Format Conversion of Optical Multilevel Signals Using FWM-Based Optical Phase Erasure

An optical format conversion scheme of multilevel phase-shift keying (M-ary PSK) signals using the four-wave mixing based optical phase erasure is discussed in this paper. The conversion from differential quadrature phase-shift keying (DQPSK) to differential phase shift keying at 10 and 160 Gbaud, and the conversion from differential eight-ary phase-shift keying to DQPSK at 40 Gbaud have been experimentally demonstrated. The proposed scheme could be used as a phase erasure, in which a redundant tributary of the M-ary PSK signal is removed, or as an “updater” where the unwanted phase pattern is replaced with the new pattern.