Abstract: An optical coherent receiver in one embodiment has a heterodyne configuration, and in another embodiment has a homodyne configuration, in each configuration employs multiple feedback signaling and analog/digital processing to optimize response to a modulated optical input signal, the provision of both individual RF I and RF Q channel outputs.

Abstract: A method and system for duobinary coding of optical signals, wherein a precoded duobinary signal is supplied to a phase modulator which converts it to a phase-modulated optical signal, an optical filter carries out the function of the coder and converts the phase-modulated signal to an optical duobinary signal, and the duobinary coding results in a reduction in the bandwidth. A wavelength division multiplex system is provided by precoding a number of binary signals and converting them to phase-modulated signals, which are in turn, combined via an optical multiplexer, wherein the multiplex signal formed in this way is supplied to an optical filter which operates simultaneously as a coder for all the signals and produces a group of duobinary signals, and a number of groups of duobinary signals can be interleaved in one another in order to produce a dense wavelength division multiplex signal.

Abstract: A method and system for duobinary coding of optical signals, wherein a precoded duobinary signal is supplied to a phase modulator which converts it to a phase-modulated optical signal, an optical filter carries out the function of the coder and converts the phase-modulated signal to an optical duobinary signal, and the duobinary coding results in a reduction in the bandwidth. A wavelength division multiplex system is provided by precoding a number of binary signals and converting them to phase-modulated signals, which are in turn, combined via an optical multiplexer, wherein the multiplex signal formed in this way is supplied to an optical filter which operates simultaneously as a coder for all the signals and produces a group of duobinary signals, and a number of groups of duobinary signals can be interleaved in one another in order to produce a dense wavelength division multiplex signal.