Abstract: A quantum cascade laser device includes a semiconductor substrate, an active layer provided on the semiconductor substrate, and an upper clad layer provided on a side of the active layer opposite to the semiconductor substrate side and having a doping concentration of impurities of less than 1×1017 cm?3. Unit laminates included in the active layer each include a first emission upper level, a second emission upper level, and at least one emission lower level in their subband level structure. The active layer is configured to generate light having a center wavelength of 10 ?m or more due to electron transition between at least two levels of the first emission upper level, the second emission upper level, and the at least one emission lower level in the light emission layer in each of the unit laminates.

Abstract: The laser module includes a QCL element and a light source. The QCL element includes a substrate, a lower clad layer provided on the substrate, an active layer that is provided on an opposite side of the lower clad layer from the substrate and generates a first terahertz wave, an upper clad layer provided on an opposite side of the active layer from the lower clad layer, and a first electrode provided on an opposite side of the upper clad layer from the active layer. The second terahertz wave from the light source enters the active layer through the substrate, is reflected by the first electrode, and is amplified or wavelength-converted. The third terahertz wave amplified or wavelength-converted in the active layer is emitted to the outside through the substrate.

Abstract: The laser module includes a QCL element and a support member. The QCL element has a first end surface located on a first side in a second direction orthogonal to a stacking direction and a second end surface located on a second side opposite to the first side in the second direction. The substrate has first to fourth substrate-surfaces. The support member has a first portion having a first surface facing at least a portion of the fourth substrate-surface, and a second portion having a second surface facing at least a portion of the first substrate-surface and a third surface located opposite to the second surface in the second direction. At least a part of the terahertz wave generated in the active layer is incident on the second surface of the support member through the substrate and is emitted from the third surface through the inside of the second portion.

Abstract: The laser module includes a QCL element, a diffraction grating unit including a movable diffraction grating, a first lens that transmits light emitted from an end surface of the QCL element and light returning from the movable diffraction grating to the QCL element, a second lens that transmits terahertz waves emitted from the QCL element, a first holder, and a package. The first holder has a support surface on which the QCL element is mounted and a side surface connected to the support surface and facing the first lens in a resonance direction. A distance from an intersection point between the side surface and the support surface to the end surface along the resonance direction is smaller than a distance between the intersection point and the first lens along the resonance direction.

Abstract: A quantum-cascade laser element includes: an embedding layer including a first portion formed on a side surface of a ridge portion, and a second portion extending from an edge portion of the first portion on a side of a semiconductor substrate along a width direction of the semiconductor substrate; and a metal layer formed at least on a top surface of the ridge portion and on the first portion. A surface of the second portion on a side opposite to the semiconductor substrate is located between a surface of an active layer on a side opposite to the semiconductor substrate and a surface of the active layer on a side of the semiconductor substrate. When viewed in the width direction of the semiconductor substrate, a part of the metal layer on the first portion overlaps the active layer. The metal layer is directly formed on the first portion.

Abstract: A quantum cascade laser element includes: a semiconductor substrate; a semiconductor laminate having a first end surface and a second end surface; a first electrode; a second electrode; and an anti-reflection film formed on the first end surface. The semiconductor laminate is configured to oscillate laser light having a center wavelength of 7.5 ?m or more. The anti-reflection film includes an insulating film being a CeO2 film formed on the first end surface, a first refractive index film being a YF3 film or a CeF3 film disposed on a side opposite the first end surface with respect to the insulating film, and a second refractive index film formed on the first refractive index film on a side opposite the first end surface with respect to the first refractive index film and having a refractive index of larger than 1.8.

Abstract: A quantum cascade laser includes a semiconductor substrate, an optical waveguide formed on a first surface of the semiconductor substrate, and a temperature adjusting member. The optical waveguide includes a first region and a second region located on one side with respect to the first region in the optical waveguide direction of the optical waveguide. The first region generates a first light having a first wavelength, and the second region generates a second light having a second wavelength. The optical waveguide generates an output light having a frequency corresponding to a difference between the first wavelength and the second wavelength by difference-frequency generation. A recess for suppressing heat transfer between the first region and the second region is formed at a second surface of the semiconductor substrate. The temperature adjusting member includes a first temperature adjusting member for adjusting the temperature of the second region.

Abstract: A laser module including a quantum cascade laser that includes a substrate having a main surface, a first clad layer provided on the main surface, an active layer provided on the first clad layer, and a second clad layer provided on the active layer, and a lens that has a lens plane disposed at a position facing the end surface of the active layer. An end surface of the active layer constitutes a resonator that causes light of a first frequency and light of a second frequency to oscillate, and the active layer is configured to generate a terahertz wave of a differential frequency between the first frequency and the second frequency. The substrate is in direct contact or indirect contact with the lens plane, and the end surface of the active layer is inclined with respect to a portion facing the end surface in the lens plane.

Abstract: A quantum cascade laser device includes a semiconductor substrate, an active layer provided on the semiconductor substrate, and an upper clad layer provided on a side of the active layer opposite to the semiconductor substrate side and having a doping concentration of impurities of less than 1×1017 cm?3. Unit laminates included in the active layer each include a first emission upper level, a second emission upper level, and at least one emission lower level in their subband level structure. The active layer is configured to generate light having a center wavelength of 10 ?m or more due to electron transition between at least two levels of the first emission upper level, the second emission upper level, and the at least one emission lower level in the light emission layer in each of the unit laminates.

Abstract: A QCL includes a semiconductor substrate and an active layer provided on the semiconductor substrate. The active layer has a cascade structure in which a unit laminate including a light emission layer which generates light and an injection layer to which electrons are transported from the light emission layer is laminated in multiple stages. The light emission layer and the injection layer each have a quantum well structure in which quantum well layers and barrier layers are alternately laminated. A separation layer including a separation quantum well layer having a layer thickness smaller than an average layer thickness of the quantum well layers included in the light emission layer and smaller than an average layer thickness of the quantum well layers included in the injection layer is provided between the light emission layer and the injection layer in the unit laminate.

Abstract: An optical semiconductor element includes a semiconductor substrate, a first laminated structure provided on a front surface of the semiconductor substrate, and a second laminated structure provided on the front surface of the semiconductor substrate, the first laminated structure includes a first quantum cascade region, the second laminated structure includes a dummy region having the same layer structure as the first quantum cascade region, a second quantum cascade region provided on the front surface of the semiconductor substrate via the dummy region, and one of the first quantum cascade region and the second quantum cascade region is a quantum cascade laser, and the other of the first quantum cascade region and the second quantum cascade region is a quantum cascade detector.

Abstract: Provided is a superluminescent diode including an optical waveguide body configured as a double heterostructure including an active layer and a first clad layer and a second clad layer interposing the active layer. When a direction perpendicular to both an optical waveguide direction of the optical waveguide body and a facing direction of the first clad layer and the second clad layer is set as a width direction, the active layer is provided with a limitation region extending along the optical waveguide direction and partitioning the active layer in the width direction. Carriers are less likely to be generated in the limitation region than in a region other than the limitation region in the active layer.

Abstract: An optical semiconductor element includes: an optical waveguide body; a first electrode that is disposed on the second clad layer; a second electrode that is disposed on a second clad layer on one side of the first electrode in a light guiding direction of the optical waveguide body; a third electrode that is disposed on the second clad layer on the other side of the first electrode in the light guiding direction; and at least one fourth electrode that faces the first electrode, the second electrode, and the third electrode with the optical waveguide body interposed therebetween. The optical waveguide body includes a first separation region that electrically separates a first region under the first electrode from a second region under the second electrode and a second separation region that electrically separates the first region under the first electrode and a third region under the third electrode.

Abstract: An optical measurement device includes a light source configured to output a terahertz wave and coaxial light having a wavelength different from the wavelength of the terahertz wave, coaxially with the terahertz wave; an intensity modulation unit configured to perform intensity modulation of at least the terahertz wave of the terahertz wave and the coaxial light in a predetermined modulation frequency; and a light detection unit configured to synchronously detects each of the terahertz wave and the coaxial light which have acted on a measurement subject via the intensity modulation unit based on the modulation frequency.

Abstract: A terahertz wave spectroscopic measurement device includes a light source that emits a terahertz wave and probe light having a wavelength different from that of the terahertz wave, an internal total reflection prism including an incidence surface of the terahertz wave, a placement surface on which a measurement target is placed, and an emission surface of the terahertz wave, the internal total reflection prism internally totally reflecting the terahertz wave incident from the incidence surface by means of the placement surface and emitting the terahertz wave from the emission surface, and a terahertz wave detection unit that indirectly detects the terahertz wave emitted from the emission surface using the probe light. The internal total reflection prism includes an avoidance portion on which incidence of the probe light on the measurement target on the placement surface is avoided.

Abstract: A fluid analyzer includes a substrate, a quantum cascade laser formed on a surface of the substrate and including a first light-emitting surface and a second light-emitting surface facing each other in a predetermined direction parallel to the surface, a quantum cascade detector formed on the surface and including the same layer structure as the quantum cascade laser and a light incident surface facing the second light-emitting surface in the predetermined direction, and an optical element disposed on an optical path of light emitted from the first light-emitting surface across an inspection region in which a fluid to be analyzed is to be disposed and reflecting the light to feed the light back to the first light-emitting surface.

Abstract: An optical semiconductor element includes a semiconductor substrate, a first laminated structure provided on a front surface of the semiconductor substrate, and a second laminated structure provided on the front surface of the semiconductor substrate, the first laminated structure includes a first quantum cascade region, the second laminated structure includes a dummy region having the same layer structure as the first quantum cascade region, a second quantum cascade region provided on the front surface of the semiconductor substrate via the dummy region, and one of the first quantum cascade region and the second quantum cascade region is a quantum cascade laser, and the other of the first quantum cascade region and the second quantum cascade region is a quantum cascade detector.

Abstract: A method of manufacturing a quantum cascade laser beam source (1) includes: preparing a semiconductor stacked body (20); forming a pair of first excavated portions (41 and 42) and a ridge portion which is interposed between the pair of first excavated portions (41 and 42); forming channel structures (51 and 52) and circumferential edge portions (61 and 62) which are formed to interpose the channel structures (51 and 52) between the ridge portion (30) and the circumferential edge portion; forming an electrode pattern (81) in contact with a first area (29a) and forming an electrode pattern (82) in contact with a second area (22a); fixing a crystal growth surface side to a support substrate (91); removing an Fe-doped (semi-insulating) InP single-crystal substrate (21); fixing a Si substrate (93); and peeling the support substrate (91).

Abstract: An optical measurement device includes a light source configured to output a terahertz wave and coaxial light having a wavelength different from the wavelength of the terahertz wave, coaxially with the terahertz wave; an intensity modulation unit configured to perform intensity modulation of at least the terahertz wave of the terahertz wave and the coaxial light in a predetermined modulation frequency; and a light detection unit configured to synchronously detects each of the terahertz wave and the coaxial light which have acted on a measurement subject via the intensity modulation unit based on the modulation frequency.

Abstract: A terahertz wave spectroscopic measurement device includes a light source that emits a terahertz wave and probe light having a wavelength different from that of the terahertz wave, an internal total reflection prism including an incidence surface of the terahertz wave, a placement surface on which a measurement target is placed, and an emission surface of the terahertz wave, the internal total reflection prism internally totally reflecting the terahertz wave incident from the incidence surface by means of the placement surface and emitting the terahertz wave from the emission surface, and a terahertz wave detection unit that indirectly detects the terahertz wave emitted from the emission surface using the probe light. The internal total reflection prism includes an avoidance portion on which incidence of the probe light on the measurement target on the placement surface is avoided.