The orientational photorefractive effect was observed in the nematic liquid crystals E7 doped with silver nanoparticles. Both the self-diffraction and beam-coupling effects were studied in a two-wave-mixing experiment with an applied external DC field. The dependence of diffraction efficiency on the applied voltage, pump power, pump/signal ratio and grating constant were studied. Experimental results indicate that the optical non-linearity of NLCs can be enhanced significantly by doping silver nanoparticles. Further experiments demonstrate that the holographic grating formed in the sample can be switched on and off by the external DC field. PR two-beam coupling experiment was also performed in the Ag-doped NLCs cell. These results are of benefit to the applications of PR NLCs in holography and image processing.
