Construction of a matrix-matrix crossbar optical interconnect employing diffractive fan-out and fan-in elements

An optical cross-bar interconnect incorporating diffractive/holographic optics and capable of providing high-bandwidth fully non-blocking links between 64 independent electronic processors is the goal of the authors project: 'Optically Connected Parallel Machines'. To test a number of new concepts a prototype 16*16 interconnect has been assembled as a first step. The optical arrangement of the prototype 16*16 crossbar interconnect that has been constructed is shown in figure 2. The input channels correspond to single-mode fibres configured as a two-dimensional array, while, to ensure efficient fan-in of multiple incoherent light beams, the output fibres, which are again configured as a square array, are multimode. A polarising beam splitter is used to separate the signals returning from the reflective SLM and direct them towards the output. The optical elements used to implement the required fan-out and fan-in functions, are discussed.