Patent ID: 7301978

Claim:
A semiconductor laser element comprising: a substrate made of GaAs; a lower cladding layer formed above said substrate and made of In 0.49 (Al x1 Ga 1-x1 ) 0.51 P of a first conductive type which lattice-matches with GaAs, where x2<x1<1; a lower optical waveguide layer formed above said lower cladding layer and made of In 0.49 (Al x2 Ga 1-x2 ) 0.51 P which lattice-matches with GaAs, where 0<x2<x1; a strained active layer formed above said lower optical waveguide layer; an upper optical waveguide layer formed above said active layer and made of In 0.49 (Al x2 Ga 1-x2 ) 0.51 P which lattice-matches with GaAs, where 0<x2<x1; and an upper cladding layer formed above said upper optical waveguide layer and made of In 0.49 (Al x1 Ga 1-x1 ) 0.51 P of a second conductive type which lattice-matches with GaAs, where x2<x1<1; wherein a total thickness of said lower optical waveguide layer, said active layer, and said upper optical waveguide layer is 0.30 micrometers or greater; and wherein at least one of said lower cladding layer and said upper cladding layer has a thickness of 0.6 micrometers or smaller.