Most reported thermal emitters to date employing photonic nanostructures to achieve narrow bandwidth feature the rainbow effect due to the steep dispersion of the involved high-Q resonances. In this work, we propose to realize thermal emissions with high temporal coherence but free from rainbow effect, by harnessing a novel flat band design within a large range of wavevectors. This feature is achieved by introducing geometric perturbations into a square lattice of high-index disks to double the period along one direction. As a result of the first Brillouin zone halving, the guided modes will be folded to the Γ point and interact with originally existing guided-mode resonances to form a flat band of dispersion with overall high Q. Despite the use of evaporated amorphous materials, we experimentally demonstrate a thermal emission with the linewidth of 23 nm at 5.144 μm within a wide range of output angles (from -17.5° to 17.5°).
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http://dx.doi.org/10.1038/s41467-024-48499-4 | DOI Listing |
Phys Rev Lett
December 2024
University of Connecticut, University of Connecticut, School of Mechanical, Aerospace, and Manufacturing Engineering, Storrs, Connecticut 06269, USA and Institute of Materials Science, Storrs, Connecticut 06269, USA.
Flat lines within a band structure represent constant frequency bands for all momentum values (i.e., they maintain zero group velocity for all wave numbers).
View Article and Find Full Text PDFPhys Rev Lett
December 2024
Clermont INP, Institut Pascal, PHOTON-N2, Université Clermont Auvergne, CNRS, F-63000 Clermont-Ferrand, France.
The combination of an in-plane honeycomb potential and of a photonic spin-orbit coupling (SOC) emulates a photonic or polaritonic analog of bilayer graphene. We show that modulating the SOC magnitude allows us to change the overall lattice periodicity, emulating any type of moiré-arranged bilayer graphene with unique all-optical access to the moiré band topology. We show that breaking the time-reversal symmetry by an effective exciton-polariton Zeeman splitting opens a large topological gap in the array of moiré flat bands.
View Article and Find Full Text PDFThe recent surge of interest in moiré photonics arises from the possibility of exploring many groundbreaking physical phenomena in photonics. These phenomena include photonic topological states and magic-angle lasing, which offer an attractive platform for manipulating the flow and confinement of light from remarkably simple device geometries. In this work, we fabricate a series of metallic moiré superlattices supporting moiré plasmon polaritons and explore the moiré-potential induced plasmonic resonances.
View Article and Find Full Text PDFMed Phys
January 2025
Department of Physics and Astronomy, University of California - Irvine, Irvine, California, USA.
Background: K-edge subtraction (KES) imaging is a dual-energy imaging technique that enhances contrast by subtracting images taken with x-rays that are above and below the K-edge energy of a specified contrast agent. The resulting reconstruction spatially identifies where the contrast agent accumulates, even when obscured by complex and heterogeneous distributions of human tissue. This method is most successful when x-ray sources are quasimonoenergetic and tunable, conditions that have traditionally only been met at synchrotrons.
View Article and Find Full Text PDFJ Cogn Neurosci
January 2025
National Central University, Taoyuan City, Taiwan.
Pitch variation of the fundamental frequency (F0) is critical to speech understanding, especially in noisy environments. Degrading the F0 contour reduces behaviorally measured speech intelligibility, posing greater challenges for tonal languages like Mandarin Chinese where the F0 pattern determines semantic meaning. However, neural tracking of Mandarin speech with degraded F0 information in noisy environments remains unclear.
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