Graphene Modulators and Switches Integrated on Silicon and Silicon Nitride Waveguide

The optoelectronic properties of graphene attracted a lot of interest in recent years. Several demonstrations of integrated graphene based modulators, switches, detectors, and nonlinear devices have been reported. We present here a comprehensive study investigating the different design tradeoffs involved in realizing, in particular, graphene-based modulators and switches. We compare four representative hybrid graphene-waveguide configurations, focusing on optimizing their dimensions, the gate-oxide thickness, the polarization, the operating wavelength, and contact definition. We study both static and dynamic behavior, defining a relevant figure of merit. We find that a 20-μm device based on silicon waveguides should allow for 25-GBit/s modulation rate and an extinction ratio of 5 dB. A 200-μm long SiN device on the other hand should allow for 23-dB extinction ratio and switching speeds down to 0.4 ns.