Phys.org August 27, 2024
The exceptional point, a spectral singularity widely existing in non-Hermitian systems, provides an indispensable route to enhance the sensitivity of optical detection. However, the exceptional point of the systems is set once the system is built or fabricated, and machining errors make it hard to reach such a state precisely. An international team of researchers (China, Spain, Singapore) developed a highly tunable and reconfigurable exceptional point system, i.e., a single spoof plasmonic resonator suspended above a substrate and coupled with two freestanding Rayleigh scatterers. Their design offered great flexibility to control exceptional point states, enabling them to dynamically reconfigure the exceptional point formed by various multipolar modes across a broadband frequency range. They experimentally implemented five distinct exceptional points. The enhanced perturbation strength offered remarkable sensitivity enhancement for detecting deep-subwavelength particles with the minimum dimension down to 0.001λ (with λ to be the free-space wavelength)… read more. Open Access TECHNICAL ARTICLE
Schematic illustration of the tunable and reconfigurable EP sensing system on a single plasmonic resonator… Credit: Advanced Photonics Nexus, Vol. 3, Issue 5, 056004 (August 2024)