All-Optical NRZ-DPSK Clock Recovery Using Chromatic-Dispersion-Induced Clock Tone

All-optical clock recovery (CR) from 10-Gb/s nonreturn-to-zero differential phase-shift-keying (NRZ-DPSK) signal is demonstrated experimentally by introducing the chromatic- dispersion-induced clock tone into a free-running semiconductor optical amplifier (SOA)-based fiber ring laser for achieving mode-locking. Since no special component is required for NRZ-DPSK demodulation, our proposed method is very promising because of its simple configuration and better stability. The good performance of our proposed configuration is fulfilled with a 20-km standard single-mode fiber to regenerate clock tone of the NRZ-DPSK signal. The recovered clock signal with the extinction ratio of 17 dB and the root-mean-square timing jitter of 718 fs is achieved under $2^{31}-1$ pseudorandom binary sequence NRZ-DPSK signals measurement.