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12 pages, 2191 KiB

Open AccessArticle

Tunable Broadband-Narrowband and Dual-Broadband Terahertz Absorber Based on a Hybrid Metamaterial Vanadium Dioxide and Graphene

by Jing Li, Yanfei Liu, Yu Chen, Wenqing Chen, Honglei Guo, Qiannan Wu and Mengwei Li

Micromachines 2023, 14(1), 201; https://doi.org/10.3390/mi14010201 - 13 Jan 2023

Cited by 22 | Viewed by 2716

Abstract

We propose a functionally tunable terahertz (THz) metamaterial absorber, which has the switching performance between broadband-narrowband and dual-broadband near-perfect absorption due to the phase transition of Vanadium dioxide (VO₂) and the tunable electrical property of graphene. The switching absorption properties are [...] Read more.

We propose a functionally tunable terahertz (THz) metamaterial absorber, which has the switching performance between broadband-narrowband and dual-broadband near-perfect absorption due to the phase transition of Vanadium dioxide (VO₂) and the tunable electrical property of graphene. The switching absorption properties are verified by computer simulation technology (CST) microwave study. The simulation results show that when VO₂ is in the metallic phase, over 90% broadband absorption is realized in the 3.85–6.32 THz range. When the VO₂ is in the insulating phase, the absorber shows quadruple narrowband absorption. By changing the Fermi level of graphene and the conductivity of VO₂, the low-frequency broadband of 3.85–6.32 THz can be switched to the high-frequency broadband of 6.92–8.92 THz, and the absorber can be switched from a quadruple narrowband to a nearly singlefold narrowband. In addition, the proposed absorber is insensitive to polarization due to its symmetry and wide incident angle. The design may have potential applications in the THz range, such as switches, electromagnetic shielding, cloaking objects, filtering, sensing, and so on. Full article

(This article belongs to the Special Issue Terahertz and Infrared Metamaterial Devices)

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8 pages, 2418 KiB

Open AccessArticle

Reprogrammable Metasurface Controlled by 2D Thermal Fields

by Ming Zhang, Fuju Ye, Hongrui Tan, Sisi Luo, Haoyang Cui and Lei Chen

Micromachines 2022, 13(11), 2023; https://doi.org/10.3390/mi13112023 - 19 Nov 2022

Viewed by 1712

Abstract

The combination of thermal field sensing and microwave operation is an innovative topic in metamaterials. Although there exists research on modulating electromagnetic waves by controlling each column of the metasurface elements for programmable metasurfaces, the regulation is not flexible. In view of this, [...] Read more.

The combination of thermal field sensing and microwave operation is an innovative topic in metamaterials. Although there exists research on modulating electromagnetic waves by controlling each column of the metasurface elements for programmable metasurfaces, the regulation is not flexible. In view of this, this paper proposes a metasurface based on distributed thermal sensing that can be independently modulated by each element. In this paper, the metasurface adopts a 1-bit coding metasurface, which is combined with PIN diodes to modulate the phase response. The voltage control circuit feeds back the change in the thermistors to the switching state of the PIN diode. Each metasurface unit contains thermistors, which are used to sense thermal stimulation and can be independently modulated. The metasurface composed of these elements can feel the field generated via heat energy. We can control electromagnetic waves by controlling this field. In order to prove the feasibility of this scheme, a metasurface sample of 8 × 8 elements was designed. Three patterns were used for the design, fabrication, and measurement of the samples. Meanwhile, printed circuit board (PCB) technology was applied. The results show that the simulated results are highly consistent with the experimental results, which verifies that this scheme is practicable. Full article

(This article belongs to the Special Issue Terahertz and Infrared Metamaterial Devices)

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14 pages, 5282 KiB

Open AccessArticle

Terahertz Enhanced Sensing of Uric Acid Based on Metallic Slot Array Metamaterial

by Yuke Han, Xiaomeng Bian, Misheng Liang, Tianshu Li, Lianqing Zhu, Xiaoguang Zhao and Rui You

Micromachines 2022, 13(11), 1902; https://doi.org/10.3390/mi13111902 - 3 Nov 2022

Cited by 6 | Viewed by 2145

Abstract

An enzyme-free terahertz uric acid sensor based on a metallic slot array metamaterial was proposed and realized both theoretically and experimentally. The sensing model was verified in simulation and femtosecond laser processing technology was employed to ablate slots in the copper plate to [...] Read more.

An enzyme-free terahertz uric acid sensor based on a metallic slot array metamaterial was proposed and realized both theoretically and experimentally. The sensing model was verified in simulation and femtosecond laser processing technology was employed to ablate slots in the copper plate to fabricate metamaterials. Analytes were tested with liquid phase deposition on the metamaterial by a terahertz frequency domain spectroscopy system. Gradient concentrations of uric acid, ascorbic acid, and a mixture of them were measured separately with a good linear response. A significant decrease in sensitivity was observed in the ascorbic acid assay compared with the uric acid assay. The test results of the mixture also proved that our device is resistant to ascorbic acid. It is a simple and effective method for monitoring uric acid concentrations and the strategy of eliminating interference while modulating the resonance peak location mentioned here can be rationally projected for the development of other sensors. Full article

(This article belongs to the Special Issue Terahertz and Infrared Metamaterial Devices)

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7 pages, 1647 KiB

Open AccessArticle

Suppression of the Electrical Crosstalk of Planar-Type High-Density InGaAs Detectors with a Guard Hole

by Jiaxin Zhang, Wei Wang, Haifeng Ye, Runyu Huang, Zepeng Hou, Chen Liu, Weilin Zhao, Yunxue Li, Xu Ma and Yanli Shi

Micromachines 2022, 13(10), 1797; https://doi.org/10.3390/mi13101797 - 21 Oct 2022

Cited by 1 | Viewed by 1746

Abstract

The resolution of InGaAs FPA detectors is degraded by the electrical crosstalk, which is especially severe in high–density FPAs. We propose a guard-hole structure to suppress the electrical crosstalk in a planar-type 640 × 512 15 μm InGaAs short wavelength infrared FPA detector. [...] Read more.

The resolution of InGaAs FPA detectors is degraded by the electrical crosstalk, which is especially severe in high–density FPAs. We propose a guard-hole structure to suppress the electrical crosstalk in a planar-type 640 × 512 15 μm InGaAs short wavelength infrared FPA detector. For comparison, the frequently used guard ring is also prepared according to the same processing. The calculation results show that the electrical crosstalk with a guard hole is suppressed from 13.4% to 4.5%, reducing by 66%, while the electrical crosstalk with a guard ring is suppressed to 0.4%. Furthermore, we discuss the effects of the guard ring and the guard hole on the dark current, quantum efficiency, and detectivity. Experimental results show the detector with a guard-hole structure has higher performance compared with the detector with a guard-ring structure, the dark current density is reduced by 60%, the QE is increased by 64.5%, and the detectivity is increased by 1.36 times, respectively. The guard-hole structure provides a novel suppression method for the electrical crosstalk of high-density InGaAs detectors. Full article

(This article belongs to the Special Issue Terahertz and Infrared Metamaterial Devices)

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10 pages, 3478 KiB

Open AccessArticle

Graphene-Based Absorption–Transmission Multi-Functional Tunable THz Metamaterials

by Shulei Zhuang, Xinyu Li, Tong Yang, Lu Sun, Olga Kosareva, Cheng Gong and Weiwei Liu

Micromachines 2022, 13(8), 1239; https://doi.org/10.3390/mi13081239 - 1 Aug 2022

Cited by 14 | Viewed by 1954

Abstract

The paper reports an absorption–transmission multifunctional tunable metamaterial based on graphene. Its pattern graphene layer can achieve broadband absorption, while the frequency selective layer can achieve the transmission of specific band. Furthermore, the absorption and transmission can be controlled by applying voltage to [...] Read more.

The paper reports an absorption–transmission multifunctional tunable metamaterial based on graphene. Its pattern graphene layer can achieve broadband absorption, while the frequency selective layer can achieve the transmission of specific band. Furthermore, the absorption and transmission can be controlled by applying voltage to regulate the chemical potential of graphene. The analysis results show that the absorption of the metamaterial is adjustable from 22% to 99% in the 0.72 THz~1.26 THz band and the transmittance is adjustable from 80% to 95% in 2.35 THz. The metamaterial uses UV glue as the dielectric layer and PET (polyethylene terephthalate) as the flexible substrate, which has good flexibility. Moreover, the metamaterial is insensitive to incident angle and polarization angle, which is beneficial to achieve excellent conformal properties. Full article

(This article belongs to the Special Issue Terahertz and Infrared Metamaterial Devices)

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14 pages, 7091 KiB

Open AccessArticle

A Terahertz Optomechanical Detector Based on Metasurface and Bi-Material Micro-Cantilevers

by Hailiang Zhu, Kai Wang, Ganyu Liu, Gengchen Wang, Jinchao Mou, Weiwei Zhang and Gao Wei

Micromachines 2022, 13(5), 805; https://doi.org/10.3390/mi13050805 - 21 May 2022

Cited by 6 | Viewed by 2491

Abstract

Terahertz imaging technology has shown great potential in many fields. As the core component of terahertz imaging systems, terahertz detectors have received extensive attention. In this paper, a metasurface-based terahertz optomechanical detector is proposed, which is made of two fabrication-friendly materials: gold and [...] Read more.

Terahertz imaging technology has shown great potential in many fields. As the core component of terahertz imaging systems, terahertz detectors have received extensive attention. In this paper, a metasurface-based terahertz optomechanical detector is proposed, which is made of two fabrication-friendly materials: gold and silicon nitride. The optomechanical detector is essentially a thermal detector composed of metasurface absorber, bi-material micro-cantilevers and heat insulation pillars. Compared with traditional thermal terahertz detectors, the optomechanical detector employs a metasurface absorber as the terahertz radiation coupler and obtains an absorptivity higher than 90% from 3.24 to 3.98 THz, which is much higher than that of traditional terahertz detectors with absorbers made from natural materials. Furthermore, the detector is fabricated by MEMS process and its responsivity has been verified by a specifically designed optical read-out system; the measured optomechanical responsivity is 24.8 μm/μW, which agrees well with the multi-physics simulation. These results indicated that the detector can be employed as a pixel to form a terahertz focal plane array in the future, and further realize real-time terahertz imaging at room temperature. Full article

(This article belongs to the Special Issue Terahertz and Infrared Metamaterial Devices)

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12 pages, 2831 KiB

Open AccessArticle

Vanadium Dioxide-Based Terahertz Metamaterial Devices Switchable between Transmission and Absorption

by Haoqing Jiang, Yue Wang, Zijian Cui, Xiaoju Zhang, Yongqiang Zhu and Kuang Zhang

Micromachines 2022, 13(5), 715; https://doi.org/10.3390/mi13050715 - 30 Apr 2022

Cited by 24 | Viewed by 2848

Abstract

Terahertz metamaterial plays a significant role in the development of imaging, sensing, and communications. The function of conventional terahertz metamaterials was fixed after fabrication. They can only achieve a single function and do not have adjustable characteristics, which greatly limits the scalability and [...] Read more.

Terahertz metamaterial plays a significant role in the development of imaging, sensing, and communications. The function of conventional terahertz metamaterials was fixed after fabrication. They can only achieve a single function and do not have adjustable characteristics, which greatly limits the scalability and practical application of metamaterial. Here, we propose a vanadium dioxide-based terahertz metamaterial device, which is switchable between being a transmitter and an absorber. The transmission and absorption characteristics and temperature tunable properties of phase change metamaterials in the terahertz band were investigated. As the temperature of vanadium dioxide is varied between 20 °C and 80 °C, the device can switch between transmission and quad-band resonance absorption at the terahertz frequency range, with a high transmission rate of over 80% and a peak absorbance of 98.3%, respectively. In addition, when the device acts as an absorber, the proposed metamaterial device is tunable, and the modulation amplitude can reach 94.3%; while the device is used as a transmissive device, the modulation amplitude of the transmission peak at 81%. The results indicate that the proposed metamaterial device can promote the applications of terahertz devices, such as switching, modulation, and sensing. Full article

(This article belongs to the Special Issue Terahertz and Infrared Metamaterial Devices)

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9 pages, 1329 KiB

Open AccessArticle

Ultra-Thin Terahertz Deflection Device Based on Laser Direct Writing Graphene Oxide Paper

by Yixin Suo, Luming Zhang, Yihang Li, Yu Wu, Jian Zhang and Qiye Wen

Micromachines 2022, 13(5), 686; https://doi.org/10.3390/mi13050686 - 28 Apr 2022

Cited by 1 | Viewed by 1729

Abstract

In the world of terahertz bands, terahertz beam deflection has gradually attracted substantial attention, due to its great significance in wireless communications, high-resolution imaging and radar applications. In this paper, a low-reflection and fast-fabricated terahertz beam deflection device has been realized by utilizing [...] Read more.

In the world of terahertz bands, terahertz beam deflection has gradually attracted substantial attention, due to its great significance in wireless communications, high-resolution imaging and radar applications. In this paper, a low-reflection and fast-fabricated terahertz beam deflection device has been realized by utilizing graphene oxide paper. Using laser direct writing technology, graphene oxide has been patterned as a specific sample. The thickness of the graphene oxide-based terahertz devices is around 15–20 μm, and the processing takes only a few seconds. The experimental results show that the beam from this device can achieve 5.7° and 10.2° deflection at 340 GHz, while the reflection is 10%, which is only 1/5 of that of existing conventional devices. The proposed device with excellent performance can be quickly manufactured and applied in the fields of terahertz imaging, communication, and perception, enabling the application of terahertz technology. Full article

(This article belongs to the Special Issue Terahertz and Infrared Metamaterial Devices)

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