1. An optical switching system comprising: a fixed structure high-dimensional interconnect architecture comprising a plurality of fixed and structured optical links, the links arranged in a k-ary n-cube, ring, mesh, torus, direct binary n-cube, indirect binary n-cube, Omega network or hypercube architecture; a plurality of optical switching units communicating over the high-dimensional interconnect architecture; a top of rack (ToR) switch connected to each optical switching unit through wavelength division multiplexing (WDM) transceivers; wherein each optical switching unit is connected to one or more other optical switching units through fixed optical links in the high-dimensional interconnect architecture, and wherein the plurality of optical switching units multiplex the WDM signals transmitted from the ToR switches and broadcast all the transmitted WDM signals to the high-dimensional interconnect architecture, and wherein the plurality of optical switching units receive and select the WDM signals transmitted from other optical switching units connected through the high-dimensional interconnect architecture, and demultiplex the WDM signals for ToR switch receiving via the WDM transceivers; and a plurality of circulators which support bi-directional optical communications between the plurality of optical switching units and the fixed structure high-dimensional interconnect architecture.