Patent ID: 8000365

Claim:
A semiconductor laser device comprising: a substrate; and a multilayer structure made of group III nitride semiconductors formed on the substrate, the multilayer structure including an active layer, wherein the multilayer structure includes a stripe-shaped waveguide extending in parallel to a principal surface of the multilayer structure, a step region selectively formed in an upper portion of the multilayer structure in the vicinity of the waveguide, a first region, which is formed in an area of the waveguide in the vicinity of the step region, and in which the active layer has a bandgap energy of Eg1, and a second region, which is formed in an area of the waveguide other than in the vicinity of the step region, and in which the active layer has a bandgap energy of Eg2 (Eg2≠Eg1); the first region and the second region are adjacent to each other; and the waveguide is formed in a region that does not include the step region, so as to perform self-oscillation.