Patent ID: 7983570

Claim:
A differential polarization-phase-shift keying optical communication system comprising: a transmitter to generate a differentially encoded polarization-phase modulated optical signal from input data, the transmitter consisting essentially of: an electrical encoder for mapping at least two data channels into at least two differentially encoded data sequences, the electrical encoder comprising: an encoder for encoding two synchronous binary input data streams d 1 and d 2 into two encoded data streams D 1 and D 2 , each said input data stream having a single bit period T between successive data bits; a first time delay circuit for delaying D 1,k by a period T to produce a first time-delayed encoded signal D 1,k−1 ; a second time delay circuit for delaying D 2,k by a period T to produce a second time-delayed encoded signal D 2,k−1 ; and a logic circuit for producing encoded signals D 1 and D 2 according to the logical relationships D 1,k =d 1,k ⊕D 1,k−1 D 2,k =d 2,k ⊕D 2,k−1 ; an optical source to provide an optical carrier; and an optical encoder for receiving the optical carrier and the at least two differentially encoded data sequences to generate the differentially encoded polarization-phase modulated optical signal, the optical encoder including: a first polarization element to separate a first and a second polarization component of the optical source; at least two optical modulators connected in parallel for modulating the first and a second polarization component with the at least two differentially encoded data sequences to produce at least two phase-modulated signals; and a second polarization element for combining the at least two phase-modulated signals to generate the differentially encoded polarization-phase modulated optical signal; an optical transmission medium; and a receiver for optically demodulating and detecting the differentially encoded polarization-phase modulated optical signal to recover the input data in the differential polarization-phase-shift keying optical communication system.