Self-contained autonomous transmitter-power control of ONUs for energy and dynamic-range reduction in PONs

In passive optical networks (PONs), optical network units (ONUs) account for most of the power consumption, leading to a large carbon footprint. Here, we demonstrate 10G-ONUs equipped with a self-contained, autonomous transmitter-power-control algorithm that relies solely on the received optical power (ROP) without requiring communication with the optical line terminal (OLT). Our experiments and simulations show that the algorithm reduces ONU power consumption in PONs, adjusts the ONU-transmitter power in response to variations in optical path loss, and levels the OLT ROP. We also examine the feasibility of the algorithm for ONUs with different slope efficiencies and fiber lengths and show that, by tuning the conversion factor that translates the ONU ROP into ONU-transmitter power, the wavelength-dependent losses in downstream/upstream propagation can be mitigated. Such ONUs implemented with the power-control algorithm are promising for power saving in both existing and future PON systems.