The accurate modeling of frequency-dispersive materials is a challenging task, especially when a scheme with a transient nature is utilized, as it is the case of the finite-difference time-domain method. In this work, a novel implementation for the modeling of graphene-oriented dispersive materials via the piecewise linear recursive convolution scheme, is introduced, while the time-varying conductivity feature is, additionally, launched. The proposed algorithm is employed to design a reduced graphene-oxide antenna operating at 6 GHz. The transient response to graphene's conductivity variations is thoroughly studied and a strategy to enhance the antenna performance by exploiting the time-varying graphene oxide is proposed. Finally, the use of the featured antenna for modern sensing applications is demonstrated through the real-time monitoring of voltage variation.
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http://dx.doi.org/10.3390/nano13030384 | DOI Listing |
Sci Rep
December 2024
College of Education, Department of Physics, Misan University, Amarah, Iraq.
This study introduces a high-performance 4-channel Metal-Insulator-Metal (MIM) diplexer, employing silver and Teflon, optimized for advanced photonic applications. The proposed diplexer, configured with two novel band-pass filters (BPFs), operates across four distinct wavelength bands (843 nm, 1090 nm, 1452 nm, 1675 nm) by precisely manipulating the passband dimensions. Utilizing Finite-Difference Time-Domain (FDTD) simulations, the designed diplexer achieves exceptional sensitivity values of 3500 nm/RIU, 4250 nm/RIU, 3375 nm/RIU, and 4003 nm/RIU, along with high figures of merit (FOM) ranging from 113.
View Article and Find Full Text PDFQuant Imaging Med Surg
December 2024
Department of Biomedical Engineering, State University of New York at Buffalo, Buffalo, NY, USA.
Background: Low-field open magnetic resonance imaging (MRI) systems, typically operating at magnetic field strengths below 1 Tesla, has greatly expanded the accessibility of MRI technology to meet a wide range of patient needs. However, the inherent challenges of low-field MRI, such as limited signal-to-noise ratios and limited availability of dedicated radiofrequency (RF) coils, have prompted the need for innovative coil designs that can improve imaging quality and diagnostic capabilities. In this work, we introduce a multimodal axial array resonator and its implementation in a volume coil, or referred to as a coupled stack-up volume coil, to address these challenges in low-field open MRI.
View Article and Find Full Text PDFWe propose what we believe to be a novel metastructure consisting of silicon nanoblock tetramer clusters and investigated theoretically and experimentally how to enhance surface sensing capabilities with polarization-independent properties through bound states in the continuum (BICs). By introducing square defects, three quasi-BIC modes are excited at the wavelengths of 1013.29 nm, 1109.
View Article and Find Full Text PDFACS Nano
November 2024
Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH, U.K.
Monolayers of semiconducting transition metal dichalcogenides (TMDs) have long attracted interest for their intriguing optical and electronic properties. Recently, TMDs in their quasi-bulk form have started to show considerable promise for nanophotonics thanks to their high refractive indices, large optical anisotropy, wide transparency windows reaching to the visible, and robust room temperature excitons promising for nonlinear optics. Adherence of TMD layers to any substrate via van der Waals forces is a further key enabler for the nanofabrication of complex photonic structures requiring heterointegration.
View Article and Find Full Text PDFNanomaterials (Basel)
August 2024
Faculty of Engineering, Holon Institute of Technology (HIT), Holon 5810201, Israel.
This paper proposes a unique configuration for an all-optical D Flip Flop (D-FF) utilizing a quasi-square ring resonator (RR) and T-Splitter, as well as NOT and OR logic gates within a 2-dimensional square lattice photonic crystal (PC) structure. The components realizing the all-optical D-FF comprise of optical waveguides in a 2D square lattice PC of 45 × 23 silicon (Si) rods in a silica (SiO) substrate. The utilization of these specific materials has facilitated the fabrication process of the design, diverging from alternative approaches that employ an air substrate, a method inherently unattainable in fabrication.
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