Liquid crystal metasurfaces for versatile electrically tunable diffraction

Liquid crystal (LC) metasurfaces self-assemble on polymer alignment layers patterned by focused ion beam inducing micrometre and submicrometre scale modulations of LC director imparting specific wavefront profiles to the transmitted light required for versatile optical functionalities. We report on the design, optimisation, fabrication and characterisation of LC metasurfaces performing as Dammann gratings distributing light uniformly in many diffraction channels. Comparing them with the previously reported diffracting and beam-steering LC metasurfaces, we demonstrate how the same approach can be applied to create photonic devices with qualitatively different diffraction properties switchable between diffracting and transparent states by low voltage within several milliseconds. Analysing the achievements, we elucidate the future potential of the LC metasurface concept and discuss particular application prospects.