Semiconductor laser device

摘要

An n-InP second upper cladding layer is laid on a p-InP lower cladding layer while an active layer having upper and lower boundary surfaces that are uniformly flat in an optical waveguide direction is interposed therebetween. A diffraction layer having a phase-shifted structure in the optical waveguide direction is interposed between the lower cladding layer and the active layer or between the second upper cladding layer and the active layer. The length L of the diffraction grating layer in the direction of the optical waveguide is L<=260 mum; a mean coupling factor kappa of a diffraction grating layer is kappa>=150 cm<-1>; and kappaL satisfies 5.6>kappaL>3.0.