US Patent 7180925 Semiconductor laser device and manufacturing method therefor

A light confinement layer constructed of a semiconductor that has a refractive index different from that of p-type second cladding layers is formed to a small film thickness of not greater than 2 μm (about 0.5 μm) on the whole surface of ridge portions of two semiconductor lasers. Thus, the light confinement layer on the ridge portions is made roughly flat so as to be easily removable by etching. As a result, the exposure of p-type second cladding layers of the ridge portions due to deep etching is prevented to allow the confinement of light into the p-type cladding layers to be stably effected. A dielectric film is formed on the light confinement layer and reinforces the current constriction function lost by the reduction in the thickness of the light confinement layer.