Liquid Crystals Tunable Optical Metamaterials

Khoo, Iam Choon; Díaz, Arturo Pulido; Liou, J.; Stinger, M. V.; Huang, Jian; Ma, Yuxiang

doi:10.1109/jstqe.2009.2032246

Cited by 49 publications

(6 citation statements)

References 43 publications

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“…(1) where indicates that we choose the sign of the square root for which the imaginary part n is positive, i.e. we follow the convention where power flow is in the +z direction, so a positive imaginary part n corresponds to an exponential attenuation of the fields propagating through a lossy medium [40]. With the introduction of liquid crystals or other materials [e.g., so-called phase change materials] in the fabrication of metamaterials, the refractive index value can be designed to be tunable/reconfigurable over a wide range from negative through zero to positive.…”

Section: Tunable Near Zero and Negative Index Of Refraction; Metamate...mentioning

confidence: 99%

“…Another serious drawback in the development of metamaterial is the large optical loss [coming from imaginary part of index n"]. To reduce loss, one possibility is incorporation of gain materials such as dyes [40,[49][50][51]; however, to date, large optical losses still pose almost unsurmountable challenges to developing negative-index metamaterials. Most current studies are focused on metamaterials with sub-unity (but positive) or near zero index values where the optical losses are lower and acceptable for practical applications.…”

Section: Tunable Near Zero and Negative Index Of Refraction; Metamate...mentioning

confidence: 99%

See 1 more Smart Citation

Liquid crystals for optical switches, smart windows, reconfigurable/tunable meta-structures, micro-resonator coupling and plasmonic nanostructures

Khoo

2023

Liquid Crystals XXVII

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This review provides an overview of the wide-ranging dynamical nonlinear- and electro- optical responses of liquid crystals and reexamine some exemplary photonic applications such as smart windows/display, tunable/reconfigurable metamaterials or metasurfaces, plasmonic nanostructures, micro-ring resonator, and chiral photonic crystals for polarizations and manipulations of ultrafast pulsed lasers of complex polarization states.

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Section: Tunable Near Zero and Negative Index Of Refraction; Metamate...mentioning

confidence: 99%

Section: Tunable Near Zero and Negative Index Of Refraction; Metamate...mentioning

confidence: 99%

Liquid crystals for optical switches, smart windows, reconfigurable/tunable meta-structures, micro-resonator coupling and plasmonic nanostructures

Khoo

2023

Liquid Crystals XXVII

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“…As mentioned in Section 3, LC reorientations would result in a dramatic change in the refractive index of LC, which in turn, would further change the response to electromagnetic waves. In nematic LCs, the crystal is in a rod-shape and the external stimulations such as thermal heating, pressure, and the magnetic and electric field, can control its directional order, resulting in good refractive index tunability [42,59,[74][75][76][77][78][79][80][81][82][83][84][85][86][87][88][89][90][91]. Therefore, LCs are extensive used as the liquid background of solid metamaterials [51,52,92].…”

Section: Recent Development and Applications 41 Tunable Metamaterials With Liquid Crystalsmentioning

confidence: 99%

A Review of Tunable Electromagnetic Metamaterials With Anisotropic Liquid Crystals

Yang

Fan

et al. 2021

Front. Phys.

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The performance of metamaterial is limited to a designed narrow band due to its resonant nature, it is highly desirable to incorporate active inclusions in metamaterials to extend the operation bandwidth. This review summarizes the development in realizing the tunability of electromagnetic response in metamaterials incorporated with nematic liquid crystal (LC). From rigorous comparison, it is found that the anisotropic property of nematic LC is essential in predicting the influence of LC molecular director orientation on the resonant frequency of metamaterials. By carefully designing the metamaterials and properly infiltrating LC, the operation frequency of single/double negative parameters of metamaterials can be dynamically modulated with remarkable red/blue-shift, depending on the LC molecular orientation angle. Moreover, the recent liquid crystal-based developments and novel applications are investigated and highlighted.

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“…Liquid crystals in various phases possess electro-optical and nonlinear-optical properties resulting from an assortment of highly molecular and collective mechanisms with response time ranging from conventional (milliseconds) to ultrafast (femtoseconds) time scales [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. A particular class of liquid crystals, namely, chiral nematics or cholesteric liquid crystals (CLC's) possess special characteristics of photonic crystals in addition to the unique properties of liquid crystals [1][2][3][6][7][8][9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Dual-frequency field assembly of over mm-thick nonlinear chiral photonic crystals for advanced photonic applications

Khoo,

Chen,

Lin

et al. 2023

Liquid Crystals XXVII

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We report a room-temperature dual-frequency field assembly technique that is capable of fabricating large-areal size (~cm2 or larger), well-aligned cholesteric liquid crystals to thicknesses up to 2.2 mm, corresponding to period number N (thickness/index grating period) of nearly10,000 in the visible spectral regime. The method employs successive application of low- and high- frequency electric field on a thick cell of CLC starting mixture containing a nematic constituent of negative anisotropy. The low-frequency field creates conductive hydrodynamical instabilities that mash the mixture to a state with completely randomized orientation of the cholesteric helices; the next application of a high-frequency field at a field strength below the dielectric hydrodynamic instability reorient all the helices into uniform standing helices. Such extraordinarily thick chiral photonic crystals exhibit many never-before-realized chiral photonic properties such as giant rotation of optical polarization with high transmission (low scattering loss), polarization switching and ultrafast pulse modulation capabilities for visible to mid-infrared lasers, in addition to dynamic tunability by electrical, thermal, or optical means.

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Liquid Crystals Tunable Optical Metamaterials

Cited by 49 publications

References 43 publications

Liquid crystals for optical switches, smart windows, reconfigurable/tunable meta-structures, micro-resonator coupling and plasmonic nanostructures

Liquid crystals for optical switches, smart windows, reconfigurable/tunable meta-structures, micro-resonator coupling and plasmonic nanostructures

A Review of Tunable Electromagnetic Metamaterials With Anisotropic Liquid Crystals

Dual-frequency field assembly of over mm-thick nonlinear chiral photonic crystals for advanced photonic applications

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