Improved pilot-aided optical carrier phase recovery using average processing for pilot phase estimation

Abstract

We propose and numerically investigate an improved pilot-aided (PA) optical carrier phase recovery (CPR) method using average processing for pilot phase estimation in order to suppress the amplified spontaneous emission (ASE) noise in PA coherent transmission systems. Extensive simulations for 28Gbuad QPSK systems are implemented. The performance of proposed PA-CPR with averaging is comprehensively investigated and compared with PA-CPR without averaging and Viterbi & Viterbi phase estimation (VVPE). Results show that, PA-CPR with averaging can significantly improve the performance of PA-CPR without averaging, and the best averaging length in the average operation is determined by trading off between ASE noise and laser phase noise (PN). By comparing the optical-signal-to-noise-ratio (OSNR) penalties at bit error rate (BER) of 1×10−3using PA-CPR without averaging, PA-CPR with averaging and VVPE, the advantage of PA-CPR with averaging is further confirmed. Quantitatively, the tolerable linewidth-symbol-duration products (Δf·T) at 1-dB OSNR penalty by using PA-CPR without averaging, VVPE, and PA-CPR with averaging are 6×10−5, 1.2×10−4, and 5×10−4, respectively.