Patent ID: 8649410

Claim:
A semiconductor laser comprising: a semiconductor substrate having a principal surface; a first reflective region; and a second reflective region disposed opposite to the first reflective region, in a predetermined direction of an optical axis, such that no optical gain is provided along the optical axis other than by the first reflective region and the second reflective region, wherein the first reflective region has a plurality of gain waveguides each including an active layer generating light and a plurality of refractive-index controlling waveguides each having a first diffraction grating formed therein, the active layers and the first diffraction gratings being arranged alternately and periodically on the principal surface in the direction of the optical axis, and the first diffraction gratings being formed in only the refractive-index controlling waveguides and not in the gain waveguides, and wherein the second reflective region has a second diffraction grating.