Multi-Channel NRZ/RZ-DPSK to CSRZ-DPSK Format Conversion Based on Nonlinear Polarization Rotation of SOA

We present an all-optical nonreturn-to-zero/return-to-zero (NRZ/RZ) to carrier-suppressed return-to-zero (CSRZ) format conversion scheme for differential phase-shift keying (DPSK) signals. The conversion is based on nonlinear polarization rotation of a semiconductor optical amplifier (SOA). The 4-channel NRZ-DPSK or RZ-DPSK signals at 10 Gb/s are simultaneously converted to the corresponding CSRZ-DPSK signals, with -0.8 and 1.4 dB average power penalties, respectively. Additionally, high quality format conversion performances are shown with the optical spectra and eye diagrams.