Optical phase-locked loop based carrier phase recovery and compensation for 8-PSK coherent optical links

Coherent optical links with analog and optical signal processing are expected to replace existing intensity modulation and direct detection based techniques in the near future for achieving energy efficiency in inter and intra data center interconnects. Carrier synchronization is one of the key challenges in these optical links. We propose an optical phase-locked loop based carrier offset compensation architecture for achieving synchronization in 8-PSK coherent optical links. The optical phase-locked loop uses a cross-correlator based phase detector with four-level quantizer and phase modulator for phase variations compensation. The system-level behavioral simulations show promising results for the 8-PSK links.