US Patent 7778299 Semiconductor laser

A semiconductor laser having a double channel ridge structure includes: a ridge; channel portions located on opposite sides of the ridge, sandwiching the ridge, and having an equivalent refractive index lower than the equivalent refractive index of the ridge; and layers defining outside surfaces of the channel portions and, having an equivalent refractive index higher than the equivalent refractive index of the channel portions. The ridge has a flare ridge structure with a width that is widened toward a light outgoing end surface, and the width of the channel portions where the width of the ridge is the narrowest is wider than the channel portions at the light outgoing end surface.