Abstract: A semiconductor laser device includes first and second conductivity type cladding layer side guide layers disposed in direct contact with respective surfaces of an active layer, sandwiching the active layer; and first and second conductivity type cladding layers disposed in direct contact with the first and second conductivity type cladding layer side guide layer, respectively. The first and second conductivity type cladding layer side guide layers are InGaAsP which is lattice-matched to GaAs and have an As composition ratio more than 0 and not exceeding 0.3. The first and second conductivity type cladding layers are AlGaAs, having an Al composition ratio less than 1.0 and at least equal to an Al composition ratio at which refractive index of the AlGaAs is less than the refractive index of the InGaAsP.

Abstract: An n-type first cladding layer, a first guide layer, a first enhancing layer, an active layer, a second enhancing layer, a second guide layer, and a p-type second cladding layer are sequentially stacked on an n-type GaAs substrate. The thickness of each of the first guide layer and the second guide layer is 100 nm or more. In such a semiconductor laser, the difference between the Eg (band gap energy) of the first guide layer and the Eg of the active layer (or the difference between the Eg of the second guide layer and the Eg of the active layer) is made 0.66 times or less of the difference between the Eg of the first cladding layer and the Eg of the active layer (or the difference between the Eg of the second cladding layer and the Eg of the active layer).

Abstract: A semiconductor optical element having a includes an n-type GaAs buffer layer, an n-type AlGaInP cladding layer, a first InGaAsP (including zero As content)guide layer without added dopant impurities, an InGaAsP (including zero In content) active layer, a second InGaAsP (including zero As content)guide layer without added dopant impurities, a p-type AlGaInP cladding layer, a p-type band discontinuity reduction layer, and a p-type GaAs contact layer sequentially laminated on an n-type GaAs substrate C or Mg is the dopant impurity in the p-type GaAs contact layer, the p-type band discontinuity reduction layer, and the p-type AlGaInP cladding layer.

Abstract: An n-type first cladding layer, a first guide layer, a first enhancing layer, an active layer, a second enhancing layer, a second guide layer, and a p-type second cladding layer are sequentially stacked on an n-type GaAs substrate. The thickness of each of the first guide layer and the second guide layer is 100 nm or more. In such a semiconductor laser, the difference between the Eg (and gap energy) of the first guide layer and the Eg of the active layer (or the difference between the Eg of the second guide layer and the Eg of the active layer) is made 0.66 times or less of the difference between the Eg of the first cladding layer and the Eg of the active layer (or the difference between the Eg of the second cladding layer and the Eg of the active layer).

Abstract: A semiconductor laser device comprises an active layer, a cladding layer, an end face for emitting light. A low-reflective film is provided on the end face. The reflectance of the low-reflective film changes with wavelength. A wavelength at which the reference of the low-reflective film is minimized is on the long wavelength side of a wavelength at which the gain of the semiconductor laser device is maximized. The gain and the loss of the semiconductor laser device become equal at a wavelength only in a wavelength region in which the reflectance of the low-reflective film decreases with increasing wavelength. The reflectance of the low-reflective film is preferably set to 1% or less at the wavelength at which the gain of the semiconductor laser device is maximized.

Abstract: method for manufacturing a semiconductor optical device includes forming an epitaxial structure containing at least an active layer which can emit light, of a III-V group semiconductor material; forming an insulating layer over the epitaxial structure, which prevents the V group element from escaping from the epitaxial structure during heat treatment; heat treating the epitaxial structure at at least 800 degrees C; and removing the insulating layer, thereby enhancing the reliability of the device.

Abstract: A semiconductor laser device includes: on an n-GaAs substrate, an n-type cladding layer of n-(Al0.3Ga0.7)0.5In1.5P, an n-side guide layer of i-In0.49Ga0.51P lattice-matched to GaAs, an active layer having a larger refractive index than the n-side guide layer, and including an In0.07Ga0.93As quantum well layer, a p-side guide layer of i-In0.49Ga0.51P, and a p-type cladding layer of p-(Al0.3Ga0.7)0.5In0.5P. Therefore, the anti-COD level increased, and internal loss minimized.

Abstract: A semiconductor laser device includes an optical fiber having an optical fiber grating formed therein, a semiconductor laser having an active layer with a single quantum well, for emitting laser light, and a coupling optical system for coupling the laser light emitted out of the semiconductor laser into the optical fiber. The coupling optical system can include a narrow-band filter for adjusting an incident angle of the laser light emitted out of the semiconductor laser. The optical fiber grating can have a reflection bandwidth wider than or substantially equal to a 3dB bandwidth of the gain of the semiconductor laser or a spectrum full width at half maximum of the laser light of the semiconductor laser.

Abstract: The present invention provides a semiconductor laser device including a heat sink having one main surface, an n-AlGaAs cladding layer disposed on the main surface of the heat sink, an AlGaAs active layer disposed on the n-AlGaAs cladding layer and a p-AlGaAs cladding layer disposed on the AlGaAs active layer. An effective refractive index and a thermal resistance between a main surface on the heat sink side, of the AlGaAs active layer and a main surface on the heat sink side, of the n-AlGaAs cladding layer are respectively set smaller than those between a main surface on the side opposite to the heat sink, of the AlGaAs active layer and a main surface on the side opposite to the heat sink, of the p-AlGaAs cladding layer.

Abstract: A semiconductor optical element having a includes an n-type GaAs buffer layer, an n-type AlGaInP cladding layer, a first InGaAsP (including zero As content) guide layer without added dopant impurities, an InGaAsP (including zero In content) active layer, a second InGaAsP (including zero As content) guide layer without added dopant impurities, a p-type AlGaInP cladding layer, a p-type band discontinuity reduction layer, and a p-type GaAs contact layer sequentially laminated on an n-type GaAs substrate C or Mg is the dopant impurity in the p-type-GaAs contact layer, the p-type band discontinuity reduction layer, and the p-type AlGaInP cladding layer.

Abstract: A semiconductor laser device producing light having a TE-polarized component suitable for practical use. A semiconductor laser device includes a GaAsP active layer, InGaP guide layers, and, AlGaInP cladding layers. The GaAsP active layer emits light. The GaAsP active layer is interposed between the InGaP guide layers. The InGaP guide layers and the GaAsP active layer are interposed between the AlGaInP cladding layers. Polarization ratio, which is a ratio of light intensity of TM-polarized light to light intensity of TE-polarized light, is less than 2.3.

Abstract: A coating film is provided on an end surface of a semiconductor photonic element including an active layer through which light propagates. The coating film has a two-layer structure including a first layer film and a second layer film arranged in a stacked relation. The thicknesses of the first and second layer films are determined so that the value of the amplitude reflectivity of the coating film is equal to an imaginary number.

Abstract: A semiconductor laser array device for outputting a higher power includes: a plurality of semiconductor laser chips, arranged in a predetermined pitch; a submount for mounting each semiconductor laser chip; and a heat sink for dissipating heat from the semiconductor laser chip through the submount; wherein a distance S between the centers of the chips and a thickness T of the submount satisfy the following inequality: 2×T?S?10×T, whereby improving efficiency of heat dissipation with a good process yield.

Abstract: A semiconductor optical device includes a waveguide layer and a reflecting multi-layer film. The waveguide layer includes two cladding layers and an active layer sandwiched between the two cladding layers. The reflecting multi-layer film including multiple layers is on at least one of a pair of opposing end faces of the waveguide layer. A summation ?nidi of products nidi of refractive indexes ni and thicknesses di of the layers denoted i in the reflecting multi-layer film, and a wavelength ?0 of light guided through the waveguide layer satisfies a relationship, ?nidi>?0/4. A first wavelength bandwidth ?? is wider than a second wavelength bandwidth ??. ?? is a wavelength range including the wavelength ?0 in which a reflectance R of the reflecting multi-layer film is not higher than +2.0% from reflectance R at the wavelength ?0. ?? is a wavelength range including the wavelength ?0 in which a reflectance R? of a hypothetical layer is not higher than +2.

Abstract: An optical semiconductor device includes a semiconductor laser having an equivalent refractive index nc; and a low-reflective coating film disposed on one end face of the semiconductor laser. The low-reflective coating film includes a first-layer coating film having a refractive index n1 and a thickness d1; and a second-layer coating film having a refractive index n2 and a thickness d2. n0 and ?0 denote refractive index of free space on a surface of the second-layer coating film and the wavelength of laser light produced by the semiconductor laser. Both a real part and an imaginary part of amplitude reflectance, determined by the wavelength ?0, the refractive indexes n1 and n2, and the thicknesses d1 and d2, are zero and only one of refractive indexes n1 and n2 is smaller than the square root of a product of the refractive indexes nc and n0.

Abstract: A nonreflective film includes films having refractive indices higher than 1 and a high-refractive index film (first film, third film, fifth film) and a low-refractive index film (second film, fourth film, sixth film, seventh film) respectively having refractive indices higher and lower than the square root of an effective refractive index of a semiconductor laser. The films have least three different compositions. Each film has a single composition. The films bring a real part and an imaginary part of an amplitude reflectance to zero, as a whole. Therefore, a semiconductor optical device with an improved degree of freedom in design of the nonreflective film is provided, even when a total thickness of the films is different from one quarter wavelength of the incident light.

Abstract: The present invention provides a semiconductor laser device including a heat sink having one main surface, an n-AlGaAs cladding layer disposed on the main surface of the heat sink, an AlGaAs active layer disposed on the n-AlGaAs cladding layer and a p-AlGaAs cladding layer disposed on the AlGaAs active layer. An effective refractive index and a thermal resistance between a main surface on the heat sink side, of the AlGaAs active layer and a main surface on the heat sink side, of the n-AlGaAs cladding layer are respectively set smaller than those between a main surface on the side opposite to the heat sink, of the AlGaAs active layer and a main surface on the side opposite to the heat sink, of the p-AlGaAs cladding layer.

Abstract: A semiconductor laser device comprises an active layer, a cladding layer, an end face for emitting light. A low-reflective film is provided on the end face. The reflectance of the low-reflective film changes with wavelength. A wavelength at which the reference of the low-reflective film is minimized is on the long wavelength side of a wavelength at which the gain of the semiconductor laser device is maximized. The gain and the loss of the semiconductor laser device become equal at a wavelength only in a wavelength region in which the reflectance of the low-reflective film decreases with increasing wavelength. The reflectance of the low-reflective film is preferably set to 1% or less at the wavelength at which the gain of the semiconductor laser device is maximized.

Abstract: A semiconductor laser device includes an optical fiber having an optical fiber grating formed therein, a semiconductor laser having an active layer with a single quantum well, for emitting laser light, and a coupling optical system for coupling the laser light emitted out of the semiconductor laser into the optical fiber. The coupling optical system can include a narrow-band filter for adjusting an incident angle of the laser light emitted out of the semiconductor laser. The optical fiber grating can have a reflection bandwidth wider than or substantially equal to a 3 dB bandwidth of the gain of the semiconductor laser or a spectrum full width at half maximum of the laser light of the semiconductor laser.

Abstract: A semiconductor laser device comprises an optical fiber having an optical fiber grating formed therein, a semiconductor laser having an active layer with a single quantum well, for emitting laser light, and a coupling optical system for coupling the laser light emitted out of the semiconductor laser into the optical fiber. The coupling optical system can include a narrow-band filter for adjusting an incident angle of the laser light emitted out of the semiconductor laser. The optical fiber grating can have a reflection bandwidth wider than or substantially equal to a 3 dB bandwidth of the gain of the semiconductor laser or a spectrum full width at half maximum of the laser light of the semiconductor laser.