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

• We find that estimating the phase noise became a tough job in time packing system.
• We proposed an optical domain PA-CPE scheme in a time packing Nyquist system.
• The middle pilot can be used for carrier phase recovery in both side signal channels.
• The proposed PA-CPE can track the phase noise successfully despite the ISI.
• The linewidth tolerance value is well even the compression factor is as small as 0.625.

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 1 dB OSNR penalty at the bit error rate (BER) of 1 × 10−3 even though the compression factor α is as small as 0.625.