Electro-optic symmetry breaking of BIC modes for tunable infrared emissivity

We present an electro-optic pathway to break symmetry to enable dynamic light-matter interaction in guided-mode resonance grating. Breaking of mirror symmetry allows accessing bounds states in the continuum (BIC) that are otherwise inaccessible. We design an electrically tunable GaAs-based guided-mode resonance grating that exhibits infrared absorption peaks in the longwave IR. The grating consists of GaAs dielectric sandwiched between the top gold contacts and the bottom gold reflector. We analyze the dependence of Q-factors on the choice of the design. We show that by careful design of the structure, a substantial radiative coupling can be obtained with broken symmetry. Our simulations predict that due to the electro-optic properties of GaAs, the application of a voltage across the dielectric allows a change in the refractive index to break the symmetry of the structure and turns the emission peak ON. Reversible refractive index tuning restores symmetry and turns the emission OFF. The concept presents a novel route toward tunable directional absorption and emission.