Analyzing the polarization response of a chiral metasurface stack by semi-analytic modeling.

We investigate a class of stacked metasurfaces where the interaction between layers is dominated by their respective far-field response. Using a semi-analytic scattering matrix approach, we exploit the Fabry-Perot-type response for different layer distances to show the spectral tunability of the resonant effect. This method presents a faster and more intuitive route to modeling Fabry-Perot-type effects than rigorous numerical simulations. The results are illustrated for a chiral metasurface stack that exhibits asymmetric transmission. Here, the effect of asymmetric transmission is highly sensitive to the layer distance, which is used as a free parameter in our model. To prove our theoretical findings we fabricate two variants of the stack with different layer distances and show that far-field interaction between layers is sufficient to generate the effect while being accessible by semi-analytic modeling. The analyticity of the approach is promising for designing sophisticated layered media containing stacks of arbitrary metasurfaces.