Тип публикации: статья из журнала
Год издания: 2018
Идентификатор DOI: 10.1364/PRJ.6.001094
Ключевые слова: Capacitance, Cholesteric liquid crystals, Dielectric relaxation, Electric fields, Electrodes, Infrared devices, Nematic liquid crystals, Photonic devices, Tin oxides, Electrically tunable, Equivalent resistance, Helical superstructure, Induced temperature, Negative dielectric anisotropy, Spectral properties, Tin oxide electrodes, Tunable photonic devices, Tuning
Аннотация: We propose to dynamically control the reflective color of a cholesteric liquid crystal (CLC) by electrically tuning the center wavelength (lambda(c)) of the bandgap. The CLC, sandwiched in a planar-aligned cell with indium-tin-oxide electrodes, possesses We propose to dynamically control the reflective color of a cholesteric liquid crystal (CLC) by electrically tuning the center wavelength (λc) of the bandgap. The CLC, sandwiched in a planar-aligned cell with indium–tin-oxide electrodes, possesses negative dielectric anisotropy and thermo-responsive spectral properties. The helix in the Grandjean planar state, which is subject to vertically applied voltage, should be undisturbed in that the long molecular axis is initially perpendicular to the direction of the electric field. Surprisingly, when the frequency of the applied voltage is higher than a critical value, λc of the CLC cell varies as a function of the voltage. The underlying mechanism is the voltage-induced temperature change through dielectric heating in the frequency regime of pseudo-dielectric relaxation, attributable to the significant equivalent resistance–capacitance circuit of the cell due to the use of electrode layers with finite conductance. The driving voltage enabling the tuning of λc in the entire visible spectrum is as low as 12 Vrms in a 5 μm thick cell at a frequency of 2 MHz. The proposed CLC cell, exhibiting a broad electrically tunable spectral range from the near-infrared to ultraviolet, holds great promise for developing tunable photonic devices such as multicolor reflectors, filters, and sensors. © 2018 Chinese Laser Press.
Журнал: PHOTONICS RESEARCH
Выпуск журнала: Vol. 6, Is. 12
Номера страниц: 1094-1100
ISSN журнала: 23279125
Место издания: WASHINGTON
Издатель: OPTICAL SOC AMER
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