Evaluation of Add/Drop Flexibility Requirements in Future SDM-Enabled ROADMs

In this paper, we evaluate five different architectures for implementing the Add/Drop module of future Spatial Division Multiplexing (SDM)-enabled Re-configurable Optical Add & Drop Multiplexers (ROADMs) with different degrees of flexibility, from a completely static transponder to spatial channel assignment to a fully-flexible transceiver to fibre and spatial channel assignment. The performance of the proposed architectures is compared in a single SDM-enabled ROADM scenario, where local as well as bypass traffic is injected, supported by spectral super-channels at diverse bit-rates and employing different modulation formats. The obtained results illustrate the additional benefits attainable by more flexible Add/Drop architectures versus their increased hardware complexity.