Demonstration of Spectral Defragmentation in Flexible Bandwidth Optical Networking by FWM

Flexible bandwidth elastic optical networking is an attractive solution for efficiently matching allocated bandwidth with link demand, but suffers from inevitable spectral fragmentation. In this letter, we discuss spectral defragmentation in flexible bandwidth networks using four-wave mixing (FWM) and wavelength selective switch (WSS)-based wavelength conversion blocks. Simulations show a defragmentation degree of one (i.e., the number of defragmentation blocks equals one) results in 71% and 47% reductions in blocking probability under high offered load (680 Erlangs) and low offered load (220 Erlangs), respectively. Further reductions in blocking probability result from an increased defragmentation degree. Experimental results show spectral defragmentation over 500 GHz of bandwidth for a defragmentation degree of one, validating FWM- and WSS-based spectral defragmentation in flexible bandwidth networks.