Optical frequency synthesis for high spectral efficiency WDM transmission

In this paper an optical frequency synthesis technique using optical injection phase-locked loop is discussed. An optical frequency comb generator produces a complete set of channel frequencies is extracted from the comb spectrum using an active filtering arrangement, based on the combined use of injection locking and phase locking in an optical injection phase lock loop (OIPLL). This approach eliminates the wide bandwidth, short (<1 ns) loop propagation delay design constraints of conventional optical phase lock loops for use with non line-narrowed semiconductor lasers.