Electrically Controlled Structures in Cholesteric Droplets with Planar Anchoring

Structure transformations in cholesteric droplets with planar anchoring induced by an electric field are studied experimentally. The radial spherical structure is formed initially, then it transforms into the quasi-nematic untwisting state under the action of an electric field E=1.75 V/μm. The dependence of structure transformations on the voltage switching-off mode is examined. At the one-step voltage-off mode, the Lyre structure is realized in cholesteric droplets at the relative chiral parameter in the range 4.3≤N≤8.5. The axis-symmetric bipolar structure and the low-symmetric planar bipolar structure are obtained at the multi-step voltage-off mode. The possibility of forming such structures and their stability are determined by the type of voltage switching-off mode, the N value, the surface anchoring strength (the value of cholesteric helix pitch), and the presence of the surface point defects.