Patent ID: 7813398

Claim:
A semiconductor optical element for an external cavity laser having a pair of cleavage surfaces, comprising: a semiconductor substrate having a base surface; and a planer structure provided on said base surface, and provided with a waveguide having an active layer, wherein said waveguide has first and second end surfaces defined by said respective cleavage surfaces, said first end surface of said waveguide has first reflectivity, and said second end surface of said waveguide has second reflectivity, said waveguide includes one end portion having an optical axis being at a first angle to a normal to said first end surface, and one end portion having an optical axis being at a second angle to a normal to said second end surface, said waveguide guides light so that said light is output from said first end surface in a first direction, and that said light is output from said second end surface in a second direction parallel to said first direction, and said light guided by said waveguide in the vicinity of said first end surface has a first spot size measured in a lateral direction of said waveguide, and said light guided by said waveguide in the vicinity of said second end surface has a second spot size measured in said lateral direction of said waveguide, said first spot size being different from said second spot size to make said first reflectivity be different from said second reflectivity.