Patent ID: 7260128

Claim:
A semiconductor laser device comprising a cladding layer of a first conductive type, an active layer and a cladding layer of a second conductive type, said layers being stacked on a semiconductor substrate of the first conductive type in bottom-to-top order, wherein the active layer comprises a layered structure composed of at least one pair of a well layer and a barrier layer, an upper semiconductor layer directly formed on top of the layered structure and having a thickness of 10 nm or more, and a lower semiconductor layer directly formed beneath the layered structure and having a thickness of 10 nm or more, the cladding layer of the first conductive type and the cladding layer of the second conductive type are made of a material containing phosphorus, and the at least one pair of the well layer and barrier layer and the lower semiconductor layer are made of a material that contains arsenic but does not substantially contain phosphorus.