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Cui X, Fang Q, Qian L, Zheng G. Weyl semimetal/dielectric/Weyl semimetal stack for highly circularly polarized thermal radiation. Phys Chem Chem Phys 2024; 26:24423-24430. [PMID: 39258730 DOI: 10.1039/d4cp02476a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/12/2024]
Abstract
Highly circularly polarized (CP) infrared thermal radiation is greatly in demand because of its significant potential in mid-infrared (mid-IR) applications. To exploit the magnitude and quality factor of circular dichroism (CD) simultaneously, a lithography-free platform consisting of a Weyl semimetal (WSM)/dielectric (Ge)/WSM stack sitting on a metallic substrate (Mo) is proposed. A chiral response and varying CD values from -1 to 0.957 have been demonstrated. The numerical results from a generalized 4 × 4 transfer matrix algorithm verify that the chiral structure manifests a remarkably high quality factor (Q-factor) of 605. The effect of the thickness of each layer in the stack on the CD value is investigated. Moreover, it is identified that the design results in an angle-independent performance. A dual-channel chiral absorber operating in the 18-21 μm wavelength range has also been achieved. Our simple yet powerful paradigm could offer a new way of manipulating the Q-factor and resonance wavelength of a chiral absorber while maintaining near-unity CD, offering a new approach for the advancement of more efficient and tunable chiral optical devices. The approach is generally applicable to other planar configurations with different WSMs and can be extended to other wavelengths.
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Affiliation(s)
- Xin Cui
- Jiangsu Key Laboratory for Optoelectronic Detection of Atmosphere and Ocean, Nanjing University of Information Science and Technology, Nanjing, 210044, China
| | - Qi Fang
- Jiangsu Key Laboratory for Optoelectronic Detection of Atmosphere and Ocean, Nanjing University of Information Science and Technology, Nanjing, 210044, China
| | - Liming Qian
- Jiangsu Key Laboratory for Optoelectronic Detection of Atmosphere and Ocean, Nanjing University of Information Science and Technology, Nanjing, 210044, China
| | - Gaige Zheng
- Jiangsu Key Laboratory for Optoelectronic Detection of Atmosphere and Ocean, Nanjing University of Information Science and Technology, Nanjing, 210044, China
- Jiangsu Collaborative Innovation Center on Atmospheric Environment and Equipment Technology, Nanjing, 210044, China.
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Chen J, Zong S, Liu X, Liu G, Zhan X, Liu Z. Gradient-assisted metasurface absorber with dual-band chiral switching and quasi-linearly tunable circular dichroism. OPTICS LETTERS 2023; 48:4917-4920. [PMID: 37707936 DOI: 10.1364/ol.500248] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Accepted: 08/21/2023] [Indexed: 09/15/2023]
Abstract
Chiral metasurfaces with tunable or switchable circular dichroism (CD) responses hold great potential for advanced optical devices. In this work, we theoretically propose and numerically demonstrate a chiral metasurface absorber composed of periodically serrated Ge2Sb2Te5 (GST) resonators. By harnessing strong plasmonic resonance using the gradient geometry, we achieve a strongly enhanced chiral response with a CD value of 0.98 at λ2 = 2359 nm and a CD value of 0.7 at λ1 = 2274 nm. Additionally, by controlling the gradient difference in the serrated GST resonator, we can modify the CD intensity in multiple dimensions and near-perfectly optimize the chiral properties. Furthermore, it is worth noting that the CD value can be strongly varied by adjusting the phase transition characteristics of GST in the range of 0.007 to 0.7 at λ1 and 0.002 to 0.98 at λ2, corresponding to a switch between "on" and "off" states. The findings give new insight into multi-functional chiroptics and hold wide applications.
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Li D, Xu C, Xie J, Lee C. Research Progress in Surface-Enhanced Infrared Absorption Spectroscopy: From Performance Optimization, Sensing Applications, to System Integration. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:2377. [PMID: 37630962 PMCID: PMC10458771 DOI: 10.3390/nano13162377] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Revised: 08/13/2023] [Accepted: 08/17/2023] [Indexed: 08/27/2023]
Abstract
Infrared absorption spectroscopy is an effective tool for the detection and identification of molecules. However, its application is limited by the low infrared absorption cross-section of the molecule, resulting in low sensitivity and a poor signal-to-noise ratio. Surface-Enhanced Infrared Absorption (SEIRA) spectroscopy is a breakthrough technique that exploits the field-enhancing properties of periodic nanostructures to amplify the vibrational signals of trace molecules. The fascinating properties of SEIRA technology have aroused great interest, driving diverse sensing applications. In this review, we first discuss three ways for SEIRA performance optimization, including material selection, sensitivity enhancement, and bandwidth improvement. Subsequently, we discuss the potential applications of SEIRA technology in fields such as biomedicine and environmental monitoring. In recent years, we have ushered in a new era characterized by the Internet of Things, sensor networks, and wearable devices. These new demands spurred the pursuit of miniaturized and consolidated infrared spectroscopy systems and chips. In addition, the rise of machine learning has injected new vitality into SEIRA, bringing smart device design and data analysis to the foreground. The final section of this review explores the anticipated trajectory that SEIRA technology might take, highlighting future trends and possibilities.
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Affiliation(s)
- Dongxiao Li
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583, Singapore; (D.L.); (C.X.); (J.X.)
- Center for Intelligent Sensors and MEMS (CISM), National University of Singapore, Singapore 117608, Singapore
| | - Cheng Xu
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583, Singapore; (D.L.); (C.X.); (J.X.)
- Center for Intelligent Sensors and MEMS (CISM), National University of Singapore, Singapore 117608, Singapore
| | - Junsheng Xie
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583, Singapore; (D.L.); (C.X.); (J.X.)
- Center for Intelligent Sensors and MEMS (CISM), National University of Singapore, Singapore 117608, Singapore
| | - Chengkuo Lee
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583, Singapore; (D.L.); (C.X.); (J.X.)
- Center for Intelligent Sensors and MEMS (CISM), National University of Singapore, Singapore 117608, Singapore
- NUS Suzhou Research Institute (NUSRI), Suzhou 215123, China
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Wang Q, Chen Y, Mao J, Yang F, Wang N. Metasurface-Assisted Terahertz Sensing. SENSORS (BASEL, SWITZERLAND) 2023; 23:5902. [PMID: 37447747 DOI: 10.3390/s23135902] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Revised: 06/20/2023] [Accepted: 06/22/2023] [Indexed: 07/15/2023]
Abstract
Terahertz (THz) waves, which fall between microwaves and infrared bands, possess intriguing electromagnetic properties of non-ionizing radiation, low photon energy, being highly sensitive to weak resonances, and non-polar material penetrability. Therefore, THz waves are extremely suitable for sensing and detecting chemical, pharmaceutical, and biological molecules. However, the relatively long wavelength of THz waves (30~3000 μm) compared to the size of analytes (1~100 nm for biomolecules, <10 μm for microorganisms) constrains the development of THz-based sensors. To circumvent this problem, metasurface technology, by engineering subwavelength periodic resonators, has gained a great deal of attention to enhance the resonance response of THz waves. Those metasurface-based THz sensors exhibit high sensitivity for label-free sensing, making them appealing for a variety of applications in security, medical applications, and detection. The performance of metasurface-based THz sensors is controlled by geometric structure and material parameters. The operating mechanism is divided into two main categories, passive and active. To have a profound understanding of these metasurface-assisted THz sensing technologies, we review and categorize those THz sensors, based on their operating mechanisms, including resonators for frequency shift sensing, nanogaps for enhanced field confinement, chirality for handedness detection, and active elements (such as graphene and MEMS) for advanced tunable sensing. This comprehensive review can serve as a guideline for future metasurfaces design to assist THz sensing and detection.
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Affiliation(s)
- Qian Wang
- School of Microelectronics, Shanghai University, Shanghai 200000, China
| | - Yuzi Chen
- School of Microelectronics, Shanghai University, Shanghai 200000, China
| | - Jinxian Mao
- School of Microelectronics, Shanghai University, Shanghai 200000, China
| | - Fengyuan Yang
- School of Microelectronics, Shanghai University, Shanghai 200000, China
- Shanghai Key Laboratory of Chips and Systems for Intelligent Connected Vehicle, Shanghai University, Shanghai 200000, China
| | - Nan Wang
- School of Microelectronics, Shanghai University, Shanghai 200000, China
- Shanghai Key Laboratory of Chips and Systems for Intelligent Connected Vehicle, Shanghai University, Shanghai 200000, China
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Hao D, Zhang Y, Yang D, Li R, Zhao D, Zhang Z, Wang S, Jin W, Tian H, Duan J, Fan F, Chang S, Maro R, Ma L. Silicon bowtie structure based adjustable nonrigid all-nonmetal metamaterial terahertz filter. OPTICS LETTERS 2022; 47:6101-6104. [PMID: 37219182 DOI: 10.1364/ol.471704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Accepted: 10/31/2022] [Indexed: 05/24/2023]
Abstract
An all-nonmetal metamaterial (ANM) terahertz device with a silicon bowtie structure has been developed, which has comparable efficiency to that of its metallic counterparts, and better compatibility with modern semiconductor fabrication processes. Moreover, a highly tunable ANM with the same structure was successfully fabricated through integration with a flexible substrate, which demonstrated large tunability over a wide frequency range. Such a device can be used in terahertz systems for numerous applications, and is a promising substitute for conventional metal-based structures.
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Zong S, Zeng D, Liu G, Wang Y, Liu Z, Chen J. Multiple resonant modes coupling enabled strong CD response in a chiral metasurface. OPTICS EXPRESS 2022; 30:40470-40481. [PMID: 36298979 DOI: 10.1364/oe.475060] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Accepted: 10/11/2022] [Indexed: 06/16/2023]
Abstract
The chiral structures with strong circular dichroism (CD) response and narrow linewidth are desirable in chiral sensing, circularly-polarized light detection, and polarization imaging. Here, we theoretically proposed a hybrid chiral metasurface for differential absorption of circularly polarized light. Based on the multiple resonant modes coupling effect in a two-dimensional dielectric slab, it is realizable then to achieve a nearly perfect absorption for right circularly polarized light and simultaneously reflects 90% of left circularly polarized light, suggesting the generation of strong CD of 0.886 within a narrowly spectral linewidth of 4.53 nm. The multipole analysis reveals that the electric dipole, the magnetic dipole, and the electric quadrupole make dominant contributions to chiral absorption and the high CD response in this metsurface. The excitation of guided mode resonance enhances the ability of this metasurface to absorb electric field. Moreover, the optical chirality response can be further manipulated through the geometry features. These findings pave a powerful way to realize the narrowing and strong CD platform for single-band and multiband chirality behaviors.
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Sun Y, Zhang D, Wu B, Liu H, Yang B, Wu X. Metasurfaces Assisted Twisted α-MoO 3 for Spinning Thermal Radiation. MICROMACHINES 2022; 13:1757. [PMID: 36296110 PMCID: PMC9609790 DOI: 10.3390/mi13101757] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Revised: 10/14/2022] [Accepted: 10/15/2022] [Indexed: 06/16/2023]
Abstract
Spinning thermal radiation has demonstrated applications in engineering, such as radiation detection and biosensing. In this paper, we propose a new spin thermal radiation emitter composed of the twisted bilayer α-MoO3 metasurface; in our study, it provided more degrees of freedom to control circular dichroism by artificially modifying the filling factor of the metasurface. In addition, circular dichroism was significantly enhanced by introducing a new degree of freedom (filling factor), with a value that could reach 0.9. Strong-spin thermal radiation resulted from the polarization conversion of circularly polarized waves using the α-MoO3 metasurface and selective transmission of linearly polarized waves by the substrate. This allowed for extra flexible control of spinning thermal radiation and significantly enhanced circular dichroism, which promises applications in biosensing and radiation detection. As a result of their unique properties, hyperbolic materials have applications not only in spin thermal radiation, but also in areas such as near-field thermal radiation. In this study, hyperbolic materials were combined with metasurfaces to offer a new idea regarding modulating near-field radiative heat transfer.
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Affiliation(s)
- Yasong Sun
- Basic Research Center, School of Power and Energy, Northwestern Polytechnical University, Xi’an 710072, China
- Center of Computational Physics and Energy Science, Yangtze River Delta Research Institute of NPU, Northwestern Polytechnical University, Taicang 215400, China
| | - Derui Zhang
- Basic Research Center, School of Power and Energy, Northwestern Polytechnical University, Xi’an 710072, China
- Center of Computational Physics and Energy Science, Yangtze River Delta Research Institute of NPU, Northwestern Polytechnical University, Taicang 215400, China
- Shandong Institute of Advanced Technology, Jinan 250100, China
| | - Biyuan Wu
- Basic Research Center, School of Power and Energy, Northwestern Polytechnical University, Xi’an 710072, China
- Center of Computational Physics and Energy Science, Yangtze River Delta Research Institute of NPU, Northwestern Polytechnical University, Taicang 215400, China
- Shandong Institute of Advanced Technology, Jinan 250100, China
| | - Haotuo Liu
- Shandong Institute of Advanced Technology, Jinan 250100, China
- School of Energy Science and Engineering, Harbin Institute of Technology, Harbin 150001, China
| | - Bing Yang
- Centre for Advanced Laser Manufacturing (CALM), School of Mechanical Engineering, Shandong University of Technology, Zibo 255000, China
| | - Xiaohu Wu
- Shandong Institute of Advanced Technology, Jinan 250100, China
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Liu P, Zhou L, Tang J, Wu B, Liu H, Wu X. Spinning thermal radiation from twisted two different anisotropic materials. OPTICS EXPRESS 2022; 30:32722-32730. [PMID: 36242327 DOI: 10.1364/oe.470856] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Accepted: 08/10/2022] [Indexed: 06/16/2023]
Abstract
Thermal radiation has applications in numerous fields, such as radiation cooling, thermal imaging, and thermal camouflage. Micro/nanostructures such as chiral metamaterials with polarization-dependent or symmetry-breaking properties can selectively emit circularly (spin) polarized polarization waves. In this paper, we propose and demonstrate the spinning thermal radiation from two twisted different anisotropic materials. Taking industrial polymer and biaxial hyperbolic material α-MoO3 as an example, it is found that broadband spinning thermal radiation can be obtained from 13 µm to 18 µm. The spin thermal radiation of the proposed twisted structure originates from the combined effect of polarization conversion of circularly polarized wave and selective absorption of linearly polarized wave by the top and bottom layers of anisotropic materials, respectively. Besides, the narrowband spinning thermal radiation with 0.9 circular dichroism is achieved at wavelength of 12.39 µm and 18.93 µm for finite thickness α-MoO3 due to the epsilon-near-zero mode, and the magnetic field distribution can confirm the phenomenon. This work achieves broadband and narrowband spin thermal radiation and significantly enhances circular dichroism, which may have applications in biological sensing and thermal detection.
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Quasi-Bound States in the Continuum Enabled Strong Terahertz Chiroptical Response in Bilayer Metallic Metasurfaces. CRYSTALS 2022. [DOI: 10.3390/cryst12081052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Bound state in the continuum (BIC) as a novel non-radiating state of light in the continuum of propagating modes has received great attention in photonics. Recently, chiral BICs have been introduced in the terahertz regime. However, strong chiroptical effects of transmitted waves remain challenging to achieve in metallic terahertz metasurfaces, especially for intrinsic chirality at normal incidences. Here, we propose a chiral quasi-BIC by simultaneously breaking the out-of-plane mirror and in-plane C2 rotation symmetries in a bilayer metallic metasurface, in which spin-selective terahertz transmittance is successfully realized. Benefiting from the symmetry-protected nature of our proposed BIC, precise tuning of structural parameters can lead to anticipated chiroptical performance. As a degree of freedom, the rotation angle of the split ring gaps can fully determine the handedness, linewidth, and working frequency with strong circular dichroism. Besides, the sensing performance shows a surrounding refractive index sensitivity of 200 GHz/RIU, which is similar to those of previous works based on terahertz metasurfaces. Taking advantage exclusively of symmetry-protected BICs to realize transmitted terahertz chiroptical response provides fresh insights into the creation of novel BICs, which enables profound advancements in the surging field of novel terahertz devices.
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A Dual-Frequency Terahertz Metasurface Capable of Distinguishing the Handedness of Circularly Polarized Light. COATINGS 2022. [DOI: 10.3390/coatings12060736] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Circularly polarized light can present more optical properties of chiral materials and is widely used to analyze and detect biomolecules. In this paper, a dual-frequency terahertz circular polarization detection structure, which is based on multilayer metamaterials, is proposed. The proposed structure consists of a dual-frequency quarter-wave plate, a polyimide spacer, and a filter. The simulation results show that the structure can distinguish the handedness of circularly polarized light by filtering. The extinction ratios are 4 dB and 5.26 dB at 0.952 THz and 1.03 THz, respectively, and the maximum transmittance efficiency reaches 40%. Given the advantages of easy integration and dual-frequency operation, our design is bound to facilitate the development of multi-frequency detection in biomedical imaging devices.
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