Demonstration of Dispersion-Enhanced Phase Noise in RGI CO-OFDM Systems

We report the first experimental demonstration of dispersion-enhanced phase noise (DEPN) in reduced-guard-interval (RGI) coherent optical orthogonal frequency-division multiplexing (CO-OFDM) systems. It is first shown that channel estimation enhances DEPN. Then we experimentally demonstrate that for 28 Gbaud dual-polarization QPSK (112 Gb/s) RGI CO-OFDM systems with different inverse fast Fourier transform sizes, the transmission distance at a bit error rate = 3.8×10
^-3
is limited to 1830-2550 km by DEPN when a distributed feedback laser with a 2.6-MHz linewidth is employed as the local oscillator. We also, however, show that using DEPN compensation can increase the distance to 3320-4400 km.