Abstract

We discuss the characterization and numerical simulation of vertical Ge-on-Si waveguide photodetectors (VPIN WPDs) of the Cisco platform for data communications in the O-band ( $1.31 \,\mu \mathrm{m}$ ), with the goal of optimizing their frequency response while integrating them into low-power systems. In a large set of WPDs belonging to 6 different structural variants, at a standard bias voltage of $-2 \,\mathrm{V}$ the best specimens exhibit an intrinsic electro-optic bandwidth of more than $40 \,\mathrm{G}\mathrm{Hz}$ , which is reduced to about $10 \,\mathrm{G}\mathrm{Hz}$ at zero bias. A comprehensive 3D multiphysics model, validated through the characterization campaign, provides design guidelines towards intrinsic bandwidths not only wider than $60 \,\mathrm{G}\mathrm{Hz}$ at $-2 \,\mathrm{V}$ , directly suitable for application in 200 Gbit/s systems, but also wider than $40 \,\mathrm{G}\mathrm{Hz}$ at zero bias, not including the possible recourse to extrinsic parameter engineering.