Figure 3. Electromechanical modulation from ultraviolet to near-infra red regions.

Measured reflection spectra (left column) of the graphene/hBN/nanoarray for (a) s-polarized light (R_s) in the ultraviolet/blue range and (b) p-polarized light (R_p) in the visible. (c,d) Ellipsometric reflection in the near-infrared. All spectra were measured with θ=70°. Modelling results (right column) reveal that the electrically induced reflection modulation is explained by a changing air gap. The sharp reflection minima in (a) (centred at λ=275 nm) stems from the complex ultraviolet absorption spectrum of hBN. The features in (b–d) correspond to the fourth-, third- and second-order Rayleigh cutoff wavelengths of the nanoarray, respectively.