Schematic illustration of the deformation of the chiral nematic helical director structure (a) due to flexoelectro-optic (b) and dielectric (c) coupling to an electric field applied orthogonal to the helical axis. The effect of the deformation is viewed along (upper figure) and perpendicular (lower figure) to the helical axis to illustrate the source of the resulting birefringence. Note in the flexoelectric example the differing electric-field direction for the two views, necessary for illustrative purposes.
The chemical structures and formulas for the bimesogenic liquid crystals used in this study.
Schematic diagram of the cell geometry of the Grandjean-textured in-plane field cell (not to scale).
Electric-field-induced birefringence at differing field amplitudes and frequencies for mixture (1) at .
Electric-field-induced birefringence at differing field amplitudes and frequencies for mixture (2) at .
Electric-field-induced birefringence at differing field amplitudes and frequencies for mixture (3) at .
The field-following (flexoelectrically induced) portion of the induced birefringece in the Grandjean-textured cell, as a function of the flexoelectro-optic tilt angle measured in the uniform lying helix (ULH) texture, for the three mixtures at .
Diagram illustrating the small change in effective refractive index in the direction of light polarization for small flexoelectro-optic tilt angles due to the ellipsoidal shape of the indicatrix.
The averaged 10%–90% and 90%–10% response times observed in both the Grandjean-textured in-plane field cell and the ULH-textured flexoelectro-optic cells. All times are measured at for a switch from and back in the Grandjean case and from and back in the ULH case.
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