All-Optical Clock Recovery and Pulse Reshaping Using Semiconductor Optical Amplifier and Dispersion Compensating Fiber in a Ring Cavity

An all-optical clock recovery device capable of continuously recovering the clock frequency of optical return-to- zero signals from a 10- to 12.5-GHz repetition rate is reported. The recovered clock consists of chirp-free Gaussian pulses at a diffraction limit with low timing jitter of ~200 fs. We employ intracavity dispersion-compensating fiber (DCF) in order to eliminate chirp and asymmetry of semiconductor optical amplifier (SOA)-amplified pulses. This SOA+DCF ring configuration allows us to easily recover the clock over a 40-nm tuning range corresponding to the SOA gain bandwidth.