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

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