Affiliation:
1. State Key Laboratory of Extreme Photonics and Instrumentation ZJU‐Hangzhou Global Scientific and Technological Innovation Center Zhejiang University Hangzhou 310027 China
2. International Joint Innovation Center The Electromagnetics Academy at Zhejiang University Zhejiang University Haining 314400 China
3. Key Lab. of Advanced Micro/Nano Electronic Devices & Smart Systems of Zhejiang Jinhua Institute of Zhejiang University Zhejiang University Jinhua 321099 China
4. Shaoxing Institute of Zhejiang University Zhejiang University Shaoxing 312000 China
Abstract
AbstractWhen an electromagnetic wave is incident onto an object, the scattering from the object leads to its exposure. An invisibility cloak can bend the electromagnetic wave around the object with phase velocities exceeding the light speed in free space, which seems only possible over a narrow bandwidth, as manifested in the existing approaches, such as transformation optics and scattering cancellation. Here, it is experimentally demonstrated that this bandwidth limitation can be overcome by strategically positioning objects at topological nodes, characterized by minimal electromagnetic field amplitudes and indeterminate phases. This is accomplished using all‐dielectric photonic crystal slabs, which are engineered to exhibit a pair of topological nodes at fixed planes across an extensive bandwidth. This bandwidth expansion is facilitated not by resonance, but by the enforcement of mirror and time‐reversal symmetry. These findings thus introduce a novel topological paradigm for the broadband invisibility devices.
Funder
National Natural Science Foundation of China
Key Research and Development Program of Zhejiang Province
Fundamental Research Funds for the Central Universities
China Postdoctoral Science Foundation
Excellent Young Scientists Fund
Ministry of Science and Technology of the People's Republic of China