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Development of a liquid crystal laser using a simple cubic liquid crystalline blue phase platform
摘要： A liquid crystal laser using a polymer-stabilized simple cubic blue phase (BPII) platform has been scarcely reported because the polymer stabilization of a BPII is relatively di?cult compared to that of a body-centered-cubic BP (BPI). In this study, we succeeded in fabricating a dye-doped polymer-stabilized BPII laser with wide operating-temperature ranges over 15 (cid:1)C including room temperature. A narrow and sharp single laser peak with a full width at half maximum of approximately 2 nm was derived from the photonic band edge e?ect of the BPII-distributed feedback optical resonator. As a result, the laser emission was a circularly polarized light, which matched the chirality of the proposed pure BPII.
关键词： liquid crystal laser,circularly polarized light,photonic band edge effect,polymer-stabilized,BPII,simple cubic blue phase
更新于2025-09-16 10:30:52
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[IEEE 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Huangshan, China (2019.8.5-2019.8.8)] 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Liquid Crystal Tunable Narrow Linewidth Filter Based On Subwavelength Gratings Reflector
摘要： We present a electro-tunable liquid crystal (LC) filter consisting of a DBRs and SWGs reflectors which enables uniform alignment of LC. The filter achieve a wide-continuous tuning range of 60 nm and a linewidth of less than 1 nm.
关键词： optical microcavity,subwavelength grating,liquid crystal,tunable
更新于2025-09-16 10:30:52
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Reconfigurable resonator in decoupled empty SIW technology using liquid crystal material
摘要： This Letter presents a novel continuously tunable microwave resonator based on liquid crystal (LC) material. The recon?gurable device is implemented in Decoupled Empty Substrate Integrated Waveguide (DESIW) technology. DESIW technology allows both magnetic and electric DC (or low frequency) biasing of the LC. The resonator is continuously tunable in a range of 600 MHz, resulting in a measured tunability range of 8.5% around a centre frequency of 7 GHz. Moreover, the measured insertion loss of the recon?gurable device is between 4.3 and 6.8 dB, thus obtaining a Q-factor of 190-172.
关键词： Q-factor,tunable,liquid crystal,microwave resonator,DESIW technology
更新于2025-09-16 10:30:52
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Determination of Phase Transition and Electro-optical Behaviors of Quantum Dot Doped Polymer Dispersed Liquid Crystal
摘要： This paper describes our research into phase transition, electro-optical and dielectric behaviors of polymer dispersed liquid crystal (PDLC) and cadmium selenide sulphide/zinc sulphide quantum dot (QD) doped PDLC (PDLC/QD). The PDLC was prepared with nematic liquid crystal (E63) and UV-curable photopolymer (NOA65) by using a polymerization induced phase separation technique. Dielectric properties of composites were investigated with a dielectric/impedance analyzer at 1 kHz–10 MHz frequency range. Electro-optical measurements of investigated samples were carried out using an electro-optical switching method. Phase transition temperature of PDLC and PDLC/QD composites was also determined, using a differential scanning calorimeter. The results showed that the introduction of QD signi?cantly changes the physical properties of PDLC, and these changes could become a focus of interest for future applications.
关键词： quantum dot,electro-optical and dielectric behaviors,Polymer dispersed liquid crystal,phase transition
更新于2025-09-16 10:30:52
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Propagating transverse electric and transverse magnetic modes in liquid crystal-clad planar waveguides
摘要： In a planar dielectric waveguide, weak con?nement of a propagating mode in a high index core leads to a measurable evanescent interaction with the cladding. In this work, we study the e?ect of a reorientable anisotropic cladding on the behaviour of Transverse Electric (TE) and Transverse Magnetic (TM) mode polarisations using a liquid crystal (LC)-clad waveguide architecture. The polarised evanescent ?eld of a guided mode interacts with a voltage-tunable birefringent LC cladding to de?ect an out-coupled beam. Experimental measurements are coupled with a theoretical framework and show good consistency with simulation results. We isolate the e?ect of mode con?nement by changing the thickness of the high index core. Interactions between the LC index ellipsoid and the mode polarisation are probed by changing the initial alignment of the LC. Finally, we examine the di?erence in de?ection between TE and TM modes, which incorporates both a change in mode con?nement and a di?erence in LC index components.
关键词： planar waveguides,Liquid crystal,polarization,waveguides,liquid crystal devices
更新于2025-09-12 10:27:22
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Emergent biaxiality in nematic microflows illuminated by a laser beam
摘要： Anisotropic fluids (e.g. liquid crystals) offer a remarkable promise as optofluidic materials owing to the directional, tunable, and coupled interactions between the material, flow, and the optical fields. Here we present a comprehensive in silico treatment of this anisotropic interaction by performing nonequilibrium molecular dynamics simulations. We quantify the response of a nematic liquid crystal (NLC) undergoing a Poiseuille flow in the Stokes regime, while being illuminated by a laser beam incident perpendicular to the flow direction. We adopt a minimalistic model to capture the interactions, accounting for two features: first, the laser heats up the NLC locally; and second, the laser polarises the NLC and exerts an optical torque that tends to reorient molecules of the nematic phase. Because of this reorientation the liquid crystal exhibits small regions of biaxiality, where the nematic director is one symmetry axis and the axis of rotation for the reorientation of the molecules is the other one. We find that the relative strength of the viscous and the optical torques mediates the flow-induced response of the biaxial regions, thereby tuning the emergence, shape and location of the regions of enhanced biaxiality. The mechanistic framework presented here promises experimentally tractable routes toward novel optofluidic applications based on material-flow-light interactions.
关键词： optofluidics,Liquid crystal,biaxiality,nematic phase,nonequilibrium molecular dynamics
更新于2025-09-12 10:27:22
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[IEEE 2019 IEEE MTT-S International Microwave Workshop Series on Advanced Materials and Processes for RF and THz Applications (IMWS-AMP) - Bochum, Germany (2019.7.16-2019.7.18)] 2019 IEEE MTT-S International Microwave Workshop Series on Advanced Materials and Processes for RF and THz Applications (IMWS-AMP) - Characterization of Liquid Crystals Using a Temperature-Controlled 60 GHz Resonator
摘要： This paper presents a resonant liquid crystal (LC) characterization at 60 GHz using a temperature controlled automated measurement setup. For the measurements the resonator is perturbed with LC inside a thin silica quartz tube. The LC orientation is accomplished by means of permanent rare earth magnets. Measurements are performed at 20 ?C. The investigated LC is the GT3-23001 mixture from Merck KGaA. The extracted values are compared with characterization results at 19 GHz. The extracted permittivities are ranging from 3.14 to 2.43 and the loss tangents from 0.0035 to 0.0191 for parallel and orthogonal orientation, respectively.
关键词： microwave measurements,material characterization,resonator,liquid crystal,millimeter wave
更新于2025-09-12 10:27:22
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Green and red phosphor for LED backlight in wide color gamut LCD
摘要： Wide color gamut (WCG) backlight for liquid crystal display (LCD) utilizing white light-emitting diodes (LED) has attracted considerable attention for their high efficiency and color reduction. In this review, recent developments in crystal structure, luminescence and applications of phosphors for wide color gamut LED backlight are introduced. As novel red phosphors, Mn4+ activate fluoride and aluminate phosphors are advanced in quantum efficiency, thermal quenching and color saturation for their characteristic spectrum with broad excitation band and linear emission. The crystal structure and fluorescence properties of Mn4+ doped fluosilicate, fluorogermanate, fluotitanate, as well as Sr4Al14O25, CaAl12O19 and BaMgAl10O17 phosphors are discussed in detail. A serial of narrow-band red-emitting Eu2+, Eu3+ and Pr3+-doped nitride silicates and molybdate phosphors are also introduced. Rare-earth-doped oxynitride and silicate green-emitting phosphors have attracted more and more attention because of the wide excitation, narrow emission, high quenching temperature, high quantum efficiency, such as β-sialon:Eu2+, Ba3Si6O12N2:Eu2+, MSi2O2N2:Eu2+ (M=Ca, Sr, Ba), γ-AlON: Mn2+ and Ca3Sc2Si3O12:Ce3+. All above phosphors demonstrate their adaptability in wide color gamut LCD display. Especially for Mn4+ doped fluosilicate red phosphor and β-sialon: Eu2+ green phosphor. To achieve an ultra-high color gamut in white LED backlight and against the OLED, innovative narrow-band emission red and green phosphor materials with independent intellectual property rights are continuously pursed.
关键词： Rare earths,Liquid crystal display,Backlight,Wide color gamut,White LED,Phosphor
更新于2025-09-12 10:27:22
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[IEEE 2019 IEEE/MTT-S International Microwave Symposium - IMS 2019 - Boston, MA, USA (2019.6.2-2019.6.7)] 2019 IEEE MTT-S International Microwave Symposium (IMS) - Liquid Crystal Phase Shifter Based on Nonradiative Dielectric Waveguide Topology at W-Band
摘要： This paper presents a continuously tunable nonradiative dielectric waveguide (NRD) phase shifter based on liquid crystal (LC) technology at W-band. LC is inserted in the NRD’s dielectric core to obtain tunability. Compared to other dielectric waveguides, which are prone to radiation losses, the NRD is radiation free even at bends and discontinuities. A maximum differential phase shift of 280? was achieved with an electric biasing voltage of ±150 V, accompanied with insertion losses between 2.9 dB to 4.9 dB, resulting in a maximum Figure-of-Merit of 85 ?/dB.
关键词： millimeter wave devices,tunable circuits and devices,phase shifter,Liquid crystal,nonradiative dielectric waveguide
更新于2025-09-12 10:27:22
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Light-fuelled freestyle self-oscillators
摘要： Self-oscillation is a phenomenon where an object sustains periodic motion upon non-periodic stimulus. It occurs commonly in nature, a few examples being heartbeat, sea waves and fluttering of leaves. Stimuli-responsive materials allow creating synthetic self-oscillators fuelled by different forms of energy, e.g. heat, light and chemicals, showing great potential for applications in power generation, autonomous mass transport, and self-propelled micro-robotics. However, most of the self-oscillators are based on bending deformation, thereby limiting their possibilities of being implemented in practical applications. Here, we report light-fuelled self-oscillators based on liquid crystal network actuators that can exhibit three basic oscillation modes: bending, twisting and contraction-expansion. We show that a time delay in material response dictates the self-oscillation dynamics, and realize a freestyle self-oscillator that combines numerous oscillation modes simultaneously by adjusting the excitation beam position. The results provide new insights into understanding of self-oscillation phenomenon and offer new designs for future self-propelling micro-robots.
关键词： Twisting,Bending,Micro-robotics,Contraction-expansion,Liquid crystal network actuators,Light-fuelled,Self-oscillation
更新于2025-09-12 10:27:22