Flexible metro network architecture based on wavelength blockers and coherent transmission

A flexible semi-filterless architecture for metro DWDM networks with ring- or horseshoe topologies is presented. ROADM nodes are based on wavelength blockers. Coherent transmission enables filterless channel selection. Critical parameters are determined and a 4-span, 160-km horseshoe with 100Gbit/s DP-QPSK and 200Gbit/s DP-16QAM is demonstrated.