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 nitride semiconductor device and its manufacturing method are provided which are capable of achieving low-resistance ohmic properties and high adhesion. A nitride semiconductor device has an n-type GaN substrate over which a semiconductor element is formed and an n-electrode as a metal electrode formed over the back surface of the GaN substrate. A surface denatured layer functioning as a carrier supply layer is provided between the GaN substrate and the n-electrode. The surface denatured layer is formed by denaturing the back surface of the GaN substrate by causing it to react with a material that contains silicon.

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 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 P-type electrode material is provided on a top surface of a P-type contact layer. The P-type electrode material is formed with an AuGa film, an Au film, a Pt film, and an Au film. The AuGa film is provided on the P-type contact layer. The Au film is provided on the AuGa film. The Pt film is provided on the Au film. The Au film is provided on the Pt film. With this, a nitride semiconductor device having a P-type electrode which can decrease a contact resistance between a P-type contact layer and the P-type electrode is obtained.

Abstract: A nitride semiconductor device is manufactured by the step of forming a nitride semiconductor layer form on a GaN substrate main surface, the step of polishing a back surface of the GaN substrate formed with the above-mentioned nitride semiconductor layer, the step of dry etching the back surface of the GaN substrate subjected to the above-mentioned polishing by using a gas mixture of chlorine and oxygen, and the step of forming an n-type electrode on the back surface of the GaN substrate subjected to the above-mentioned dry etching.

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: The density of plated thru holes in a glass fiber based chip carrier is increased by off-setting holes to positions in which fibers from adjacent holes will not connect. Elongated strip zones or regions having a width approximately the diameter of the holes and running along orthogonal columns and rows of holes, parallel to the direction of fibers, define regions of fibers that can possibly cause shorting between holes. Rotating a conventional X-Y grid pattern of equidistant holes so as to position, for example, alternate holes in one direction between the elongated strip zones running in the opposite direction significantly increases the distance between holes along the elongated strip zones running in each direction. The holes are positioned between elongated strip zones with sufficient clearance to compensate for variations in the linear path of fibers.

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 density of plated thru holes in a glass fiber based chip carrier is increased by off-setting holes to positions in which fibers from adjacent holes will not connect. Elongated strip zones or regions having a width approximately the diameter of the holes and running along orthogonal columns and rows of holes, parallel to the direction of fibers, define regions of fibers that can possibly cause shorting between holes. Rotating a conventional X-Y grid pattern of equidistant holes so as to position, for example, alternate holes in one direction between the elongated strip zones running in the opposite direction significantly increases the distance between holes along the elongated strip zones running in each direction. The holes are positioned between elongated strip zones with sufficient clearance to compensate for variations in the linear path of fibers.

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 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 multilayer film includes alternately laminated, a first film with a refractive index of n1 and a second film with a refractive index of n2, the multilayer film having the first film in contact with an end face of a semiconductor laser element. The first film and the second film satisfy relations expressed by the formulas n1<(nc)1/2 and n2>(nc)1/2. The reflectivity characteristic of the multilayer film has a 1 maximum at a wavelength &lgr;1 in a wavelength region and minimums at wavelengths &lgr;2 and &lgr;3 on a shorter-wavelength side and a longer-wavelength side of the wavelength &lgr;1, respectively.

Abstract: A semiconductor optical device includes a waveguide layer (10) and a reflecting multi-layer film (20). The waveguide layer includes two cladding layers and an active layer sandwiched between the two cladding layers. The reflecting multi-layer film is formed on at least one of a pair of opposing end faces of the waveguide layer. A summation &Sgr;nidi of products nidi of refractive index ni and film thickness di of a layer denoted with i in the reflecting multi-layer film, and a wavelength &lgr;0 of light guided through the waveguide layer satisfies a relationship, &Sgr;nidi>&lgr;0/4. A first wavelength bandwidth &Dgr;&lgr; is wider than a second wavelength bandwidth &Dgr;&Lgr;. The &Dgr;&lgr; is a wavelength range including the wavelength &lgr;0 in which a reflectance R of the reflecting multi-layer film is not higher than +2.0% from reflectance R at the wavelength &lgr;0.