Active tuning of angular asymmetric thermal emission via carrier injection in metal-insulator-metal resonance gratings

Abstract

We present a method to break the angular symmetry of infrared thermal emission using dynamic electrical control. An electrically tunable GaAs grating is designed to exhibit narrowband angular emission in the longwave infrared. The grating has GaAs stripes sandwiched between the top metallic contacts and the bottom reflector layer. The application of voltage across the GaAs allows for the change of the refractive index. Tuning one of the dielectric stripes within each unit cell enables symmetry-breaking index perturbation. The perturbed structure exhibits angular asymmetric thermal emission. We analyze our findings based on coupling coefficients and variational principle. Due to the reversible nature of the perturbation, this concept presents a route toward tunable asymmetric emission and directional ‘steering’ of thermal emission.