Impact of Transmission Impairments on Demultiplexed Channels in WDMPONs Employing AWG-Based Remote Nodes

This paper deals with the performance evaluation of a passive optical network (PON) using wavelength division multiplexing (WDM) by employing an arrayed-waveguide grating (AWG) in the remote node (RN). In such WDM-based PONs (WDMPONs) the RN demultiplexes the downstream WDM signal via distinct output ports through a static wavelength-routing mechanism. An analytical model is developed for evaluating the bit error rate (BER) performance of the demultiplexed channels as a function of the output port location in the AWG by incorporating a novel spectral-to-spatial domain transformation technique. The proposed model captures the impact of finite laser linewidth as well as the AWG characteristics in determining the received signal power at the individual optical network unit (ONU) attached to the output port (due to spectral-to-spatial mapping). Furthermore, the BER model accounts for several transmission impairments, including beat noise due to interchannel crosstalk in the AWG. Results indicate that the signal power captured by the output ports of AWGs and hence their BER values are not only determined by the Gaussian focal-field pattern of the AWG but also by the power spillover from adjacent ports for broader linewidths and higher data rates. A significant interplay is observed between data rate, source linewidth, and relevant device parameters while examining the loss and BER characteristics of a given AWG-based WDMPON.