Propagation characteristics of a shear horizontal wave in a liquid-crystal cell having temperature-dependent phase states.

Propagation characteristics of the zeroth-order symmetric (S[sub 0]) mode shear-horizontal (SH) wave in a cell structure containing a thermotropic liquid crystal layer with chiral smectic-C (SmC[sup *]), smectic-A (SmA), chiral nematic (N[sup *]) and isotropic (Iso) phase states, are examined. The SH wave propagation is numerically analyzed with consideration of the directional dependence of the viscosity and elastic constant of the SmA liquid crystal. Temperature dependencies of acoustic phase delay and propagation loss of the SH wave are observed. The critical behavior of the acoustic phase delay and the propagation loss of the SO mode SH wave in the vicinity of the N[sup *]-SmA phase transition temperature are explained by the existence of the elastic constant related to layer compression. The layer compression elasticity is predominant in the SmA phase, and is determined from the comparison of numerical analysis with experimental results. [ABSTRACT FROM AUTHOR]