Optical switching through graphene-induced exceptional points

The switching properties of coupled nanophotonic waveguides under the influence of a loss-induced exceptional point are analytically and numerically investigated. The specific requirements for switching/routing functionality are determined, and an analytically predicted lower boundary for the insertion losses is established. These passive Parity-Time-Symmetric dynamics are substantiated in a silicon photonic coupler through the use of graphene layers. Graphene’s chemical potential is properly tuned, in accordance with the exceptional point requirements, for the electro-optic control of its surface conductivity. All analytically derived findings are numerically verified enabling linear, low-loss, and high-extinction-ratio switching elements. Finally, a polarization-dependent photonic switch is proposed based on both exceptional points and graphene’s anisotropic surface conductivity.