Implementation and testing of a ASK polarization-independent coherent receiver for UDWDM-PON

This paper presents the implementations and test results of the novel polarization-independent receiver for ASK format, realized in the framework of COCONUT FP7 Project. COCONUT exploits low-cost optical components and simple electronics, so that the cost of typical line terminals would be affordable to the end-users. Among the different technical approaches considered within the project; we focus here on the solutions based on simple OOK-NRZ format. We developed an original improvement of the conventional phase-diversity coherent detection schemes, providing for polarization independent operations without doubling the receiver structure. As a result we demonstrated that polarization-independent coherent detection is feasible within the constraint of limited cost typical of passive access networks. The developed receivers can allow for high-power budget (> 45 dB and ultra-dense WDM operation (6.25 GHz grid).