Patent ID: 6856636

Claim:
A semiconductor laser device comprising: a GaAs substrate of a first conductive type; a lower cladding layer of said first conductive type, the lower cladding layer being formed on said GaAs substrate; a lower optical waveguide layer of said first conductive type or an undoped type made of InGaP, the lower optical waveguide layer being lattice-matched with said GaAs substrate and formed on said lower cladding layer; an active layer made of In x1 Ga 1−x1 As 1−y1 P y1 with compressive strain where 0<x1≦0.4 and 0≦y1≦0.1, the active layer being formed on said lower optical waveguide layer; an upper first optical waveguide layer of a second conductive type or an undoped type made of InGaP, the upper first optical waveguide layer being lattice-matched with said GaAs substrate and formed on said active layer; a current confinement layer of a first conductive type made of In 0.49 (Al z2 Ga 1−z2 ) 0.51 P, where 0.15≦z2≦1, the current confinement layer having an opening serving as a current passage and being formed on said upper first optical waveguide layer, wherein an equivalent refractive index step difference between the opening serving as the current passage and a region where the current confinement layer exists is in a range of 1.5×10 −3 to 7.0×10 −3 ; an upper second optical waveguide layer of the second conductive type formed so as to bury said opening, the upper second optical waveguide layer being formed on said current confinement layer; an upper cladding layer of the second conductive type, the upper cladding layer being formed on said upper second optical waveguide layer; a GaAs contact layer of the second conductive type, the GaAs contact layer being formed on said upper cladding layer; an electrode formed on said GaAs contact layer; and resonator facets formed of two opposite facets, wherein a current injection control structure that controls a current injection to said active layer is provided in the vicinity of at least one of said facets.