Patent ID: 7933304
Filing Date: 2011-04-26
Classification: H01S

Abstract:
1. A semiconductor laser device comprising: an active layer region to emit laser light, formed over a first section of a semiconductor substrate; a waveguide layer region formed over a second section of the semiconductor substrate adjacent to the first section; a diffraction grating layer formed on the active layer region; a cladding layer formed so as to cover a section which includes the diffraction grating layer and the waveguide layer; a top electrode formed in a predetermined section on the cladding layer; and a reflection film which is formed on one side edge of the semiconductor substrate to reflect the laser light emitted in the active layer region; wherein a length (L) of the active layer region is 10 to 200 μm in length; a distributed Bragg reflection mirror or a distributed feedback mirror, which comprises the diffraction grating layer and the cladding layer, is formed as an optical feedback system for a laser cavity; the active layer is so formed that a product (kL) of an optical reflection coefficient (k) of the diffraction grating layer and the length (L) of the active layer region is at least 3; and longitudinal oscillation modes occur simultaneously at plural wavelengths.