Patent ID: 7039084

Claim:
A semiconductor laser comprising: a substrate; a plurality of layers laminated on the substrate, including an active layer in which a light beam is generated, the plurality of layers including end facets transverse to the plurality of layers, including the active layer, and to the substrate; and a window section contiguous to one of the end facets and through which the light is emitted, the window section comprising: a first semiconductor layer which has a first carrier concentration; a second semiconductor layer on the first semiconductor as an extension of the active layer and which has a second carrier concentration lower than the first carrier concentration; and a third semiconductor layer which has a third carrier concentration, on the second semiconductor layer, so that a distribution of refractive index of the light beam at the window section is symmetrical, in a laminating direction of the plurality of layers, about a center, with an extension of the active layer as the center.