Light-Induced Higher-Order Bragg Resonance in Heliconical Cholesteric Liquid Crystals

Higher-order reflections from a cholesteric liquid crystal have been investigated for a long time after early observations of an oblique incidence of light. Even with the restriction of the required oblique geometry, wavelength tuning would make this property very attractive for photonic application...

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Main Authors: Ashot H. Gevorgyan, Francesco Simoni
Format: Article
Language:English
Published: MDPI AG 2025-05-01
Series:Crystals
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Online Access:https://www.mdpi.com/2073-4352/15/6/513
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author Ashot H. Gevorgyan
Francesco Simoni
author_facet Ashot H. Gevorgyan
Francesco Simoni
author_sort Ashot H. Gevorgyan
collection DOAJ
description Higher-order reflections from a cholesteric liquid crystal have been investigated for a long time after early observations of an oblique incidence of light. Even with the restriction of the required oblique geometry, wavelength tuning would make this property very attractive for photonic applications in the near-UV range of the electromagnetic spectrum. Unfortunately, this is quite difficult to achieve in cholesterics, and it has been obtained in special configurations that lead to the deformation of the helical structure. We show here that a new opportunity is provided by heliconical cholesteric liquid crystals and demonstrate that second-order Bragg resonance with high reflectivity and a narrow band can be produced by a light beam with intensity high enough to give rise to a significant optical torque with the consequent distortion of the helical structure. Exploiting the well-known properties of heliconical cholesterics under electric fields, we also demonstrate that the easy tuning of the second-order reflection band is achieved in the near-UV range.
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spelling doaj-art-ca454075d7a440c79d2db3e7814e6ff52025-08-20T02:24:38ZengMDPI AGCrystals2073-43522025-05-0115651310.3390/cryst15060513Light-Induced Higher-Order Bragg Resonance in Heliconical Cholesteric Liquid CrystalsAshot H. Gevorgyan0Francesco Simoni1School of Natural Sciences, Far Eastern Federal University, 10 Ajax Bay, Russky Island, 690922 Vladivostok, RussiaUniversità Politecnica delle Marche, 60131 Ancona, ItalyHigher-order reflections from a cholesteric liquid crystal have been investigated for a long time after early observations of an oblique incidence of light. Even with the restriction of the required oblique geometry, wavelength tuning would make this property very attractive for photonic applications in the near-UV range of the electromagnetic spectrum. Unfortunately, this is quite difficult to achieve in cholesterics, and it has been obtained in special configurations that lead to the deformation of the helical structure. We show here that a new opportunity is provided by heliconical cholesteric liquid crystals and demonstrate that second-order Bragg resonance with high reflectivity and a narrow band can be produced by a light beam with intensity high enough to give rise to a significant optical torque with the consequent distortion of the helical structure. Exploiting the well-known properties of heliconical cholesterics under electric fields, we also demonstrate that the easy tuning of the second-order reflection band is achieved in the near-UV range.https://www.mdpi.com/2073-4352/15/6/513higher-order Bragg resonanceheliconical liquid crystalsnonlinear opticspitch tuning
spellingShingle Ashot H. Gevorgyan
Francesco Simoni
Light-Induced Higher-Order Bragg Resonance in Heliconical Cholesteric Liquid Crystals
Crystals
higher-order Bragg resonance
heliconical liquid crystals
nonlinear optics
pitch tuning
title Light-Induced Higher-Order Bragg Resonance in Heliconical Cholesteric Liquid Crystals
title_full Light-Induced Higher-Order Bragg Resonance in Heliconical Cholesteric Liquid Crystals
title_fullStr Light-Induced Higher-Order Bragg Resonance in Heliconical Cholesteric Liquid Crystals
title_full_unstemmed Light-Induced Higher-Order Bragg Resonance in Heliconical Cholesteric Liquid Crystals
title_short Light-Induced Higher-Order Bragg Resonance in Heliconical Cholesteric Liquid Crystals
title_sort light induced higher order bragg resonance in heliconical cholesteric liquid crystals
topic higher-order Bragg resonance
heliconical liquid crystals
nonlinear optics
pitch tuning
url https://www.mdpi.com/2073-4352/15/6/513
work_keys_str_mv AT ashothgevorgyan lightinducedhigherorderbraggresonanceinheliconicalcholestericliquidcrystals
AT francescosimoni lightinducedhigherorderbraggresonanceinheliconicalcholestericliquidcrystals