Pulse carver alignment monitoring for RZ-DPSK and DQPSK signals based on delay-tap sampling technique

In this paper, we propose a novel pulse carver alignment monitoring method for RZ-DPSK and RZ-DQPSK signals by using equivalent tenth symbol delay phase portrait generated by delay-tap sampling technique. The sign and value of the time mis-alignment can be distinguished and quantized by simple pattern recognition on the phase portrait. The proposed method is tested in 10-Gb/s RZ-DPSK and 50-Gb/s RZ-DQPSK systems by VPI transmission maker 9.0.