Retiming and reshaping function of all-optical clock extraction at 160 Gb/s in monolithic mode-locked laser diode

Retiming and reshaping behaviors in an all-optical clock extraction operation at 160 Gb/s using a monolithic 160-GHz mode-locked laser diode was investigated in detail. The investigation of the basic clock extraction performance revealed that the clock extraction was stable against the input of data signals with a long zero sequence and with a poor extinction ratio. The clock extraction performance when the input data had random intensity and timing fluctuations was also discussed. We revealed that the generated clock pulse train absorbed well the intensity and timing fluctuations of the input data. Stable clock extraction remained even when the input data had 25% of the peak-intensity fluctuations. A timing jitter reduction from 0.85 to 0.32 ps was also achieved. The detailed investigation in the frequency-domain analysis of the jitter spectra revealed that the timing jitter reduction originated from the short-term stability of the slave 160-GHz mode-locked laser diode.