Tunable Terahertz Free Spectra Range Using Electric Split-Ring Metamaterial

2021

Nanomaterials

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We present two types of refractive index sensors by using tunable terahertz (THz) metamaterial (TTM) based on two concentric split-ring resonators (SRRs) with different splits. By modifying the distance between SRRs and substrate, TTM shows tunable single- and dual-resonance characteristic. The maximum tuning range of resonance is 0.432 THz from 0.958 THz to 1.390 THz. To demonstrate a great flexibility of TTM in real application, TTM device is exposed on the surrounding ambient with different refractive index (n). The sensitivity of TTM can be enhanced by increasing SRR height, which is increased from 0.18 THz/RIU to 1.12 THz/RIU under the condition of n = 1.1. These results provide a strategy to improve the sensing performance of the metamaterial-based sensing device by properly arranging the geometric position of meta-atoms. The proposed TTM device can be used for tunable filters, frequency-selective detectors, and tunable high-efficiency sensors in the THz frequency range.

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Design of Tunable Terahertz Metamaterial Sensor with Single- and Dual-Resonance Characteristic

Yang

2021

Nanomaterials

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“…In the IR wavelength range, ESA-based metamaterials are also reported to realize active modulation of the polarization state, as shown in Figure 5g [86]. In Figure 5h-j, Xu et al propose several SRR patterns integrated with the comb driver platform to be operated at different frequencies, which can be applied in many fields, such as tunable filters, frequency-selective detectors, polarization switches, high-efficient environmental sensors, and more [87][88][89]. From these literature reports, the ESA-based platform shows great applicability for the horizontal tunable metamaterial.…”

Section: Horizontal Tuning Methodsmentioning

confidence: 99%

Actively MEMS-Based Tunable Metamaterials for Advanced and Emerging Applications

2022

Electronics

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In recent years, tunable metamaterials have attracted intensive research interest due to their outstanding characteristics, which are dependent on the geometrical dimensions rather than the material composition of the nanostructure. Among tuning approaches, micro-electro-mechanical systems (MEMS) is a well-known technology that mechanically reconfigures the metamaterial unit cells. In this study, the development of MEMS-based metamaterial is reviewed and analyzed based on several types of actuators, including electrothermal, electrostatic, electromagnetic, and stretching actuation mechanisms. The moveable displacement and driving power are the key factors in evaluating the performance of actuators. Therefore, a comparison of actuating methods is offered as a basic guideline for selecting micro-actuators integrated with metamaterial. Additionally, by exploiting electro-mechanical inputs, MEMS-based metamaterials make possible the manipulation of incident electromagnetic waves, including amplitude, frequency, phase, and the polarization state, which enables many implementations of potential applications in optics. In particular, two typical applications of MEMS-based tunable metamaterials are reviewed, i.e., logic operation and sensing. These integrations of MEMS with metamaterial provide a novel route for the enhancement of conventional optical devices and exhibit great potentials in innovative applications, such as intelligent optical networks, invisibility cloaks, photonic signal processing, and so on.

“…Metamaterials show many unique electromagnetic properties including field enhancement [ 11 , 12 ], negative refraction index [ 13 ], artificial magnetism [ 14 ], electromagnetically induced transparency (EIT) [ 15 ], and so on. By properly tailoring the geometric parameters, metamaterials are able to be easily operated in a wide spectrum range that includes terahertz (THz), infrared (IR), and visible light [ 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 ]. Among the whole electromagnetic spectra, THz wave is the transition spectrum that usually occupies the spectrum in the frequency range from 0.1 THz to 10 THz, which is between the IR and microwave wavelength.…”

Section: Introductionmentioning

confidence: 99%

Tunable Terahertz Metamaterial with Electromagnetically Induced Transparency Characteristic for Sensing Application

Zhong

2021

Nanomaterials

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We present and demonstrate a MEMS-based tunable terahertz metamaterial (TTM) composed of inner triadius and outer electric split-ring resonator (eSRR) structures. With the aim to explore the electromagnetic responses of TTM device, different geometrical parameters are compared and discussed to optimize the suitable TTM design, including the length, radius, and height of TTM device. The height of triadius structure could be changed by using MEMS technique to perform active tunability. TTM shows the polarization-dependent and electromagnetic induced transparency (EIT) characteristics owing to the eSRR configuration. The electromagnetic responses of TTM exhibit tunable characteristics in resonance, polarization-dependent, and electromagnetically induced transparency (EIT). By properly tailoring the length and height of the inner triadius structure and the radius of the outer eSRR structure, the corresponding resonance tuning range reaches 0.32 THz. In addition to the above optical characteristics of TTM, we further investigate its potential application in a refraction index sensor. TTM is exposed on the surrounding ambient with different refraction indexes. The corresponding key sensing performances, such as figure of merit (FOM), sensitivity (S), and quality factor (Q-factor) values, are calculated and discussed, respectively. The calculated sensitivity of TTM is 0.379 THz/RIU, while the average values of Q-factor and FOM are 66.01 and 63.83, respectively. These characteristics indicate that the presented MEMS-based TTM device could be widely used in tunable filters, perfect absorbers, high-efficient environmental sensors, and optical switches applications for THz-wave optoelectronics.