Patent ID: 6111998
Filing Date: 2000-08-29
Classification: G02B,H01S

Abstract:
A semiconductor optical device comprising:an optical waveguide being operative in a multi-mode in a direction perpendicular to a light propagation direction in said waveguide, said multi-mode direction being a widthwise direction of said waveguide; anda mode filter provided in at least a part of said optical waveguide such that said optical waveguide has an inlet port side part adjacent to an inlet port of said mode filter and an outlet port side part adjacent to an outlet port of said mode filter sandwiching said mode filter and light of a fundamental mode and light of a higher-order mode are excited in said inlet port side part of said optical waveguide toward said mode filter, a width of said optical waveguide, a width of said mode filter perpendicular to the light propagation direction and a length of said mode filter being determined such that light of the fundamental mode of said inlet port side part of said optical waveguide entering said mode filter from said inlet port side part of said optical waveguide has a light intensity distribution in said outlet port of said mode filter approximately equal to that in said inlet port of said mode filter, while light of the higher-order mode of said inlet port side part of said optical waveguide entering said mode filter from said inlet port side part of said optical waveguide has a light intensity distribution in said outlet port in which light is concentrated outside said outlet port side part of said optical waveguide, said width of said mode filter being larger than that of said optical waveguide, whereby said light of the higher mode entering said mode filter from said inlet port side part of said optical waveguide is blocked from entering said outlet port side part of said optical waveguide.