DIRECT POLARIZATION AND MODULATION LIGHT-SOURCE CONTROL SYSTEM, ITS APPARATUS, INTEGRATED SEMICONDUCTOR DEVICE, ITS DRIVING METHOD AND OPTICAL COMMUNICATION METHOD USING IT

摘要

PURPOSE:To obtain a direct polarization and modulation light-source control system or apparatus in which a dynamic wavelength change is small and in which a modulation state can be kept well, to obtain an integrated semiconductor device, to obtain its driving method and to obtain an optical communication system using it. CONSTITUTION:A semiconductor laser 1-1 is used as a light source for optical communication. The semiconductor laser 1-1 has a structure in which a current flowing to a part of an optical waveguide is modulated and in which two oscillation and polarization modes having different planes of polarization are switched. The semiconductor laser is provided with a means 102 by which two orthogonal polarized waves of output light from the semiconductor laser 1-1 are separated and with means 1-3-1, 1-3-2 which individually receive two separated orthogonal polarized waves. By using signals from the respective receiving means 1-3-1, 1-3-2, an injection current to the semiconductor laser 1-1 is feedback-controlled.