Design and demonstration of a colorless WDM-OFDMA PON system architecture achieving symmetric 20-Gb/s transmissions with residual interference compensation.

In this paper, we propose a two-tiered colorless WDM-OFDMA PON system architecture that draws strengths from each individual WDM and OFDM PON systems. Specifically, the two-tiered architecture enables a colorless transceiver to be shared by a group of ONUs, resulting in drastic reduction of the system cost. For achieving colorlessness via reusing downstream light sources, we discover the residual power of downstream signal unexpectedly springs back after transmissions, causing severe interference to the upstream signal, and thus limiting the data rate of the upstream signal. We devise a method of adopting a common dispersion compensation module at OLT to reduce the residual power over all wavelengths. Experimental results show that, with an improvement of upstream signal's SNR up to 10 dB, the system successfully achieves 20-Gb/s bidirectional OFDM-signal transmissions on the same wavelength over a 20-km SMF.

21 Gb/s after 100 km OFDM long-reach PON transmission using a cost-effective electro-absorption modulator.

We experimentally demonstrate a superior performance of 2.1-Tb/s·km OFDM signal transmission over 100-km long-reach PONs. While the bandwidth of a 100-km SMF transmission system is limited to 4.3 GHz due to positive chirp, we successfully achieve spectrally-efficient 21-Gb/s signaling by using a cost-effective and low-chirp EAM, and adopting the 128-QAM format and adaptive subcarrier pre-emphasis.