We present a theory of the Fano resonance for optical resonators, based on a temporal coupled-mode formalism. This theory is applicable to the general scheme of a single optical resonance coupled with multiple input and output ports. We show that the coupling constants in such a theory are strongly constrained by energy-conservation and time-reversal symmetry considerations. In particular, for a two-port symmetric structure, Fano-resonant line shape can be derived by using only these symmetry considerations. We validate the analysis by comparing the theoretical predictions with three-dimensional finite-difference time-domain simulations of guided resonance in photonic crystal slabs. Such a theory may prove to be useful for response-function synthesis in filter and sensor applications.
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http://dx.doi.org/10.1364/josaa.20.000569 | DOI Listing |
Phys Rev Lett
November 2024
Institute of High-Performance Computing, Agency for Science, Technology, and Research (A-STAR), Fusionopolis, 1 Fusionopolis Way, #16-16 Connexis, Singapore 138632, Singapore.
In this study, we construct Fabry-Perot cavities in which nanostructured, thin resonant metasurfaces act as mirrors. We develop a temporal coupled-mode theory and provide an accurate description of the resonances supported by these cavities, deriving analytically their transmission characteristics. The presence of metasurface mirrors introduces a substantial group delay, causing the field concentration to shift from the bulk of the cavity towards the regions close to the two metasurfaces.
View Article and Find Full Text PDFAnal Chem
December 2024
Key Laboratory of Optoelectronic Technology and System, Ministry of Education of China, College of Optoelectronic Engineering Chongqing University, Chongqing 400044, P. R. China.
Chemically synthesized gold nanoantennas possess easy processability, low cost, and suitability for large-area fabrication, making them advantageous for surface-enhanced infrared (SEIRA) biosensing. Nevertheless, current gold nanoantennas face challenges with limited enhancement of biomolecular signals that hinder their practical applications. Here, we demonstrate that the coupling rate between antennas and molecules critically impacts the enhancement of molecular signals based on temporal coupled mode theory.
View Article and Find Full Text PDFNano Lett
November 2024
Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Innovis #08-03, Singapore 138634, Republic of Singapore.
J Am Chem Soc
November 2024
Institute of Quantum Biophysics, Sungkyunkwan University, Suwon 16419, Republic of Korea.
Quantum mechanics is applied to create numerous electronic devices, including lasers, electron microscopes, magnetic resonance imaging, and quantum information technology. However, the practical realization of cavity quantum electrodynamics (QED) in various applications is limited due to the demanding conditions required for achieving strong coupling between an optical cavity and excitonic matter. Here, we present biological cavity QED with self-aligned nanoring doublets: QED-SANDs, which exhibit robust room-temperature strong coupling with a biomolecular emitter, chlorophyll-.
View Article and Find Full Text PDFAdv Sci (Weinh)
November 2024
Research Institute of Superconductor Electronics (RISE) & Key Laboratory of Optoelectronic Devices and Systems with Extreme Performances of MOE, School of Electronic Science and Engineering, Nanjing University, Nanjing, 210023, China.
Emerging reconfigurable metasurfaces offer various possibilities for programmatically manipulating electromagnetic waves across spatial, spectral, and temporal domains, showcasing great potential for enhancing terahertz applications. However, they are hindered by limited tunability, particularly evident in relatively small phase tuning over 270°, due to the design constraints with time-intensive forward design methodologies. Here, a multi-bit programmable metasurface is demonstrated capable of terahertz beam steering facilitated by a developed physics-informed inverse design (PIID) approach.
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