All-optical logic XOR gate for high-speed CSRZ-DPSK signals based on cSFG/DFG in PPLN waveguide

A report is presented on all-optical logic XOR operation for high-speed carrier-suppressed return-to-zero differential phase-shift keying (CSRZ-DPSK) signals based on cascaded sum- and difference-frequency generation (cSFG/DFG) in a periodically poled lithium niobate (PPLN) waveguide. The linear relationship of complex amplitudes between the converted idler and input signals enables a CSRZ-DPSK logic XOR gate with the converted idler carrying the RZ-DPSK format. An all-optical logic XOR gate for 40 Gbit/s CSRZ-DPSK signals is demonstrated in the experiment. Dual-channel-output and wavelength variable-in variable-out operations are also shown for the PPLN-based CSRZ-DPSK logic XOR gate.