Patent ID: 8805204

Claim:
An optical communication method comprising: modulating at least one optical carrier at a channel wavelength with a binary data stream using at least one nQAM modulator to provide at least one nQAM signal, where n is an integer greater than one (1); and coupling the at least one nQAM signal into at least one delay line interferometer (DLI) to generate at least one n m QAM signal, where m is an integer greater than 1, wherein the DLI splits the nQAM signal into at least first and second nQAM signals on at least first and second DLI arms, and wherein at least one of the first and second DLI arms provides a time delay sufficient for a one symbol shift such that at least one of the at least first and second nQAM signals is shifted by one symbol relative to another of the at least first and second nQAM signals; and transmitting the at least one n m QAM signal over an optical transmission path.