Electrooptic response of reflective-mode, pi/4-twisted-nematic liquid crystal cell in the voltage regions close to and distant from the Freedericksz transition threshold

Abstract

Two reflective-mode, pi/4-twisted-nematic liquid crystal cells were prepared using E7 and ZLI4801-000 liquid crystals and their electrooptic responses were measured in the voltage regions close to and distant from the Freedericksz transition threshold. Our reflectivity data distant from the threshold voltage (V-th) could not be described by the model that assumed a linearized distribution of the twist angle across the cell and considered the voltage dependency of the tilt angle to follow the equation suggested by Lu and Saleh [Appl. Opt. 30 (1991) 2354], although the fit is good near V-th. We determined that the reflectivity in the voltage region distant from V-th Should be calculated using the model that considers the distributions of the tilt angle and the twist angle. The director-axis distributions were obtained from the numerical integration of the Ericksen-Leslie equation.