Patent ID: 6411640
Filing Date: 2002-06-25
Classification: H01S,H04B

Abstract:
A distributed feedback semiconductor laser comprising:a waveguide comprising an active layer and a diffraction grating, said waveguide extending along a cavity-axial direction and being defined such that propagation of light in two different polarization modes is permitted in said waveguide; a plurality of electrodes arranged in series along said cavity-axial direction; and a first phase shift region formed in -a waveguide part of said waveguide located under one of said plurality of electrodes, wherein the waveguide part comprises said first phase shift region and a region other than said first phase shift region, said first phase shift region extending along the cavity-axial direction and having a polarization dependency that an effective refractive index for propagating light of said first phase shift region differs from an effective refractive index for propagation light of the other region such that a phase shift of a quarter wavelength of the propagation light is created for one of the two polarization modes and a phase shift of a half wavelength of the propagation light is created for the other of the two polarization modes in said first phase shift region.