Abstract: A quantum cascade laser includes a semiconductor substrate, and an active layer that is provided on the substrate, and has a cascade structure in which emission layers and injection layers are alternately laminated by multistage-laminating unit laminate structures each consisting of the quantum well emission layer and the injection layer, the active layer generates light by intersubband transition in a quantum well structure. Further, in a laser cavity structure for light with a predetermined wavelength to be generated in the active layer, reflection control films including at least one layer of CeO2 film are formed on a first end face and a second end face facing each other. Thereby, it is possible to realize a quantum cascade laser capable of preferably realizing reflectance control for light within a mid-infrared wavelength region on the laser device end face.

Abstract: A quantum cascade laser includes a semiconductor substrate, and an active layer that is provided on the substrate, and has a cascade structure in which emission layers and injection layers are alternately laminated by multistage-laminating unit laminate structures each consisting of the quantum well emission layer and the injection layer, and generates light by intersubband transition in a quantum well structure. Further, in a laser cavity structure for light with a predetermined wavelength to be generated in the active layer, CeO2 insulating films and reflection control films are formed in order on respective faces of a first end face and a second end face facing each other. Thereby, it is possible to realize a quantum cascade laser capable of preferably realizing reflectance control for light within a mid-infrared region on the laser device end face.

Abstract: A microparticle dispersion liquid manufacturing apparatus 10 includes a controller 11, a light source 12, an irradiation optical system 13, and a container 14. A solid object 1 is contained in and a solvent 2 is injected into an interior of the container 14 to enable attainment of a state where the solid object 1 is in contact with the solvent 2. The light source 12 repeatedly outputs pulsed light. By repeatedly irradiating the solvent 2 with the pulsed light from the light source 12, expansion and contraction of the solvent 2 is made to occur repeatedly at the irradiated portion, thereby generating a pressure wave in the solvent 2, and the pressure wave is made to act on the solid object 1 to finely pulverize the solid object 1 and thereby manufacture a microparticle dispersion liquid in which microparticles are dispersed in the solvent.

Abstract: A quantum cascade laser includes a semiconductor substrate, and an active layer being provided on the substrate, and having a cascade structure in which quantum well emission layers and injection layers are alternately laminated, and the laser has a base portion including the substrate, and a stripe-shaped ridge portion including the active layer. Further, a reflection control film is formed from a ridge end face over a base end face on an end face in a resonating direction of the laser, and, on the base end face, for a second side and a third side adjacent to a first side on the ridge portion side of the base end face, and a fourth side facing the first side, the reflection control film is formed on a region other than regions near those three sides with predetermined widths.

Abstract: A quantum cascade laser 1 includes a semiconductor substrate, an active layer 15 that is disposed on the semiconductor substrate and has a cascade structure in which a unit layered structure 16 including a quantum well light emitting layer and an injection layer is stacked in multiples to alternately stack the quantum well light emitting layer and the injection layer, and a diffraction grating layer 20 disposed on the active layer.

Abstract: A quantum cascade laser 1 includes a semiconductor substrate, an active layer 15 that is disposed on the semiconductor substrate and has a cascade structure in which a unit layered structure 16 including a quantum well light emitting layer and an injection layer is stacked in multiples to alternately stack the quantum well light emitting layer and the injection layer, and a diffraction grating layer 20 disposed on the active layer.

Abstract: A quantum cascade laser manufacturing method includes: a step of pressing a mother stamper against a resin film having flexibility to make a resin stamper 201 having a second groove pattern P2; a step of making a wafer with an active layer formed on a semiconductor substrate; a step of forming a resist film 304 on a surface on the active layer side of the wafer; a step of pressing the resin stamper against the resist film 304 by air pressure to form a third groove pattern P3 on the resist film 304; and a step of etching the wafer with the resist film 304 serving as a mask to form a diffraction grating on a surface of the wafer.

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 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 dental therapy apparatus which enables a dental therapy more surely and less invasively is provided. A dental therapy apparatus (10A) comprises a laser light source (11) emitting laser light (L) having a wavelength within a wavelength region of 5.7 to 6.6 ?m; a controller (12) pulse-driving the laser light source and controlling at least one of pulse width and repetition frequency of pulsed laser light emitted from the laser light source; and an irradiation optical system for irradiating a tooth (20) including a carious part (21) with the light emitted from the laser light source. In this dental therapy apparatus, the controller controls at least one of the pulse width and repetition frequency of the pulsed light, so as to selectively cut the carious part (21).

Abstract: A quantum cascade laser includes a semiconductor substrate, and an active layer that is provided on the substrate, and has a cascade structure in which emission layers and injection layers are alternately laminated by multistage-laminating unit laminate structures each consisting of the quantum well emission layer and the injection layer, the active layer generates light by intersubband transition in a quantum well structure. Further, in a laser cavity structure for light with a predetermined wavelength to be generated in the active layer, reflection control films including at least one layer of CeO2 film are formed on a first end face and a second end face facing each other. Thereby, it is possible to realize a quantum cascade laser capable of preferably realizing reflectance control for light within a mid-infrared wavelength region on the laser device end face.

Abstract: A quantum cascade laser includes a semiconductor substrate, and an active layer that is provided on the substrate, and has a cascade structure in which emission layers and injection layers are alternately laminated by multistage-laminating unit laminate structures each consisting of the quantum well emission layer and the injection layer, and generates light by intersubband transition in a quantum well structure. Further, in a laser cavity structure for light with a predetermined wavelength to be generated in the active layer, CeO2 insulating films and reflection control films are formed in order on respective faces of a first end face and a second end face facing each other. Thereby, it is possible to realize a quantum cascade laser capable of preferably realizing reflectance control for light within a mid-infrared region on the laser device end face.

Abstract: A wavelength-tunable light source includes a quantum cascade laser that emits light from a first end and a second end, an optical system that collimates the light emitted from the first end, a first reflecting section on which the light collimated by the optical system is made incident, and a second reflecting section that partially reflects the light emitted from the second end of the quantum cascade laser and transmits the remaining light. The first reflecting section includes a plurality of diffractive gratings whose diffractive properties are different from each other and whose lattice plane directions are variable, and the first reflecting section diffracts a light at a particular wavelength corresponding to the diffractive property and the lattice plane direction of the selected diffractive grating in the direction opposite to the incident direction.

Abstract: A microparticle dispersion liquid manufacturing apparatus 10 includes a controller 11, a light source 12, an irradiation optical system 13, and a container 14. A solid object 1 is contained in and a solvent 2 is injected into an interior of the container 14 to enable attainment of a state where the solid object 1 is in contact with the solvent 2. The light source 12 repeatedly outputs pulsed light. By repeatedly irradiating the solvent 2 with the pulsed light from the light source 12, expansion and contraction of the solvent 2 is made to occur repeatedly at the irradiated portion, thereby generating a pressure wave in the solvent 2, and the pressure wave is made to act on the solid object 1 to finely pulverize the solid object 1 and thereby manufacture a microparticle dispersion liquid in which microparticles are dispersed in the solvent.

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 each including a quantum well emission layer and an injection layer. Moreover, the unit laminate structure has, in its subband level structure, an emission upper level, a lower level, and an injection level 4 of higher energy than the upper level, and light h? is generated by intersubband transition of electrons from the level to the level in the emission layer, and electrons after emission transition are injected into the injection level 4 of the subsequent stage via the injection layer. In addition, the emission layer 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 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 wavelength-tunable light source includes a quantum cascade laser that emits light from a first end and a second end, an optical system that collimates the light emitted from the first end, a first reflecting section on which the light collimated by the optical system is made incident, and a second reflecting section that partially reflects the light emitted from the second end of the quantum cascade laser and transmits the remaining light. The first reflecting section includes a plurality of diffractive gratings whose diffractive properties are different from each other and whose lattice plane directions are variable, and the first reflecting section diffracts a light at a particular wavelength corresponding to the diffractive property and the lattice plane direction of the selected diffractive grating in the direction opposite to the incident direction.

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.