US Patent 7949027 Semiconductor laser device

A semiconductor laser device includes: an n-type cladding layer; a p-type cladding layer; and an optical waveguide portion disposed between the n-type and p-type cladding layers and including spaced-apart active layers. The optical waveguide portion permits lasing in a crystal growth direction of the active layers in at least three modes, including the fundamental mode and two higher order modes. The number of active layers is equal to or greater than the number of extreme points of the electric field of a particular one of the higher order modes. At least one of the active layers is disposed near each extreme point of the electric field of the particular higher order mode, within the optical waveguide portion.