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 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 photodetector 1A comprises an optical element 10, having a structure including first regions and second regions periodically arranged with respect to the first regions along a plane perpendicular to a predetermined direction, for generating an electric field component in the predetermined direction when light is incident thereon along the predetermined direction; arid a semiconductor multilayer body 4 having a quantum cascade structure, arranged on the other side opposite from one side in the predetermined direction with respect to the optical element, for producing a current according to the electric field component in the predetermined direction generated by the optical element 10; while the quantum cascade structure includes an active region 4b having a first upper quantum level and a second upper quantum level lower than the first upper quantum level, and an injector region 4c for transporting an electron excited by the active region 4b.

Abstract: A quantum cascade laser is configured to include a semiconductor substrate, and an active layer that is provided on the substrate and has a cascade structure formed by alternately laminating emission layers and injection layers 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. In a laser cavity structure for light with a predetermined wavelength generated in the active layer, a front reflection film with a reflectance of not less than 40% and not more than 99% for laser oscillation light is formed on the front end face that becomes a laser beam output surface, and a back reflection film with a reflectance higher than that of the front reflection film for the laser oscillation light is formed on the back end face.

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 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 quantum cascade laser is configured to include a semiconductor substrate, and an active layer that is provided on the substrate and has a cascade structure formed by alternately laminating emission layers and injection layers 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. In a laser cavity structure for light with a predetermined wavelength generated in the active layer, a front reflection film with a reflectance of not less than 40% and not more than 99% for laser oscillation light is formed on the front end face that becomes a laser beam output surface, and a back reflection film with a reflectance higher than that of the front reflection film for the laser oscillation light is formed on the back end face.

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 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 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: There is disclosed a waveguide structure that propagates surface plasmon waves, comprising: a quantum well structure, disposed on a semiconductor substrate; wherein the quantum well structure has a quantum well layer, in turn having an intersecting region that intersects a hypothetical plane substantially orthogonal to an alignment direction of the quantum well structure with respect to the semiconductor substrate, and a real part of a dielectric constant of the quantum well structure is negative for THz waves of a predetermined wavelength.

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: There is disclosed a waveguide structure that propagates surface plasmon waves, comprising: a quantum well structure, disposed on a semiconductor substrate; wherein the quantum well structure has a quantum well layer, in turn having an intersecting region that intersects a hypothetical plane substantially orthogonal to an alignment direction of the quantum well structure with respect to the semiconductor substrate, and a real part of a dielectric constant of the quantum well structure is negative for THz waves of a predetermined wavelength.

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: There is provided a magnetooptic device including a substrate; a semiconductor layer having a quantum well structure formed on the substrate, in which the semiconductor layer is formed by alternately laminating a well layer and a barrier layer and at least the barrier layer in those layers contains magnetic ions; and electrodes to apply an electric field to the semiconductor layer. A light which was polarized in a predetermined direction is input to the semiconductor layer. A magnetic field is applied to the semiconductor layer. An electric field is applied to the semiconductor layer by the electrodes. The light which was transmitted in the semiconductor layer is extracted. A degree of leakage of a wave function of the carrier in the well layer into the barrier layer changes. An effective magnetic field which a carrier spin feels changes by an exchange interaction between the carrier spin and a magnetic moment associated with the magnetic ions.

Abstract: The disclosed light emitting semiconductor device has an n-type (or p-type) base region sandwiched by a p-type (or n-type) emitter region and a p-type (or n-type) collector region. An injecting voltage source is connected across the emittter region and base region so as to apply a constant voltage therebetween, while a control voltage source is connected across the emitter region and the collector region so as to selectively apply a reverse bias to a base-collector junction for controlling recombination of carriers injected to the base region. The control voltage source produces such non-emitting period voltage and emitting period voltage that carriers injected during the non-emitting period voltage are captured in the base region while the carriers thus captured are allowed to recombine during the emitting period voltage.

Abstract: Adjacent memory layers of a multi-layered integrated device as optically coupled, so that data written on one layer can be copied onto its adjacent layers through the optical coupling.