Dependence of the transmission performance of multi-band OFDM-UWB signals in LR-PONs on the modulator bias and driving voltages

The influence of the Mach-Zehnder bias and driving voltages on the performance of the simultaneous distribution of nine orthogonal frequency division multiplexing (OFDM) ultra wideband (UWB) sub-bands in dispersion compensated long-reach passive optical networks (LR-PONs) is assessed experimentally. Particularly, the performance of the double sideband (DSB) OFDM-UWB signal is evaluated for systems employing the modulator biased at the conventional quadrature bias point and at the quasi-minimum transmission point for different standard single mode fiber lengths between the optical line termination and the optical network unit. It is shown that improved performance on the different transmitted DSB OFDM-UWB sub-bands is obtained when the modulator is biased at the quasi-minimum transmission point rather than at the quadrature due to the higher electro-optic conversion efficiency of the modulator. In addition, it is also shown that the OFDM-UWB radio signal presents a significant tolerance to the residual dispersion as low transmission degradation is obtained for LR-PONs comprising a residual dispersion deviation from the full compensation case between -325 ps/nm and 270 ps/nm.