In this paper, we proposed and numerically verified a perfect absorber composed of unstructured nature hyperbolic material α-MoO layers on top of photonic crystal (PhC) layers and reflecting mirrors, which can attain nearly perfect absorption of 99.94% at 24.7 terahertz (THz) in Transverse Magnetic (TM) mode. We demonstrate that the absorption efficacy can be regulated by adjusting structural parameters, meeting the requirements of the absorption spectrum spanning from the microwave to the infrared (IR) region. This study presents an exemplary application of natural hyperbolic materials in the realm of perfect absorption, offering significant potential for use in sensing and detection.
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http://dx.doi.org/10.1364/OE.537238 | DOI Listing |
Phys Chem Chem Phys
January 2025
School of Physics and Optoelectronic Engineering, Yangtze University, Jingzhou, 434023, P.R. China.
Metamaterials hold great promise for application in the field of perfect absorbers due to their remarkable ability to manipulate electromagnetic waves. In this work, a full-spectrum ultra-wideband solar absorber with a multilayer metal-dielectric stacked structure is designed. Our absorber is simple and easy to manufacture, with Ti serving as the substrate, overlaid with SiN spacer layers and four pairs of Ti-SiN ring columns.
View Article and Find Full Text PDFIn this paper, we theoretically analyze the optimization of a Fabry-Pérot cavity for the purpose of detecting partially absorbing objects placed inside without photon exchange. Utilizing the input-output formalism, we quantitatively relate the probability of correctly inferring the presence or absence of the object to the probability of avoiding absorption. We show that, if the cavity decay rate due to absorption by the object is comparable to that of the empty cavity and to the object-induced detuning, the product of the two probabilities is maximized by an undercoupled cavity, in which case detection in transmission is favorable to that in reflection.
View Article and Find Full Text PDFSci Adv
January 2025
School of Electrical and Computer Engineering, Cornell University, Ithaca, NY 14853, USA.
Using time as an additional design parameter in electromagnetism, photonics, and wave physics is attracting considerable research interest, motivated by the possibility to explore physical phenomena and engineering opportunities beyond the limits of time-invariant systems. Here, we report the experimental demonstration of enhanced broadband absorption of electromagnetic waves in a continuously modulated time-varying system, exceeding one of the key theoretical limits of linear time-invariant absorbers. This is achieved by harnessing the frequency-wave vector transitions and enhanced interference effects enabled by breaking both continuous space- and time-translation symmetries in a periodically time-modulated absorbing structure operating at radio frequencies.
View Article and Find Full Text PDFMicrosyst Nanoeng
January 2025
Sichuan University, 610207, Chengdu, China.
In conventional nondispersive infrared (NDIR) gas sensors, a wide-spectrum IR source or detector must be combined with a narrowband filter to eliminate the interference of nontarget gases. Therefore, the multiplexed NDIR gas sensor requires multiple pairs of narrowband filters, which is not conducive to miniaturization and integration. Although plasmonic metamaterials or multilayer thin-film structures are widely applied in spectral absorption filters, realizing high-performance, large-area, multiband, and compact filters is rather challenging.
View Article and Find Full Text PDFSensors (Basel)
December 2024
Wireless Sensing and Imaging Laboratory & 6G Research Laboratory, SRM University AP, Amaravati 522502, India.
This study presents a numerical modeling approach that utilizes millimeter-wave (mm-Wave) Frequency-Modulated Continuous-Wave (FMCW) radar to reconstruct and classify five weapon types: grenades, knives, guns, iron rods, and wrenches. A dataset of 1000 images of these weapons was collected from various online sources and subsequently used to generate 3605 samples in the MATLAB (R2022b) environment for creating reflectivity-added images. Background reflectivity was considered to range from 0 to 0.
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