Low Latency Asynchronous Optical Bus for Distributed Multiprocessor Systems

: We present an investigation on how to reduce the internode communication latency in distributed multiprocessor systems. The strategy consists of replacing the "store and forward" mechanism that is usually carried out on each electronic node by a free diffusion of optical packets along an optical bus. No routing, no extraction of optical packets and no access arbitration into the bus are needed. Intermediate nodes between two processors engaged in a communication are optically transparent. These specifications considerably simplify the optoelectronic interface of the node and reduce the latency of communication. In the asynchronous operation mode that we consider, each node multiplexer inserts on the fly optical packets into the bus. The optical demultiplexer identifies the packet destination address before transmitting the data to the node electronics. The key point is to make the intranode latency shorter than the internode propagation time to attain a network latency close to ulti..