Optoelectronic Phase Locked Loop with Balanced Photodetection for Clock Recovery in High-Speed Optical Time Division Multiplexed Systems

An optoelectronic phase locked loop for clock recovery in high-speed optical time division multiplexed systems is proposed and experimentally demonstrated. The proposed scheme incorporates a pair of balanced photodetector through which the well-known polarity ambiguity in error signal is resolved, and the cancellation of laser noise enables clock recovery with low timing jitter. Using an electroabsorption modulator as a phase detector, a 10 GHz clock signal with 300 fs rms timing jitter is successfully extracted from 40 and 80 Gbit/s RZ data stream. A 40 to 10 Gbit/s demultiplexing is performed by using the recovered clock signal with no penalty introduced in the bit error rate performance.