SPEED AND ENERGY ANALYSIS OF DIGITAL INTERCONNECTIONS - COMPARISON OFON-CHIP, OFF-CHIP, AND FREE-SPACE TECHNOLOGIES

We model and compare on-chip (up to wafer scale) and off-chip (multich ip module) high-speed electrical interconnections with free-space opti cal interconnections in terms of speed performance and energy requirem ents for digital transmission in large-scale systems. For all technolo gies the interconnections are first modeled and optimized for minimum delay as functions of the interconnection length for both one-to-one a nd fan-out connections. Then energy requirements are derived as functi ons of the interconnection length. Free-space optical interconnections that use multiple-quantum-well modulators or vertical-cavity surface- emitting lasers as transmitters are shown to offer a speed-energy prod uct advantage as high as 30 over that of the electrical interconnectio n technologies. (C) 1998 Optical Society of America.