Abstract: A semiconductor laser device includes a base, a semiconductor laser chip and a resin layer enclosing the laser chip. The base may have a monitor photodiode mounted thereon in the vicinity of the laser chip. The resin layer enclosing the laser chip or both of the laser chip and the monitor diode chip is made of a single synthetic resin having a thickness not greater than 500 .mu.m and also having a surface substantially parallel to an outwardly oriented beam emitting end face of the laser chip.

Abstract: A semiconductor laser device is disclosed which emits laser light from a facet. The semiconductor laser device comprises a multi-layered structure formed on a semiconductor substrate, the multi-layered structure having an AlGaAs active layer for laser oscillation, and a protective film formed on the facet, wherein a film containing sulfur is provided between the facet and the protective film.

Abstract: A semiconductor laser device comprising a semiconductor laser chip emitting infrared laser beams in a predetermined direction and a visible light source emitting visible light beams in the same direction. The semiconductor laser chip and the visible light source are disposed close to each other on a package stem. An optical element is disposed in a direction where both light beams are emitted so as to collimate or converge the visible light beams while allowing the infrared laser beams to pass therethrough without change. By this configuration, the operator can visually locate the infrared laser beams by knowing the location of the visible light beams.

Abstract: A semiconductor laser device is disclosed which emits laser light from a facet. The semiconductor laser device comprises a multi-layered structure formed on a semiconductor substrate, the multi-layered structure having an AlGaAs active layer for laser oscillation, and a protective film formed on the facet, wherein a film containing sulfur is provided between the facet and the protective film.

Abstract: A semiconductor laser device is disclosed which emits laser light from an end facet. The semiconductor laser device comprises a multi-layered structure formed on a semiconductor substrate, the multi-layered structure having an active layer for laser oscillation, and a pair of cleavage planes on the side of the multi-layered structure, wherein a graded-band-gap layer is formed on at least one of the cleavage planes, the graded-band-gap layer having a forbidden band gap which increases gradually with an increase in the distance from the cleavage plane, and the surface of the graded-band-gap layer constituting the end facet.

Abstract: A semiconductor laser device with a protective film on the facets, wherein said protective film is made of a multi-layered dielectric film composed of alternate layers consisting of at least two kinds of dielectric film, one of which is a first dielectric film of low refractive index and the other of which is a dielectric film of high refractive index, said multi-layered dielectric film which covers at least one of the facets therewith being a light-permeable film with a reflectivity of 30% or less.

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: 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 micro-displacement measuring apparatus using a semiconductor laser, comprises a compound resonator system containing the semiconductor laser, and a light detector receiving a light from said semiconductor laser. The compound resonator system is constructed such that a light from the semiconductor laser irradiates an object to be measured and the reflected light therefrom returns to the semiconductor laser, wherein the relationship between the reflectivity R.sub.f at the front facet of the semiconductor laser from which a laser light irradiates the object, and the reflectivity Rr at the rear facet of the semiconductor laser which is opposite the front facet is as follows: 0.1<R.sub.f Rr<1.

Abstract: A semiconductor laser device comprising: a ring-shaped resonator constituted by a square-shaped optical waveguide composed of four straight optical waveguide sides in which facing sides are positioned in a parallel manner and a reflecting mirror is formed at each of the four corners of said square-shaped optical waveguide in a manner to divide the intersection angle of two each of said four sides at each of said four corners into two equal parts, and a means, for releasing laser light from said ring-shaped resonator, which is disposed on or near a part or the whole area of at least one of said four sides of said square-shaped optical waveguide.

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 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.

Abstract: A micro-displacement measuring apparatus using a semiconductor laser, comprises a compound resonator system containing the semiconductor laser, and a light detector receiving the light from the semiconductor laser, and with the compound resonator system being constructed such that light from said laser irradiates an object to be measured and the reflected light therefrom returns to the semiconductor laser. The light detector detects and measures the number of fluctuations and the level of the optical output of the laser to determine the displacement of the object and of the direction of the displacement of the object, respectively.

Abstract: A GaAlAs semiconductor laser element includes a Ga.sub.1-x Al.sub.x As active layer sandwiched by a first and second Ga.sub.1-y Al.sub.y As cladding layers. A Ga.sub.1-z Al.sub.z As substrate layer supports the first cladding layer, and a Ga.sub.1-z Al.sub.z As cap layer covers the second cladding layer. The AlAs mole fraction (z) of the substrate layer and the cap layer is selected slightly smaller than the AlAs mole fraction (x) of the active layer. Further, the active layer is located in the laser element so that the active layer is separated from the mounted surface by more than 35% of the laser element thickness, and is separated from the opposing surface by more than 18% of the laser element thickness.

Abstract: A GaAs semiconductor laser includes a GaAs semiconductor laser element, and a Cu heat sink attached to the GaAs semiconductor laser element through the use of an In solder. The GaAs semiconductor laser element includes an active layer sandwiched by cladding layers, and a substrate upon which various layers are formed. The GaAs semiconductor laser element is constructed so that the active layer is separated from the mounted surface by at least a distance which corresponds to about 32 to 35% of the entire thickness of the GaAs semiconductor laser element, thereby minimizing the stress applied to the active layer.