US Patent 7369594 Semiconductor laser

A semiconductor laser of effective index type which has a lower cladding layer, an active layer, and an upper cladding layer, which are sequentially arranged upward, with said upper cladding layer being formed into the stripe ridge structure, wherein the upper cladding layer forming the foot and slope of said stripe ridge structure is covered with a buried layer of layered structure made up of two or more low refractive index layers to prevent absorption of the laser light, with a light-absorbing layer interposed between them which absorbs the laser light of oscillatory wavelength. This semiconductor laser prevents kinks due to higher-order modes, and hence it realizes a high level of output.