Fig. 2. Optical absorption enhancement in BSTS achiral metamaterial.

(A) Measured (dashed lines) and simulated (continuous lines) optical absorption of an unstructured BSTS flake and a nanostructured BSTS metamaterial (experimental data were collected with unpolarized light at normal incidence and numerical aperture = 0.7, while simulations correspond to circularly polarized light incident at θ = 0° and θ = 45°); at λ = 532 nm, the absorption of the BSTS metamaterial is ~0.7, twice that of the unstructured BSTS flake (~0.35). (B and C) Maps of the electric field intensity, |E|², at 10 nm below the top surface of the metamaterial unit cell at normal incidence, for left (LCP) and right (RCP) circular polarization, respectively.