Switchable diffraction gratings based on inversion of the dielectric anisotropy in nematic liquid crystals

A switchable liquid crystal diffraction grating, responsive to both the frequency and magnitude of an applied voltage, is demonstrated. The grating is based on polymer stabilization of modulated states of the liquid crystal optic axis induced at frequencies near a sign inversion of the dielectric anisotropy. In a particular case of frequency-based switching, 70% of the transmitted intensity of a 633 nm laser beam can be shifted into or out of a ± 12° forward arc by changing the frequency of an applied voltage between 10 and 16 kHz at a fixed amplitude of 27 V.