Towards 200 Gbit/s low-bias-operation vertical Ge-on-Si waveguide photodetectors

Abstract

We discuss the characterization and numerical simulation of vertical Ge-on-Si waveguide photodetectors (WPDs) of the Cisco platform for data communications in the O-band (1.31 μm), with the goal of optimizing their frequency response while integrating them into low-power systems. The photodetectors under test have an electro-optic bandwidth of more than 40 GHz at a standard bias voltage of -2 V. Bandwidths larger than 10 GHz are observed even at zero bias, suggesting that vertical WPDs can be exploited in optical communication systems with minimal power consumption. In fact, the characterization campaign has allowed the validation of a complex multiphysics model that is providing design guidelines towards bandwidths not only wider than 60 GHz at -2 V, suitable for application in 200 Gbit/s systems, but also wider than 40 GHz at zero bias.