Patent ID: 6876680

Claim:
A semiconductor laser device comprising: a compressive strain quantum well active layer; a tensile strain quantum well active layer; a resonator formed between a radiation end face and a reflection end face of a laser beam; and a diffraction grating formed between said radiation end face and said reflection end face, said diffraction grating being positioned in the vicinity of said compressive strain quantum well active layer and/or said tensile strain quantum well active layer, said diffraction grating being configured to select a laser beam having a plurality of oscillation longitudinal modes having a specific central wavelength, wherein said compressive strain quantum well active layer and said tensile strain quantum well active layer are arranged so that an output laser beam is obtained by polarization-multiplexing a laser beam in the TE mode generated in said compressive strain quantum well active layer and a laser beam in the TM mode generated in said tensile strain quantum well active layer.