Theoretical and experimental optical studies of cholesteric liquid crystal films with thermally induced pitch gradients

Dimitrios C Zografopoulos , Emmanouil Kriezis (1) , Michel Mitov (2, 3) , Corinne Binet (2)

1 Department of Electrical & Computer Engineering [Thessaloniki]
2 CEMES - Centre d'élaboration de matériaux et d'études structurales
3 CEMES-NeO - Nano-Optique et Nanomatériaux pour l'optique

The reflection properties of cholesteric films with thermally induced pitch gradients are theoretically and experimentally studied. It is shown that the optical behavior of such films corresponds to the averaged contribution of a number of stochastic pitch variation profiles, due to the transversal and longitudinal nonuniformities that develop in the helical structure of such samples. Depending on the annealing time, both narrow-band and broadband behavior can be selectively achieved. The influence of the pitch profile gradient on the broadband reflection performance of cholesteric samples is theoretically analyzed, and a multi-slab structure for achieving optimum efficiency is proposed.

Mots clés: Cholesteric Liquid Crystals; Bragg reflections; Finite-difference time domain method

Domaines: Matière Molle [cond-mat.soft]; Optique [physics.optics]

Dimitrios C Zografopoulos, Emmanouil Kriezis, Michel Mitov, Corinne Binet. Theoretical and experimental optical studies of cholesteric liquid crystal films with thermally induced pitch gradients. Physical Review E : Statistical, Nonlinear, and Soft Matter Physics, 2006, 73 (6), ⟨10.1103/PhysRevE.73.061701⟩. ⟨hal-02887349⟩