DFB laser with ar coating selected to provide wide temperature range of operation

摘要

This invention provides a semiconductor laser that enables to oscillate at a wavelength defined by a Bragg grating formed therein in a wide temperature range without any temperature-controlling. The semiconductor laser comprises an active region and the Bragg grating formed with the active region. A light-emitting surface and a light-reflecting surface are formed so as to sandwiches the active region. The light-emitting surface has an anti-reflective coating, the reflectivity of which is so adjusted that the minimum thereof is at the wavelength where the gain attributed to the FP modes is the maximum and is smaller than 0.3%.