Fig. 1. (a) Demonstration of tunable metalens focusing the light of wavelengths of 488 nm, 532 nm and 633 nm by varying voltages to V1, V2 and V3, respectively. (b) Underlying mechanism of the step zoom metalens for different focal points at a wavelength of 633 nm. (c) Perspective view of the designed meta-atom with parameters (P = 350 nm) height (H = 500 nm), length (L = 250 nm) width (W = 65 nm) that works in the visible range (d) single tunable metasurface displaying hologram at two different wavelengths by merely varying voltages.
