We propose a convolutional-recurrent channel equalizer and experimentally demonstrate 1dB Q-factor improvement both in single-channel and 96×WDM, DP-16QAM transmission over 450km of TWC fiber. The new equalizer outperforms previous NN-based approaches and a 3-steps-per-span DBP.

No abstract

No abstract

DOI to the publisher's website. • The final author version and the galley proof are versions of the publication after peer review. • The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal. If the publication is distributed under the terms of Article 25fa of the Dutch Copyright Act, indicated by the "Taverne" license above, please follow below link for the End User Agreement:

Increase in transmission symbol-rate as well as order of quadrature amplitude modulation (QAM) is identified as the most economical way to reduce cost per transmitted bit. In particular, next generation transponders aim at supporting datarates up to 1 Tb/s employing superchannels due to electrical components' bandwidth limitations. Furthermore, the introduction of a flexible-grid architecture can maximize throughput by minimizing spectral gaps in available optical spectrum. Keeping in view these design options, we conducted several high capacity experiments with tier1 operator Orange using their field deployed standard single mode fiber (SSMF, G.652), having a total length of 762 km, connecting the cities Lyon and Marseille in France. In particular we employed four subcarriers per Tb/s superchannel, each modulated by PM-16QAM, PM-32QAM and PM-64QAM with per carrier symbol-rates of 41.2 GBd, 33 GBd and 34 GBd, respectively. The subcarrier spacing was 50 GHz for the PM-16QAM case and 37.5 GHz for both the PM-32QAM and PM-64QAM cases allowing in total 24×1.0 Tb/s, 32×1.0 Tb/s and 32×1.2 Tb/s superchannels over C-band and resulting in potential C-band capacities of 24.0 Tb/s, 32.0 Tb/s and 38.4 Tb/s, respectively. After field transmission the maximum available OSNR0.1nm margin compared to the required OSNR0.1nm at forward error correction (FEC) threshold was 8.2 dB, 5.4 dB and 4.2 dB for PM-16QAM, PM-32QAM and PM-64QAM, respectively. The transmission reach for PM-16QAM and PM-32QAM modulated superchannels was extended to ∼1571 km and ∼1065 km using erbium doped fiber amplified SSMF spans of ∼101 km length.