Patent ID: 7653104

Claim:
A semiconductor laser device, comprising: a first semiconductor laser structure and a second semiconductor laser structure formed on a semiconductor substrate with an isolation groove interposed therebetween, the first semiconductor laser structure having a first ridge stripe portion and the second semiconductor laser structure having a second ridge stripe portion extending in parallel with the first ridge stripe portion, wherein the first semiconductor laser structure has a first cladding layer, a first active layer, a second cladding layer, and a first current block layer which are sequentially formed on the semiconductor substrate, the second semiconductor laser structure has a third cladding layer, a second active layer, a fourth cladding layer, and a second current block layer which are sequentially formed on the semiconductor substrate with the isolation groove interposed between the first semiconductor laser structure and the second semiconductor laser structure, a first strain relaxing layer is formed on a side surface of, and on a region located on a side of, the first ridge stripe portion of the second cladding layer on an opposite side to the second semiconductor laser structure, a second strain relaxing layer is formed on a side surface of, and on a region located on a side of, the second ridge stripe portion of the fourth cladding layer on an opposite side to the first semiconductor laser structure, and provided that Tc is a thermal expansion coefficient of the second cladding layer and the fourth cladding layer, Tb is a thermal expansion coefficient of the first current block layer and the second current block layer, and Ts is a thermal expansion coefficient of the first strain relaxing layer and the second strain relaxing layer, a relation of Tb<Tc<Ts is satisfied.