Tunable beam deflector by mutual motion of cascaded bilayer metasurfaces

Tunable metasurface devices are highly desired within the development of metasurfaces, which have superior capabilities for tailoring the wavefront of light. Inspired by the diffractive Alvarez lens and Moiré lens, we find that cascaded bilayer metasurfaces can not only realize active lenses, but also other tunable functional devices. To demonstrate, two kinds of deflectors tuned by lateral and rotational mutual motions of the double metasurface layers are designed and verified by simulations. The presented method is anticipated to realize compact tunable metasurface devices in optical communication, measurement, bio-imaging and display.