- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Liquid Crystal Tunable Dielectric Metamaterial Absorber in the Terahertz Range
摘要： In this paper, we propose a tunable dielectric metamaterial absorber in the terahertz (THz) range. The absorber is composed of a silicon pillar array embedded in a liquid crystal (LC) layer, which is sandwiched by two graphene electrodes. By way of varying the applied bias, the LC orientation can be continuously tuned. At a saturated bias, all LCs are vertically driven, and an absorption peak of 0.86 is achieved at 0.79 THz. When the bias is turned off, the same LCs are horizontally aligned, and the absorption peak degenerates into two smaller ones. A 47% modulation depth at 0.79 THz is obtained via numerical simulation with experimental feasibility considered. Such an active THz dielectric absorber may be utilized as part of various active THz apparatuses in THz imaging, sensing, switching, and filtering.
关键词： liquid crystal,metamaterial,dielectric absorber,terahertz,tunable
更新于2025-09-04 15:30:14
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Semi-fluorinated p-terphenyl liquid crystals
摘要： p-Terphenyls carrying two or four fluorine atoms in the central ring were synthesized via Suzuki-Miyaura cross-coupling reaction using phenylboronic acids and fluorinated dibromobenzenes. By calorimetric and X-ray diffraction analyses it was found that the p-terphenyls carrying two fluorine atoms develop nematic and/or smectic (A and C) phases. On the contrary, the p-terphenyls substituted with four fluorine atoms are not liquid crystals. Differences found in the thermal behavior are explained in terms π – πF interactions arising from the electron withdrawing ability of the fluorine atom. Such π – πF interactions let the p-terphenyls stack in a staggered configuration that explains the stability of the smectic C phase. On the other hand, the semi-fluorinated p-terphenyls absorb and emit in the blue region of the electromagnetic spectrum; a measured large Stokes shift indicates that these compounds are nearly transparent to their own emitted light. This optical characteristic, combined with liquid crystals properties of low order, makes these new p-terphenyls potential candidates for linearly polarized blue-emitting layers in electroluminescent devices.
关键词： Fluorescence,Liquid crystal,p-terphenyl,Fluorine
更新于2025-09-04 15:30:14
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27.2: <i>Invited Paper:</i> True 3D displays for AR applications
摘要： Augmented reality (AR) technology, which integrates virtual computer-generated information into the real world scene, is believed to be the next-generation human-machine interface. However, most AR products adopt stereoscopic 3D display technique, which causes the accommodation-vergence conflict. To solve this problem, we have proposed two approaches. The first is a multi-planar volumetric display using fast switching polymer-stabilized liquid crystal (PSLC) films. By rapidly switching the films between scattering and transparent states while synchronizing with a high-speed projector, the 2D slices of a 3D volume could be displayed in time sequence. We delved into the research on developing high-performance PSLC films in both normal mode and reverse mode; moreover, we also realized the demonstration of four-depth AR images with correct accommodation cues. For the second approach, we realized a holographic AR display using digital blazed gratings and a 4f system to eliminate zero-order and higher-order noise. With a 4k liquid crystal on silicon device, we achieved a field of view (FOV) of 32 deg. Moreover, we designed a compact waveguide- based holographic 3D display. In the design, there are two holographic optical elements (HOEs), each of which functions as a diffractive grating and a Fresnel lens. Because of the grating effect, holographic 3D image light is coupled into and decoupled out of the waveguide by modifying incident angles. Because of the lens effect, the collimated zero order light is focused at a point, and got filtered out. The optical power of the second HOE also helps enlarge FOV.
关键词： 3D display,holographic display,Augmented reality,volumetric display,liquid crystal
更新于2025-09-04 15:30:14
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Tunable Liquid Crystal Based Phase Shifter with a Slot Unit Cell for Reconfigurable Reflectarrays in F-Band
摘要： An electrically tuned phase shifter based on the single slot unit cell and liquid crystal for a reconfigurable reflectarray antenna was presented. The simulation and measured results obtained at the F-band were used to demonstrate that the dielectric properties of a nematic state liquid crystal could be exploited to realize a slot unit cell phase shifter for the reconfigurable reflectarrays antennas. By reducing the inhomogeneous of the external electric field in the liquid crystal layer, a lower control voltage and improved model accuracy was obtained. In the experiments test, the achieved saturation bias voltage (10 V) was smaller than the previously reported structure, and the phase shift of the reflectarray greater than 300? was achieved in the frequency range 121.5–126 GHz. The maximum phase shift of 306? occurred at 124.5 GHz.
关键词： phase shifter,phase control,liquid crystal device,reconfigurable reflectarray
更新于2025-09-04 15:30:14
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Liquid-Crystal-on-Silicon for Augmented Reality Displays
摘要： In this paper, we review liquid-crystal-on-silicon (LCoS) technology and focus on its new application in emerging augmented reality (AR) displays. In the first part, the LCoS working principles of three commonly adopted LC modes—vertical alignment and twist nematic for amplitude modulation, and homogeneous alignment for phase modulation—are introduced and their pros and cons evaluated. In the second part, the fringing field effect is analyzed, and a novel pretilt angle patterning method for suppressing the effect is presented. Moreover, we illustrate how to integrate the LCoS panel in an AR display system. Both currently available intensity modulators and under-developing holographic displays are covered, with special emphases on achieving high image quality, such as a fast response time and high-resolution. The rapidly increasing application of LCoS in AR head-mounted displays and head-up displays is foreseeable.
关键词： head-mounted displays,fringing field effect,augmented reality displays,head-up displays,liquid-crystal-on-silicon
更新于2025-09-04 15:30:14
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Method for Mueller matrix acquisition based on a division-of-aperture simultaneous polarimetric imaging technique
摘要： The Mueller matrix is an important parameter in the field of polarization optics, and how to measure it efficiently and accurately becomes considerably significant for its practical applications. In this paper, for the first time to our knowledge, we propose a new method for Mueller matrix acquisition based on a division-of-aperture simultaneous polarimetric imaging technique. Different from the traditional method where, for obtaining the 16 elements of the Mueller matrix, a 16-times-measurement must be conducted by jointly changing the states of polarization (SOPs) of the input and output lights, while in our method it is enough by just changing the SOPs of the input light 4 times. This time-saving and easy-calculating feature is owing to our specific polarimetric camera, where a full-Stokes vector is obtained easily since 3 linear SOPs (0o, 45o, 90o) and 1 circular SOP can be recorded simultaneously by spatially sharing the same detector. To simply verify the effectiveness of our method, a specific polarization device patched by 8 sub-polarizers is chosen as the sample to be measured. Experimental results show that they are consistent with the theoretical results, both in the Mueller matrix and the corresponding images. We predict that this method for Mueller matrix acquisition can get wide potential applications for rapid identifications in biomedicine and material science.
关键词： Division-of-aperture polarimetric camera,Mueller matrix,Liquid crystal variable retarder,Polarization
更新于2025-09-04 15:30:14
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[IEEE 2018 International Conference on Microwave and Millimeter Wave Technology (ICMMT) - Chengdu, China (2018.5.7-2018.5.11)] 2018 International Conference on Microwave and Millimeter Wave Technology (ICMMT) - Ku-Band Liquid-Crystal-Based Frequency Reconfigurable Comb SIW Slot Leaky-Wave Antenna
摘要： In this paper, based on liquid crystal anisotropy characteristics, a kind of frequency reconfigurable comb substrate integrate waveguide slot leaky-wave antenna use liquid-crystal-based is proposed at Ku band. It adopt comb shape and defected ground structure to compose comb SIW’s top and bottom. The slots are etched at top and bottom surface. The resonant point of propose antenna move from 15.85GHz to 14.37GHz, the tunable range is 1.5GHz by changing liquid crystal’s permittivity. Return loss less than -30dB at resonant point and the maximum gain is 8.79dB. The bandwidth of proposed antenna is 1 GHz. All the results show the reconfigurable of proposed antenna is good.
关键词： leaky-wave antenna,reconfigurable,comb substrate integrate waveguide,liquid crystal
更新于2025-09-04 15:30:14