Interdependence of the electrical and optical properties of liquid crystals for phase modulation applications

Abstract

The electrical capacitance and conductance of nematic liquid crystal (LC) cells were measured in combination with their optical properties as functions of applied voltage magnitude and frequency. A single experimental system was used in order to determine the correlation between these characteristics. These parameters are crucial for understanding and optimizing the performance of modal LC devices. Both ordinary and dual frequency LCs were investigated. For the latter type, Cole-Cole diagrams show a Debye type frequency dispersion in a limited range of 4-9 kHz. Also, a phenomenological theory of the measured parameters was developed and is in good agreement with experimental data. Two examples are discussed, and they illustrate the importance of taking into account the equivalent conductance of LC cells. © 2000 American Institute of Physics.