Optical characterization of liquid crystals by means of half-leaky guided modes

Guided mode studies of liquid crystal layers

“…According to the guided mode theory it is obvious that there can be no true guided waves in the liquid crystal guiding layer with these conditions satisfied. However analytical treatment, as well as numerical modelling, of this situation shows [54] that there is a special wavevector range in which there are strong polarisation conversion signals in the reflectivity spectrum. This in-plane wavevector range is between k 0 n s to k 0 n′ where n′ is the maximum effective index of the liquid crystal probed by the radiation, n o < n′ < n e .…”

“…The advantages of the HLGM technique have been analysed in detail [54]. From numerical modelling it has been found that the technique has very good sensitivity to all changes in the director twist and tilt, even less than 1 ο .…”

“…Since the HLGM technique was developed in 1993 [55] a significant amount of work has been undertaken using this powerful tool. The first study, using this technique, was to explore the detailed optical tensor configuration in a homogeneously aligned SSFLC (Merck-BDH SCE3) [55].…”

“…The first study, using this technique, was to explore the detailed optical tensor configuration in a homogeneously aligned SSFLC (Merck-BDH SCE3) [55]. In the test cell the aligning surface layers were silicon oxide deposited by evaporation at 60 ο to create in-plane homogeneous alignment in the nematic phase.…”

Combined X-Ray and Fully Leaky Guided Mode Studies of the Smectic Layer and Optic Tensor Configuration in a Ferroelectric Liquid-Crystal Cell

“…However, the fully guiding technique originally used by Elston et al is not ideally suited to studies of polyimide aligned SSFLCs as the thin silver layers used to create the optical cavity are damaged by the mechanical rubbing process used to texture the polyimide. Further development in optical waveguide probing of liquid crystal cells led to the fully leaky technique [7] (with high index cells) and later the half-leaky technique [8] which enabled the director profile in SSFLC cells with the conventional polyimide alignment layers to be studied in detail.…”