US Patent 7333523 Semiconductor laser device

A semiconductor laser device comprising: a first cladding layer of a first conductivity type; an active layer provided on the first cladding layer and having a quantum well structure; an overflow blocking layer of a second conductivity type provided on the overflow blocking layer. The active layer includes a region having an impurity concentration is 3×1017 cm−3 or more and having a thickness of 30 nm or less between the overflow blocking layer and a well layer in the active layer closet to the overflow blocking layer.