Comparison of bandwidth limits for on-card electrical and optical interconnects for 100 Gb/s and beyond

Aggregate chip bandwidths in server and high performance computing have exceeding Tb/s, and if present trends are to continue would lead to doubling the number of signal pins in each generation. For high bandwidth switch and server applications, bandwidth requirements could exceed the package pin limit as early as 2012. We defined metrics to compare the performance of electrical and optical interconnects, which includes bandwidth density (Gb/s/mm2/port), media bandwidthdistance product (GHzm), power consumption (mW/Gb/s/Port), and technology comparison metric (Gb/s/mm2/port* GHz*m/mW/Port). We will show that optical interconnects offer a performance metric improvement factor of greater than 25 over electrical interconnects.