Speed and energy analysis of digital interconnections: comparison of on-chip, off-chip, and free-space technologies

Abstract

We model and compare on-chip (up to wafer scale) and off-chip(multichip module) high-speed electrical interconnections withfree-space optical interconnections in terms of speed performance andenergy requirements for digital transmission in large-scalesystems. For all technologies the interconnections are firstmodeled and optimized for minimum delay as functions of theinterconnection length for both one-to-one and fan-outconnections. Then energy requirements are derived as functions ofthe interconnection length. Free-space optical interconnectionsthat use multiple-quantum-well modulators or vertical-cavitysurface-emitting lasers as transmitters are shown to offer aspeed-energy product advantage as high as 30 over that of the electrical interconnection technologies.

Generalized methods for algorithm development on optical systems

“…This measure captures both of the wiring cost (electrical and/or optical) and the total I/O ports required for realizing a network. More discussion on the cost of OTIS and its performance modeling can be found in [2,7].…”

“…Recent studies revealed that free-space optical interconnects offer a speed advantage over electrical interconnects [2]. Compared with the fastest off-chip electrical interconnects and for lengths up to few centimeters, optical interconnects provide as much as a twice better speed performance [2].…”

“…Compared with the fastest off-chip electrical interconnects and for lengths up to few centimeters, optical interconnects provide as much as a twice better speed performance [2]. To simplify the analysis, there is no distinction between electronic and optical channels in the subsequent expressions.…”

“…The standard procedure to carry out matrix triangulization is Gaussian elimination (GE). The GE procedure generates a sequence of n × n matrices A (1) , A (2) , . .…”

“…In principle, free-space optical technologies offer several fronts to improve this trade-off. The improved transmission rates, dense interconnects, power consumption, and signal interference are few examples on these fronts [1,2,6,7].…”