Maximizing capacity,flexibility and efficiency in G-PON networks using VCSEL-based OOK and 2/4-PAM formats

This work experimentally demonstrates the potential of multi-level pulse amplitude modulation with direct detection to maximize carrier spectral efficiency and double the Gigabit passive optical networks (G-PON) network data rate. Three scenarios have experimentally been exploited. First, a 1310?nm vertical surface-emitting laser (VCSEL) has directly been modulated with a 10?Gbps OOK data. A receiver sensitivity of ?19.11?dBm is attained, and a successful error free transmission over 22?km SMF fibre achieved, with a transmission penalty of 0.46?dB. To maximize carrier spectral efficiency, 2/4 PAM modulation formats are adopted respectively. A receiver sensitivity of ?14.64 and ?11.63?dBm is attained for 2-PAM and 4-PAM formats respectively. However, a 3.21?km fibre transmission introduces a penalty of 0.64 and 3.30?dB for 2-PAM and 4-PAM formarts respectively. 2/4-PAM modulation formats significantly increase the aggregated data rate at different ONUs within the G-PON without expensive optics investment, though at the cost of reduced transmission reach due to the high bitrate attained. We further demonstrate the design of a software defined digital signal processing assisted receiver to recover the 2/4 PAM transmitted signal without employing costly receiver hardware.