Hypersensitive and Tunable Terahertz Wave Switch Based on Non-Bragg Structures Filled with Liquid Crystals

Zhang, Lu; Fan, Ya-Xian; Liu, Huan; Xu, Lanlan; Xue, Jiu-Ling

doi:10.1109/jlt.2017.2707554

Cited by 20 publications

(16 citation statements)

References 40 publications

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“…The blue and red solid lines in Figure a denote the fundamental and first modes, respectively. They indicate that the Bragg gaps denoted by the blue shadows are caused by the same fundamental modes while the non‐Bragg gaps in pink shadows above 3700 Hz are caused by the different transverse modes (the fundamental and first ones) . According to the experimental results in Figure b, those band gaps in

P g_{i}

can also be observed in

G_{i}

at the same frequencies when

i \geq 3

, although some of them just have the trends to be the forbidden bands.…”

mentioning

confidence: 82%

Non‐Bragg Bands in Acoustic Quasi‐Periodic Fibonacci Waveguides

Liu

et al. 2019

Physica Rapid Research Ltrs

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In this Letter, an algebraic topology analysis on the bandgaps in phononic Fibonacci waveguides consisting of wide and narrow stainless steel pipes is presented. It has been found that the non‐Bragg forbidden gaps can also exist in quasi‐periodic waveguide structures based on the constructed relations between the quasi‐periodic and periodic waveguides. The so‐called non‐Bragg gaps are caused by the resonances between different transverse modes while the same modes with matching longitudinal wavenumbers always result in the traditional Bragg gaps. In the experiments in this study, the observed non‐Bragg gap appears earlier than the Bragg one in the previous generations of Fibonacci sequences, and the sound attenuation is much more intense, because the lower generations with shorter lengths can only provide enough interaction effects in the transverse dimension. The algebraic topology methods and the observations of non‐Bragg gaps in quasi‐periodic waveguides can not only enrich the knowledge on wave structure interactions but also benefit various applications in wave control engineering.

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P g_{i}

can also be observed in

G_{i}

at the same frequencies when

i \geq 3

, although some of them just have the trends to be the forbidden bands.…”

mentioning

confidence: 82%

Non‐Bragg Bands in Acoustic Quasi‐Periodic Fibonacci Waveguides

Liu

et al. 2019

Physica Rapid Research Ltrs

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“…In the terahertz frequency range, LC can be treated as a lossy and dispersive media [23,34]. We employ the polynomial model to fit the refractive index (n) and absorption coefficient (α) of E7, which is used as the LC material throughout the paper.…”

Section: Theoretical Basismentioning

confidence: 99%

“…[18][19][20]. Recently, there has been growing interest in utilizing the LC for devices working in the terahertz range [21][22][23]. In addition to the extension of the applied frequencies using the LC, ways to adjust the LC are also diversified.…”

Section: Introductionmentioning

confidence: 99%

Design of a Liquid-Crystal-Tunable Terahertz Demultiplexer Based on a Metal-Insulator-Metal Waveguide

Feng

et al. 2019

Applied Sciences

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A tunable demultiplexer with three output channels infiltrated by liquid crystal (LC) is presented, which is based on a metal-insulator-metal (MIM) waveguide. The operating frequencies of the three output channels can be tuned simultaneously at will by changing the external bias electric field applied to the LC. By analyzing the Fabry-Pérot (FP) resonance modes of the finite-length MIM waveguide both theoretically and numerically, the locations of the three channels are delicately determined to achieve the best demultiplexing effects. Terahertz (THz) signals input from the main channel can be demultiplexed by channels 1, 2 and 3 at 0.7135 THz, 1.068 THz and 1.429 THz, respectively. By applying an external electric field to alter the tilt angle of the infiltrating LC material, the operating frequencies of channels 1, 2 and 3 can be relatively shifted up to 12.3%, 9.6% and 9.7%, respectively. The designed demultiplexer can not only provide a flexible means to demultiplex signals but also tune operating bands of output channels at the same time.

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“…As shown in Figure 1b, a defect with length L was inserted. The dispersion relation of Bragg structures can be formulated as follows [20]:…”

Section: Bragg Defect Modementioning

confidence: 99%

“…Vast potential for future development was obtained in many areas such as military, medical, security checks, astronomy, and more [11][12][13][14][15][16]. Many types of THz functional devices have been disclosed, such as phase shifters [17,18], optical switches [19,20], sensors [21,22], modulators [23,24], and detectors [25].…”

Section: Introductionmentioning

confidence: 99%

A High-Resolution Terahertz Electric Field Sensor Using a Corrugated Liquid Crystal Waveguide

Gong

Fan

2019

Crystals

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Liquid crystals (LCs) can always reflect variable optical properties in a broad terahertz (THz) band under external electric or magnetic fields. Based on the measurements of these varying properties, we can realize electric and magnetic field sensing with very high sensitivity. Here, we theoretically and numerically demonstrate a type of electric field sensor in the THz frequency range based on the defect mode arising in a periodically corrugated waveguide with liquid crystals. The Bragg defect structure consisting of periodically corrugated metallic walls and a defect in the middle can provide a narrow transmitted peak with controllable bandwidth, which can be used for external field sensing when it is filled with LCs. The molecular orientation of nematic LCs (E7) is not only very sensitive to the applied DC electric field but also very crucial to the effective refractive index of E7. Changing the effective index can efficiently shift the frequency of the transmitted peak in the THz spectrum. The simulated results show that the sensitivity can reach as high as 9.164 MHz/(V/m) and the smallest resolution is 0.1115 V/m. The proposed sensor and its significant performance could benefit electric field sensing and extend the applications of THz technology.

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Hypersensitive and Tunable Terahertz Wave Switch Based on Non-Bragg Structures Filled with Liquid Crystals

Cited by 20 publications

References 40 publications

Non‐Bragg Bands in Acoustic Quasi‐Periodic Fibonacci Waveguides

Non‐Bragg Bands in Acoustic Quasi‐Periodic Fibonacci Waveguides

Design of a Liquid-Crystal-Tunable Terahertz Demultiplexer Based on a Metal-Insulator-Metal Waveguide

A High-Resolution Terahertz Electric Field Sensor Using a Corrugated Liquid Crystal Waveguide

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