Patent ID: 8111726

Claim:
A semiconductor laser device comprising: an n-type cladding layer; a p-type cladding layer; an active layer located between said n-type cladding layer and said p-type cladding layer; an n-side guiding layer located on the same side of said active layer as said n-type cladding layer; and a p-side guiding layer located on the same side of said active layer as said p-type cladding layer, wherein said n-side guiding layer, said active layer, and said p-side guiding layer are undoped or substantially undoped, the sum of the thicknesses of said n-side guiding layer, said active layer, and said p-side guiding layer is not less than 0.5 times the lasing wavelength of said semiconductor laser device and is not more than 2 μm, and said p-side guiding layer is thinner than and has a lower refractive index than said n-side guiding layer.