100 Gbps/λ C-Band CD Digital Pre-Compensated and Direct-Detection Links With Simple Non-Linear Compensation

Abstract

In the scenario of downstream Passive Optical Networks (PON), we analyze through simulations and experiments a 100 Gbps/λ link using digital signal processing (DSP) over up to 50 km single mode fiber (SMF) in C-band. In particular, we propose chromatic dispersion digital pre-compensation (CD-DPC) and quaternary pulse amplitude modulation (PAM-4) levels optimization at the transmitter side (TX), and simple non-linear compensation (NLC) in combination with adaptive equalization (AEQ) at the receiver side (RX). Regarding NLC, we compare two approaches: a quadratic polynomial function and a square-root-like function respectively. In this paper, we analyze in detail the performances of four proposed options, namely equispaced PAM-4 levels without NLC (baseline case), equispaced PAM-4 levels in combination with NLC, optimized PAM-4 levels without NLC, and optimized PAM-4 levels in combination with NLC. We demonstrate through simulations and experiments that optimized PAM-4 levels can only offer limited enhancement when NLC is applied, and up to 3.3 dB sensitivity gain can be obtained thanks to NLC at RX when setting the optimum parameters, with respect to the baseline case.

Overview of high-speed TDM-PON beyond 50 Gbps per wavelength using digital signal processing [Invited Tutorial]

“…DSP techniques to counteract the effect if non-linearities, such as preand post-equalizers based on VNLE [42], neural networks (NN) [43] or NL Tomlinson-Harashima precoding (THP) [44], to mention some popular approaches, have been proposed. Simplified ad-hoc solutions to deal with NL distortion, such as polynomial functions [45] and look-uptables [46] have been also analyzed.…”

200 Gbps/λ PON Downstream C-Band Direct-Detection Links with ≥29 dB Power Budget

“…Therefore, it is expected that the next generation beyond 50G-PON will target (at least) 200 Gbps per λ in DS. To meet the 29 dB ODN loss and 20 km fiber reach at 100 Gbps is very challenging, as we showed in previous works [14][15][16][17]. For a 200 Gbps per λ transmission, the situation becomes extremely critical.…”

“…However, nextgeneration 5G and 6G systems will require even higher data rates, and PONs represent a suitable practical technology to support future optical access solutions [5][6][7][8]. Currently, research efforts are targeting data rates of 100 Gbps per λ and beyond [9][10][11][12][13][14][15][16][17] for the next step of PON evolution.…”

“…Increasing the target data rate requires pushing the system into nonlinear operation [16,17,21] to be able to increase the transmitter launch power and the optical modulation index to achieve the demanding power-budget requirements. In [16], we analyzed simple nonlinear compensation techniques, i.e., square-rootlike (SQRT) and polynomial (POLY) techniques.…”

“…Increasing the target data rate requires pushing the system into nonlinear operation [16,17,21] to be able to increase the transmitter launch power and the optical modulation index to achieve the demanding power-budget requirements. In [16], we analyzed simple nonlinear compensation techniques, i.e., square-rootlike (SQRT) and polynomial (POLY) techniques. We simulatively and experimentally confirmed about 2 dB gain in terms of maximum optical distribution network (ODN) loss for a 100 Gbps downstream transmission, thanks to SQRT and POLY.…”