I. Introduction
All-Optical clock recovery (AOCR) is a key requirement for realizing signal processing functions such as all-optical 3R regeneration, demultiplexing, and modulation format conversion. Many schemes for AOCR have been demonstrated, including spectral filtering [1], Fabry–Perot lasers [2], injection-locked optoelectronic oscillators [3] and actively mode-locked fiber ring lasers [4]–[8]. Mode-locked fiber ring lasers have the advantage of high speed operation, wide wavelength tunability, and low timing jitter.