Patent ID: 9325425
Filing Date: 2016-04-26
CPC Classification: H04B

Claim Text:
1. A DPSK/DQPSK optical receiver comprising: a) an optical splitter having an input that receives a DPSK/DQPSK modulated optical signal and a plurality of outputs, the optical splitter separating the DPSK/DQPSK modulated optical signal into a plurality of channels according to a fixed non-equal optical power splitting ratio C:(1−C) propagating a plurality of received optical signals to the plurality of outputs, the optical power splitting ratio being chosen to reduce degradation caused by at least one of chirping, chromatic dispersion, polarization-mode dispersion, and spectrally narrowing; b) a plurality of delay interferometers, an input of a respective one of the plurality of delay interferometers being optically coupled to a respective one of the plurality of outputs of the optical splitter, each of the plurality of delay interferometers passing a filtered optical signal, the delay interferometers comprising an optical delay and a variable phase shifter being configured so that a free spectral range and a phase shift of each of the plurality of delay interferometers are separately tuned to reduce degradation caused by at least one of chirping, chromatic dispersion, polarization-mode dispersion, and spectrally narrowing; c) a plurality of optical detectors, an input of a respective one of the plurality of optical detectors being optically coupled to an output of a respective one of the plurality of optical filters, each of the plurality of optical detectors generating an electrical detection signal related to a power of a respective filtered optical signal; d) a plurality of electrical amplifiers, an output of each of the plurality of optical detectors being electrically coupled to an input of one of the plurality of amplifiers, each of the plurality of electrical amplifiers generating an amplified electrical signal; and e) at least one electrical signal combiner having a plurality of inputs, an output of a respective one of the plurality of electrical amplifiers being electrically connected to a respective one of the plurality of inputs of the at least one electrical combiner so that each input of the least one electrical signal combiner receives a signal corresponding to a channel propagating a received optical signal separated by the splitter with the fixed non-equal optical power splitting ratio C:(1−C), the at least one electrical combiner adding or subtracting the amplified electrical detection signals generated by the plurality of electrical amplifiers into a combined reception signal at an output.