COHERENT OPTICAL-FIBRE COMMUNICATIONS SYSTEM USING POLARIZATION MODULATION

摘要

A coherent optical communications system using polarization modulation. At the transmitter, the polarization modulation of the optical signals is obtained by using two lasers emitting orthogonally polarized radiations at different frequencies, which are combined without losses prior to transmission over a line. The system does not require the use of external modulators, thereby, eliminating attenuation problems. At the receiver, the received signal is combined with a signal emitted by a local oscillator having a component polarized in the plane of each of the components of the received signal. The combined signal is separated by a polarization separator into two components and each component is converted into electrical signals, filtered to eliminate one of the frequencies and then demodulated.