Refractive indices and birefringence of hybrid liquid crystal - nanoparticles composite materials in the terahertz region

Mavrona, Elena; Chodorow, Urszula; Barnes, M. E.; Parka, Janusz; Pałka, Norbert; Saitzek, Sébastien; Blach, Jean‐François; Apostolopoulos, Vasilis; Kaczmarek, Malgosia

doi:10.1063/1.4927392

Cited by 30 publications

(19 citation statements)

References 32 publications

(49 reference statements)

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“…Here, the transmission method is used to measure n for E7 and E7-ZnO samples [38,39]. Using equations (1 and 2), the calculated values of n at 30 • C are found to be 0.22 and 0.23 for E7 and E7-ZnO, respectively, which is in good agreement with earlier work [39,40]. An increase in n after dispersion of NPs can be attributed to the formation of large dipole moments, which produces a large electric field between NPs.…”

Section: Pom Studysupporting

confidence: 86%

“…Further, a decrease in birefringence with temperature as shown in figure 6 can be due to a change in molecular re-orientation and optical anisotropy of LCs. This shows that the system is moving to a less ordered state with an increase in the kinetic energy of the system and a decrease in optical anisotropy [31,40]. Additionally, the contrast ratio (CR), an important measure of the performance for any display device and defined as I max /I min , is calculated from the maximum and minimum transmission data [41,42].…”

Section: Pom Studymentioning

confidence: 99%

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Improvement in electro-optical and dielectric characteristics of ZnO nanoparticles dispersed in a nematic liquid crystal mixture

et al. 2019

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Reported herein is the effect of dispersion of a fixed amount of 0.5% (wt/wt) ZnO nanoparticles (NPs) in a nematic (E7) liquid crystal (LC) mixture. Dispersion of ZnO NPs results in a significant improvement in electro-optical and dielectric parameters of the nematic mixture. Comparative analysis of undoped and NP-dispersed samples shows a reduced threshold voltage with better transmittance without compromising dielectric permittivity characteristics. In addition, an increase in the contrast ratio, birefringence, alternating-current conductivity and band gap was observed after dispersion of ZnO NPs in LCs. A polarized optical microscopic study of the NP-dispersed sample substantiates a slight increase in nematic-isotropic phase transition temperature of LCs.

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Section: Pom Studysupporting

confidence: 86%

Section: Pom Studymentioning

confidence: 99%

Improvement in electro-optical and dielectric characteristics of ZnO nanoparticles dispersed in a nematic liquid crystal mixture

et al. 2019

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“…Среди перспективных сред / материалов, подходящих для использования в электрическиперестраиваемых устройствах мм-/ субмм-диапазона и составляющих конкуренцию полупроводниковым / графеновым структурам, следует отметить жидкие кристаллы (ЖК) [23][24][25][26][27]. Последние обладают рядом преимуществ следующего характера.…”

Section: аннотацияunclassified

Application of the Concept of Ultra-Thin Resonant Absorbers for Controlling Millimeter-Wave Radiation by Means of Liquid Crystals

Kuznetsov

Николаев

Trashkeev

et al. 2019

SJPhys

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A consideration of ultra-thin resonant absorbers of electromagnetic radiation utilizing high-impedance metasurfaces is carried out in terms of an equivalent circuit theory. By incorporating a thin layer of tunable dielectric into such structures it is feasible to manipulate the radiation amplitude and phase under the condition of a small thickness of the dielectric layer in comparison with the radiation wavelength. As such a dielectric, the nematic liquid crystal 5CB with a thickness of 80 um was chosen, and a 5CB-based prototype of an absorbing metastructure of the reflective type optimized for operation in the vicinity of a frequency of 140 GHz was fabricated and experimentally studied. Testing the structure revealed good agreement between the calculated and experimental reflection spectra. The results of this work can be useful for modeling and developing quasi-optical and integrated active devices of terahertz photonics.

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“…The combination of ferroelectric solid state materials in the form of nanoparticles with liquid crystals has been an active research field in the past few years. Inclusion of the nanoparticles led to drastic improvement of switching voltage [14], the electro-optic response [15] or the optical properties in the THz region [16]. We expect that the combination of ferroelectric thin films with liquid crystal layers will lead to a similar improvement in certain liquid crystal switching modes.…”

Section: Introductionmentioning

confidence: 95%

Ferroelectric thin films with liquid crystal for gradient index applications

Willekens¹,

George²,

Neyts³

et al. 2016

Opt. Express

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We report on the first ever combination of a thin film of lead zirconate titanate (PZT) with a liquid crystal (LC) layer. Many liquid crystal applications use a transparent conductive oxide to switch the liquid crystal. Our proposed processing does not, instead relying on the extremely high dielectric constant of the ferroelectric layer to extend the electric field from widely spaced electrodes over the liquid crystal. It eliminates almost entirely the fringe field problems that arise in nearly all the liquid crystal devices that use multiple addressing electrodes. We show, both via rigorous simulations as well as experiments, that the addition of a PZT layer over the addressing electrodes leads to a markedly improved LC switching performance at distances of up to 30 µm from the addressing electrodes with the current PZT-layer thickness of 0.84 µm. This improvement in switching is used to tune the focal length of the microlens with electrodes spaced at 30 µm.

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Refractive indices and birefringence of hybrid liquid crystal - nanoparticles composite materials in the terahertz region

Cited by 30 publications

References 32 publications

Improvement in electro-optical and dielectric characteristics of ZnO nanoparticles dispersed in a nematic liquid crystal mixture

Improvement in electro-optical and dielectric characteristics of ZnO nanoparticles dispersed in a nematic liquid crystal mixture

Application of the Concept of Ultra-Thin Resonant Absorbers for Controlling Millimeter-Wave Radiation by Means of Liquid Crystals

Ferroelectric thin films with liquid crystal for gradient index applications

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