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 polarized light quantifies the complex dependence of the photonic band-gap 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.