Patent ID: 8385379

Claim:
An optical semiconductor device, comprising: a semiconductor substrate; a first cladding layer formed on one flat surface of said semiconductor substrate, an active layer formed on said first cladding layer; a second cladding layer formed on said active layer; said first cladding layer, said active layer and said second cladding layer being formed as a mesa-shape structure, first current blocking layers of a first conductive type formed on said first cladding layer, said active layer and a part of said second cladding layer at both side surfaces of said mesa-shape structure; and second current blocking layers of a second conductive type formed as covering said first current blocking layers; wherein upper surfaces of said second current blocking layers are same or substantially same as an upper surface of said second cladding layer, and said second current blocking layers are formed as films deposited at a deposition temperature T satisfying that the following formula is negative regarding said deposition temperature T of said second current blocking layer, and have a structure wherein end portions of said upper surfaces of said second current blocking layers extend over said first current blocking layer, and ride over said second cladding layer so as to enter the inside of said second cladding layer by the mass-transport phenomenon W 1− W 2 (μm)=−0.0092× T+ 6.18, where, W 1 is a distance between said end portions of said second current blocking layers and W 2 is a width between said first current blocking layers contacting said second cladding layer.