All-optical encryption/decryption for nonreturn-to-zero differential phase-shift keying signals using four-wave mixing in semiconductor optical amplifier

Abstract

By experiment we demonstrate an all-optical encryption/decryption scheme for nonreturn-to-zero dif- ferential phase-shift keying (NRZ-DPSK) signals at 10 Gbit∕s using all-optical exclusive-OR (XOR) logic. The key bit stream is performed by a pseudorandom bit stream. The all-optical XOR logic is achieved by nonde- generate four-wave mixing (FWM) in a semiconductor optical amplifier (SOA), which allows high data rate oper- ation and asymmetric optical powers of the two input bit streams. The gain dynamics and pattern effect associated with the SOA carrier lifetime are alleviated due to the constant envelope of the NRZ-DPSK signals.