Beam Steering Efficiency in Resonant Reflective Metasurfaces
Goran Isić, Dimitrios C. Zografopoulos, Danka B. Stojanović, Borislav Vasić, Milivoj R. Belić
Abstract
Beam steering is one of the prevailing functions performed by electromagnetic metasurfaces. Its efficiency depends on a large number of physical parameters associated with resonant elements comprising the metasurface and is thus notoriously difficult to optimize. Here we formulate a theoretical model for evaluating the diffraction efficiency of an array of lossy resonant elements whose spectral response is dominated by the coupling between a leaky eigenmode and a single incoming/outgoing channel. We use it to deduce a formula for the maximum attainable diffraction efficiency and the gradient parameter profile for which it is achieved. The optimization procedure is demonstrated on the example of an electrically tunable liquid-crystal terahertz beam steering metasurface. Finally, the proposed model is benchmarked against rigorous metasurface simulations.