Direct Optical Modulation of RF Radiation Patterns in a Loaded Dielectric Resonator

Here we demonstrate the direct optical modulation of RF radiation patterns in a high permittivity (ϵ ∼ 80) cylindrical dielectric resonator antenna (DRA) loaded with a silicon superstrate. A hybrid mode (HEM
_11δ
) is excited via microstrip. The far-field radiation pattern is characterized with an angle-dependent RF radiation measurement setup, and the near-field is measured using an optically induced conductance technique. We show that when light is incident upon the superstrate, the optically generated electron-hole-pairs (EHPs) in the silicon superstrate modulate and inhibit the far-field RF radiation. We compare our experimental results with finite element method simulations and show excellent agreement. Finally, we perform a proof of principle experiment to mix optically modulated signals with the baseband RF far-field radiation, paving the pathway for future free space optical/RF hybrid communications setups and modulation schemes as well as phase circuitry-free RF beam shaping and steering.