LIGHT SOURCE, DRIVING METHOD THEREFOR AND OPTICAL COMMUNICATION SYSTEM EMPLOYING IT

摘要

PROBLEM TO BE SOLVED: To obtain a light source in which switching can be made between two polarization modes by an arrangement wherein the threshold gain of two polarization modes is varied not through phase control but by varying the propagation loss of light for a part of optical waveguide independently from two polarization modes. SOLUTION: Propagation loss of light from a polarization mode splitter B coupled optically with a semiconductor laser A is varied independently from two polarization modes and the relationship of the magnitude of gain is controlled thus making a switching between two polarization modes. A semiconductor laser A is coupled optically with a waveguide type polarization mode splitter B for branching two polarization modes in different propagating directions. Oscillation of semiconductor laser A can be selected between two polarization modes by varying the propagation loss of light being guided through the polarization mode splitter B independently for two polarization modes.