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1.
液晶光阀的偏光显示特性分析 总被引:2,自引:1,他引:1
讨论了液晶光阀的偏光扭曲向列性效应, 分析了液晶光阀中液晶分子在交流电场作用下重新取向后的扭曲, 测量了TB3639型液晶光阀在特定的频率连续改变外加交流电压条件下,液晶分子重新取向后的扭曲角度以及液晶光阀的电光特性。测量结果表明,在外加电压连续改变时,入射线偏振光的透射率呈现连续非线性变化,这种非线性变化可以由液晶分子的扭曲量来改变。同时液晶分子180°的扭曲使得液晶光阀具有较陡的电光特性曲线,这对于多通道矩阵寻址方式的液晶光阀而言在矩阵显示中可有更多的通道寻址线和更高的对比度。 相似文献
2.
B. Bellini M. A. Geday N. Bennis A. Spadło X. Quintana J. M. Otón R. Dąbrowski 《Opto-Electronics Review》2006,14(4):269-273
Liquid crystal (LC) phased arrays and gratings have been employed in optical switching and routing [1]. These diffractive
optic elements are of great interest because they can be scaled up to a large number of elements and their optical properties
can be electrically addressed with a low driving voltage. LC phase gratings have been achieved either by periodic addressing
of pixels or by using periodically-modified structures. The latter approach leads to less reconfigurable devices but the addressing
is simpler.
In this paper we focus on optical phased arrays where the phase is varied either continuously or discretely and where the
periodicity is induced by electrode configuration. We first describe a possible structure based on a conductive silicon wafer.
We argue that this structure can induce either continuously or discretely varying arrays while applying single voltage to
the array. In the second part we simulate the behaviour of such arrays. We base the simulation on a LC synthesized at the
Military University of Technology, this high-birefringence nematic LC shows in a 4-μm thick cell a linear phase shift range
of more than 360° between 1.2 V and 1.8 V. We calculate the distribution of the LC molecule director and assess the performance
of the array with respect to the applied voltage. Finally, the relevance of such technology for switchable phased arrays is
discussed. 相似文献
3.
We report a new kind of experimental realization of a molecular rectifier, which is based on a single azafullerene C59N molecule in a double-barrier tunnel junction via the single electron tunneling effect. An obvious rectifying effect is observed. The positive onset voltage is about 0.5-0.7 V, while the negative onset voltage is about 1.6-1.8 V. Theoretical analyses show that the half-occupied molecular orbital of the C59N molecule and the asymmetric shift of the molecular Fermi level when the molecule is charged are responsible for the molecular rectification. 相似文献
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5.
T. D. Ibragimov N. J. Ismailov E. A. Allahverdiyev I. S. Hasanov 《Journal of Applied Spectroscopy》2008,75(6):766-770
The possibility for homogeneous orientation of liquid-crystal (LC) molecules was studied after argon-ion bombardment of substrates
(Si, Ge) transparent in the infrared (IR) spectral region. The orientation of the LC molecules was monitored by IR spectroscopy.
Nematic LC 4-methoxybenzylidene-4′-butylaniline (MBBA) was used to study the molecular orientation. Absorption spectra were
analyzed near the band with maximum at 1630 cm−1 corresponding to − CH=N-group vibrations along the long axis of the MBBA molecule. The type and degree of initial orientation
of the LC molecules were determined from the correlation of the integrated absorptions of this band without and with an applied
electric field (above the threshold voltage for the Fredericksz effect). It has been established that an increased ion fluence
results in a planar orientation of the LC molecules and in a gradual transformation of the planar orientation of the molecules
to a homeotropic one with preliminary argon-ion bombardment of substrates at energies of 250 eV and 1.25 keV, respectively.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 6, pp. 763–767, November–December, 2008. 相似文献
6.
In this paper we consider the movement of an electron in the single electron tunnel process through a mesoscopic capacitor. The results show that, due to the Coulomb force, there is a threshold voltage Vt in the mesoscopic LC circuit. When the external voltage is lower than the threshold voltage, the tunnel current value is zero, and the Coulomb blockade phenomenon arises. Furthermore, considering that the mesoscopic dimension is comparable to the coherence length in which charge carriers retain the phase remembrance, a weak coupling can be produced through the proximity effect of the normal metal electrons of both electrodes of a mesoscopic capacitor. By varying the external voltage, we can observe the Shapiro current step on the current-voltage characteristic curve of a mesoscopic LC circuit. 相似文献
7.
D. A. Pan X. F. Wang J. J. Tian S. G. Zhang A. A. Volinsky L. J. Qiao 《Applied Physics A: Materials Science & Processing》2010,100(4):1069-1072
This paper presents the inductance–capacitance (LC) resonance effect in the magnetoelectric (ME) composites characterization
system. The measured magnetoelectric voltage coefficient is significantly affected by the LC resonance at the electromechanical
resonant frequency, but not at 1 kHz, typically reported in the literature. Decreasing the measuring circuit inductance and/or
capacitance helps to reduce the LC resonance effect. While it is impossible to completely eliminate the coil inductance and
capacitance, they should be accounted for by proper circuit balancing. One can accurately calculate the sample intrinsic ME
voltage coefficient knowing L and C of the measuring circuit. This study is helpful for designing and building the ME characterization systems. 相似文献
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Liquid crystals (LC) are anisotropic materials which experience a torque if an electric field is present. This field can be due to an external voltage or to the presence of a light beam. Reorientation due to light leads to non-linear behavior in the optical behavior. Due to this kind of nonlinearity therefore it is possible to generate optical spatial soliton beam in LC by bias voltage or without it and interestingly chiral nematic liquid crystals has a opportunity to generate spatial optical solitons without the need for a bias voltage. In this paper we also demonstrate that a sharp switching of the helix structure occurs when the spatial soliton is launched in the middle of two regions where soliton generation is favorable. Due to the optical nonlinearity, the helical structure becomes asymmetric and a sharp switching in one direction can be obtained. Moreover, in this paper, the torque and reorientation of the liquid crystal and the change in angular momentum of the light are discussed. 相似文献
12.
《Current Applied Physics》2008,8(2):142-145
Voltage-dependent liquid crystal textures in a homeotropically aligned nematic liquid crystal (LC) device, where the chiral-doped liquid crystal with negative dielectric anisotropy is locked by polymer walls with crossed polarizers, have been investigated. The device shows wide viewing angle characteristics with advantages that it is free from rubbing process and spacer. The time-resolved LC textures show that they are not stable enough during an instantaneous reorientation of LC when a voltage is applied. To improve dynamic characteristics, we propose advanced cell structure where the bend and twist deformation is controlled by polymer wall plus an oblique electric field through patterned electrode. Consequently, dynamic characteristics of the device are greatly improved. 相似文献
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14.
Pappu Lakshmi Madhuri Shuddhodana Zaher M. A. Judeh Ibrahim Abdulhalim 《Particle & Particle Systems Characterization》2020,37(5):2000067
A diversity of fascinating hollow and porous micro and nanoparticles are being developed for drug delivery purposes; however, their applications in other systems are barely touched. When filled by an active material, they form a tunable photonic metamaterial. Here, a small concentration of organic hollow cylinders called cochleates embedded into liquid crystals (LCs) is demonstrated to form a new switchable composite to control light scattering with voltage and temperature. The biocompatible cochleates, which are hollow, tube-like, and hydrophilic in nature, can trap the liquid crystal molecules thus altering the system behavior. A switching device as thin as 6 µm with 12 wt% cochleates concentration is shown to be adequate to reveal a switchable privacy window. Possible molecular arrangement of the liquid crystal within the cochleate particles is suggested, and unexpected increase of the scattering with temperature depending on the applied voltage is observed as a result of change in the cochleate aggregation depending on the LC molecule orientation. 相似文献
15.
S.-Y. Huang T.-C. Wung A. Y.-G. Fuh H.-C. Yeh C.-Y. Huang C.-M. Ma S.-C. Huang T.-S. Mo C.-R. Lee 《Applied physics. B, Lasers and optics》2009,97(4):749-752
This work presents an electro- and photo-controllable spatial filter that is based on a liquid crystal (LC) film with a photoconductive
layer. The controllable spatial filter can be formed because of the controllability of the photoelectro-induced screen effect
of the space charge in the LC cell. An applied dc voltage or incident pumped intensity can be controlled to enable different spatial distributions of the diffraction pattern
of the target object to be selected for filtering by the LC cell, such that various reconstructed images can be obtained.
A simulation using Fourier analysis is developed, and its results agree closely with experimental results. Additionally, the
LC spatial filter has the extra advantage of controllable low or high filtering functions: they are controlled by switching
the configuration between normally black and normally white modes. 相似文献
16.
Modified SQUID Operator Equation for a Single-Qubit Structure Coupled to a Quantum Resonator
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Role of self-inductance in superconducting quantum interference device (SQUID) charge qubit is considered. It is found that when an SQUID charge qubit is coupled to a quantum LC resonator, the SQUID voltage operator equation is modified in accompanying with the modification of operator Faraday equation describing the inductance. It is shown that when the extra energy is applied to the junction, the mean phase will be squeezed according to a damping factor. 相似文献
17.
Number-Phase Quantization and Deriving Energy-Level Gap of Two LC Circuits with Mutual-Inductance
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For two LC circuits with mutual-inductance, we introduce a new quantization scheme in the context of number- phase quantization through the standard Lagrangian formalism. The commutative relation between the charge operator and the magnetic flux operator is derived. Then we use the Heisenberg equation of motion to obtain the current and voltage equation across the inductance and capacity. The results clearly show how the current and voltage in a single LC circuit are affected by the circuit parameters and inductance coupling coettlcient. In addition, adopting invariant eigen-operator method the energy-level gap of the dynamic Hamiltonian which describes two LC circuits with mutual-inductance is obtained. 相似文献
18.
近年来,太赫兹(THz)波段电磁辐射的研究引起科学技术界广泛的关注.液晶(LC)材料具有宽带可调的特性且拥有成熟的工业技术基础,在基于液晶设计的太赫兹可调器件研究中显示了巨大的应用潜力.因此,为了快速发展实用的LC-THz调制器件,对液晶材料在太赫兹频率范围内的光电特性进行系统的了解是至关重要的.分子极化率是表征分子中电荷分布的重要物理量.采用密度泛函理论方法对液晶分子PCH5,5CB和5OCB在太赫兹波段的极化率性质进行计算研究,从电子结构的角度,利用极化率密度分析方法考察了分子不同区域对极化率数值的贡献,详细探讨了尾链、核心结构和极性取代基等不同基团对极化率及其各向异性的影响. 相似文献
19.
Susumu Sato 《Optical Review》1999,6(6):471-485
Liquid Crystal (LC) lens cells with variable focusing properties are fabricated using nematic LC materials and applicable to optical devices, and our recent work on these cells is described. First, the LC lens cells are prepared using lens-shaped substrates coated with transparent electrodes. Their focal length can be continuously varied between the values for an ordinary ray and an extraordinary ray by changing the voltage passing across them. Methods of improving properties and some applications of the lens-shaped LC lens are briefly described. The lens properties of these cells with plane-paralleled structure are then demonstrated, where the refractive index is graded to a quadratic distribution resulting from an axially symmetric non-uniform electric field. LC cells with axially distributed tilt angles are constructed using a pair of circular hole-patterned electrode substrates and very small LC lens (LC microlens) with variable focusing can be fabricated. Optimizing the electrode structure, device parameters, and material parameters of the LCs, excellent focusing properties can be obtained. The properties of the LC microlens are improved by using the polymer stabilization technique. The LC microlens with a divided electrode structure shows three-dimensional beam steering and focusing properties, and the astigmatic aberration caused by the molecular orientation effect can be compensated. Applications of the LC microlens to optical devices and systems are introduced. 相似文献
20.
《Current Applied Physics》2001,1(1):88-89
Polyacetylene fibrils synthesized in chiral nematic (N*) liquid crystals (LCs) as a polymerization solvent show clockwise helical morphology when a clockwise N* LC is used as a solvent and vice versa. To explain the concordant result in terms of screw direction, a model is proposed in which the conjugated molecule makes a loose loop with a radius of micrometer order, twisting clockwise or counterclockwise. The observed twisted morphology of the fibril can be explained by the condensation of many loosely looped molecular chains grown in a twisted domain of the N* LC solvent. 相似文献