ABSTRACT
This chapter clarifies that Vertical-cavity surface-emitting lasers (VCSELs)-based optical interconnects are going to replace the conventional copper-based technology. VCSELs can deliver higher bandwidths below the cost of copper and enable highly scalable solutions with their small footprint. Future supercomputers can only be realized by the broad application of VCSELs. VCSELs are an answer to the question that optical technology could be a workhorse of future interconnects. VCSELs are capable of delivering highest modulation speeds beyond 40 Gbps at high operation temperatures. In order to be applied in short optical interconnects, VCSELs have to deliver high serial bandwidths, with small footprints allowing dense packaging and uncooled operation. Directly modulated VCSELs have bandwidth limitations that have to be conquered to enable highest bandwidths at ultralow cost. In a first-order approximation, for a given directly modulated VCSEL device, the resonance frequency rises with the square root of the VCSEL power.
