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Optical-trapping of a red Bessel beam controlled by co-propagating green Gaussian beam in azobenzene liquid crystal
摘要： Simultaneous co-propagation of red nondiffracting Bessel beam and green Gaussian beam at milliwatt powers in a photosensitive azobenzene liquid crystal has been studied. The fine displacement of the narrow-width Gaussian beam relative to the Bessel beam central maximum showed the Bessel beam distortion and controlled bending of its core in the direction opposite to the location of green Gaussian beam. After switching off the green beam, the dynamics of restoration of Bessel beam demonstrated the pronounced optical-trapping feature of its central core and transient soliton-like propagation with reduced diameter and increased intensity and propagation depth thus forming a waveguiding channel.
关键词： spatial soliton,Bessel beam,self-focusing,azobenzene liquid crystal,photo-isomerization
更新于2025-09-11 14:15:04
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Evaluation of Energy and Daylight Performance of Old Office Buildings in South Korea with Curtain Walls Remodeled Using Polymer Dispersed Liquid Crystal (PDLC) Films
摘要： Globally, energy standards for new buildings are being reinforced to improve energy efficiency, and remodeling policies are being promoted for old buildings. The South Korean Government is promoting green remodeling projects, and focusing on research and product development to improve the performance of old windows and curtain walls. In line with this, the present study proposes two remodeling methods using polymer dispersed liquid crystal (PDLC) films, which can adjust solar radiation for old office buildings. In addition, energy efficiency improvement and daylight performance according to remodeling were analyzed. Attaching PDLC films to the glass of old curtain walls was analyzed; this can reduce heating and cooling energy, reduce the annual discomfort glare occurrence rate, and increase the annual indoor appropriate illuminance ratio. Furthermore, producing a window by laminating a PDLC film between two sheets of glass and putting it over the existing curtain wall was also analyzed; this can reduce annual building energy consumption and the annual discomfort glare occurrence rate, and improve the annual indoor appropriate illuminance ratio. Therefore, PDLC film is expected to be applicable as a next-generation green remodeling material because using it in remodeling can improve energy efficiency of old office buildings and indoor daylight performance.
关键词： EnergyPlus,polymer dispersed liquid crystal,green remodeling,building energy efficiency
更新于2025-09-11 14:15:04
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Effect of fluorinated achiral chain length on structural, dielectric and electro-optic properties of two terphenyl based antiferroelectric liquid crystals
摘要： Two antiferroelectric liquid crystals of different fluorinated chain length have been studied. Although both exhibit antiferroelectric (SmCA*), ferroelectric (SmC*) and paraelectric (SmA*) phases, melting point decreases with increasing achiral chain length but clearing point shows opposite trend. Thermal ranges of SmCA* and SmC* phases exhibit odd-even effect like the dipole moments and spontaneous polarization. Layer spacings, average intermolecular distances and correlation lengths across the smectic planes also increase with chain length. Temperature dependence of layer spacings, x-ray tilt, optical tilt and spontaneous polarization suggest tricritical nature of SmC*–SmA* transition. Dielectric increments decrease with increased achiral chain. Both soft mode and Goldstone mode critical frequencies decrease with decreasing temperature in the lower derivative but opposite behaviour is observed in the higher derivative. Both the compounds show Curie–Weiss behaviour in soft mode near SmC*–SmA* transition temperature (Tc). Goldstone mode critical frequency is much higher in the higher derivative. Both in-phase and anti-phase antiferroelectric modes are observed in SmCA* phase in the higher derivative but in the lower derivative only anti-phase antiferroelectric mode is observed. Optical tilts suggest orthoconic nature of the SmCA* phase of both the compounds. Ferroelectric-antiferroelectric transition temperature decreases with increasing ac field in both compounds.
关键词： Dielectric increment,Switching time,Spontaneous polarization,Orthoconic antiferroelectric liquid crystal,Critical frequency
更新于2025-09-11 14:15:04
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Effect of CdSeS/ZnS quantum dot concentration on the electro-optical and dielectric properties of polymer stabilized liquid crystal
摘要： Our research paper has been discussed electro-optical and dielectric characterization of polymer stabilized liquid crystal (PSLC) and its doped form with different concentration of CdSeS/ZnS quantum dot (QD). PSLC composite was prepared using a nematic liquid crystal (E63) and Poly(methyl methacrylate) (PMMA) polymer. In order to improve physical properties, composites were dispersed with different concentration of CdSeS/ZnS QD. The electro-optical and dielectric properties of the composites were investigated depending on the frequency and voltage. Considerable physical parameters such as threshold voltage, dielectric anisotropy, relaxation frequency and response time were obtained from the experimental data. The results show that QD contribution and polymer networks change the electro-optical and dielectric properties of PSLC and these can become a focus of interest for new applications of PSLC composites in the future.
关键词： polymer network,quantum dot,dielectric properties,Polymer stabilized liquid crystal
更新于2025-09-11 14:15:04
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Effect of molecular weight of side chain liquid crystalline polymers on properties of liquid crystal physical gels
摘要： A series of side chain liquid crystalline polymers (SCLCPs) poly[ω-4′-cyano-(1, 1′-biphenyl)] acrylate (P0ACB) with di?erent molecular weight were prepared and used as gelator to fabricate liquid crystalline physical gels (LCPGs). The relationship between molecular weight of side chain liquid crystalline polymers and the properties of liquid crystalline physical gels were also discussed in detail. Testing results showed that when the molecular weight of polymers was less than 3.61 × 104, the minimum gelation concentration (MGC) of liquid crystalline physical gels decreased from 3 wt% to 0.2 wt% and gel-sol phase transition temperature (TGS) increased from 99 °C to 185 °C with increasing molecular weight. The driving voltage and contrast ratio increased obviously and the o? state response time decreased with increasing molecular weight. However, when the molecular weight of polymers was greater than 3.61 × 104, the stability and the electro-optical response properties of the liquid crystalline physical gels basically unchanged. The mechanical properties of liquid crystalline physical gels were a?ected signi?cantly by the molecular weight of polymers. The energy storage modulus of liquid crystalline physical gels increased from 1.6 × 103 Pa to 3.1 × 104 Pa with increasing molecular weight when the gelator concentration is 6.0 wt%.
关键词： Side chain liquid crystalline polymers,Liquid crystal physical gels,Molecular weight,Electro-optical response properties,Thermal stability
更新于2025-09-10 09:29:36
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Mitigation of Image Blurring for Performance Enhancement in Transparent Displays Based on Polymer-Dispersed Liquid Crystal
摘要： In this paper, we propose an effective real-time image enhancing technology for transparent displays based on polymer-dispersed liquid crystal (PDLC). The image enhancing technology consists of both global and local enhancement functions. It not only removes the affected haze but also sharpens the edge regions for transparent PDLC displays. This technology can improve the image quality such as contrast, brightness, color saturation, and gamma correction for transparent PDLC displays. The experimental results indicated that our proposed method can effectively enhance the visibility and remove the affected haze in the transparent PDLC display.
关键词： polymer-dispersed liquid crystal (PDLC),Image enhancing technology,transparent display
更新于2025-09-10 09:29:36
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Optical control of polarized terahertz waves using dye-doped nematic liquid crystals
摘要： We propose an optically tunable terahertz (THz) polarization converter based on use of a dye-doped nematic liquid crystal (LC). The dye-doped LC exhibits a photothermally-induced nematic-isotropic phase transition under irradiation by a laser beam with a wavelength that lies within the absorption band of the dye. We investigate the transmission spectra and the polarization-conversion properties of the dye-doped LC cell with twisted alignment using THz time-domain spectroscopy. The polarization state of a THz wave transmitted through the proposed dye-doped LC cell can be controlled using the laser beam irradiation based on the photothermal effect. The experimental results also demonstrate that optical control of this dye-doped LC cell offers an advantage in terms of response speed when compared with voltage-based control of LC cells via their electrodes. The dye-doped LC proposed in this study presents the possibility that a variety of LC-based THz elements with optical tunability may be realized.
关键词： terahertz,polarization converter,liquid crystal,optical control,photothermal effect
更新于2025-09-10 09:29:36
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Self-Assembly Behavior of an Oligothiophene-Based Conjugated Liquid Crystal and Its Implication for Ionic Conductivity Characteristics
摘要： In this work, a joint experimental and computational study on the synthesis, self-assembly, and ionic conduction characteristics of a new conjugated liquid crystal quaterthiophene/poly(ethylene oxide) (PEO4) consisting of terminal tetraethyleneglycol monomethyl ether groups on both ends of a quaterthiophene core is performed. In agreement with molecular dynamic simulations, temperature-dependent grazing-incidence wide angle X-ray scattering and X-ray diffraction indicate that the molecule spontaneously forms a smectic phase at ambient temperature as characterized both in bulk and thin film configurations. Significantly, this smectic phase is maintained upon blending with bis(trifluoro-methanesulfonyl)imide as ion source at a concentration ratio up to r = [Li+]/[EO] = 0.05. Nanosegregation between oligothiophene and PEO moieties and π–π stacking of thiophene rings lead to the formation of efficient 2D pathways for ion transport, resulting in thin-film in-plane ionic conductivity as high as 5.2 × 10?4 S cm?1 at 70 °C and r = 0.05 as measured by electrochemical impedance spectroscopy. Upon heating the samples above a transition temperature around 95 °C, an isotropic phase forms associated with a pronounced drop in ionic conductivity. Upon cooling, partial and local reordering of the conducting smectic domains leads to an ionic conductivity decrease compared to the as-cast state.
关键词： oligothiophene,self-assembly,liquid crystal,ionic conductivity,π–π interactions
更新于2025-09-10 09:29:36
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Investigations of dual-frequency nematic liquid crystals doped with dichroic dye
摘要： In this work, we studied and analysed a particular variety of liquid crystals, the so-called dual-frequency nematic liquid crystals (DFNLCs). The interest was to perform dielectric spectroscopy and optical characterisation with two pure and doped mixtures of DFNLCs. By means the dielectric spectroscopy we observed a low value of crossover frequency at room temperature for one dye doped mixture. Additionally, in the spectra studies, a scattering of light at cross-frequency, and a stable and unstable focal conical state was observed, respectively, for the investigated mixtures.
关键词： relaxation frequency,crossover frequency,dielectric spectroscopy,optical characterisation,Dual-frequency liquid crystal
更新于2025-09-10 09:29:36
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State transition at electrohydrodynamic convection of twisted nematic liquid crystals
摘要： We study electrohydrodynamic convection (EHC) patterns in twisted nematic liquid crystal (TNCL) cells with an initial homeotropic alignment. In addition, we demonstrate switching characteristics due to the transition between the 90° and ?90? twisted states. The pattern formations are similar to those obtained in a parallel-aligned nontwisted liquid crystal cell. Calculations of the free energy in an initially, homeotropically aligned TNLC in an electric ?eld demonstrate that the energy barrier between the two states decreases with the increase of the electric ?eld. The mutual transition is caused by the ?uctuating ?ow at the dynamic scattering mode 2, where the energy barrier between the two states is reduced by applying a strong electric ?eld. These properties may be employed for the development of a redirectable dynamic lenticular lens, as an extended version of the dynamic lenticular lens using EHC. The transition between the two states caused by EHC is reversible, and the convection roll pattern of the Williams domain rotates by 90° at each transition.
关键词： state transition,homeotropic alignment,electrohydrodynamic convection,dynamic lenticular lens,twisted nematic liquid crystal
更新于2025-09-10 09:29:36