Optical transmitter, optical receiver and optical transmission apparatus and control method of optical receiver

Abstract From the Canadian patent

A unipolar original electrical signal is encoded by alternate mark inversion and combined with a DC bias current for injection of a semiconductor laser to produce a bipolar FSK optical signal that is transmitted to a receiver. At the receiver, the received signal is coupled with optical local power and fed to an optical/electrical transducer preferably a, semiconductor, to produce an electrical signal that is demodulated to produce the original unipolar signal. The demodulator may be of different types, for example employing delaying part of the amplified electrical signal and mixing the delayed part wish the original signal for passage of the combined signal through a low pass filter; with …