Optical switching of liquid-crystal polarization gratings with nanosecond pulses

Optical switching with single nanosecond laser pulses of 532 nm wavelength is reported using high-efficiency optical axis gratings made with a nematic liquid crystal doped with an azobenzene dye. The azobenzene dye we have synthesized exhibits enhanced photosensitivity at green wavelengths, allowing for low threshold switching (approximately 10 mJ/cm(2)). The dye is also characterized by fast relaxation of isomers, allowing for restoration of the diffractive properties of the grating within approximately 100 ms. Change of the diffraction efficiency of the zeroth-order beam from 10% to 70% is observed in a micrometer-thick material layer.