The method presented in this paper outlines a kind of free-space optical network that is achieved using a mixture of regular- optical interconnected links and dynamic- electrical switching control elements. Free-space optics can provide a large number of regular connections, which we explore with an electrical switching element. Recent work on optical connections provides design techniques for using regular free-space interconnects within processing nodes and between node's of the hypercube computer. This electro- optical adaptive switching network takes advantage of the best features of two technologies by using optics for hologram interconnections and electronics for controlling space-invariant interconnections. Therefore, a device whose reflectance may be varied spatially and temporally like a spatial light modulator (SLM) is not needed to dynamically perform a large number of interconnections. This is because of the small electrical switching element associated with each optical link. Here, available optical paths need not be specified by a source node and communicated to a SLM for path setup. Instead the message routing header can be modified in response to congestion as an optical path is established. This architecture takes advantage of the best features of both technologies as they currently exist. Future devices, aimed at reducing the optics- to- electronics conversion penalty, will make such architectures attractive.
"Electro-Optical Adaptive Switching Network For The Hypercube Computer", Proc. SPIE 0880, High Speed Computing, (20 April 1988); doi: 10.1117/12.944031; https://doi.org/10.1117/12.944031