Dynamic Anchoring of Liquid Crystals: Path to New Applications – Lachezar Komitov

Date: Mon. June 2nd, 2003, 12:30 pm-1:30 pm
Location: Rockefeller 221

Liquid crystals are widely used as electro-optic active media in display devices. The alignment of the liquid crystal molecules is crucial for the operation of liquid crystal displays. In field-free conditions, the liquid crystal alignment is essentially governed by the surface/liquid crystal interactions. Therefore, these interactions have been the focus of intensive studies for many years. Their importance is clearly demonstrated by surface stabilized ferroelectric liquid crystals (SSFLC) where the ferroelectric state emerges as a consequence of the surface/liquid crystal interactions. It has been shown previously that the changes taking place at the liquid crystal/solid substrate surface affect the behaviour of the liquid crystal volume and, in some cases, they may even cause so called alignment transitions. Due to the anisotropic optical properties of liquid crystals, however, changes in their alignment result in corresponding changes in their optical performance. Here, several optical effects, that arise from the surface-mediated switching of the liquid crystal, are briefly presented and discussed. The switching, triggered by different external factors like temperature, light, material flow, electric field, etc., is due to the changes in the liquid crystal/surface interactions caused by these factors. Most of the presented effects seem to have a potential for application in a number of liquid crystal displays and devices as well as in liquid crystal photonic devices. Some applications will be briefly discussed.