Ultrafast all-optical three-input Boolean XOR operation for differential phase-shift keying signals using periodically poled lithium niobate

We propose and demonstrate that periodically poled lithium niobate (PPLN) can act as an ultrafast three- input XOR gate for differential phase-shift keying (DPSK) signals based on cascaded sum- and difference- frequency generation. PPLN-based all-optical three-input Boolean XOR operations for 20 Gbits / s return-to- zero DPSK (RZ-DPSK), 40 Gbits / s RZ-DPSK, and 20 Gbits / s non-return-to-zero DPSK signals are all successfully verified in the experiment.