Transformation optics (TO) provides a powerful tool to manipulate electromagnetic waves, enabling the design of invisibility cloaks, which can render objects invisible. Despite many years of research, however, invisibility cloaks experimentally realized thus far can only operate at a single frequency. The narrow bandwidth significantly restricts the practical applications of invisibility cloaks and other TO devices. Here, a general design strategy is proposed to realize a multiband anisotropic metamaterial characterized by two principal permittivity components, i.e., one infinite and the other spatially gradient. Through a proper transformation and combination of such metamaterials, an omnidirectional invisibility cloak is experimentally implemented, which is impedance-matched to free space at multiple frequencies. Both far-field numerical simulations and near-field experimental mappings confirm that this cloak can successfully suppress scattering from multiple large-scale objects simultaneously at 5 and 10 GHz. The design strategy and corresponding practical realization bring multiband transformation optical devices one step closer to reality.
Download full-text PDF |
Source |
|---|---|
| http://www.ncbi.nlm.nih.gov/pmc/articles/PMC11267388 | PMC |
| http://dx.doi.org/10.1002/advs.202401295 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Transformation-Invariant Laplacian Metadevices Robust to Environmental Variation.
Adv Mater
January 2025
National Key Laboratory of Microwave Photonics, Nanjing University of Aeronautics and Astronautics, Nanjing, 211106, China.
As one of the typical applications of metamaterials, the invisibility cloak has raised vast research interests. After many years' research efforts, the invisibility cloak has extended its applicability from optics and acoustics to electrostatics and thermal diffusion. One scientific challenge that has significantly restricted the practical application of the invisibility cloak is the strong background dependence, that is, all passive cloaking devices realized thus far are unable to resist variation in the background refractive index.
View Article and Find Full Text PDFFlexSARCloak: A Flexible SAR Cloak Driven by Task-Oriented Learning.
ACS Appl Mater Interfaces
January 2025
Interdisciplinary Center for Quantum Information, State Key Laboratory of Modern Optical Instrumentation, ZJU-Hangzhou Global Scientific and Technological Innovation Center, Zhejiang University, Hangzhou 310027, China.
Invisibility─the remarkable ability to render objects imperceptible─has long been a persistent dream of humankind. However, traditional cloaking materials are typically rigid and inflexible, limiting their adaptability to various shapes and requirements. Even when flexibility is achieved, uncontrollable scattering in complex electromagnetic environments continues to pose significant challenges in the design of flexible cloaks.
View Article and Find Full Text PDFOn-demand zero-drag hydrodynamic cloaks resolve D'Alembert paradox in viscous potential flows.
Microsyst Nanoeng
December 2024
School of Mechanical and Power Engineering, East China University of Science and Technology, Shanghai, 200237, China.
Article Synopsis
- Manipulating fluid flow is crucial for advances in microfluidics, nanoengineering, and biomedicine, and can help address the global energy crisis by achieving zero-drag hydrodynamics.
- The research tackles challenges posed by the D'Alembert paradox and unresolved Navier-Stokes equations, introducing a new type of hydrodynamic cloak that operates with isotropic and homogeneous viscosity.
- Key findings highlight the importance of controlling vorticity for achieving zero-drag and hydrodynamic cloaking, challenging the notion that zero drag is impossible and offering insights beneficial for various technologies, including drug delivery systems.
Article Synopsis
- A moving dielectric medium can influence light's propagation by adding velocity, known as Fresnel drag, but conventional moving dielectric slabs cause boundary reflections and are ineffective near a refractive index of one.
- This study employs a geometric approach to create a virtual moving geometry that avoids boundary reflections, using a stationary bianisotropic spatiotemporal transformation medium that combines spatial and temporal elements for advanced electromagnetic manipulation.
- The research leads to applications like a nonreciprocal reflectionless field shifter and an invisibility cloak, providing theoretical advancements in the emerging area of time-varying metamaterials.
Light propagation in non-Euclidean geometry has become a hot topic in recent years, while transformation optics theory demonstrates unique advantages in this respect. A notable application of transformation optics in non-Euclidean space is non-Euclidean invisibility cloak which avoids the challenges of negative refraction and anisotropic materials. In this work, we propose another configuration for non-Euclidean invisibility, capable of achieving invisible across a wide spectrum.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!