New controllable optical switching by the frequency modulation method in nematic liquid crystals

A new type of sensitive electro-optic effect in a nematic liquid-crystal (4-cyano-4′-5-alkyl-bipheneyl) cell with polymer thin films is reported. Optical switching in a transmitted intensity of light passing through a cell is experimentally observed by dual low-frequency modulation method using a triangular wave application. Dielectric relaxation effects in the thin polymer layer as part of the cell serve to reduce the effective voltage acting on the liquid-crystal layer for lower frequencies but not for higher frequencies. The mean effective applied voltage to a liquid-crystal layer is efficiently controlled by changing only the frequency.