Practical packaging constraints and infra-computer optical interconnections

Abstract

Optical links were compared to electrical transmission lines for interconnections within computers. Current optoelectronic technology does not seem to be competitive with existing electrical solutions for distances under one meter-a distance comprising the bulk of uniprocessor and tightly coupled multi-processor interconnections. However, there is growing interest in loosely coupled, parallel processing environments which require high-capacity data links over tens to hundreds of meters. In these types of applications, propagation delay and latency are usually not key issues. Moreover, the low dispersion, low attenuation, and high bandwidth offered by fibers become critical at these distances, and are already forcing the choice of optics for data transmission rates in excess of 100 Mb/s. Advances in technology in this arena will, in turn, prompt a reassessment of the performance comparison between electrical and optical interconnects in the future.