25 Gbit/s per user coherent all-optical OFDM for tbit/s-capable PONs

We propose and experiment a coherent all-optical orthogonal frequency-division multiplexing (AO-OFDM) system, based on all-optical (de)multiplexing and coherent detection, for multi-Tb/s passive optical networks (PON). The proposed approach allows to largely increase the downstream data rate per user and extend the standard single mode fiber (SSMF) reach for future long-reach applications. The compliance with NG-PON2 layout is guaranteed thanks to the exploitation of cyclic arrayed waveguide gratings (AWGs). Five user transmission with 12.5-Gbaud quadrature phase shift keying (QPSK) modulation per each user (125-Gb/s downstream capacity per wavelength) over more than 40-km link has been successfully demonstrated.