TY - JOUR
T1 - Probabilistic Shaping for the Optical Phase Conjugation Channel
AU - Yankov, Metodi Plamenov
AU - Hansen, Henrik Enggaard
AU - Da Ros, Francesco
AU - Kaminski, Pawel Marcin
AU - Porto da Silva, Edson
AU - Galili, Michael
AU - Oxenlowe, L.K.
AU - Forchhammer, Søren
PY - 2021
Y1 - 2021
N2 - Probabilistic constellation shaping is studied and developed for optical phase conjugation (OPC)-based nonlinearity compensation of Kerr nonlinearities in optical fiber links. The mid-link OPC scenario is considered for dispersion compensated systems. It is demonstrated in simulations and experimentally that transmission strategies optimal for classical additive white Gaussian noise (AWGN) channels can be sub-optimal for these systems without nonlinearity compensation. On the contrary, when nonlinearity compensation is applied with mid-link OPC, the channel noise is demonstrated to be Gaussian and AWGNlike transmission strategies thus remain effective. A channelagnostic probability mass function (PMF) optimization algorithm is proposed for the input constellation in order to further improve the shaping gains in both scenarios. Operating arbitrary PMFs on arbitrary channels is enabled by a channel-agnostic digital signal processing (DSP) chain. After ≈2000 km of transmission, mid-link OPC is demonstrated to provide ≈1 dB of gain in effective SNR, which translates to ≈0.4 bits/QAM symbol of gain in achievable information rate. The gain is then increased by an extra ≈0.2 bits/QAM symbol by applying probabilistic shaping.
AB - Probabilistic constellation shaping is studied and developed for optical phase conjugation (OPC)-based nonlinearity compensation of Kerr nonlinearities in optical fiber links. The mid-link OPC scenario is considered for dispersion compensated systems. It is demonstrated in simulations and experimentally that transmission strategies optimal for classical additive white Gaussian noise (AWGN) channels can be sub-optimal for these systems without nonlinearity compensation. On the contrary, when nonlinearity compensation is applied with mid-link OPC, the channel noise is demonstrated to be Gaussian and AWGNlike transmission strategies thus remain effective. A channelagnostic probability mass function (PMF) optimization algorithm is proposed for the input constellation in order to further improve the shaping gains in both scenarios. Operating arbitrary PMFs on arbitrary channels is enabled by a channel-agnostic digital signal processing (DSP) chain. After ≈2000 km of transmission, mid-link OPC is demonstrated to provide ≈1 dB of gain in effective SNR, which translates to ≈0.4 bits/QAM symbol of gain in achievable information rate. The gain is then increased by an extra ≈0.2 bits/QAM symbol by applying probabilistic shaping.
KW - Constellation shaping
KW - OPC
KW - DSP
KW - Optical communications
KW - Nonlinearities
U2 - 10.1109/JSTQE.2020.3024843
DO - 10.1109/JSTQE.2020.3024843
M3 - Journal article
SN - 1077-260X
VL - 27
JO - IEEE Journal of Selected Topics in Quantum Electronics
JF - IEEE Journal of Selected Topics in Quantum Electronics
IS - 2
M1 - 7700716
ER -