Evolution of photonic structure on deformation of cholesteric elastomers

We subject a monodomain cholesteric liquid crystal elastomer to uniaxial strain perpendicular to its helical axis and study the response of its texture to deformation. A combination of mechanical, optical and X-ray scattering measurements confirms the prediction for the director rotation, coarsening and then unwinding the cholesteric helix. The study of optical absorption of circularly polarised light quantifies the complex dependence of the photonic bandgap structure on strain and directly relates to the microscopic deformation of elastomer. Agreement is found with the recently proposed theoretical prediction of the photonic structure of cholesteric elastomers.