Optically Tunable Terahertz Metasurfaces Using Liquid Crystal Cells Coated with Photoalignment Layers

An optically tunable terahertz filter was fabricated using a metasurface-imbedded liquid crystal (LC) cell with photoalignment layers in this work. The LC director in the cell is aligned by a pump beam and makes angles θ of 0, 30, 60 and 90° with respect to the gaps of the split-ring resonators (SRRs) of the metasurface under various polarized directions of the pump beam. Experimental results display that the resonance frequency of the metasurface in the cell increases with an increase in θ, and the cell has a frequency tuning region of 15 GHz. Simulated results reveal that the increase in the resonance frequency arises from the birefringence of the LC, and the LC has a birefringence of 0.13 in the terahertz region. The resonance frequency of the metasurface is shifted using the pump beam, so the metasurface-imbedded LC cell with the photoalignment layers is an optically tunable terahertz filter. The optically tunable terahertz filter is promising for applications in terahertz telecommunication, biosensing and terahertz imaging.

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Passively Tunable Terahertz Filters Using Liquid Crystal Cells Coated with Metamaterials

Coatings ◽

10.3390/coatings11040381 ◽

2021 ◽

Vol 11 (4) ◽

pp. 381

Author(s):

Wei-Fan Chiang ◽

Yu-Yun Lu ◽

Yin-Pei Chen ◽

Xin-Yu Lin ◽

Tsong-Shin Lim ◽

...

Keyword(s):

Liquid Crystal ◽

Ring Resonators ◽

Maximum Frequency ◽

Split Ring ◽

Split Ring Resonators ◽

Terahertz Region ◽

Resonance Frequencies ◽

Terahertz Communication ◽

Terahertz Sensing ◽

Crystal Cells

Liquid crystal (LC) cells that are coated with metamaterials are fabricated in this work. The LC directors in the cells are aligned by rubbed polyimide layers, and make angles θ of 0°, 45°, and 90° with respect to the gaps of the split-ring resonators (SRRs) of the metamaterials. Experimental results display that the resonance frequencies of the metamaterials in these cells increase with an increase in θ, and the cells have a maximum frequency shifting region of 18 GHz. Simulated results reveal that the increase in the resonance frequencies arises from the birefringence of the LC, and the LC has a birefringence of 0.15 in the terahertz region. The resonance frequencies of the metamaterials are shifted by the rubbing directions of the polyimide layers, so the LC cells coated with the metamaterials are passively tunable terahertz filters. The passively tunable terahertz filters exhibit promising applications on terahertz communication, terahertz sensing, and terahertz imaging.

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Multiple-band terahertz filter device using coupling effect of two nest metallic split-ring resonators

Modern Physics Letters B ◽

10.1142/s0217984920502115 ◽

2020 ◽

Vol 34 (21) ◽

pp. 2050211

Author(s):

Pengcheng Lou ◽

Chao Tang ◽

Qingshan Niu ◽

Yuanhao He ◽

Ben-Xin Wang

Keyword(s):

Coupling Effect ◽

Design Method ◽

Ring Resonators ◽

Quality Factors ◽

Terahertz Waves ◽

Split Ring ◽

Split Ring Resonators ◽

Nested Design ◽

Multiple Band ◽

Terahertz Filter

Multiple-band terahertz filter device consisting of two different-sized metallic split rings with the nested design method is proposed and investigated in this paper. Five separated filtering resonant dips having different resonance amplitudes and quality factors are gained, which are mainly attributed to the hybrid coupling effect between the two nested split-ring resonators. More importantly, the resonance features of the five filtering dips show a significant dependence on the designed parameters, especially the gap between two nested split rings. The multiple-band filtering resonance device given here can open up new avenues to control terahertz waves in many technology-related fields.

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Theoretical Model for Estimation of Resonance Frequency of Rotational Circular Split-Ring Resonators

Electromagnetics ◽

10.1080/02726343.2012.701540 ◽

2012 ◽

Vol 32 (6) ◽

pp. 345-355 ◽

Cited By ~ 10

Author(s):

Chinmoy Saha ◽

Jawad Y. Siddiqui

Keyword(s):

Theoretical Model ◽

Resonance Frequency ◽

Ring Resonators ◽

Split Ring ◽

Split Ring Resonators

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Design and evaluation of split-ring resonators for aptamer-based biosensors

Journal of Sensors and Sensor Systems ◽

10.5194/jsss-7-101-2018 ◽

2018 ◽

Vol 7 (1) ◽

pp. 101-111 ◽

Cited By ~ 6

Author(s):

Tobias Reinecke ◽

Johanna-Gabriela Walter ◽

Tim Kobelt ◽

André Ahrens ◽

Thomas Scheper ◽

...

Keyword(s):

Resonance Frequency ◽

Split Ring Resonator ◽

Target Protein ◽

Ring Resonators ◽

Split Ring ◽

Split Ring Resonators ◽

Molecular Binding ◽

Novel Approach ◽

Highly Sensitive ◽

Line Theory

Abstract. Split-ring resonators are electrical circuits, which enable highly sensitive readout of split capacity changes via a measurement of the shift in the resonance frequency. Thus, functionalization of the split allows the development of biosensors, where selective molecular binding causes a change in permittivity and therefore a change in split capacity. In this work, we present a novel approach using transmission line theory to describe the dependency between permittivity of the sample and resonance frequency. This theory allows the identification of all relevant parameters of a split-ring resonator and thus a target-oriented optimization process. Hereby all setup optimizations are verified with measurements. Subsequently, the split of a resonator is functionalized with aptamers and the sensor response is investigated. This preliminary experiment shows that introducing the target protein results in a shift in the resonance frequency caused by a permittivity change due to aptamer-mediated protein binding, which allows selective detection of the target protein.

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