Recently, it was shown that a Mie particle in an evanescent field ought to experience optical forces that depend on the helicity of the totally internally reflected beam. As yet, a direct measurement of such helicity-dependent forces has been elusive, as the widely differing force magnitudes in the three spatial dimensions place stringent demands on a measurement's sensitivity and range. In this study, we report the simultaneous measurement of all components of this polarization-dependent optical force by using a 3D force spectroscopy technique with femtonewton sensitivity. The vector force fields are compared quantitatively with our theoretical calculations as the polarization state of the incident light is varied and show excellent agreement. By plotting the 3D motion of the Mie particle in response to the switched force field, we offer visual evidence of the effect of spin momentum on the Poynting vector of an evanescent optical field.
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http://dx.doi.org/10.1103/PhysRevLett.120.223901 | DOI Listing |
Chem Asian J
January 2025
Universidad Austral de Chile, Instituto de Ciencias Químicas, CHILE.
Plasmonic materials can be utilized as effective platforms to enhance luminescent signals of luminescent metal nanoclusters (LMNCs). Both surface enhanced fluorescence (SEF) and shell-isolated nanoparticle-enhanced fluorescence (SHINEF) strategies take advantage of the localized and increased external electric field created around the plasmonic metal surface when excited at or near their characteristic plasmonic resonance. In this context, we present an experimental and computational study of different plasmonic composites, (Ag) Ag@SiO2 and (Au) Au@SiO2 nanoparticles, which were used to enhance the luminescent signal of Au nanoclusters coated with glutathione (GSH) molecule (Au25GSH NCs).
View Article and Find Full Text PDFSci Rep
January 2025
Terahertz Research Section, Electronics and Telecommunications Research Institute, Deajeon, 34129, Republic of Korea.
The complex dynamics of terahertz (THz) wave scattering by subwavelength-scale structures remain largely unexplored. This article examines the spectral scattering characteristics of subwavelength-sized spherical particles probed by tightly focused THz waves through numerical simulations and experimental techniques. The simulations reveal that the scattering intensity for lower Mie resonance modes (magnetic dipole and electric dipole modes) remains largely unaffected when THz waves are focused down to 0.
View Article and Find Full Text PDFOpen Forum Infect Dis
January 2025
Department of Microbiology and Immunology, School of Pharmaceutical Sciences, Wakayama Medical University, Wakayama, Japan.
Background: Human norovirus (HuNoV) is a major cause of enteric infectious gastroenteritis and is classified into several genotypes based on its capsid protein amino acid sequence and nucleotide sequence of the polymerase gene. Among these, GII.4 is the major genotype worldwide.
View Article and Find Full Text PDFLab Chip
January 2025
Key Laboratory of Biomedical Engineering of Ministry of Education, Department of Biomedical Engineering, Zhejiang University, Hangzhou, 310027, China.
The utilization of acoustic fields offers a contactless approach for microparticle manipulation in a miniaturized system, and plays a significant role in medicine, biology, chemistry, and engineering. Due to the acoustic radiation force arising from the scattering of the acoustic waves, small particles in the Rayleigh scattering range can be trapped, whilst their impact on the acoustic field is negligible. Manipulating larger particles in the Mie scattering regime is challenging due to the diverse scattering modes, which impacts the local acoustic field.
View Article and Find Full Text PDFNanophotonics
June 2024
POLIMA-Center for Polariton-driven Light-Matter Interactions, University of Southern Denmark, Odense M, Denmark.
We discuss the possibility of self-hybridisation in high-index dielectric nanoparticles, where Mie modes of electric or magnetic type can couple to the interband transitions of the material, leading to spectral anticrossings. Starting with an idealised system described by moderately high constant permittivity with a narrow Lorentzian, in which self-hybridisation is visible for both plane-wave and electron-beam excitation, we embark on a quest for realistic systems where this effect should be visible. We explore a variety of spherical particles made of traditional semiconductors such as Si, GaAs, and GaP.
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