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: There is provided a method for the production of a semiconductor laser device which emits laser light from a facet. The method includes the steps of: growing a multi-layered structure containing an active layer for laser oscillation on a semiconductor substrate to form a wafer; etching the multi-layered structure to form a striped groove perpendicular to the direction of an optical waveguide, resulting in a pair of resonator facets; bringing the facets into contact with a sulfur-containing solution; subjecting the facets to heat treatment; growing a semiconductor layer on the surface of the facets, which has a band gap greater than that of the active layer; and cleaving the wafer along the striped groove to obtain a semiconductor laser device.

Abstract: A semiconductor laser device and a method for the production of the semiconductor laser device are provided, which semiconductor laser device includes a striped channel formed in a semiconductor substrate through a current blocking layer on the substrate and at least two dummy grooves formed in the current blocking layer on each side of the striped channel. Also provided are a semiconductor wafer prepared for the purpose of producing optical devices with an optical waveguide, and a method for the production of the semiconductor wafer. The semiconductor wafer includes a semiconductor substrate, the surface of which has an orientation inclined from the [100] direction to one of the [011] and [011] directions of an angle .theta. satisfying the relationship 0.1.degree.<.vertline..theta..vertline.<4.degree.

Abstract: A semiconductor laser device is disclosed which comprises a semiconductor substrate and a multi-layered crystal structure disposed on the substrate, the multi-layered crystal structure containing a first cladding layer, a quantum-well active layer for laser oscillation, and a second cladding layer with a striped ridge portion for current injection, wherein the difference in the effective refractive index between the region underneath the striped ridge portion and the adjacent regions thereto is greater in the vicinity of at least one of the facets than inside of the facets.

Abstract: A semiconductor laser device is disclosed which comprises a semiconductor substrate, a striped mesa disposed on the substrate and having an active layer for laser oscillation, a current injection layer disposed on the striped mesa and having a width smaller than that of the striped mesa, and a burying layer disposed on both sides of the current injection layer so as to come into contact with the side walls of the current injection layer, the burying layer being capable of absorbing laser light produce in the active layer and of preventing current from flowing through the outside of the striped mesa.

Abstract: There is disclosed a semiconductor laser device with a strip-channeled substrate and a double-heterostructure multi-layered crystal disposed over the substrate, the multi-layered crystal containing an active layer for laser oscillation.

Abstract: A semiconductor laser device comprising a substrate; a current blocking layer disposed on the substrate; a striped channel formed in a manner to reach the substrate through the current blocking layer; a striped mesa disposed on the area of the V-channel, the striped mesa being of a multi-layered crystal that is composed of a first cladding layer, an active layer, a second cladding layer, and a protective layer in that order; and burying layers having at least one of the following two, a pn-reverse bias junction and a high resistant crystal, the burying layer being formed on both sides of the striped mesa, wherein the protective layer is made of Ga.sub.1-x Al.sub.x As (x>O).