Real-time experimental demonstration of PS-QPSK transmission with manipulated rotating and novel correlated CMA.

In this paper, we propose a novel manipulated rotating polarization switched quadrature phase shift keying (MR-PS-QPSK) technique, and corresponding correlated constant modulus algorithm (CMA) for signal recovery. The latter utilizes the correlation between the PS-QPSK symbols in the two polarizations to lock the phase of output signals. Then the signals in the two polarizations are merged according to the recovered switching bit, which suppresses the noise and simplifies the subsequent process. A field programmable gate array (FPGA) based real-time platform is built for experimental demonstration. The experimental results show that the proposed MR-PS-QPSK modulation format with correlated CMA can provide 3.2 dB optical signal-to-noise ratio (OSNR) improvement over dual-polarization QPSK (DP-QPSK) at back-to-back case and 3.8 dB OSNR improvement after fiber transmission at the same symbol rate, which corresponds to be about 2 dB OSNR improvement at the same bit rate. The resource consumption analysis in FPGA digital signal processing blocks and logic utilizations shows that the MR-PS-QPSK with correlated CMA only requires a small additional computational effort.