Patent ID: 8270847

Claim:
An optical communication system comprising: a driver configured to receive a data signal having an original data rate of 2R Gb/s, and configured to separate the data signal into first and second data signals, each of the first and second data signals having a data rate of R Gb/s; a first differential phase shift keying (DPSK) modulator for modulating the first data signal on a first optical signal using a first DPSK modulation scheme to provide a first optical data signal; a second DPSK modulator for modulating the second data signal on a second optical signal with a second DPSK modulation scheme to provide a second optical data signal, wherein the first DPSK modulation scheme uses a first phase shift to represent data bits that is different than a second phase shift used by the second DPSK modulation scheme to represent data bits; an optical delay element coupled to the second DPSK demodulator configured for imparting a delay to the second optical data signal compared to first optical data signal; and a combiner coupled to an output of the first DPSK modulator and an output of the second DPSK modulator and configured for combining the first optical data signal and the second optical data signal into an aggregate signal for coupling to an optical information channel, the first optical data signal being relatively orthogonally polarized relative to the second optical data signal; a first DPSK demodulator configured for receiving the aggregate signal and to demodulate the first optical signal, said first DPSK demodulator being configured to separate light onto associated first and second optical paths, said second optical path of said first DPSK demodulator being configured to impart a first delay to said first and second optical signals to cause coherent summation of neighboring bits of said first optical signal and incoherent summation of neighboring bits of said second optical signal when light from said first and second optical paths of said first DPSK demodulator is combined interferometrically; and a second DPSK demodulator configured for receiving the aggregate signal and to demodulate the second optical signal, said second DPSK demodulator being configured to separate light onto associated first and second optical paths, said second optical path of said second DPSK demodulator being configured to impart said first delay and said second phase shift to said first and second optical signals to cause coherent summation of neighboring bits of said second optical signal and incoherent summation of neighboring bits of said first optical signal when light from said first and second optical paths of said second DPSK demodulator is combined interferometrically.