Abstract: A window semiconductor laser device comprising a stripe-channeled substrate, an active layer for laser oscillation and a cladding layer disposed under the active layer, wherein the surface of the active layer is flat and the thickness of the portion of the active layer corresponding to the striped channel of said substrate in each of the window regions in the vicinity of the facets is thinner than that of the portion of the active corresponding to the striped channel of said substrate in the stimulated region positioned between the window regions.

Abstract: A waveguide type optical head comprises a thin film waveguide of semiconductor or dielectric substance formed on a semiconductor or dielectric substrate, an optical element with an optical signal processing function provided on the thin film waveguide, and a semiconductor laser fixed on the substrate for emitting laser beam into the waveguide, and is characterized in that part of the laser beam emitted from the semiconductor laser is reflected by the incident end surface of the thin film waveguide and returned to the semiconductor laser.

Abstract: An external cavity type semiconductor laser apparatus comprising a semiconductor laser device and an external reflector, which are mounted on a single mounting base with a distance therebetween, wherein laser light from the light-emitting rear facet of the laser device is reflected by the reflector and returns to the laser device, the coefficient of linear expansion of the mounting base being smaller than that of Cu and being greater than those of both the laser device and the reflector.

Abstract: An external cavity type semiconductor laser apparatus comprising a semiconductor laser device and an external cavity, which are mounted on a single mounting base with a space therebetween, wherein laser light emitted from the light-emitting rear facet of the laser device is reflected by the external cavity and returns to the laser device. The reflectivity of the light-emitting rear facet of the laser device being different from that of the light-emitting front facet of the laser device.

Abstract: The external resonator type semiconductor laser of the present invention includes a semiconductor laser element, a reflection member having a reflecting mirror surface for feeding back to the laser element a laser beam emitted from an emitting end surface of the semiconductor laser element, and a mount member for fixedly mounting the laser element and reflection member thereon. The coefficient of linear expansion of the mount member is adapted to be smaller than the coefficient of linear expansion of the semiconductor laser element and reflection member so that the distance between the emitting surface and the reflecting surface (i.e. the external resonator length) decreases with a rise in temperature.

Abstract: An external resonator type semiconductor laser apparatus comprising a semiconductor laser device, a reflector positioned behind said laser device in a manner to face the light-emitting rear facet of said laser device, and a photodetector, for detecting the optical output of said laser device, positioned backward of said reflector, wherein a part of the laser light from said light-emitting rear facet is reflected by said reflector and the reflected light is then incident to said photodetector.

Abstract: A semiconductor laser includes a front mirror facet and a rear mirror facet. An Al.sub.2 O.sub.3 film coating is formed on the front mirror facet by electron beam evaporation so that the front mirror facet has a reflectance between 10 and 20%. A multi-layered coating is formed on the rear mirror facet so that the rear mirror facet has a reflectance higher than 90%.

Abstract: A semiconductor laser apparatus and housing are designed so that laser light leaving the housing through a window glass in the housing satisfies the following equation (3): ##EQU1## wherein d is the distance between the window glass and the laser light-emitting facet of the semiconductor laser device, .lambda.o is the oscillation wavelength of laser light, and .DELTA..lambda. is the space between the adjacent longitudinal modes.

Abstract: A semiconductor laser device comprising a laser-oscillating optical waveguide composed of a control region which functions to absorb light and main regions which function to oscillate laser light, said control region being positioned in the center portion of said optical waveguide and said main regions being positioned on both ends of said control region, wherein said laser device further comprises a shunting means by which the ratio of the current Ig flowing to said control region to the total current It injected into said laser device is set to meet the inequality (1): ##EQU1## wherein Lg is the length of said control region and Lt is the length of said optical waveguide.

Abstract: A multilayered crystal structure in a semiconductor laser device contains an active layer for laser oscillation on a V-stripe channeled substrate having a current-blocking layer thereon. The active layer further includes regions by means of which carriers within the active layer are prevented from diffusing outside of the active layer. These regions are disposed facing each other with an optical waveguide therebetween which is formed by the absorption of light by the portions of the current-blocking layer which are positioned at both sides of the striped channel. The distance between the regions is narrower than the width of the optical waveguide in the vicinity of both facets and wider than the width of the optical waveguide inside of both facets.

Abstract: A semiconductor laser array device comprising an active layer for laser oscillation having a plurality of curved portions at substantially right angles to the resonance direction to thereby create a distribution of the refractive index between the curved portions and the flat portions of the active layer, resulting in a plurality of laser oscillation operation areas which are positioned between the curved portions of the active layer and which are optically coupled therebetween.

Abstract: A compound resonator type semiconductor laser device comprising a multiple-layered crystal structure having a first laser operation area which contains a resonator for laser oscillation and a second laser operation area which contains a resonator a facet of which is shared with that of the resonator in the first laser operation area; and an electric current feeder for injecting a current into said multiple-layered crystal structure, and wherein said facet of the resonator in the first laser operation area, which is shared with the facet of the resonator in the second laser operation area, is covered with a protective film to attain a high reflectivity therein, the other facet of the resonator in the first laser operation area is covered with a protective film to attain a low reflectivity therein, and the other facet of the resonator in the second laser operation area is covered with a protective film to attain a high reflectivity therein.

Abstract: A semiconductor laser comprising a substrate; a current blocking layer formed on said substrate; a striped channel formed in said current blocking layer on said substrate, said striped channel being narrow in the vicinity of the facets and being wide inside of the facets; an active layer, a portion of the active layer corresponds to the narrow portion of said striped channel being a plane to form a window region and another portion of the active layer corresponds to the wide portion of said striped channel being a crescent shape to form a laser operation area with a mesa-structure which is surrounded by burying layers to cut off current leakage from said laser operation area, the width of the mesa-portion of said laser operation area being not less than that of a current injection region formed within said striped channel.