Optical to microwave frequency conversion with Rydberg excitons

A novel, copper-based plasmonic system is presented to provide optical to microwave photon conversion. The process uses highly excited levels in Cu2O Rydberg excitons and takes advantage of spoof plasmons, which allow for significant enhancement of the transition probability between specific excitonic energy levels. The theoretical results are verified with numerical simulations. The proposed system is very flexible, allowing for emission of microwaves wavelength from 0.1 mm to 10 mm.