High-performance homodyne optical injection phase-lock loop using wide-linewidth semiconductor lasers

The requirements for narrow linewidth lasers and short loop propagation delay limit optical phase-lock loop realizability with semiconductor lasers, Although optical injection locking can provide low-phase-error variance, its locking range is Limited by stability considerations, The first experimental results for a new architecture combining both techniques, the optical injection phase-lock loop (OIPLL), are reported, Phase error variance values as low as 0.006 rad(2) (500 MHz bandwidth) and locking ranges exceeding 26 GHz are achieved using DFB lasers of summed linewidth 36 MHz with loop delay of 15 ns and injection ratio less than -30 dB.