Optical transmitter for passive optical network

摘要

An optical signal is generated by an SOA and then modulated by an optical amplitude modulation device. The signal is transmitted into a first end of an optical transmission line with a first polarization state. A fraction of the optical signal is re-transmitted into the other end of the transmission line, such that when it has at the other end a polarization state orthogonal to the polarization state of the signal fraction present at the other end. The re-transmitted signal, when having at the first end a polarization state orthogonal to the first polarization state, is guided from the first end to the SOA, next to the modulation device and then to the first end without passing the SOA again, using a polarizing beam splitter and a polarization device. The SOA is operated in a gain saturation state, such that an amplitude modulation of the re-transmitted optical signal is cancelled.