Patent ID: 7305017

Claim:
A semiconductor optical device comprising: a semiconductor substrate having a primary surface, the primary surface intersecting with a predetermined axis; a lower cladding region of the first conductive type provided on the primary surface of the semiconductor substrate, the lower cladding region including a plurality of ridge regions and a base region, the base region having a plurality of first portions and a plurality of second portions, the first portions and the second portions being alternately arranged along a predetermined plane perpendicular to the predetermined axis, each first portion extending in an optical propagating direction, each second portion extending in the optical propagating direction, each ridge region being located on each second portion, each ridge region having a side and a top, and each first portion having a top; an upper cladding layer of the second conductive type provided on the primary surface of the semiconductor substrate; and a bulk active layer provided between the upper cladding layer and the lower cladding region, the bulk active layer including a plurality of first portions, a plurality of second portions and a plurality of third portions, each first portion of the bulk active layer being located on each first portion of the base region of the lower cladding region, each second portion of the bulk active layer being located on the top of each ridge region and each third portion of the bulk active layer being located on the side of each ridge region.