Tunable Metasurface and Flat Optical Zoom Lens on a Stretchable Substrate

A mechanically reconfigurable metasurface that can continuously tune the wavefront is demonstrated in the visible frequency range by changing the lattice constant of a complex Au nanorod array fabricated on a stretchable polydimethylsiloxane substrate. It is shown that the anomalous refraction angle of visible light at 632.8 nm interacting with the tunable metasurface can be adjusted from 11.4 degrees to 14.9 degrees by stretching the substrate by similar to 30%. An ultrathin flat 1.7X zoom lens whose focal length can continuously be changed from 150 to 250 mu m is realized, which also demonstrates the potential of utilizing metasurfaces for reconfigurable flat optics.