Ridge waveguide semiconductor laser

摘要

PROBLEM TO BE SOLVED: To solve the problem in a ridge waveguide type semiconductor laser of the prior arts, about a loss in coupling with an external optical fiber being enlarged due to distortion in the shape of electric field strength distribution in a waveguide of a core layer, a rapid refractive index change in a lateral direction in a mesa stripe implementing optical confinement by a ridge waveguide for which core processing is not required, but causing shape distortion such as recess or hollow in the shape of the electric field strength distribution and the distortion becoming the loss in coupling the optical fiber and oscillation light.SOLUTION: In a ridge waveguide type semiconductor laser of the present invention, a semiconductor buffer layer of the same composition as that of a semiconductor substrate is formed in an upper part of a sidewall and a core layer of a mesa stripe in a manner to cover the whole mesa stripe structure. A rapid change in a refractive index in the lateral direction of the mesa stripe is mitigated by the buffer layer and distortion to be generated in the shape of electric field strength distribution is reduced. Efficient of coupling between the semiconductor laser and the optical fiber can be improved by the buffer layer.SELECTED DRAWING: Figure 3