Abstract: A semiconductor laser element includes: an n-type cladding layer disposed above an n-type semiconductor substrate (a chip-like substrate); an active layer disposed above the n-type cladding layer; and a p-type cladding layer disposed above the active layer, in which the active layer includes a well layer and a barrier layer, an energy band gap of the barrier layer is larger than an energy band gap of the n-type cladding layer, and a refractive index of the barrier layer is higher than a refractive index of the n-type cladding layer.

Abstract: A semiconductor light-emitting element includes: a substrate; an n-type clad layer above the substrate; an active layer above the n-type clad layer; and a p-type clad layer above the active layer. The active layer includes: a well layer; an n-side first barrier layer on an n-type clad layer side of the well layer; and a p-side barrier layer on a p-type clad layer side of the well layer. The p-side barrier layer comprises In. The n-side first barrier layer has an In composition ratio lower than an In composition ratio of the p-side barrier layer. The n-side first barrier layer has a band gap energy smaller than a band gap energy of the p-side barrier layer.

Abstract: A semiconductor laser device lases in a multiple transverse mode and includes a stacked structure where a first conductivity-side semiconductor layer, an active layer, and a second conductivity-side semiconductor layer are stacked above a substrate. The second conductivity-side semiconductor layer includes a current block layer having an opening that delimits a current injection region. Side faces as a pair are formed in portions of the stacked structure that range from part of the first conductivity-side semiconductor layer to the second conductivity-side semiconductor layer. The active layer has a second width greater than a first width of the opening. The side faces in at least part of the first conductivity-side semiconductor layer are inclined to the substrate. A maximum intensity position in a light distribution of light guided in the stacked structure, in a direction of the normal to the substrate, is within the first conductivity-side semiconductor layer.

Abstract: A nitride light emitter includes: a nitride semiconductor light-emitting element including an AlxGa1-xN substrate (0?x?1) and a multilayer structure above the AlxGa1-xN substrate; and a submount substrate on which the nitride semiconductor light-emitting element is mounted. The multilayer structure includes a first clad layer of a first conductivity type, a first light guide layer, a quantum-well active layer, a second light guide layer, and a second clad layer of a second conductivity type which are stacked sequentially from the AlxGa1-xN substrate. The multilayer structure and submount substrate are opposed to each other. The submount substrate comprises diamond. The nitride semiconductor light-emitting element has a concave warp on a surface closer to the AlxGa1-xN substrate.

Abstract: A semiconductor laser element includes: a first conductivity-type cladding layer; a first guide layer disposed above the first conductivity-type cladding layer; an active layer disposed above the first guide layer; and a second conductivity-type cladding layer disposed above the active layer. A window region is formed in a region of the active layer including part of at least one of the front-side end face or the rear-side end face, the first conductivity-type cladding layer consists of (AlxGa1-x)0.5In0.5P, the first guide layer consists of (AlyGa1-y)0.5In0.5P, and the second conductivity-type cladding layer consists of (AlzGa1-z)0.5In0.5P, where x, y, and z each denote an Al composition ratio, 0<x?y<z?y is satisfied, and D/L>0.03 is satisfied, where L denotes a length of the resonator and D denotes a length of the window region in the first direction.

Abstract: A semiconductor laser element includes: an n-type cladding layer disposed above an n-type semiconductor substrate (a chip-like substrate); an active layer disposed above the n-type cladding layer; and a p-type cladding layer disposed above the active layer, in which the active layer includes a well layer and a barrier layer, an energy band gap of the barrier layer is larger than an energy band gap of the n-type cladding layer, and a refractive index of the barrier layer is higher than a refractive index of the n-type cladding layer.

Abstract: A semiconductor laser device includes: a first semiconductor layer on a first conductivity side; a second semiconductor layer on the first conductivity side; an active layer; a third semiconductor layer on a second conductivity side different from the first conductivity side; and a fourth semiconductor layer on the second conductivity side. Eg2<Eg3 is satisfied, where Eg2 and Eg3 denote maximum values of band gap energy of the second semiconductor layer and the third semiconductor layer, respectively. The third semiconductor layer includes a first region layer in which band gap energy monotonically decreases toward the fourth semiconductor layer. N2>N3 is satisfied, where N2 denotes an impurity concentration of the second semiconductor layer, and N3 denotes an impurity concentration of the third semiconductor layer.

Abstract: A semiconductor laser device includes: a first conductivity side semiconductor layer, an active layer; and a second conductivity side semiconductor layer. The second conductivity side semiconductor layer includes a first semiconductor layer and a second semiconductor layer, the first semiconductor layer being closer to the active layer than the second semiconductor layer is. The second semiconductor layer defines a width of a current injection region for injecting current into an optical waveguide. The current injection region includes a width varying region in which a width varies. S1>S2, where S1 denotes a width of the width varying region on a front end face side, and S2 denotes a width of the width varying region on a rear end face side.

Abstract: A nitride-based light-emitting device includes, on a GaN substrate: a first-conductivity-side first semiconductor layer; an active layer; and a second-conductivity-side first semiconductor layer, in the stated order, and further includes an electron barrier layer of a second conductivity type between the active layer and the second-conductivity-side first semiconductor layer, the electron barrier layer including a nitride-based semiconductor containing at least Al. The electron barrier layer has a first region in which an Al composition changes. The Al composition in the first region monotonically increases in a direction from the active layer to the second-conductivity-side first semiconductor layer. An impurity concentration in the second-conductivity-side first semiconductor layer is lower in a region nearer the electron barrier layer than in a region farther from the electron barrier layer.

Abstract: A nitride light emitter includes: a nitride semiconductor light-emitting element including an AlxGa1-xN substrate (0?x?1) and a multilayer structure above the AlxGa1-xN substrate; and a submount substrate on which the nitride semiconductor light-emitting element is mounted. The multilayer structure includes a first clad layer of a first conductivity type, a first light guide layer, a quantum-well active layer, a second light guide layer, and a second clad layer of a second conductivity type which are stacked sequentially from the AlxGa1-xN substrate. The multilayer structure and submount substrate are opposed to each other. The submount substrate comprises diamond. The nitride semiconductor light-emitting element has a concave warp on a surface closer to the AlxGa1-xN substrate.

Abstract: A semiconductor laser device lases in a multiple transverse mode and includes a stacked structure where a first conductivity-side semiconductor layer, an active layer, and a second conductivity-side semiconductor layer are stacked above a substrate. The second conductivity-side semiconductor layer includes a current block layer having an opening that delimits a current injection region. Side faces as a pair are formed in portions of the stacked structure that range from part of the first conductivity-side semiconductor layer to the second conductivity-side semiconductor layer. The active layer has a second width greater than a first width of the opening. The side faces in at least part of the first conductivity-side semiconductor layer are inclined to the substrate. A maximum intensity position in a light distribution of light guided in the stacked structure, in a direction of the normal to the substrate, is within the first conductivity-side semiconductor layer.

Abstract: A semiconductor laser device includes: a first semiconductor layer on a first conductivity side; a second semiconductor layer on the first conductivity side; an active layer; a third semiconductor layer on a second conductivity side different from the first conductivity side; and a fourth semiconductor layer on the second conductivity side. Eg2<Eg3 is satisfied, where Eg2 and Eg3 denote maximum values of band gap energy of the second semiconductor layer and the third semiconductor layer, respectively. The third semiconductor layer includes a first region layer in which band gap energy monotonically decreases toward the fourth semiconductor layer. N2>N3 is satisfied, where N2 denotes an impurity concentration of the second semiconductor layer, and N3 denotes an impurity concentration of the third semiconductor layer.

Abstract: A semiconductor laser device includes: a first conductivity side semiconductor layer, an active layer; and a second conductivity side semiconductor layer. The second conductivity side semiconductor layer includes a first semiconductor layer and a second semiconductor layer, the first semiconductor layer being closer to the active layer than the second semiconductor layer is. The second semiconductor layer defines a width of a current injection region for injecting current into an optical waveguide. The current injection region includes a width varying region in which a width varies. S1>S2, where S1 denotes a width of the width varying region on a front end face side, and S2 denotes a width of the width varying region on a rear end face side.

Abstract: A nitride-based light-emitting device includes, on a GaN substrate: a first-conductivity-side first semiconductor layer; an active layer; and a second-conductivity-side first semiconductor layer, in the stated order, and further includes an electron barrier layer of a second conductivity type between the active layer and the second-conductivity-side first semiconductor layer, the electron barrier layer including a nitride-based semiconductor containing at least Al. The electron barrier layer has a first region in which an Al composition changes. The Al composition in the first region monotonically increases in a direction from the active layer to the second-conductivity-side first semiconductor layer. An impurity concentration in the second-conductivity-side first semiconductor layer is lower in a region nearer the electron barrier layer than in a region farther from the electron barrier layer.

Abstract: A semiconductor laser diode includes a semiconductor multilayer structure including a first cladding layer of n-type conductivity, an active layer, and a second cladding layer of p-type conductivity having a ridge portion in an upper portion, which are sequentially formed on a substrate; a current blocking layer formed on the semiconductor multilayer structure, and having an opening exposing an upper surface of the ridge portion; an ohmic electrode formed on the upper surface of the ridge portion; an interconnect formed on the semiconductor multilayer structure to be electrically connected to the ohmic electrode; and a pad electrode formed in a region on one side of the ridge portion on the interconnect. The interconnect connects the pad electrode to the ohmic electrode through at least two current channels.

Abstract: A red laser portion and an infrared laser portion are integrated on an n-type GaAs substrate. A p-type cladding layer made of p-type AlGaInP in the red laser portion and a p-type cladding layer made of p-type AlGaInP in the infrared laser portion have a ridge stripe portion having a light emitting point. A current block layer made of SiNx is formed on both sides of each ridge stripe portion, and a strain relaxing layer made of ZrO2 is selectively formed on an outer side of each ridge stripe region on the current block layer. Provided that Tc is a thermal expansion coefficient of the p-type cladding layers, Tb is a thermal expansion coefficient of the current block layer, and Ts is a thermal expansion coefficient of the strain relaxing layer, the relation of Tb<Tc<Ts is satisfied.

Abstract: A red laser portion and an infrared laser portion are integrated on an n-type GaAs substrate. A p-type cladding layer made of p-type AlGaInP in the red laser portion and a p-type cladding layer made of p-type AlGaInP in the infrared laser portion have a ridge stripe portion having a light emitting point. A current block layer made of SiNx is formed on both sides of each ridge stripe portion, and a strain relaxing layer made of ZrO2 is selectively formed on an outer side of each ridge stripe region on the current block layer. Provided that Tc is a thermal expansion coefficient of the p-type cladding layers, Tb is a thermal expansion coefficient of the current block layer, and Ts is a thermal expansion coefficient of the strain relaxing layer, the relation of Tb<Tc<Ts is satisfied.

Abstract: An overcurrent protection circuit according to the present invention includes: overcurrent detecting means for detecting a flow of an overcurrent in a load circuit; and voltage controlling means for changing a power supply voltage and supplying the resultant power supply voltage to the load circuit. The overcurrent detecting means detects a voltage decrease occurring when an overcurrent is generated, with respect to a voltage supplied to the load circuit during normal operation. The voltage controlling means suppresses an overcurrent flowing in the load circuit based on the voltage decrease.