We perform two-photon excitation confocal experiments on coupled gold nanoantennas and observe time-integrated luminescence spectra that match plasmonic mode emission in the far-field. We show that the transversal particle plasmon mode can be excited, using excitation light that is cross-polarized with respect to the gold luminescence signal and therefore oriented along the long axis of the dipole gold antenna. We provide evidence for losses in polarization information from the excitation channel to the luminescence response due to the nature of the energy and momentum transfer. Finally, we map out the two-photon induced luminescence intensity profile for a fixed excitation wavelength λ and varying antenna arm length L.
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http://dx.doi.org/10.1364/OE.19.003686 | DOI Listing |
Phys Rev Lett
December 2024
Institute of Precision Optical Engineering, School of Physics Science and Engineering, Tongji University, Shanghai 200092, China.
Harnessing chiral optical forces facilitates numerous applications in enantioselective sorting and sensing. To date, significant challenges persist in substantiating the holistic complex theorem of these forces as experimental demonstrations employ common light waves (e.g.
View Article and Find Full Text PDFPhys Rev Lett
December 2024
Research Center for Nuclear Physics, Osaka University, Ibaraki, Osaka 567-0047, Japan.
Dipole toroidal modes appear in many fields of physics. In nuclei, such a mode was predicted more than 50 years ago, but clear experimental evidence was lacking so far. Using a combination of high-resolution inelastic scattering experiments with photons, electrons, and protons, we identify for the first time candidates for toroidal dipole excitations in the nucleus ^{58}Ni and demonstrate that transverse electron scattering form factors represent a relevant experimental observable to prove their nature.
View Article and Find Full Text PDFNanophotonics
November 2024
School of Electronic Engineering, Guangxi University of Science and Technology, Liuzhou, Guangxi 545006, China.
We report a transverse optical torque exerted on a conventional isotropic spherical particle in a direction perpendicular to that of the illuminating wave propagation. By using full-wave simulations and deriving an analytical expression of the transverse optical torque for particle of arbitrary size, the origin of this transverse optical torque is traced exclusively to the magnetic part of the spin angular momentum, regardless of the size and composition of the illuminated particle. To our surprise, for a non-magnetic dielectric particle, the transverse optical torque is found to originate mainly from the magnetic response of the particle, even when the particle size is much smaller than the illuminating wavelength.
View Article and Find Full Text PDFLangmuir
December 2024
Laboratoire Navier (Ecole Nationale des Ponts et Chaussées, Univ. Gustave Eiffel, CNRS), Champs sur Marne 77420, France.
We show that dynamic NMR relaxometry allows one to probe the particle size or the concentration evolution over time in homogeneous colloidal suspensions or the concentration in different regions of heterogeneous suspensions, up to large volume fractions. We first demonstrate that the NMR transverse relaxation time is independent of the gel structure at the particle scale so that it only slightly varies during the gelation of a colloidal suspension. The evolution over time of the NMR transverse relaxation time during gel drying and its analysis with the help of the fast-exchange assumption extended to a partially saturated medium then allowed us to identify three successive regimes: homogeneous shrinkage, desaturation, and molecular film regime.
View Article and Find Full Text PDFNanophotonics
November 2023
School of Optical-Electrical and Computer Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China.
In structured light tweezers, it is a challenging technical issue to realize the complete circular motion of the trapped particles parallel to the optical axis. Herein, we propose and generate a novel optical skipping rope via combining beam shaping technology, Fourier shift theorem, and beam grafting technology. This optical skipping rope can induce the transverse orbital angular momentum (OAM) (i.
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