Feedforward carrier recovery for polarization demultiplexed signals with unequal signal to noise ratios.
We investigate feedforward carrier recovery (FFCR) in coherent polarization diversity receivers where the signal to noise ratio (SNR) of polarization demultiplexed signals can be unequal, such as in polarization-dependent loss impaired systems. A joint-polarization FFCR mechanism for estimating the carrier phase noise based on samples from both polarizations is proposed and compared with three other plausible alternatives. We evaluated each architecture using Monte Carlo simulations and observed that the joint-polarization FFCR yields a 1.1 dB SNR penalty for a given laser linewidth x baud rate product, while the other three architectures offer 1.8 dB, 2.0 dB and 3.9 dB, for QPSK at BER = 10(-3) and 3 dB SNR imbalance.
Faculty of Electrical and Computer Engineering, University of Campinas, SP, Brazil. fgarcia@decom.fee.unicamp.br
Francisco A
FA
Garcia
Darli A
DA
Mello
Helio
H
Waldman