High-diffraction-efficiency holographic gratings in C60-doped nematics.

Holographic gratings were recorded in C60-doped nematic liquid crystals (NLCs) by two-beam coupling. The asymmetric energy transfer dependence on the polarity of the applied voltage and multiple diffractions in two-beam coupling indicated that the gratings were photorefractive and worked in the Raman-Nath regime. The diffraction efficiencies (DEs) of the main diffraction orders were investigated at different applied voltages. The diffractive intensity distribution was asymmetric, and a first-order DE as high as 66% (as high as 84% excluding the influence of the scattering) was obtained from the 20 microm thick C60-doped NLC film.