Impairment analysis of WDM-PON based on low-cost tunable lasers

WDM-PON is considered for next-generation broadband backhaul and radio access networking. Among different implementation choices, we propose to utilize low-cost tunable lasers at the remote sites, together with a centralized wavelength locker. Practical implementations require a transparently added downstream signaling channel and upstream per-channel pilot tones for channel tagging and remote wavelength control. Together with some unavoidable crosstalk effects during tuning, all of these system-related items lead to impairments. To keep penalties below 1 dB, the modulation index of the signaling channel must be kept below 15%. Similar values result for the upstream pilot tones. In order to limit crosstalk, such systems require reduced launch power during wavelength tuning and can cover up to 40 km differential reach. These results confirm that WDM-PON based on low-cost lasers is a technically viable approach.