Patent ID: 7787509

Claim:
A semiconductor laser device comprising: a first clad layer formed on a semiconductor substrate; an active layer formed on the first clad layer and having a strained multiple quantum well structure; a second clad layer formed on the active layer; and a window region formed near end facets of the semiconductor laser device, the window region including a laser light path, the window region having a window region active layer of a wider band gap than a band gap of the active layer, wherein: the active layer and the window region active layer contain AlGaInP, and the active layer includes at least one blocking layer and at least one well layer, compression strain is applied to the well layer and tensile strain is applied to the blocking layer, and a sum of products of strain amounts and film thickness in the active layer is set to a negative value, and the second clad layer contains zinc in the window region, and the band gap of the active layer is increased by diffused zinc from the second clad layer in the window region.