Chirped RZ-DPSK Based on Single Mach-Zehnder Modulator and Its Nonlinear Transmission Performance

We present a detailed analysis of positively and negatively chirped return-to-zero differential phase-shift keyed (CRZ- DPSK) signals that are generated using a single Mach-Zehnder modulator at the transmitter. Supporting CRZ-DPSK experiments at 10-Gb/s showed a nominal receiver sensitivity of -42 dBm at BER=10-9. We find that CRZ-DPSK signals with a positive chirp perform substantially better than those with a negative or zero chirp in a self-phase-modulation limited nonlinear transmission.