Accurate modelling of nematic liquid crystal under the combination of microwave signal and applied voltage

Geng, Jinling; Song, Lizhong

doi:10.1080/02678292.2019.1629657

Cited by 6 publications

(4 citation statements)

References 23 publications

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“…The reorientation of the LC molecules in the unit cell under the applied electric field can be calculated using the accurate modeling method proposed in [4]. Normally, the total energy F of the LC in the unit cell consists of the elastic bulk energy F D which is often referred to as the Frank-Oseen free energy [1,27], the surface energy F S contributed by the anchoring at the alignment layers and the electrostatic energy F E caused by the applied voltage, which is defined as [1,2].…”

Section: Theoretical Basismentioning

confidence: 99%

“…Therefore, the permittivity of the LC molecules can change with the temperature and the mixed solvent. Moreover, the dielectric constant of LC molecules can also be changed by an external electric or magnetic field [1][2][3][4]. Recently, Andrade-Silva, et al proposed a method for changing the permittivity of LC molecules by considering electromagnetic fields for dye-doped LCs in [5].…”

Section: Introductionmentioning

confidence: 99%

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Three-dimensional accurate modeling of nematic liquid crystal based dipole unit for reconfigurable reflectarray at 100 GHz

Geng

Song

2022

New J. Phys.

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In this paper, a three-dimensional accurate modeling of nematic liquid crystal has been presented for the analysis of reconfigurable reflectarray cells based on liquid crystal. Both single-dipole and multiple-dipoles constructed on a iquid crystal substrate are designed as the reflectarray unit cell. Considering the inhomogeneous and anisotropic effects, the orientation of the liquid crystal molecules at each point of the liquid crystal layer involved in the unit cell under the external electrostatic field is obtained by the finite difference numerical modeling method. Utilizing the accurate modeling results of liquid crystal, the reflection constants of the reflectarray unit cells have been simulated and also have been compared with that of in the conventional model which usually assumes the liquid crystal is homogeneous and isotropic. The error of phase range of the unit cell between the two models can exceed $45^{\circ}$ in the single-resonant unit cell, and is more than $290^{\circ}$ in the multi-resonant unit cell, which will seriously affect the practical application. The permittivity of liquid crystal in the unit cells under different applied voltages also has been calculated and given. Moreover, the gain radiation pattern of the reflectarray consisting of the proposed liquid crystal based double-dipoles is simulated in two models. The simulation results show that, in the accurate modeling, the gain and scanning angle range of the reflectarray obtained by the homogeneous and isotropic model change significantly because the phase-shift of the same unit cell for the incident wave is greatly different in the two models, which indicates that the homogeneous and isotropic model can no longer meet the needs of the design of liquid crystal based multi-dipoles reflectarray. Therefore, the accurate modeling method needs to be considered and can not be ignored when studying and designing liquid crystal based devices.

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Section: Theoretical Basismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Three-dimensional accurate modeling of nematic liquid crystal based dipole unit for reconfigurable reflectarray at 100 GHz

Geng

Song

2022

New J. Phys.

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“…Since the voltage ( ) V x LC varies along the vertical x-direction, θ is then x-dependent and is related to the electric field [i.e. gradient of 20) The rotation/ polarization angle (f) of the vertical plane with respect to the y-axis can be selected independently, 21) where we set f = 0 here for simplicity but without loss of generality. According to the ellipsoid model for birefringence, 20) ( ) n x LC of the nematic LC material (E7) 22) can be calculated through the relation…”

Section: Lcmentioning

confidence: 99%

Design of tunable microlaser with metal-optical Tamm state structure and liquid crystal

Zhao

Huang

2021

Jpn. J. Appl. Phys.

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The compact tunable single-mode microlaser is designed by combining the metal-optical Tamm state (metal-OTS) structure with the liquid crystal (LC) layer. Structural parameters are discussed for their corresponding effects on the tuning range and bandwidth of the transmission spectrum, etc. A range of 51 nm around 1.55 μm can be tuned as shown by the simulation for LC thickness of 1.4 μm. The calculated lasing characteristics of the LC-metal-OTS structure indicate that it could be promising for use as an electrically-pumped compact light source in the short-reach networks and high-speed communications in silicon-based photonic integrated circuits.

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“…Considering the optical birefringence properties and the high sensitivity to surface–interface interactions, LC biosensors can avoid the drawbacks of traditional biosensors, such as complex operations and the need for labeling biotargets [ 36 ]. Consequently, signals generated by LCs can be used to report subtle molecular events and external stimuli, and a number of materials-based optoelectronic signal transduction systems have been developed for LC-based biosensors [ 37 , 38 , 39 ].…”

Section: Introductionmentioning

confidence: 99%

Liquid Crystal Biosensors: Principles, Structure and Applications

Wang

et al. 2022

Biosensors

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Liquid crystals (LCs) have been widely used as sensitive elements to construct LC biosensors based on the principle that specific bonding events between biomolecules can affect the orientation of LC molecules. On the basis of the sensing interface of LC molecules, LC biosensors can be classified into three types: LC–solid interface sensing platforms, LC–aqueous interface sensing platforms, and LC–droplet interface sensing platforms. In addition, as a signal amplification method, the combination of LCs and whispering gallery mode (WGM) optical microcavities can provide higher detection sensitivity due to the extremely high quality factor and the small mode volume of the WGM optical microcavity, which enhances the interaction between the light field and biotargets. In this review, we present an overview of the basic principles, the structure, and the applications of LC biosensors. We discuss the important properties of LC and the principle of LC biosensors. The different geometries of LCs in the biosensing systems as well as their applications in the biological detection are then described. The fabrication and the application of the LC-based WGM microcavity optofluidic sensor in the biological detection are also introduced. Finally, challenges and potential research opportunities in the development of LC-based biosensors are discussed.

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Accurate modelling of nematic liquid crystal under the combination of microwave signal and applied voltage

Cited by 6 publications

References 23 publications

Three-dimensional accurate modeling of nematic liquid crystal based dipole unit for reconfigurable reflectarray at 100 GHz

Three-dimensional accurate modeling of nematic liquid crystal based dipole unit for reconfigurable reflectarray at 100 GHz

Design of tunable microlaser with metal-optical Tamm state structure and liquid crystal

Liquid Crystal Biosensors: Principles, Structure and Applications

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