Abstract: Disclosed herein is a semiconductor laser device including at least an active region consisting of a semiconductor material and a semiconductor region consisting of a material having a different composition from that of the active region and confining the active region, wherein at least one p-n junction is formed inside the confining region in parallel to the active region and a current flowing through the active region at a field strength below an electric field causing degradation of the semiconductor laser device is allowed to flow through regions other than the active region via the p-n junction by controlling the impurity concentration of the region having the p-n junction. The semiconductor laser device does not undergo catastrophic degradation even when applied with a current higher than a rated value.

Abstract: A light-emitting semiconductor device is provided having a light-emitting semiconductor element emitting light in two directions. The light-emitting element is disposed in a housing so that one light-emitting face of the semiconductor element adjacent a heat sink, and a light guide is arranged to confront the other light-emitting face of the semiconductor element and to guide light from said other light-emitting face to the outside of the housing. In this device, the end face of the light guide confronting said other light-emitting face of the semiconductor element includes a face substantially inclined to the optical axis of light emitted from the semiconductor element.

Abstract: A semiconductor layer for supporting a diode chip of a semiconductor laser is formed to be higher than a semiconductor layer containing a current-conducting region, whereby stresses acting on the diode chip by mounting the diode chip are relieved to prevent degradation of performance and reduced life of the semiconductor laser.