ONU power equalization of ethernet PON systems

Power differences among optical network unit (ONU) channels received at an optical line terminal (OLT) of ethernet passive optical network systems are minimized to increase burst-mode receiver performance and acquire reliable ONU operation. The OLT measures each ONU power and sends control messages back to ONUs during registration stage. The ONU is designed to change its modulation depth using received control bits. A digital automatic power control circuit is used at the ONU site to help this process. Proposed schemes are implemented and test results are provided.