Semiconductor laser

Patent Pending PROBLEM TO BE SOLVED: To provide a self-induced oscillating semiconductor laser which stably APC drives. ; SOLUTION: There is provided a semiconductor layer 20, which is formed of an n-type clad layer 21, an active layer 22, a p-type clad layer 23 that includes a stripe shaped embedded ridge portion 28, an n-type buffer layer 24, a p-type contact layer 25, an etching stop layer 26, and a gap layer 27, laminated in this order. In the semiconductor layer 20, an emission side reflection film 33 is formed on a front end face perpendicular to a direction in which the embedded ridge 28 extends, and reflectivity Rf of the front end face is adjusted so as to satisfy P2<Pop<P1.