Patent ID: 7504664

Claim:
A semiconductor optical device comprising: a substrate; a ridge structure supported by said substrate and including opposed side surfaces, said ridge structure including an active layer and first and second cladding layers on opposite sides of said active layer, said active layer and said first and second cladding layers being exposed at said opposed side surfaces of said ridge structure; and a current blocking structure contacting both of said opposed side surfaces of said ridge structure, said current blocking structure including a buried layer, at least one intermediate layer on said buried layer, and a cover layer on said intermediate layer and covering said intermediate layer, wherein said at least one intermediate layer is Al(Ga)InAs, said cover layer has a higher oxidation resistance than said Al(Ga)InAs intermediate layer, said buried layer and said cover layer are InP, and said Al(Ga)InAs intermediate layer has a side surface parallel to a side surface of said ridge structure.