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Boychuk A, Shibaev V, Cigl M, Hamplová V, Novotná V, Bobrovsky A. Large Thermally Irreversible Photoinduced Shift of Selective Light Reflection in Hydrazone-Containing Cholesteric Polymer Systems. Chemphyschem 2023:e202300011. [PMID: 36861819 DOI: 10.1002/cphc.202300011] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Revised: 02/25/2023] [Accepted: 03/01/2023] [Indexed: 03/03/2023]
Abstract
Stimuli responsive liquid crystalline polymers are a unique class of so-called "smart" materials demonstrating various types of mesomorphic structures easily controlled by external fields, including light. In the present work we synthesized and studied a comb-shaped hydrazone-containing copolyacrylate exhibited cholesteric liquid crystalline properties with the pitch length of the helix being tuned under irradiation with light. In the cholesteric phase selective light reflection in the near IR spectral range (1650 nm) was measured and a large blue shift of the reflection peak from 1650 nm to 500 nm was found under blue light (428 or 457 nm) irradiation. This shift is related to the Z-E isomerization of photochromic hydrazone-containing groups and it is photochemically reversible. The improved and faster photo-optical response was found after copolymer doping with 10 wt % of low-molar-mass liquid crystal. It is noteworthy that both, the E and Z isomers of hydrazone photochromic group are thermally stable that enable to achieve a pure photoinduced switch without any dark relaxation at any temperatures. The large photoinduced shift of the selective light reflection, together with thermal bistability, makes such systems promising for applications in photonics.
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Affiliation(s)
- Artem Boychuk
- Department of Chemistry, Lomonosov Moscow State University, Leninskie gory, Moscow, 119991, Russia
| | - Valery Shibaev
- Department of Chemistry, Lomonosov Moscow State University, Leninskie gory, Moscow, 119991, Russia
| | - Martin Cigl
- Institute of Physics of the Czech Academy of Sciences, 1999/2 Na Slovance, 182 20, Prague 8, Czech Republic
| | - Vĕra Hamplová
- Institute of Physics of the Czech Academy of Sciences, 1999/2 Na Slovance, 182 20, Prague 8, Czech Republic
| | - Vladimíra Novotná
- Institute of Physics of the Czech Academy of Sciences, 1999/2 Na Slovance, 182 20, Prague 8, Czech Republic
| | - Alexey Bobrovsky
- Department of Chemistry, Lomonosov Moscow State University, Leninskie gory, Moscow, 119991, Russia
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Boychuk A, Shibaev V, Cigl M, Hamplová V, Pociecha D, Bubnov A, Bobrovsky A. The role of lateral substituent size in azobenzene chromophores on photo- and chiro-optical properties of photoactive polymethacrylates. J Photochem Photobiol A Chem 2023. [DOI: 10.1016/j.jphotochem.2023.114689] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/13/2023]
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Sohn HRO, Liu CD, Wang Y, Smalyukh II. Light-controlled skyrmions and torons as reconfigurable particles. OPTICS EXPRESS 2019; 27:29055-29068. [PMID: 31684647 DOI: 10.1364/oe.27.029055] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Accepted: 09/17/2019] [Indexed: 06/10/2023]
Abstract
Topological solitons, such as skyrmions, arise in field theories of systems ranging from Bose-Einstein condensates to optics, particle physics, and cosmology, but they are rarely accessible experimentally. Chiral nematic liquid crystals provide a platform to study skyrmions because of their natural tendency to form twisted structures arising from the lack of mirror symmetry at the molecular level. However, large-scale dynamic control and technological utility of skyrmions remain limited. Combining experiments and numerical modeling of chiral liquid crystals with optically controlled helical pitch, we demonstrate that low-intensity, unstructured light can control stability, dimensions, interactions, spatial patterning, self-assembly, and dynamics of these topological solitons.
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Ortega J, Folcia CL, Etxebarria J. Upgrading the Performance of Cholesteric Liquid Crystal Lasers: Improvement Margins and Limitations. MATERIALS 2017; 11:ma11010005. [PMID: 29267238 PMCID: PMC5793503 DOI: 10.3390/ma11010005] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 12/05/2017] [Accepted: 12/19/2017] [Indexed: 11/16/2022]
Abstract
The topic of cholesteric-liquid-crystal lasers is a rapidly expanding research area in the field of soft-matter photonics. The increasing interest in this field is due to the high versatility that these lasers may possibly present and the prospects of giving rise to new miniaturized devices. However, further improvements in their operation capabilities are still required for potential applications. In this paper, we critically analyze the main strategies proposed up to now to optimize their performance. We show theoretically and experimentally that possible innovations in the device structure cannot produce lasers with threshold energies below a certain limit. This limit is determined by the light scattering and absorption losses inside the liquid crystal. Even assuming the case of samples free of defects and perfectly non-absorbing, an intrinsic light scattering, typical of mesogens, still remains. Numerical estimates of the thresholds indicate that these lasers could hardly be driven by compact light sources such as current electroluminescent or light-emitting diodes. Since the improvement possibilities regarding cell architecture seem to be exhausted, the advance must come from the use of new dye molecules. These molecules should show enhanced emission cross-sections and be efficiently integrable within the mesogenic solvent. In addition, the fluorescent systems must present very small quantum yields to triplet states if continuous-wave lasing is sought. In this respect, quantum dots are an alternative to explore for further investigations.
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Affiliation(s)
- Josu Ortega
- Department of Applied Physics II, Faculty of Science and Technology, University of the Basque Country, UPV/EHU, 48080 Bilbao, Spain.
| | - César L Folcia
- Department of Condensed Matter Physics, Faculty of Science and Technology, University of the Basque Country, UPV/EHU, 48080 Bilbao, Spain.
| | - Jesús Etxebarria
- Department of Condensed Matter Physics, Faculty of Science and Technology, University of the Basque Country, UPV/EHU, 48080 Bilbao, Spain.
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Ortega J, Folcia CL, Sanz-Enguita G, Aramburu I, Etxebarria J. Kinetic behavior of light emission in cholesteric liquid crystal lasers: An experimental study. OPTICS EXPRESS 2015; 23:27369-27375. [PMID: 26480399 DOI: 10.1364/oe.23.027369] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Some dynamical aspects of fluorescence and lasing have been studied in a dye-doped cholesteric liquid crystal by measuring the response of the material to nanosecond optical pumping. It has been found that as the pumping energy is increased the fluorescence pulse duration decreases, reaching a minimum at the lasing threshold. Above the threshold the temporal profiles are irregular and consist of a set of narrow pulses whose measured duration is limited by the detector risetime (1 ns). The results are interpreted in terms of a recently proposed model [JETP, 118, 822 (2014)] that makes use of rate equations to account for the laser generation in cholesteric liquid crystals. The prediction of such equations for an experimental configuration appropriate for fluorescence lifetime measurements is analyzed.
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Etxebarria J, Ortega J, Folcia CL, Sanz-Enguita G, Aramburu I. Thermally induced light-scattering effects as responsible for the degradation of cholesteric liquid crystal lasers. OPTICS LETTERS 2015; 40:1262-1265. [PMID: 25831308 DOI: 10.1364/ol.40.001262] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We have studied the degradation process of the laser emission in a cholesteric liquid crystal laser. We have found that there exists a negative correlation between the laser efficiency and the amount of light scattered by the liquid-crystal sample in the illuminated area. The growth of scattering is attributed to the appearance of small imperfections generated in the sample as a result of certain thermal processes that involve the dye molecules. The scattering implies an increase of the coefficient of distributed losses, which is the main response of the rise of the laser threshold.
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Mohammadimasoudi M, Beeckman J, Shin J, Lee K, Neyts K. Widely tunable chiral nematic liquid crystal optical filter with microsecond switching time. OPTICS EXPRESS 2014; 22:19098-19107. [PMID: 25320996 DOI: 10.1364/oe.22.019098] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
A wavelength shift of the photonic band gap of 141 nm is obtained by electric switching of a partly polymerized chiral liquid crystal. The devices feature high reflectivity in the photonic band gap without any noticeable degradation or disruption and have response times of 50 µs and 20 µs for switching on and off. The device consists of a mixture of photo-polymerizable liquid crystal, non-reactive nematic liquid crystal and a chiral dopant that has been polymerized with UV light. We investigate the influence of the amplitude of the applied voltage on the width and the depth of the reflection band.
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Serbina MI, Kasian NA, Lisetski LN. Helical twisting in nemato-cholesteric systems based on cholesterol derivatives and photosensitive azoxy compounds. CRYSTALLOGR REP+ 2013. [DOI: 10.1134/s1063774512060119] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Inoue Y, Yoshida H, Inoue K, Shiozaki Y, Kubo H, Fujii A, Ozaki M. Tunable lasing from a cholesteric liquid crystal film embedded with a liquid crystal nanopore network. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2011; 23:5498-5501. [PMID: 22081506 DOI: 10.1002/adma.201102764] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2011] [Revised: 09/05/2011] [Indexed: 05/31/2023]
Abstract
Continuous tuning of lasing wavelength is achieved in cholesteric liquid crystal lasers by embedding a network of nanopores with an average size of 10 nm filled with liquid crystals inside a polymerized matrix with helical order. The device possesses both high transparency and a fast response time because the tuning is driven by local reorientation of the liquid crystal molecules in the nanopores.
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Affiliation(s)
- Yo Inoue
- Department of Electrical, Electronic and Information Engineering, Osaka University, Suita, Japan
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White TJ, McConney ME, Bunning TJ. Dynamic color in stimuli-responsive cholesteric liquid crystals. ACTA ACUST UNITED AC 2010. [DOI: 10.1039/c0jm00843e] [Citation(s) in RCA: 235] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Matsuhisa Y, Huang Y, Zhou Y, Wu ST, Takao Y, Fujii A, Ozaki M. Cholesteric liquid crystal laser in a dielectric mirror cavity upon band-edge excitation. OPTICS EXPRESS 2007; 15:616-622. [PMID: 19532283 DOI: 10.1364/oe.15.000616] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Low threshold laser action of dye-doped cholesteric liquid crystals (CLCs) is demonstrated using an input circularly polarized light whose handedness is the same as the cholesteric helix of the sample at the high-energy band edge of the reflection band. The mechanism originates from the dramatic increase of the photon density of state at the band edges. We also demonstrate an enhanced laser action of a CLC in a dielectric multilayer cavity. In such a device configuration, the band-edge excitation at high-energy band edge improves the lasing performance not only for the same handedness circularly polarized pump beam as the cholesteric helix but also for the opposite one. It stems from the polarization independence of the dielectric multilayers.
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