Dielectric relaxation in thin liquid crystal layers formed on cylindrical pore walls

Bengoechea, Manuel Rivera; Aliev, Fouad

doi:10.1016/j.jnoncrysol.2005.04.079

Cited by 11 publications

(12 citation statements)

References 16 publications

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“…The origin of this peculiarity deserves a more detailed discussion. According to Bengoechea and Aliev 56,67 and in agreement with subsequent dielectric studies by Calus et al 58,59 slow relaxations of confined liquid crystals suggest that the mobility of molecules in the surface layers is strongly affected by boundary conditions. Near-interfacial layers are characterized by a considerably larger effective viscosity compared to the bulk one which solely slows down the dipolar relaxation and can thus not explain an abrupt change in the response dynamics.…”

Section: Temperature-dependent Static Collective Orientational Order ...supporting

confidence: 71%

Dynamic Kerr and Pockels Electro-Optics of Liquid Crystals in Nanopores for Active Photonic Metamaterials

Kityk¹,

Nowak²,

Reben³

et al. 2021

Preprint

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Photonic metamaterials with properties unattainable in base materials are already beginning to revolutionize optical component design. However, their exceptional characteristics are often static, as artificially engineered into the material during the fabrication process. This limits their application for in-operando adjustable optical devices and active optics in general. Here, for a hybrid material consisting of a liquid crystal-infused nanoporous solid, we demonstrate active and dynamic control of its meta-optics by applying alternating electric fields parallel to the long axes of its cylindrical pores. First-harmonic Pockels and second-harmonic Kerr birefringence responses, strongly depending on the excitation frequency-and temperature, are observed in a frequency range from 50 Hz to 50 kHz. This peculiar behavior is quantitatively traced by a Landau-De Gennes free energy analysis to an order-disorder orientational transition of the rod-like mesogens and intimately related changes in the molecular mobilities and polar anchoring at the solid walls on the single-pore, meta-atomic scale. Thus, our study evidences that liquid crystal-infused nanopores exhibit integrated multi-physical couplings and reversible phase changes that make them particularly promising for the design of photonic metamaterials with thermo-electrically tunable birefringence in the emerging field of spacetime metamaterials aiming at a full spatio-temporal control of light.

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Section: Temperature-dependent Static Collective Orientational Order ...supporting

confidence: 71%

Dynamic Kerr and Pockels Electro-Optics of Liquid Crystals in Nanopores for Active Photonic Metamaterials

Kityk¹,

Nowak²,

Reben³

et al. 2021

Preprint

View full text Add to dashboard Cite

show abstract

“…The origin of this peculiarity deserves a more detailed discussion. According to dielectric studies 62,64,65,73 slow relaxations of confined LCs suggest that the mobility of molecules in the surface layers is strongly affected by the boundary con-ditions. Near-interfacial layers are characterized by a considerably larger effective viscosity compared to the bulk one which solely slows down the dipolar relaxation.…”

Section: Resultsmentioning

confidence: 99%

Dynamic Kerr and Pockels electro-optics of liquid crystals in nanopores for active photonic metamaterials

et al. 2021

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“…4(b) has been seen only at the FLC/air interface, is centred at $10 5 Hz, and is due to the molecular rotation of the mesogens about their short molecular axes. 22,30,31 To conrm the origin of this mode, temperature and electric eld dependent measurements have been performed and are shown in Fig. 5.…”

Section: Resultsmentioning

confidence: 99%

“…21 As a powerful tool for exploring the different aspects of the dynamic behaviour of conned LCs, dielectric spectroscopy investigations are done at the air interface of nematic and smectic-A (SmA) phases of the LCs. 15,22 The interfacial system becomes more complex for FLCs in the chiral smectic-C* (SmC*) phase due to the tilted molecular arrangement with respect to the layer normal. Recently, the dynamic properties of surface stabilized FLCs that are in contact with air and which have an elastic interfacial connement have been examined to determine the change in the electro-optical response spectra with the distance between the illuminated LC areas and the contact surface.…”

Section: Introductionmentioning

confidence: 99%

Probing the dynamics of geometrically confined ferroelectric mesogens at the air interface

et al. 2015

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This article focuses on the alignment and dynamics of mesogens at the ferroelectric liquid crystal (FLC)/air interface in a confined geometry. The interface has been systematically prepared and characterised with provision for applying an electric field separately to the bulk and air interface of the FLC. Polarizing optical microscopy (POM) investigations done at the FLC/air interface have exposed the concave geometry, cell thickness dependent boundary width and phase dependent optical textures of the FLC meniscus at the interface. Dielectric spectroscopy investigations revealed the presence of an additional molecular relaxation mode at the FLC/air interface, which is attributed to the short axis rotation of homeotropically aligned mesogens at the interface. Based on the observations from the POM, dielectric spectroscopy and X-ray diffraction profiles, we schematically envisaged the molecular arrangement and dynamics of the FLC/air boundary. These studies would be helpful for innovations in liquid crystal based devices and also for many other applications, where soft surfaces, interfaces and confinement play a momentous role.

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Dielectric relaxation in thin liquid crystal layers formed on cylindrical pore walls

Cited by 11 publications

References 16 publications

Dynamic Kerr and Pockels Electro-Optics of Liquid Crystals in Nanopores for Active Photonic Metamaterials

Dynamic Kerr and Pockels Electro-Optics of Liquid Crystals in Nanopores for Active Photonic Metamaterials

Dynamic Kerr and Pockels electro-optics of liquid crystals in nanopores for active photonic metamaterials

Probing the dynamics of geometrically confined ferroelectric mesogens at the air interface

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