Photographs taken of three cells filled with materials with different proportions of chiral dopant whilst (a) in the Grandjean state, accessed by driving the cell with 5 kHz, 10 Vrms μm−1, and (b) in the weakly scattering focal conic state, after the application of 10 Vrms μm−1 at 100 Hz. The textures are stable on removal of the field.
The transmission spectrum of the devices under the application of 10 Vrms μm−1 at 5 kHz (solid lines) and 100 Hz (dashed lines). The spectra are consistent with a Bragg reflecting Grandjean state when driven with 5 kHz and with a weakly scattering focal conic state when driven with 100 Hz. Blue, black, and red lines correspond to cells with measured Bragg peaks of 480, 540, and 590 nm, respectively.
Capacitance as a function of frequency (using 100 mV test voltage) for cells filled with mixtures whose Bragg reflection maxima centre on 480, 540, and 590 nm, while in stable focal conic and Grandjean states. Dispersion in the flexoelectric polarisability causes a cross-over in the frequency-dependent dielectric properties of the focal conic and Grandjean states at between 200 and 400 Hz, enabling a frequency-addressed switching between the two states.
The normalised intensity of reflected light, which is normally incident on the device, at a reflection angle of 15°, for the cell with Bragg reflection peak of 540 nm, as a function of time. The cell is addressed with 10 Vrms μm−1 that cycled between 100 Hz and 5 kHz.
Article metrics loading...
Full text loading...