Patent ID: 7720123

Claim:
A semiconductor laser comprising: a p-type semiconductor substrate; a first cladding layer of a p-type semiconductor, located on the semiconductor substrate; an active layer located on the first cladding layer for generating laser light; a second cladding layer of an n-type semiconductor and located on the active layer; a ridge section including the first cladding layer, the active layer, and the second cladding layer; a buried current blocking layer structure consisting of first, second, third, and fourth burying layers, wherein the first burying layer is p-type InP and contacts a side of the ridge section, the second burying layer is an n-type semiconductor, the third burying layer is a semi-insulating layer containing one of Fe and Ru and contacts a side and top face of the second burying layer, the fourth burying layer is located between and contacts the first burying layer and the second burying layer, is one of AlGaInAs and AlInAs, has a larger band gap energy than the band gap energy of InP, and contacts a side of the first burying layer, the third burying layer contacts a side of the fourth burying layer, and an end of the fourth burying layer is covered by an end of the first burying layer and an end of the third burying layer; and an n-type semiconductor layer which covers a top face of the second cladding layer and a top face of the third burying layer.