Design of tunable silicon metasurfaces with cross-polarization transmittance over 80%

We designed highly efficient, mechanically tunable metasurfaces based on an array of crystalline silicon nanoposts on stretchable substrates. The metasurface can continuously tune the wavefront of light by changing the lattice constant of the silicon nanoposts with a high transmission efficiency at all tuning ranges. Systematic numerical simulations were performed to determine the optimized structural parameters of the nanoposts, in which the cross-polarization transmittance was maximized. Transmission efficiency was maintained at over 80% with a maximum stretch ratio of ∼137% (2.9× flat zoom lens) and at over 75% with a maximum stretch ratio of ∼171% (1.9× flat zoom lens) in the tunable metasurface at λ = 680 nm. The simulation also showed that the tunable metasurface could be optimized at other wavelengths between 580 and 730 nm. We believe that the tunable metasurfaces will be useful for a variety of applications including information technology, biomedical sciences, integrated optics, optical communications, imaging, flat displays, or wearable consumer electronics.