Analytical Study of Bi-Layered Chiral Liquid Crystal Photonic Band Filter

Abstract

Owing to their peculiar helical structure, Chiral Liquid Crystals (CLCs) are well known for the selective spectral photonic band. This unique photonic band property is resulted from the optical rotation effect of electromagnetic wave propagation depending on the material birefringence (Δn) and rotational repeating pitch (p) following the elegant equation Δλ=Δn·p. Hitherto, a number of researchers have investigated the photonic bandgaps (PBGs) control of this fascinating chiral liquid crystal materials for various applications [1,2]. In particular, over visible wavelength range, the concept of the selective color filter exploiting the optical characteristics of CLCs can be suggested beyond the Bayer color filter which is based on chemical dye absorption. Especially, from the well design of chiral liquid crystal parameter, well controllable tuning of the wavelength position is possible in CLC band filter. In addition to the single CLC structure, bi-layered CLCs can be approached for further elaborate photonic filters [3].Herein, we studied a mathematical analysis of the reflection and transmission spectra of the bilayer CLC photonic color filter modeling. Through this analytical modeling, it was possible to achieve an in-depth understanding of the optical properties of the bilayer CLC color filter. In addition, this study will contribute to exploring a variety of further promising CLC applications including selective band filters and other various photonics sensing applications.