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.

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: 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: an optical waveguide body; a first electrode that is disposed on a second clad layer; a second electrode that is disposed on the 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: A quantum cascade laser is configured with a semiconductor substrate, and an active layer provided on a first surface of the substrate and having a cascade structure in the form of a multistage lamination of unit laminate structures each of which includes an emission layer and an injection layer. The active layer is configured to be capable of generating first pump light of a frequency ?1 and second pump light of a frequency ?2 by intersubband emission transitions of electrons, and to generate output light of a difference frequency ? by difference frequency generation from the first pump light and the second pump light. Grooves respectively formed in a direction intersecting with a resonating direction in a laser cavity structure are provided on a second surface opposite to the first surface of the substrate.

Abstract: A quantum cascade laser is configured with a semiconductor substrate, and an active layer provided on a first surface of the substrate and having a multistage lamination of unit laminate structures each of which includes an emission layer and an injection layer. The active layer is configured to be capable of generating first pump light of a frequency ?1 and second pump light of a frequency ?2, and to generate output light of a difference frequency ? by difference frequency generation. An external diffraction grating is provided constituting an external cavity for generating the first pump light and configured to be capable of changing the frequency ?1, outside an element structure portion including the active layer. Grooves respectively formed in a direction intersecting with a resonating direction are provided on a second surface of the substrate.

Abstract: A quantum cascade detector includes a semiconductor substrate; an active layer having a cascade structure; a lower cladding layer provided between the active layer and the substrate and having a lower refractive index than the active layer; a lower metal layer provided between the lower cladding layer and the substrate; an upper cladding layer provided on an opposite side to the substrate with respect to the active layer and having a lower refractive index than the active layer; and an upper metal layer provided on an opposite side to the active layer with respect to the upper cladding layer. A first end face being in a waveguide direction in a waveguide structure with the active layer, lower cladding layer, and upper cladding layer is an entrance surface for light to be detected.