Optical antennas interface an object with optical radiation and boost the absorption and emission of light by the objects through the antenna modes. It has been much desired to enhance both excitation and emission processes of the quantum emitters as well as to interface multiwavelength channels for many nano-optical applications. Here we report the experimental implementation of an optical antenna operating in the full visible range via surface plasmon currents induced in a defect-free single-crystalline Ag nanowire (NW). With its atomically flat surface, the long Ag NW reliably establishes multiple plasmonic resonances and produces a unique rainbow antenna radiation in the Fresnel region. Detailed antenna radiation properties, such as radiating near-field patterns and polarization states, were experimentally examined and precisely analyzed by numerical simulations and antenna theory. The multiresonant Ag NW nanoantenna will find superb applications in nano-optical spectroscopy, high-resolution nanoimaging, photovoltaics, and nonlinear signal conversion.
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http://dx.doi.org/10.1021/nl3002414 | DOI Listing |
ACS Nano
December 2024
Department of Physics of Information in Matter and Center for Nanophotonics, NWO-I Institute AMOLF, Science Park 104, NL 1098XG Amsterdam, The Netherlands.
Phosphor-converted micro-light emitting diodes (micro-LEDs) are a crucial technology for display applications but face significant challenges in light extraction because of the high refractive index of the blue pump die chip. In this study, we design and experimentally demonstrate a nanophotonic approach that overcomes this issue, achieving up to a 3-fold increase in light extraction efficiency. Our approach involves engineering the local density of optical states (LDOS) to generate quasi-guided modes within the phosphor layer by strategically inserting a thin low-index spacer in combination with a metasurface for mode extraction.
View Article and Find Full Text PDFAdv Mater
December 2024
Advanced Microscopy and Instrumentation Research Center, Harbin Institute of Technology, Harbin, 150080, P. R. China.
Nowadays, metasurfaces have attracted considerable attention due to their promising and advanced control of electromagnetic (EM) waves. However, it is still challenging to shape guided waves into desired free-space mode, while simultaneously manipulating spatial incident waves using a single metasurface. Herein, a class of metasurfaces capable of multiplexing guided and space waves is proposed to achieve advanced EM functionalities in microwave regions, which can find great application potentials in radar systems, wireless communications, and wireless power transfer (WPT).
View Article and Find Full Text PDFSensors (Basel)
December 2024
Department of Computer Science, College of Computer and Information Sciences, Jouf University, Sakaka 72341, Saudi Arabia.
Distributed wireless sensor networks (WSNs) are widely used to enhance the quality and safety of various applications. These networks consist of numerous sensor nodes, often deployed in challenging terrains where maintenance is difficult. Efficient monitoring approaches are essential to maximize the functionality and lifespan of each sensor node, thereby improving the overall performance of the WSN.
View Article and Find Full Text PDFSensors (Basel)
December 2024
Dipartimento di Ingegneria dell'Informazione, Università di Pisa, 56122 Pisa, Italy.
A novel design strategy for improving the radiative performance of simultaneous multibeam (SMB) phased arrays is addressed. The proposed scheme relies on the adoption of mixed and multiple antenna element factors with a dynamic selection of their radiation patterns whose choice depends on the desired SMB pointing directions. In addition, a Penrose-inspired clustering technique is also employed for reducing the array feed points.
View Article and Find Full Text PDFSensors (Basel)
December 2024
Special Design and Technology Bureau "Granit", 292 Hussainov Street, Almaty 050060, Kazakhstan.
The search for new non-invasive methods of investigating the functioning of human internal organs is an urgent task. One of these methods for assessing the functioning of the human respiratory system is electromagnetic sensing, which is based on a significant difference in the dielectric permittivity of muscle tissue and air. During breathing, when the lungs are filled with air, the dielectric permittivity of the lungs decreases, which leads to a change in the level of the electromagnetic signal passing through the body.
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