Clock extraction using an optoelectronic oscillator from high-speed NRZ signal and NRZ-to-RZ format transformation

A clock extraction scheme was demonstrated using an optoelectronic oscillator from high-speed nonreturn-to-zero (NRZ) signal. A theoretical model on the locking range of the oscillator was presented. A 10-GHz clock with a timing jitter of 0.4 ps was extracted from 10-Gb/s NRZ signal and a locking range of 800 kHz was achieved. NRZ to return-to-zero (RZ) data format conversion was also performed simultaneously with the NRZ clock extraction.