Electro optic properties of switchable gratings made of polymer and nematic liquid crystal slices

We report the diffraction properties at wavelengths of 632.8 and 1550 nm for volume transmission gratings made of a sequence of continuously aligned nematic liquid-crystal layers separated by isotropic polymer slices. The gratings are generated by holographically curing a solution of liquid crystal diluted in an isotropic prepolymer by means of a laser beam at a wavelength of 352 nm with a total intensity of approximately 10 mW/cm(2). A diffraction efficiency of 98% was measured, and an electric field as low as 5 V/mum switches off the phase grating. Measured angular spectra are fitted by use of the modified coupled-mode theory including the effects of grating birefringence. (C) 2004 Optical Society of America.