Photonic gaps in cholesteric elastomers under deformation

TL;DR

This paper investigates how mechanical deformation affects the photonic properties of cholesteric liquid crystal elastomers, revealing changes in light transmittance and structural evolution with experimental and theoretical insights.

Contribution

It provides the first detailed experimental analysis of how deformation influences photonic stop-gaps in cholesteric elastomers, supported by theoretical predictions.

Findings

Deformation broadens the photonic stop-gaps.

Mechanical strain shifts the stop-gap wavelengths.

Experimental results align with theoretical models.

Abstract

Cholesteric liquid crystal elastomers have interesting and potentially very useful photonic properties. In an ideal monodomain configuration of these materials, one finds a Bragg-reflection of light in a narrow wavelength range and a particular circular polarization. This is due to the periodic structure of the material along one dimension. In many practical cases, the cholesteric rubber possesses a sufficient degree of quenched disorder, which makes the selective reflection broadband. We investigate experimentally the problem of how the transmittance of light is affected by mechanical deformation of the elastomer, and the relation to changes in liquid crystalline structure. We explore a series of samples which have been synthesized with photonic stop-gaps across the visible range. This allows us to compare results with detailed theoretical predictions regarding the evolution of stop-gaps in cholesteric elastomers.