Diffraction grating with alternately-arranged different regions, optical semiconductor device with the diffraction grating, and apparatus and optical communication system using the same

摘要

A diffraction grating includes first regions for mainly reflecting first polarized light and second regions for mainly reflecting second polarized light. The first regions and the second regions are alternately arranged in a light propagation direction in a variety of manners to appropriately set its polarization-mode dependency according to need. An optical semiconductor device includes a semiconductor substrate, a laser structure and that diffraction grating formed in the laser structure. The laser structure is a distributed feedback semiconductor laser structure or a distributed Bragg reflector semiconductor laser structure formed on the semiconductor substrate.