US Patent 7852893 Semiconductor laser device

A semiconductor laser device includes: a substrate of a first conductivity type; a laminated body of a nitride semiconductor provided on the substrate and including at least an active layer and a cladding layer, the cladding layer being of a second conductivity type and having a ridge-shaped waveguide; a first film provided on one end surface of an optical resonator composed of the laminated body, the first film having a reflectance of 40% or more and 60% or less; and a second film provided on the other end surface of the optical resonator and having a higher reflectance than the first film. The optical resonator has a length of 400 μm or less. The one end surface serves as a light emitting surface.