Photonic properties of polymer-stabilized photosensitive cholesteric liquid crystal studied by combination of optical activity, transmission and fluorescence

Liquid Crystals. 2021. Vol. 48. No. 9. P. 1339–1348.

P. V. Dolganov, K. D. Baklanova, Bobrovsky A. Y.

We report complex optical investigations of polymer-stabilised cholesteric photonic liquid crystal doped by a dichroic fluorescent dye. For the first time, we employed a combination of various experimental methods, including measurements of spectra of transmission, reflection, rotation of the plane of polarisation of light, fluorescence, to characterise the properties of the photonic crystal. The peculiarity of the reported investigations is employing a photosensitive cholesteric mixture forming the photonic crystal. The position of the photonic band could be changed by illumination with ultraviolet light and stabilised by thermopolymerisation. In this way, the position of the cholesteric band was matched with the emission band of the fluorescent dye, which enabled to perform diversified studies on the same photonic crystal. We determined the parameters, which defined the optical properties of the photonic crystal, spectral dependence of the transformation of linearly polarised light to elliptically polarised as the light passes the photonic crystal, the photonic density of states. The interpretation of the experimental data was performed using analytical expressions obtained from the solution of Maxwell’s equations, numerical calculations by the Berreman matrix method.

Keywords: fluorescence, photonic crystals, Cholesteric, optical activity