Semiconductor laser device

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 Inx1Ga1−x1As1−y1Py1 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 made of In0.49(Alz2Ga1−z2)0.51P of a first conductive type, 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 said active layer is laminated only inwardly from a position away from at least one of said facets by a predetermined distance, and
• a layer which has a band gap larger than that of said active layer, the layer being equivalent to said upper first optical waveguide layer, is laminated on a region ranging from an end edge of said active layer positioned away from said at least one of said facets to said at least one of said facets.