Electro-optic switches based on space switching of multiplexed WDM signals: Blocking vs non-blocking design trade-offs.

Short distance optical interconnects are a promising solution for tackling the bandwidth and low energy consumption requirements of next generation Data Centers (DC) and High Performance Computing (HPC) systems. The realization of optical switching should offer scalability, allowing the interconnection of multiple racks and/or servers/compute nodes, and quick reconfiguration times. To this end, fast small-radix MicroRing Resonator (MRR)- and Mach-Zehnder Interferometer (MZI)-based space switching devices, capable of supporting multiple optical signals multiplexed through Wavelength Division Multiplexing (WDM) have been reported. Using such devices as building blocks we evaluate the performance of a number of simple electro-optic switch architectures based on successive wavelength selection, WDM multiplexing and space switching, attempting to achieve scalable switching fabrics with good throughput performance on average using little additional hardware and few switching stages, thus lower total insertion losses as well as lower power consumption. The price paid for such architectural simplicity is that it introduces additional constraints on the feasible permutation matrices of such switching fabrics, affecting performance for some traffic patterns. We discuss the trade-offs between performance and hardware requirements and based, on our findings, we propose alternative architectures that overcome these limitations.