Effects of dielectric relaxation in electrooptics of nematic cells

摘要

Recent experimental and theoretical results that link the phenomenon of dielectric relaxation in nematic liquid crystals (NLCs) to their dynamics and fast electro-optical switching are presented. Namely, we illustrate that the dielectric torque acting on the uniaxial nematic liquid crystal depends not only on the present value of the field and the present orientation of the director, but also on the prehistory of these two parameters. The resulting "dielectric memory" effect leads to a spectacular but counter-intuitive effect: director relaxation during the "switch-off" stage can be accelerated if instead of the abrupt vertical back edge, one uses a voltage pulse with a non-instantaneously vanishing back edge. The acceleration effect can be enhanced with a short high voltage pulse at the end of the "switch on" process.