US Patent 7609739 Semiconductor laser device

A semiconductor laser device includes: an active layer having a single or multiple quantum well structure including a well layer of InwGa1-wN (0.08≦w≦0.2) and a barrier layer of InbGa1-bN (0.01≦b≦0.05); a cladding layer of AlyGa1-yN (0≦y≦0.1) provided on the active layer, the cladding layer including a ridge portion extending like a stripe in axial direction of an optical cavity and a non-ridge portion located on both sides of the ridge portion; and an overflow blocking layer of AlzGa1-zN (y<z) provided between the active layer and the cladding layer. A thickness of D (μm) of the non-ridge portion and an axial length of L (μm) of the optical cavity satisfies formulas L≧750−400×(D/0.01) and 0<D≦0.01.