SEMICONDUCTOR LASER DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a semiconductor laser device of side grating structure capable of restraining the higher modes of guided light in a ridge-type optical waveguide with high controllability and reproducibility so as to be improved in single mode properties. SOLUTION: A DFB laser device is equipped with a ridge-type optical waveguide 18 having a ridge stripe layered structure composed of a lower clad layer 12, an active layer 14, and an upper clad layer 16 laminated on a semiconductor substrate 10. A diffraction grating 20 provided with a rugged external surface is formed on each side of the ridge stripe layered structure in one piece for the formation of a side grating structure. An InGaAs light absorbing layer 22a which is capable of absorbing oscillation light is formed with a prescribed thickness on the rugged external surface of the diffraction grating 20 so as to cover projections and recesses residing on the rugged external surface.