Patent ID: 7835418
Filing Date: 2010-11-16
Classification: B82Y,H01S

Abstract:
1. An optical semiconductor device comprising: a semiconductor substrate having a pair of facets mutually facing opposite directions; an active layer formed over the semiconductor substrate; an upper cladding layer formed on the active layer and having a refractive index lower than a refractive index of the active layer; a diffraction grating disposed in the upper cladding layer on both sides of a distributed feedback region in a waveguide region in planar view, the waveguide region extending in a first direction from one facet to the other of the semiconductor substrate, end regions being defined at both ends of the waveguide region in the first direction, and the distributed feedback region being disposed between the end regions; and low refractive index regions disposed in the upper cladding layer on both sides of each of the end regions of the waveguide region, the low refractive index regions being disposed between one facet of the semiconductor substrate and the diffraction grating and between the other facet of the semiconductor substrate and the diffraction grating, the low refractive index regions having a refractive index lower than a refractive index of the upper cladding layer, a length of each of the low refractive index regions in a waveguide direction being 5 μm or longer.