Single-fiber lightwave centralized WDM-OFDMA-PON with colorless optical network units

We propose and experimentally demonstrate a carrier-reuse, single-feeder, wavelength-division-multiplexed, orthogonal frequency-division-multiple-access passive optical network (WDM-OFDMA-PON) with colorless direct-detection optical network units and coherent detection optical line terminals. We examine two strategies by adjusting the frequency occupancy and the modulation format of the uplink (UL) and downlink (DL) signals. We investigate the impact of the DL signal-to-carrier ratio on the performance of both the UL andDLsignals via simulations and identify impairments limiting system performance. As a proof of concept,we demonstrate on a single wavelength channel a realization of each of the two scenarios investigated using orthogonal frequency division- multiplexing (OFDM). A quadrature phase-shift keying approachwith a wide spectrum and a narrow guard band achieves 21.6 Gb/s.A32-aryquadrature amplitudemodulation approach with a narrow spectrum and a wide guard band achieves 14.5 Gb/s and a span of over 80 km.