Comparison of all-optical co- and counter-propagating high-speed signal processing in SOA-based Mach-Zehnder interferometers

The all-optical signal processing performance of a Mach-Zehnder interferome ter (MZI) is investigated. Calculated switching windows are used to investi gate and understand the physical mechanisms limiting the high speed perform ance. Especially, the co- and counter-propagating operation of the MZI is d iscussed and important differences in the performance for the two schemes a re addressed. The non-regenerative all-optical clear and drop functionality is investigated for a 2, 4 and 8 x 40 Gbit/s signal, showing good performa nce in the co-propagating case. Regenerative simultaneous clear and drop fu nctionality in a single MZI is demonstrated experimentally and compared to the large signal model predictions.