Optical free-space interconnection network for parallel computers

The authors present an architecture for a crossbar-like, free-space interconnection network. The design follows principles and guidelines derived from an architectural study of massively parallel computers. The design has reconfigurability. Each processor can change its connections dynamically, independently of the connections made by other processors. Scalability is up to a very large number of processors (more than 10,000). Distributed operation means that no central controller is used to coordinate the network's interconnection pattern. Prudent use of the 3-D space. The design meets these goals by using a two level communication scheme formed by a local interconnection network on a single board that connects a set of processors by a fast switching crossbar. The number of processors connected is relatively small (up to 100), which enables the fast switching time (as low as nanoseconds). A global interconnection network between the boards is based on a routing switch associated with each processor. The switch is implemented by a dynamic hologram. A static hologram on each board is used to deflect the light beams towards the destination processors.