We develop a new approach for creating photonic metasurfaces based on nematic liquid crystal material. The periodical modulation of the LC director field is imposed by nanoscale change of the alignment properties of polyimide thin layer by means of focused ion beam treatment. The resulted spatially periodic modulation with a period determined by that of the pattern at the substrate provides distinct photonic properties of LC layer. A part of transmitted light is redistributed into a few first diffraction orders. The diffraction is switchable by electric field with millisecond switching times.