscillation wavelength, weakening of light seeping from the active layer 4 to the diffraction grating 7 or an increase in light leakage is prevented. Consequently, by the quantum cascade laser element 1, a single-mode light can be reliably CW-oscillated even at room temperature or a temperature in proximity thereof.

Abstract: A quantum cascade laser includes a semiconductor substrate, and an active layer which is provided on the semiconductor substrate, and has a cascade structure in which unit laminate structures 16 having quantum well emission layers 17 and injection layers 18 are laminated in multiple stages. Further, the quantum cascade laser is configured such that the unit laminate structure 16 has an emission upper level Lup, an emission lower level Llow, and a relaxation miniband MB including an energy level lower than the emission lower level in its subband level structure, and light is generated by an intersubband transition of electrons from the upper level to the lower level, and the electrons after the intersubband transition are relaxed from the lower level Llow to the miniband MB through LO phonon scattering, to be injected from the injection layer 18 to the latter stage emission layer via the miniband MB.

Abstract: A quantum cascade laser is configured to include a semiconductor substrate, and an active layer provided on the substrate and having a cascade structure formed by multistage-laminating unit laminate structures 16 each including an emission layer 17 and an injection layer 18. Further, the unit laminate structure 16 includes, in its subband level structure, a first emission upper level Lup1, a second emission upper level Lup2, and a plurality of emission lower levels Llow, one of the first and second upper levels is a level arising from a ground level in the first well layer, and the other is a level arising from an excitation level in the well layer except for the first well layer. Further, the energy interval between the first upper level and the second upper level is set to be smaller than the energy of an LO phonon, and the energy interval between the second upper level and a higher energy level Lh is set to be larger than the energy of an LO phonon.

Abstract: A quantum cascade laser is configured to include a semiconductor substrate and an active layer which is provided on the substrate and has a cascade structure formed by multistage-laminating unit laminate structures 16 each including an emission layer 17 and an injection layer 18. The unit laminate structure 16 has, in its subband level structure, a first emission upper level Lup1, a second emission upper level Lup2 of an energy higher than the first emission upper level, an emission lower level Llow, and a relaxation level Lr of an energy lower than the emission lower level, light is generated by intersubband transitions of electrons from the first and second upper levels to the lower level, and electrons after the intersubband transitions are relaxed from the lower level to the relaxation level and injected from the injection layer 18 into an emission layer 17b of a subsequent stage via the relaxation level.

Abstract: A semiconductor light emitting device including a semiconductor substrate and an active layer which is formed on the substrate and has a cascade structure formed by multistage-laminating unit laminate structures 16 each including an emission layer 17 and an injection layer 18 is configured. The unit laminate structure 16 has a first upper level L3, a second upper level L4, and a lower level L2 in the emission layer 17, and an injection level L1 in the injection layer 18, an energy interval between the levels L3 and L4 is set to be smaller than the energy of an LO phonon, the layer thickness of the exit barrier layer is set in a range not less than 70% and not more than 150% of the layer thickness of the injection barrier layer, light is generated by emission transition in the emission layer 17, and electrons after the emission transition are injected from the level L2 into the level L4 of the emission layer of a subsequent stage via the level L1.

Abstract: A quantum cascade laser is configured so as to include a semiconductor substrate and an active layer which is provided on the substrate and has a cascade structure including multistage-laminated unit laminate structures 16 each including a quantum well emission layer 17 and an injection layer 18. Moreover, the unit laminate structure 16 has, in its subband level structure, an emission upper level 3, a lower level 2, and an injection level 4 of higher energy than the upper level 3, and light hv is generated by intersubband transition of electrons from the level 3 to the level 2 in the emission layer 17, and electrons after emission transition are injected into the injection level 4 of the subsequent stage via the injection layer 18. In addition, the emission layer 17 includes two or more well layers, and the first well layer closest to the injection layer of the preceding stage is used as a well layer for injection level formation.

Abstract: A quantum cascade laser is composed of a semiconductor substrate, and an active layer provided on the semiconductor substrate and having a cascade structure formed by multistage-laminating unit laminate structures 16 each of which includes a quantum well light emitting layer 17 and an injection layer 18. The unit laminate structure 16 has, in its subband level structure, an emission upper level 3, an emission lower level 2, and an injection level 4 as an energy level higher than the emission upper level 3, and light h? is generated by means of intersubband transition of electrons from the level 3 to the level 2 in the light emitting layer 17, and electrons through the intersubband transition are injected into the injection level in a unit laminate structure of the subsequent stage via the injection layer 18, and from this injection level, electrons are supplied to the emission upper level. Thereby, a quantum cascade laser which realizes operation with a high output at a high temperature is realized.

Abstract: A quantum cascade laser 1, which generates infrared light or other light of a predetermined wavelength by making use of intersubband transitions in a quantum well structure, is arranged by forming, on a GaAs substrate 10, an AlGaAs/GaAs active layer 11 having a cascade structure in which quantum well light emitting layers and injection layers are laminated alternately. Also, at the GaAs substrate 10 side and the side opposite the GaAs substrate 10 side of active layer 11, is provided a waveguide structure, comprising waveguide core layers 12 and 14, each being formed of an n-type GaInNAs layer, which is a group III-V compound semiconductor that contains N (nitrogen), formed so as to be lattice matched with the GaAs substrate 10, and waveguide clad layers 13 and 15, each formed of an n++-type GaAs layer. A quantum cascade laser, with which the waveguide loss of generated light in the laser is reduced, is thereby realized.

Abstract: A quantum cascade laser includes a semiconductor substrate, and an active layer which is provided on the semiconductor substrate, and has a cascade structure in which unit laminate structures 16 having quantum well emission layers 17 and injection layers 18 are laminated in multiple stages. Further, the quantum cascade laser is configured such that the unit laminate structure 16 has an emission upper level Lup, an emission lower level Llow, and a relaxation miniband MB including an energy level lower than the emission lower level in its subband level structure, and light is generated by an intersubband transition of electrons from the upper level to the lower level, and the electrons after the intersubband transition are relaxed from the lower level Llow to the miniband MB through LO phonon scattering, to be injected from the injection layer 18 to the latter stage emission layer via the miniband MB.

Abstract: A DFB quantum cascade laser element that can reliably CW-oscillate a single-mode light even at room temperature or a temperature in proximity thereof is provided. In a quantum cascade laser element 1, a top-grating approach for which a diffraction grating 7 is formed on a laminate 3 is adopted, and thus in comparison with a buried-grating approach, deterioration in temperature characteristics of the laser element and decline in the yield and reproducibility are suppressed. In addition, since the thickness of a cladding layer 5 located between an active layer 4 and the diffraction grating 7 is within a range of 42±10% of the oscillation wavelength, weakening of light seeping from the active layer 4 to the diffraction grating 7 or an increase in light leakage is prevented. Consequently, by the quantum cascade laser element 1, a single-mode light can be reliably CW-oscillated even at room temperature or a temperature in proximity thereof.

Abstract: A quantum cascade laser is composed of a semiconductor substrate, and an active layer provided on the semiconductor substrate and having a cascade structure formed by multistage-laminating unit laminate structures 16 each of which includes a quantum well light emitting layer 17 and an injection layer 18. The unit laminate structure 16 has, in its subband level structure, an emission upper level 3, an emission lower level 2, and an injection level 4 as an energy level higher than the emission upper level 3, and light h? is generated by means of intersubband transition of electrons from the level 3 to the level 2 in the light emitting layer 17, and electrons through the intersubband transition are injected into the injection level in a unit laminate structure of the subsequent stage via the injection layer 18, and from this injection level, electrons are supplied to the emission upper level. Thereby, a quantum cascade laser which realizes operation with a high output at a high temperature is realized.

Abstract: In a quantum cascade laser device 1, a laminate structure 11 is formed into a stripe shape along a predetermined direction on a principal surface at one side of a substrate 10, and insulating layers 15 are formed on bilateral sides of the laminate structure 11, and an insulating layer 16 and a metal layer 17 are formed in sequence on the laminate structure 11 and the insulating layers 15. The laminate structure 11 is formed such that a cladding layer 12, an active layer 13, and a cladding layer 14 are formed in sequence from the side of the substrate 10. In the active layer 13, light emitting layers and injection layers are alternately laminated, and the active layer 13 generates light due to intersubband electron transition in a quantum well structure. A shape in a cross section of the laminate structure 11 perpendicular to the direction in which the laminate structure 11 is provided to extend is formed into a rectangle or an inverted mesa shape.

Abstract: A quantum cascade laser 1, which generates infrared light or other light of a predetermined wavelength by making use of intersubband transitions in a quantum well structure, is arranged by forming, on a GaAs substrate 10, an AlGaAs/GaAs active layer 11 having a cascade structure in which quantum well light emitting layers and injection layers are laminated alternately. Also, at the GaAs substrate 10 side and the side opposite the GaAs substrate 10 side of active layer 11, is provided a waveguide structure, comprising waveguide core layers 12 and 14, each being formed of an n-type GaInNAs layer, which is a group III-V compound semiconductor that contains N (nitrogen), formed so as to be lattice matched with the GaAs substrate 10, and waveguide clad layers 13 and 15, each formed of an n++-type GaAs layer. A quantum cascade laser, with which the waveguide loss of generated light in the laser is reduced, is thereby realized.

Abstract: A quantum cascade laser 1, which generates infrared light or other light of a predetermined wavelength by making use of intersubband transitions in a quantum well structure, is arranged by forming, on a GaAs substrate 10, an AlGaAs/GaAs active layer 11 having a cascade structure in which quantum well light emitting layers and injection layers are laminated alternately. Also, at the GaAs substrate 10 side and the side opposite the GaAs substrate 10 side of active layer 11, is provided a waveguide structure, comprising waveguide core layers 12 and 14, each being formed of an n-type GaInNAs layer, which is a group III-V compound semiconductor that contains N (nitrogen), formed so as to be lattice matched with the GaAs substrate 10, and waveguide clad layers 13 and 15, each formed of an n++-type GaAs layer. A quantum cascade laser, with which the waveguide loss of generated light in the laser is reduced, is thereby realized.

Abstract: The present invention relates to a preferred semiconductor substrate for the production of devices. The semiconductor substrate is comprised of GaAs. Then, a plurality of quantum rings, which are composed of GaSb and have a substantially elliptical shape with an aspect ratio of 2 or more but 5 or less, are formed on a surface of the semiconductor substrate. These quantum rings extend along in the substantially same direction. In a case where a light beam is irradiated onto the surface of the semiconductor substrate, among the polarized components of the irradiated light, one polarized component parallel to the long-axis direction of the ellipse that is an extending direction of each quantum ring is reflected, while another polarized component parallel to the short-axis direction thereof is transmitted. That is, the semiconductor substrate reflects one polarized component, and transmits the other polarized component.

Abstract: A laser device includes a laminated body obtained by laminating a plurality of semiconductor layers on a semiconductor substrate. One semiconductor layer of the plurality of semiconductor layers is an active layer in which a light-emission region and an injecting region are alternately laminated. The laser device is provided with a cascade laser element for outputting light L generated in the active layer from a first end face included in the laminated body, a part for supplying a voltage to the laser element and driving the laser element, a part for supplying an elastic wave traveling in the direction orthogonal to the first end face of the laminated body to the active layer, and a part for supplying a turn-on voltage in which the gain of the laser element becomes the approximate maximum value to the laser element by the element driving part, and supplying the elastic wave to the active layer by the elastic wave supplying part.

Abstract: A semiconductor photocathode comprises a p+-type semiconductor substrate of GaSb, and a p?-type light absorbing layer of InAsSb. A p+-type hole blocking layer is formed between the substrate and the light absorbing layer having wider energy band gap than that of the light absorbing layer, the blocking layer being made of AlGaSb.

Abstract: The present invention relates to a semiconductor chip and the like provided with a structure, which is applicable to a terahertz electromagnetic-wave device and capable of further reducing the life of the carriers. The semiconductor chip comprises a single crystal semiconductor substrate and a Group III-V compound semiconductor layer. The Group III-V compound semiconductor layer is characterized in that, in the vicinity of the surface, the concentration of Group V atoms is higher than the concentration of Group III atoms, and in that oxygen is included therein. In the Group III-V compound semiconductor layer, many As-clusters are deposited. It is known that the As-clusters function as a main factor for capturing the carriers; particularly, it is known that As-clusters near the upper surface of the Group III-V compound semiconductor layer contribute to the capture of carriers. Also, the Group III-V compound semiconductor layer includes oxygen; and due to this oxygen, a deep level is formed.

Abstract: The present invention relates to a preferred semiconductor substrate for the production of devices. The semiconductor substrate is comprised of GaAs. Then, a plurality of quantum rings, which are composed of GaSb and have a substantially elliptical shape with an aspect ratio of 2 or more but 5 or less, are formed on a surface of the semiconductor substrate. These quantum rings extend along in the substantially same direction. In a case where a light beam is irradiated onto the surface of the semiconductor substrate, among the polarized components of the irradiated light, one polarized component parallel to the long-axis direction of the ellipse that is an extending direction of each quantum ring is reflected, while another polarized component parallel to the short-axis direction thereof is transmitted. That is, the semiconductor substrate reflects one polarized component, and transmits the other polarized component.