Formation of photonic liquid crystal metasurfaces on rubbed polyimide substrates patterned by focused ion beam is demonstrated. Modulation of the surface anchoring conditions with periods from 1 to 6 micrometers gives rise to periodic deformation of the nematic liquid crystal director field. The exact periodicity is confirmed by the light diffraction measurements. Distinct colors originating from the specific zero-order diffraction spectra are observed and qualitatively explained in terms of an analytical model within the one-constant approximation. Quantitatively accurate optical spectra are obtained by the full scale numerical simulations taking into account all relevant material parameters. The results pave the way for hybrid liquid-crystal-based metasurfaces with tunable optical transmission, diffraction, and lasing.

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Optical liquid-crystal metasurfaces self-assemble on polymer layers locally processed with a digitally controlled focused ion beam. We expand their functionality by introducing superperiodic design consisting of parallel stripes of various widths inducing different liquid crystal alignment. We optimize the design to achieve strongly asymmetric light diffraction effectively resulting in efficient anomalous refraction. By implementing the optimal patterns of different periodicity, assembling a liquid crystal cell, and assessing its diffractive properties, we experimentally confirm the deflection of normally incident light into a particular oblique direction with 60% efficiency. Applying AC voltage of several volts amplitude across the liquid crystal reversibly straightens its orientation, suppresses the refraction, and reroutes light into the direct transmission. Time-resolved measurements reveal that the switching between refracting and transmitting states occurs within a few milliseconds in both directions.