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 (~10 mJ/cm2). The dye is also characterized by fast relaxation of isomers, allowing for restoration of the diffractive properties of the grating within ~100 ms. Change of the diffraction efficiency of the zeroth-order beam from 10% to 70% is observed in a micrometer-thick material layer.