Electrically driven torsional distortions in twisted nematic films.

The purpose of this article is to describe the physical mechanism responsible for the appearance of both traveling and nontraveling distortions in a microsized homogeneously aligned nematic (HAN) film under the effect of a large electric field. Numerical studies have been carried out to describe both the traveling and nontraveling dynamic reorientation of the director's field in a thin, in a few tens of micrometers, the HAN film under the effect of a large electric field E (∼1.0V/μm). It is shown that in response to the electric field E applied parallel to the bounding surfaces, the torques acting on the director n[over ̂] may excite the traveling distortion wave propagating normally to both boundaries, whose resemblance to a kinklike wave increases with increasing applied electric field E. Calculations show that in the HAN film the physical mechanism that is responsible for the electric-field-induced distortion of the director field n[over ̂] in the form of traveling wave provides a much faster relaxation regime than in the case of the nontraveling mode.