Active Mid-Infrared Plasmonic Beam Steering Devices

We demonstrate the steering of coherent mid-infrared radiation through plasmonic structures consisting of a single sub-wavelength slit flanked by a periodic array of grooves, fabricated on GaAs substrates. We demonstrate control of steering angle by tuning the incident radiation, and study beam quality for the transmitted light. In addition, we demonstrate that small shifts in the refractive index of the GaAs substrate can actively control the steering angle of the transmitted light, opening a path towards the development of no-moving-parts plasmonic beam steering devices.