Pilot-based bind phase estimation method for coherent optical OFDM

In this paper, a pilot-based blind (PBB) phase estimation method for coherent optical orthogonal frequency-division multiplexing (CO-OFDM) is proposed. Instead of inserting the pilot-subcarriers that are loaded with the already known information in the OFDM signal, the unknown and specially designed signal is used to replace the signal on the pilot subcarriers to decrease the waste of spectrum and also demonstrated well performance for the phase noise compensation. Both the proposed PBB and conventional pilot-aided (PA) estimation methods are demonstrated in a CO-OFDM transmission experiment, which is modulated by 4 quadrature amplitude modulation (4-QAM) format and transmitted over 1760-km standard single-mode fiber (SSMF). The experimental results show that the proposed PBB method still achieves the similar performance to that of the conventional PA method.