Patent ID: 7016386

Claim:
An AlGaAs semiconductor laser device of a multi-layered structure, comprising: a first clad layer of a first conductivity type; an active layer comprising an optical guide layer and a quantum well layer; a lower second clad layer of a second conductivity type; a specific compound semiconductor layer having a composition different from that of the lower second clad layer; and an upper second clad layer of the same composition as the lower second clad layer, wherein said layers are formed on top of a substrate in order of mention; the upper second clad layer comprises a stripe shaped ridge that has a width of greater than or equal to 20 μm and forms a current injection region, the specific compound semiconductor layer is Al x Ga 1-x As (0.4≦x≦0.8) and functions as an etch stop layer in etching the upper second clad layer; and a ratio of (B/A)×100 ranges between 8 and 12 percent, where B is the average optical intensity of a p-polarized component of a wave emitted from said semiconductor laser device and A is the maximum optical intensity of an s-polarized component of said wave.