Frequency-selective surfaces (FSS) are a class of metasurfaces with engineered reflectance, absorbance, and transmittance behavior. We study an array of metallic crossed dipole FSS elements in the infrared using interferometric scattering-type scanning near-field optical microscopy (s-SNOM). We resolve the dependence of the near-field phase on the dimensions of the elements and compare with numerical models. The combined phase and amplitude information of the underlying near-field mode distribution compared to conventional far-field absorption spectroscopy greatly improves the targeted design of frequency-selective surfaces.
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http://dx.doi.org/10.1364/OE.20.011986 | DOI Listing |
Lab Chip
December 2024
College of Engineering and Applied Sciences, Nanjing University, Jiangsu 210093, China.
Acoustic waves provide an effective method for object manipulation in microfluidics, often requiring high-frequency ultrasound in the megahertz range when directly handling microsized objects, which can be costly. Micro-air-bubbles in water offer a solution toward low-cost technologies using low-frequency acoustic waves. Owing to their high compressibility and low elastic modulus, these bubbles can exhibit significant expansion and contraction in response to even kilohertz acoustic waves, leading to resonances with frequencies determined and tuned by air-bubble size.
View Article and Find Full Text PDFPolymers (Basel)
November 2024
Harbin Engineering University, Harbin 150001, China.
Multifunctional structures with excellent wave-absorbing and load-bearing properties have attracted much attention in recent years. Unlike other wave-absorbing materials, honeycomb wave-absorbing materials have appealing radar absorption and mechanical properties. However, the existing honeycomb wave-absorbing materials have problems such as narrow absorption band and poor compression resistance.
View Article and Find Full Text PDFNanophotonics
November 2024
College of Electronic Engineering, Chengdu University of Information Technology, Chengdu 610225, China.
Flexible and diverse manipulation of electromagnetic (EM) waves in half space (reflection or transmission) has facilitated strong aspiration toward full-space wave control. However, it remains challenging to achieve independent amplitude and phase control, which seriously hinder the real-world applications. Herein, an innovative strategy of trifunctional metasurface is proposed to independently and simultaneously manipulate the amplitude and phase of circular polarized waves in full space.
View Article and Find Full Text PDFSci Rep
November 2024
Department of Communication Engineering, School of Electronics Engineering, Vellore Institute of Technology, Vellore, Tamil Nadu, India.
A reflective dual-band linear-to-circular polarizer for C and X-band application is presented. The proposed elliptical Frequency Selective Surface (FSS) is capable of enhancing the polarization control and minimizes the cross-polarization compared to traditional circular or square geometries. The linear-to-circular polarization is achieved through two elliptical apertures, where each shape generates orthogonal modes with a 90° phase shift.
View Article and Find Full Text PDFThis work presents a design approach for optically transparent low-loss frequency selective surfaces (FSSs) based on the simultaneous optimization of a conductive layer, dielectric layer, and fabrication process. Three bandpass FSSs working in millimeter-wave bands with low insertion losses are investigated and fabricated based on low-loss Rogers RT5870 and cyclic olefin copolymer (COC) substrates. The measured results of the RT5870 based FSS (case 1) and COC based FSS (case 2) indicate that the COC substrate possesses lower dielectric loss tangent at the K band.
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