Impact of crosstalk in an arrayed-waveguide router on an optical add-drop multiplexer

The impact of crosstalk in an arrayed-waveguide (AWG) router on the performance of an N-channel optical add-drop multiplexer (OADM), with m add/drop channels and n-pass channels is theoretically investigated. A single arrayed-waveguide router is simultaneously used for multiplexing and demultiplexing. This results in crosstalk not only from the incoming channels, but from the outgoing channels as well. We show that the performance of the OADM degrades as either N or m are increased, suggesting that the number of channels in a network based on OADM's is limited by crosstalk in the AWG router. When an optical filter is added at the output of the OADM the digital signal-to-noise ratio Q is independent of N and m, and within a few tenths of a decibel of the perfect filtering case.