Energy-efficient and temperature-stable high-speed VCSELs for optical interconnects

A “copper” interconnection bottleneck is preventing the continued performance scaling and environmental impact minimization of today´s information technology and cloud service systems most notably by limiting the bandwidth and operating costs of supercomputers and data centers. As conventional electrical interconnects suffer from damping and crosstalk at high frequencies, there are physical limitations to increasing data rates and distances. Even so, system manufacturers continue to develop and employ conventional metal interconnects, postponing the inevitable transition to more energy and cost efficient optical interconnects. The general deployment rate of optical links is expected to follow the most recent progress in the development of suitable, reliable, and commercially available light sources. Vertical-cavity surface-emitting lasers (VCSELs) are ideally suited to solve the copper bottleneck dilemma. We review our work on high speed VCSELs that are well suited for optical interconnects with record high bit rates, low energy consumption, and high temperature operation. We also review our ground breaking work with the University of Illinois on metal-clad surface emitting lasers with a footprint that is about one order of magnitude smaller than a conventional VCSEL.