Behavior of Director Orientation near Interface of Nematic Liquid-Crystal Cell Evaluated Using Shear Horizontal Wave Propagation

Abstract

The nematic liquid-crystal director orientation in the vicinity of a glass plate is investigated in relation to the acoustic phase delay change of a shear horizontal (SH) wave propagating in a cell structure. The relationships between the phase delay change and the electric field applied to the liquid-crystal layer are given for various layer thicknesses of the liquid-crystal layer, comparing with the penetration depth of the mechanical displacement. The phase-velocity change of the SH wave observed upon applying an electric field is related to the change of the liquid-crystal director angle near the interface with the glass plate, which is independent of the thickness of the liquid-crystal layer. The decay time of the director reorientation under application and removal of applied voltage is nearly independent of the applied electric field and the thickness of the liquid-crystal layer. The present method using an SH wave propagating in the liquid-crystal cell is favorable for estimating the liquid-crystal director orientation in the region very near the substrate glass.