Abstract: A semiconductor laser such as a laser diode includes a semiconductor substrate and a laser diode region disposed on said semiconductor substrate and having a laser beam emission end. The semiconductor substrate has a front surface directly below said laser beam emission end, said front surface being retracted from said laser beam emission end. The front surface may be formed as an optically roughened surface as a side wall surface of a groove when the groove is defined in the semiconductor substrate by dicing. The laser diode region includes an active layer of GaAs or AlGaAs. The front surface may further be optically roughened by etching or sputtering.

Abstract: An object is to provide a semiconductor laser device having a continuous distribution in reflection and transmission at the end surface thereof, and a method therefor. In the semiconductor laser device having at the end surface thereof an end surface protection film for preventing oxidation of the end surface and an optical thin film for controlling reflectance, the end surface protection film has continuously-varying film thickness and the optical thin film has constant film thickness. By designing the end surface in a mirror-surface form and varying reflectance, characteristics such as high output, low power consumption, etc. can be improved.