Challenges and opportunities for integrated optics in computing systems

Abstract

The confluence of highly integrated computation chips, huge off-chip interconnectivity requirements, increasingly high channel speeds, and the large spatially extended systems being considered for future high end servers, together with the looming issues of thermal and power management offer an opportunity for optical interconnects to become the preferred solution for many interconnect domains. Optical interconnects are already the technology of choice for the longer length links required in computing systems (10's of meters). However, to achieve this status for link distances at the backplane and card level will require increasingly integrated optical interconnect solutions, which presents many challenges as well as opportunities. The primary inhibitor to adoption of optical interconnects in this ultra-short distance regime is poor cost competitiveness with electrical links. The cost reductions possible with evolutionary enhancement of today's parallel optical modules will not be enough. Potential technologies which could break this cost barrier include the use of waveguides on card to eliminate the optical "module," and chip integrated photonics plus electronics. This paper will discuss the issues and challenges for optics in this short distance regime and present some of the technical solutions that we are pursuing.