An effective scheme of optical pilot aided carrier phase estimation for a time packing Nyquist optical communication system

Abstract

An optical domain pilot aided carrier phase estimation (PA-CPE) scheme in a double-carrier time packing Nyquist system is proposed, in which the middle pilot can be used for carrier phase estimation in both side time packing signal channels. The proposed PA-CPE method can effectively overcome the scale of the inter-symbol interference (ISI) introduced by time packing, with the good characteristics of high phase noise tolerance and simple hardware complexity. The comprehensive mathematical descriptions of laser phase noise model and PA-CPE scheme are provided. The analyses show that the proposed PA-CPE can estimate the phase noise successfully despite ISI caused by time packing. In the double-carrier time packing Nyquist system mentioned above, using the proposed PA-CPE algorithm, the linewidth tolerance value of 6×10−5 can be reached with 1dB OSNR penalty at the bit error rate (BER) of 1×10−3 even though the compression factor α is as small as 0.625.