Effects of applied electric field on orientational photorefraction in porphyrin:Zn-doped nematic liquid crystals

摘要

We observed an orientational photorefractive effect in porphyrin:Zn-doped nematic liquid crystals by measuring two beam coupling gain and diffraction efficiency under the influence of applied electric field. The gain and diffraction efficiency curves against applied electric field typically reveal resonant type curves, rapidly increasing to its maximum values and then gradually decreasing, but have clearly distinct peak positions. Based on the material equations and the torque balance equation of director axis reorientation of liquid crystals, we theoretically derived the expressions for the orientational photorefractive gain and diffraction efficiency, showing good agreement with the experimental results.