Fig. 1. (a) Schematic of the designed metasurface acting as a reconfigurable 1D FZP with varying focal positions in both longitudinal and lateral dimensions and its unit cell. Characterization of the GMR in the designed metasurface. (b) Transmission spectrum under x-polarized normal incidence. Distribution of the real part of electric field E_z in the (c) x–z plane (y = 0 nm) and (d) y–z plane [x = 100 nm, marked by the black dashed line in (c)] at the resonant wavelength λ₀.

Fig. 2. Electro-optical modulation of the resonance of the designed metasurface. (a) Simulated distribution of the normalized electrostatic field induced by applying a DC voltage of 1 V. (b) The variation of the transmission spectrum as the applied DC voltage changes. The variation of (c) the resonant wavelength and (d) the transmittance at 829.10 nm (resonant wavelength under an external voltage of −6 V) as a function of the applied voltage. The red line in (c) is a linear fit to the simulated data (blue dots). (e) Simulated distribution of the electrostatic field under periodically applied voltage.

Fig. 3. The implementation of longitudinal reconfigurable light focusing. (a) Simulated intensity distributions of transmitted light in the y–z plane (x = 0 nm). (b) The designed and simulated focal lengths for different spatial distributions of applied voltages. The designed and simulated (c) FWHMs and (d) efficiencies of the five focal lines with different focal lengths.

Fig. 4. The implementation of lateral reconfigurable light focusing by adjusting the applied voltages along the y-axis. (a) Simulated intensity distributions of transmitted light in the y–z plane (x = 0 nm). (b) The designed and simulated lateral displacements of the focal lines with a longitudinal focal length of 3 mm for different spatial distributions of applied voltages. The designed and simulated (c) FWHMs and (d) efficiencies of the five focal lines with different lateral displacements.