| 摘要 |
PURPOSE:To obtain a semiconductor laser which can be modulated by polarized wave and of which variation of output can be suppressed when polarization state is changed. CONSTITUTION:A distributed feedback type semiconductor laser in which a phase sift region is formed. The phase shift region contains a material 112 with Pockels effect. When a constant voltage is applied to two electrode 109 and a voltage is applied to an electrode 113 gradually, the refractive index of the material layer 112 changes by the Pockels effect. In this case, the phase matched wavelength of the TE mode hardly changes but the phase matched wavelength of the TM mode changes. The threshold gain at the TM mode decreases and it becomes smaller than the threshold gain of the TE mode, a TM mode light is outputted. As the phase matched wavelength of the TE mode hardly changes before and after the application of the voltage to the electrode 113, the variation of the intensity of the light output becomes smaller by the time the oscillation of TM mode is started. |
