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Electro-Optical and Dielectric Responses of ZnO Nanoparticles Doped Nematic Liquid Crystal in In-Plane Switching (IPS) Mode
摘要： In present work, electro-optical and dielectric characteristics of ZnO nanoparticles (NPs) doped nematic liquid crystal mixture are studied in In-Plane Switching (IPS) mode. Effect of doping of ZnO nanoparticles on phase transition behaviour, threshold and operating voltage were studied. Polarising Optical Microscope (POM) study confirms a reduction in nematic to isotropic (N-I) phase transition temperature after doping of ZnO NPs. A decrease in threshold and operating voltages with better contrast ratio was observed. Further, a significant change in dielectric behaviour of NLC was also perceived in doped sample.
关键词： ZnO nanoparticles,threshold voltage,nematic liquid crystals,In-plane switching,inter-digital electrodes
更新于2025-09-12 10:27:22
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Electrically tunable multicolored filter using birefringent plasmonic resonators and liquid crystals
摘要： Dynamic tuning of color filters finds numerous applications including displays or image sensors. Plasmonic resonators are sub–wavelength nanostructures which can tailor the phase, polarization and amplitude of the optical field but they are limited in color vibrancy when used as filters. In this work, birefringence–induced colors of plasmonic resonators and a fast switching thin liquid crystal cell are combined in a multicolored electrically tunable filter. With this mechanism, the color gamut of the plasmonic surface and the liquid crystal cell is mutually enhanced in order to generate all primary additive and subtractive colors with high saturation as well as different tones of white. A single filter is able to cover more than 70% of the color gamut of standard RGB filters by applying a voltage ranging between 2V and 6.5V. This spectral selectivity is added in transmission without any loss in the image resolution. The presented approach is foreseen to be implemented in a variety of devices including miniature sensors or smart-phone cameras to enhance the color information, ultra–flat multispectral imagers, wearable or head–worn displays as well as high resolution display panels.
关键词： liquid crystals,color display,nanoimprint lithography,multispectral imaging,Plasmonic colors,tunable filters
更新于2025-09-12 10:27:22
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Electrostatically controlled surface boundary conditions in nematic liquid crystals and colloids
摘要： Differing from isotropic fluids, liquid crystals exhibit highly anisotropic interactions with surfaces, which define boundary conditions for the alignment of constituent rod-like molecules at interfaces with colloidal inclusions and confining substrates. We show that surface alignment of the nematic molecules can be controlled by harnessing the competing aligning effects of surface functionalization and electric field arising from surface charging and bulk counterions. The control of ionic content in the bulk and at surfaces allows for tuning orientations of shape-anisotropic particles like platelets within an aligned nematic host and for changing the orientation of director relative to confining substrates. The ensuing anisotropic elastic and electrostatic interactions enable colloidal crystals with reconfigurable symmetries and orientations of inclusions.
关键词： colloids,nematic alignment,liquid crystals,surface boundary conditions,electrostatic control
更新于2025-09-12 10:27:22
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Plasmonic Metamaterial Gels with Spatially Patterned Orientational Order via 3D Printing
摘要： Optical properties can be programmed on mesoscopic scales by patterning host materials while ordering their nanoparticle inclusions. While liquid crystals are often used to define the ordering of nanoparticles dispersed within them, this approach is typically limited to liquid crystals confined in classic geometries. In this work, the orientational order that liquid crystalline colloidal hosts impose on anisotropic nanoparticle inclusions is combined with an additive manufacturing method that enables engineered, macroscopic three-dimensional (3D) patterns of co-aligned gold nanorods and cellulose nanocrystals. These gels exhibit polarization-dependent plasmonic properties that emerge from the unique interaction between the host medium’s anisotropic optical properties defined by orientationally ordered cellulose nanocrystals, from the liquid crystal’s gold nanorod inclusions, and from the complexity of spatial patterns accessed with 3D printing. The gels’ optical properties that are defined by the interplay of these effects are tuned by controlling the gels’ order, which is tuned by adjusting the gels’ cellulose nanocrystal concentrations. Lithe optical responsiveness of these composite gels to polarized radiation may enable unique technological applications like polarization-sensitive optical elements.
关键词： liquid crystals,optical properties,nanoparticles,plasmonic properties,cellulose nanocrystals,gold nanorods,3D printing
更新于2025-09-12 10:27:22
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Reversible LED controlled optical activity of a cholesteric liquid crystal layer
摘要： A thin layer of the photosensitive cholesteric liquid crystal possessing a high value of the optical activity is studied. Reversible change in the optical activity controlled by two light emission diodes (LEDs) with different emission wavelengths is applied for information recording. The behavior of this structure under exposure to UV and blue light is investigated. A smooth decrease in optical activity caused by the UV light resulting in a change in the color of the structure between crossed polarizers is obtained. The reverse process occurs under exposure to the blue light. On the basis of the obtained results, two methods of optical information recording in such a layer have been demonstrated.
关键词： information recording,optical activity,cholesteric liquid crystals
更新于2025-09-12 10:27:22
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Monte Carlo Study of Slot-waveguide Liquid Crystal Phase Shifters
摘要： We present detailed Monte Carlo simulations of a simple model of a nematic liquid crystal slot waveguide shifter, investigating the effect of an applied electric external field. The simulations are based on the Lebwohl-Lasher lattice spin model with boundary conditions chosen to mimic the planar alignment as in Silicon Organic Hybrid waveguides anchoring appropriate for Polydimethylsiloxane polymer walls. The external field is modeled by adding a term to the Hamiltonian which describes its coupling to the mesogenic molecules. We have investigated the effect of the external field on the optical transmission and the ordering across the cell.
关键词： Monte Carlo,confined nematic liquid crystals,anchoring,waveguide shifters
更新于2025-09-12 10:27:22
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Thermally tunable and electrically switchable solid sphere shell three-layer 3D Bragg microcavity laser based on cholesteric-liquid-crystals
摘要： This letter reports a thermally tunable and electrically switchable three-layer 3D Bragg resonance cavity consisting of dye-doped cholesteric-liquid-crystal (DDCLC) microdroplet, polyglycerol-2 and hollow-glass-microsphere (HGM). The whispering-gallery-mode and photonic bandgap mode can be controlled by varying the CLC refractive indices in HGM. The effects of the temperature and electric field on the peaks wavelengths were studied. The study results present the prospect of thermally and electrically controlled the output mode of the microlaser and such solid shell tunable DDCLC microsphere lasers have an outstanding potential applications in integrated microlasers, tunable optical devices and highly sensitive sensor.
关键词： thermally tunable,cholesteric-liquid-crystals,electrically switchable,3D Bragg microcavity,microlaser
更新于2025-09-11 14:15:04
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[IEEE 2019 IEEE International Symposium on Antennas and Propagation and USNC-URSI Radio Science Meeting - Atlanta, GA, USA (2019.7.7-2019.7.12)] 2019 IEEE International Symposium on Antennas and Propagation and USNC-URSI Radio Science Meeting - Measurement of Dielectric Constants of Liquid Crystals Using Double-Ridged Waveguide Cavity
摘要： Liquid crystals (LCs) are widely used in reconfigurable microwave devices for their voltage tunable dielectric constant and loss. For the design of materials and devices, accurate measurements of the complex permittivity of LCs are required. This paper presents a method of performing microwave characterizations of LCs using a double ridged waveguide cavity and the perturbation method. To realize the broadband test and make operating frequency points distribute uniformly, the multi-mode technique is introduced and 6 modes (TE1,0,2n-1,n= 1, 2, 3, 4, 5, 6) are chosen as operating modes to work at 5-22 GHz by one cavity. Besides, the sample loading area in the double-ridged waveguide cavity is much smaller and the sample volume required is only about 0.02 ml. Several LCs are measured: a certain commercial mixture MM (Merck), and M1~M3, as developed LC compositions with large dielectric anisotropy and low microwave losses.
关键词： perturbation method,liquid crystals,complex permittivity,multi-mode
更新于2025-09-11 14:15:04
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Self-Assembled Asymmetric Microlenses for Four-Dimensional Visual Imaging
摘要： Visual imaging that can extract three-dimensional (3D) space or polarization information on the target is essential in broad sciences and technologies. The simultaneous acquisition of them usually demands expensive equipment and sophisticated operations. Therefore, it is of great significance to exploit convenient approaches for four-dimensional (3D and polarization) visual imaging. Here, we present an efficient solution based on self-assembled asymmetric liquid crystal microlenses, with freely manipulated phase profiles and symmetry-breaking properties. Accordingly, characteristics of multi-focal functionality and polarization selectivity are exhibited, along with the underlying mechanisms. Moreover, with a specific sample featured by radially increased unit sizes and azimuthally varied domain orientations, the discriminability of four-dimensional information is extracted in a single snapshot, via referring to the coordinates of the clearest images. Demultiplexing of depth/polarization information is also demonstrated. This work will unlock a variety of revolutionary apparatuses and lighten extensive applications.
关键词： polarization detection,liquid crystals,visual imaging,microlens array,self-assembly
更新于2025-09-11 14:15:04
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Electrically Controlled Self-Focusing and Self-Localization in the Guided Channels
摘要： In this paper, we demonstrate the potential of liquid crystals (LCs) on the applications of small, simple, and tunable optical guided channels. Experimental results show that three operation modes of beam coupling can be achieved, depending on the feature of the electrically controllable refractive index, the incident position, and the specific design of electrodes. The dependence of the beam polarization on self-focusing and coupling effect are also discussed. The electrically controllable self-focusing and beam coupling are highly potential on integrated photonic circuits.
关键词： electrically controllable,self-focusing,liquid crystals (LCs),beam coupling,guided channels
更新于2025-09-11 14:15:04