| 摘要 |
PROBLEM TO BE SOLVED: To provide a semiconductor laser device, such as distribution feedback type semiconductor laser comprising polarization switching function, which allows efficient polarization modulation. SOLUTION: A distribution feedback type semiconductor laser at least comprises optical waveguides 2, 3, and 4, an active layer 2, and a diffraction grating 7. The optical waveguides 2, 3, and 4 are configured so as to allow the propagation of light of two different polarization modes. A phase shifting region 9 is formed, which extending in the optical propagation direction, has such polarization dependence as to be different from the other region in effective refractive index with respect to propagation light, so that a phase shift of a quarter of wavelength is generated for one polarization. The phase shifting region 9 is preferably formed so that a phase shift of half a wavelength is generated with respect to the other polarization. |
