Novel type of tunable infrared filters based on the Al _2O _3 particles - Liquid crystal system

摘要

The optical transmission of small aluminum oxide particles in liquid crystal 4-methoxybenzylidene-4′-butylaniline (MBBA) and dual-frequency liquid crystal mixture consisting of 4-n-pentyl-4′-cyanobiphenyl (5CB), 4-hexyloxyphenyl ester 4′-hexyloxy-3-nitrobenzoic acid (C2), 4-n-pentanoyloxy-benzoic acid-4′-hexyloxyphenyl ester (H 22) was studied. It was established that there was a transmission band which was shifted on application of a voltage and depended on temperature. At using the dual-frequency liquid crystal as a matrix, a transmission band maximum switched at changing of the frequency. The experimental results are explained by the optical homogeneity of the system in a narrow wavenumber interval when the refractive indices of the particle material and the matrix are close, and also by re-orientation of the liquid crystal molecules when a voltage is applied. The obtained results can be used in constructing of tunable filters and compact monochromators.