Challenges for the introduction of board-level optical interconnect technology into product development roadmaps

Abstract

Optical interconnects have gradually replaced electrical interconnects in the long-distance telecom, local-area, and rack-to-rack link classes. We believe that this transition will also happen in the card-backplane-card datacom link class, both for bandwidth*length reasons and for density reasons. In analogy to the transition from individually wired boards to integrated printed circuit boards, we believe that eventually board-level optical interconnects will be based on an integrated technology such as board-embedded waveguides. In order to bring optical waveguide technology into mainstream product development plans, however, numerous challenges on many levels have to be met. Problems to be tackled span from the base level of materials (stability, processability) and devices (reliability, lifetime), over the subsystem level of packages (concepts, cost-efficient assembly and alignment) all the way up to the system level (link architecture, system packaging, heat management). A sustainable solution can only be reached if the development of all individual technology components is done with the whole system in mind. Important figures of merit are the cost per gigabit per second, the power per gigabit per second, and the maturity/reliability of the technology. We will give an overview of our optical interconnect activity, with respect to these challenges. We will discuss the options, explain our technology decisions and present some results of our multi-disciplinary activity.