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.

Abstract: A nonreflective film is formed with a plurality of films having refractive indices higher than 1 and formed using 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 a square root of an effective refractive index of a semiconductor laser. The plurality of films are formed so as to have at least three kinds of compositions while each film is formed with a single composition, and to bring a real part and an imaginary part of an amplitude reflectance to zero as a whole. Therefore, a semiconductor optical device which can enhance a degree of freedom in a design of the nonreflective film can be provided even when a total film thickness of the plurality of films is different from a value &lgr;/4.

Abstract: A nonreflective film is formed with a plurality of films having refractive indices higher than 1 and formed using 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 a square root of an effective refractive index of a semiconductor laser. The plurality of films are formed so as to have at least three kinds of compositions while each film is formed with a single composition, and to bring a real part and an imaginary part of an amplitude reflectance to zero as a whole. Therefore, a semiconductor optical device which can enhance a degree of freedom in a design of the nonreflective film can be provided even when a total film thickness of the plurality of films is different from a value &lgr;/4.

Abstract: A multilayer film 1 obtained as a result of alternately laminating a first film 2 with a refractive index of n1 and a second film 3 with a refractive index of n2, the multilayer film 1 being formed such that the first film 2 is in contact with an end face of the semiconductor laser element 101. The first film 2 and the second film 3 satisfy relations expressed by the formulas n1<(nc)1/2 and n2>(nc)1/2. A reflectivity characteristic of the multilayer film 1 is such that a reflectivity of the multilayer film 1 is maximized at a wavelength &lgr;1 in a predetermined wavelength region and minimized at wavelengths &lgr;2 and &lgr;3 on a shorter-wavelength side and a longer-wavelength side of the wavelength &lgr;1, respectively.

Abstract: An optical semiconductor device of the present invention comprises: a semiconductor laser having an equivalent refractive index of nc; and a low-reflective coating film disposed on one end face of the semiconductor laser; wherein the low-reflective coating film includes: a first-layer coating film having a refractive index of n1 and a film thickness of d1; and a second-layer coating film having a refractive index of n2 and a film thickness of d2; and wherein the low-reflective coating film is formed in such a way that when n0 and &lgr;0 denote a refractive index of a free space on a surface of the second-layer coating film and a given laser light wavelength of the semiconductor laser, respectively, both a real part and an imaginary part of an amplitude reflectance decided by the wavelength &lgr;0, the refractive indexes n1 and n2, and the film thickness d1 and d2 are zero, and only one of refractive indexes n1 and n2 is smaller than a square root of a product of said refractive. indexes nc and n0.

Abstract: A semiconductor laser includes a semiconductor substrate of a first conductivity type and having a front surface; a first semiconductor layer disposed on the front surface of the semiconductor substrate and having a refractive index that increases with distance from the semiconductor substrate; an active layer disposed on the first semiconductor layer; and a second semiconductor layer disposed on the active layer, having a refractive index that decreases with distance from the active layer, and having a ridge. In this laser, the refractive index distribution between the ridge and the substrate is asymmetrical about the active layer so that the center of the light intensity distribution shifts from the active layer toward the substrate, in the direction perpendicular to the front surface of the substrate.

Abstract: A semiconductor laser that has a large laser light aspect ratio, a high kink level, and a small variation in optical output efficiency. A semiconductor laser in which an increase in threshold current and a reduction in the optical output efficiency at an elevated temperature are prevented. The semiconductor laser includes a low refractive index layer between a guide layer and a cladding layer, and the total layer thickness of an active layer and the guide layer is not less than about 15% of an oscillation wavelength.

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.

Abstract: A semiconductor laser includes a semiconductor substrate of a first conductivity type and having a front surface; a first semiconductor layer disposed on the front surface of the semiconductor substrate and having a refractive index that increases with distance from the semiconductor substrate; an active layer disposed on the first semiconductor layer; and a second semiconductor layer disposed on the active layer, having a refractive index that decreases with distance from the active layer, and having a ridge. In this laser, the refractive index distribution between the ridge and the substrate is asymmetrical about the active layer so that the center of the intensity of light generated in the semiconductor laser distribution shifts from the active layer toward the substrate, in the direction perpendicular to the front surface of the substrate.

Abstract: A semiconductor laser includes a semiconductor substrate of a first conductivity type and having a front surface; a first semiconductor layer disposed on the front surface of the semiconductor substrate and having a refractive index that increases with distance from the semiconductor substrate; an active layer disposed on the first semiconductor layer; and a second semiconductor layer disposed on the active layer, having a refractive index that decreases with distance from the active layer, and having a ridge. In this laser, the refractive index distribution between the ridge and the substrate is asymmetrical about the active layer so that the center of the light intensity distribution shifts from the active layer toward the substrate, in the direction perpendicular to the front surface of the substrate.

Abstract: A method of screening semicondutor laser devices which fail due to sudden deterioration and initial failures. Semiconductor laser devices are screened by thermal cycling wherein the devices are kept at a high temperature and a low temperature alternately while supplying a driving current.

Abstract: A semiconductor laser device includes a semiconductor laser chip emitting a laser light from its front facet and rear facet, a photodiode which receives the light emitted from the rear facet of said semiconductor laser chip, an upper end of the light receiving surface of said photodiode being positioned at a height equal to or lower than the light emitting position of said semiconductor laser chip. Therefore, the return light which returns the monitor photodiode is reduced and the controllability of the APC control can be enhanced.

Abstract: A semiconductor light emitting device includes a semiconductor light emitting element mounted on a package stem via a radiating heatsink block, the light emitting point of the light emitting element being positioned on the central axis of the stem and at or near the center of mass of the heatsink block. Another light emitting device includes a light emitting element mounted on a stem via a heatsink block, the light emitting point of the element being positioned on the central axis of the stem with only a portion of a lower surface of the heatsink block close to the central axis of the stem attached to the stem. The movement of the light emitting point with temperature variations is suppressed. Another light emitting device includes a laser chip element mounted on a package stem via a heatsink block, the laser chip element being mounted on the heatsink block so that the emitted light forms an angle .theta.

Abstract: A semiconductor device having a semiconductor element and a heat sink radiating heat generated by the semiconductor element incudes an amorphous semiconductor film disposed on the heat sink and the semiconductor element disposed on the amorphous semiconductor film. Therefore, the stress applied to the semiconductor element is reduced because of the amorphous semiconductor film. In one structure, an amorphous semiconductor film comprising amorphous silicon or amorphous germanium is sandwiched between first and second metal films and the semiconductor element is bonded to the second metal film. An ohmic contact is made by alloys formed between the amorphous semiconductor film and the first and second metal films.

Abstract: A semiconductor optical device includes a semiconductor laser having an effective refractive index n.sub.c, a first film having a refractive index n.sub.1 and a thickness d.sub.1, a second film having a refractive index n.sub.2 and a thickness d.sub.2, and a third film having a refractive index n.sub.3 and a thickness d.sub.3. The first to third films are successively disposed on a facet of the semiconductor laser. In this structure, the refractive indices and thicknesses of the first to third films are determined so that a characteristic matrix Xa of the three films is equal to a characteristic matrix Y of a single film whose refractive index n.sub.f is the square root of the effective refractive index n.sub.c of the semiconductor laser and whose thickness is obtained by dividing an oscillation wavelength .lambda. of the semiconductor laser by 4n.sub.f as represented by the following equation ##EQU1## where .phi.1=2.pi.n.sub.1 d.sub.1 /.lambda., .phi.2=2.pi.n.sub.2 d.sub.2 /.lambda., and .phi.3=2.pi.n.sub.

Abstract: A semiconductor device having a semiconductor element and a heat sink radiating heat generated by the semiconductor element includes an amorphous semiconductor film disposed on the heat sink and the semiconductor element disposed on the amorphous semiconductor film. Therefore, the stress applied to the semiconductor element is reduced because of the amorphous semiconductor film. In one structure, an amorphous semiconductor film comprising amorphous silicon or amorphous germanium is sandwiched between first and second metal films and the semiconductor element is bonded to the second metal film. An ohmic contact is made by alloys formed between the amorphous semiconductor film and the first and second metal films.

Abstract: A method for producing a box type quantum well structure includes generating ion clusters, linearly accelerating the clusters with an electric field, passing the accelerated cluster ions through a further field perpendicular to the accelerating direction, causing the cluster ions to follow different ion orbits in accordance with the number of constituent atoms of the respective cluster ions, intercepting the cluster ions having a predetermined number of atoms with a substrate arranged in the orbit of the cluster ions having a predetermined number of atoms. A neutral particle shielding plate is provided along a straight line between the substrate and the cluster ion source to prevent neutral particles from flowing toward the substrate. Thereby, GaAs boxes having the same size can be obtained and variations in the quantum effects of the boxes can be reduced.

Abstract: A method of selectively coating one of two spaced apart facets of respective light-emitting regions on the same surface of a semiconductor device formed in a semiconductor wafer includes forming at least one first groove in a wafer and forming at least one second groove in the wafer intersecting the first groove, exposing light-emitting region facets on a side wall surface of the second groove. A stream of an evaporated coating material is directed across an edge, formed by the intersection of a side wall surface of the second groove with the first groove, at an angle relative to the wafer surface so that the edge shadows one of the light-emitting region facets but not the other. After the coating process, the wafer is divided into individual devices that may include adjacent, differently coated light-emitting region facets. The invention avoids a mechanical mask alignment step by employing in the coating process first grooves that are self aligning relative to the light-emitting region facets.