Novel scheme for reduction of the pattern effect in all-optical clock recovery based on SOA using CW assist light

Abstract

A numerical model considering carrier heating and spectrum hole burning effects is given to study the pattern effect of clock recovery based on injection mode-locked SOA fiber laser, which is applicable for ultrashort pulses with several picoseconds pulsewidth. The reduction of pattern effect in the recovered clock at 40GHz successfully demonstrated by using a CW assist light at the transparency wavelength or gain region to SOA. The obtained minimum recovery time is less than 10ps, amplitude fluctuation will reduce from 64% to 5% and timing jitter will reduce from more than 3ps to 0.5ps. Moreover, the dependence of pattern effect on the power and wavelength of CW assist light and the bias current of SOA is analyzed, which is a useful guide to optimize this system. In order to get lower pattern effect, the required injection power of CW light at transparency wavelength will be higher than that of a wavelength in gain region, the minimum pattern effect occurs at a wavelength around the gain maximum. In this sense, a CW assist light in gain region is superior to the assist light at transparency wavelength. This scheme is an attractive method for SOA-based clock recovery and other all-optical signal processing.