US Patent 7561609 Semiconductor laser device and method of fabricating the same

A semiconductor laser device includes a first cavity and a second cavity formed apart from each other over a semiconductor substrate. The first cavity includes a first buffer layer and a first semiconductor layer including a first active layer, and the second cavity includes a second buffer layer and a second semiconductor layer including a second active layer. A window structure is provided in a region near an end face of each of the first semiconductor layer and the second semiconductor layer. A band gap of the first buffer layer is greater than that of the first active layer, and a band gap of the second buffer layer is greater than that of the second active layer.