title: Digital back-propagation for spectrally efficient WDM 112 Gbit/s PM m-ary QAM transmission.
abstract: We report the performance of coherently-detected nine-channel WDM transmission over high dispersion fibers, using polarization multiplexed m-ary quadrature amplitude modulation (m=4, 16, 64, 256) at 112 Gbit/s. Compensation of fiber nonlinearities via digital back-propagation enables up to 10 dB improvement in maximum transmittable power and ~8 dB Qeff improvement which translates to a nine-fold enhancement in transmission reach for PM-256QAM, where the largest improvements are associated with higher-order modulation formats. We further demonstrate that even under strong nonlinear distortion the transmission reach only reduces by a factor of ~2.5 for a 2 unit increase in capacity (log2m) when full band DBP is employed, in proportion to the required back-to-back OSNR.
authors: Photonics Systems Group, Tyndall National Institute and Department of Electrical Engineering/Physics, University College Cork, Dyke Parade, Prospect Row, Cork, Ireland. danish.rafique@tyndall.ie
authors: Danish
authors: D
authors: Rafique
authors: Jian
authors: J
authors: Zhao
authors: Andrew D
authors: AD
authors: Ellis