Free-space optical interconnections for VLSI systems: a technology roadmap

The purpose of this paper is to present a roadmap that details a possible evolution of optoelectronic-VLSI technology as silicon feature sizes shrink, and the dimensions of GaAs/AlGaAs MQW diodes are reduced. The progress of silicon CMOS technology is expected to follow the projections of the Semiconductor Industry Association (SIA) roadmap. The anticipated technology parameters for succeeding generations of hybrid CMOS-MQW systems are detailed. These optoelectronic technology parameters represent a conservative estimate as to the evolution of the photonic technology based on our current understanding of device fabrication and system issues. With these assumptions on the availability of sufficient laser power to drive the optoelectronic devices, the optical system loss, and ability to dissipate the power consumed on-chip, we project limits on the maximum number of optical inputs and outputs (I/O) and the electrical circuit complexity per optical I/O for current and future generations of OE-VLSI chips.