arXiv subjects

Marine Laroche

Publications and source records attributed to Marine Laroche.

4 recordsLinked to original sources

arXiv2012

Optical extinction in a single layer of nanorods

We demonstrate that almost 100 % of incident photons can interact with a monolayer of scatterers in a symmetrical environment. Nearly-perfect optical extinction through free-standing transparent nanorod arrays has been measured. The sharp spectral opacity window, in the form of a characteristic Fano resonance, arises from the coherent multiple scattering in the array. In addition, we show that nanorods made of absorbing material exhibit a 25-fold absorption enhancement per unit volume compared to unstructured thin film. These results open new perspectives for light management in high-Q, low volume dielectric nanostructures, with potential applications in optical systems, spectroscopy, and optomechanics.

physics.optics↗

arXiv2008

Radiative heat transfer between metallic nanoparticles

In this letter, we study the radiative heat transfer between two nanoparticles in the near field and in the far field. We find that the heat transfer is dominated by the electric dipole-dipole interaction for dielectric particles and by the magnetic dipole-dipole interaction for metallic nanoparticles. We introduce polarizabilities formulas valid for arbitrary values of the skin depth. While the heat transfer mechanism is different for metallic and dielectric nanoparticles, we show that the distance dependence is the same. However, the dependence of the heat flux on the particle radius is different.

physics.optics↗

arXiv2008

Near-field induction heating of metallic nanoparticles due to infrared magnetic dipole contribution

We revisit the electromagnetic heat transfer between a metallic nanoparticle and a metallic semi-infinite substrate, commonly studied using the electric dipole approximation. For infrared and microwave frequencies, we find that the magnetic polarizability of the particle is larger than the electric one. We also find that the local density of states in the near field is dominated by the magnetic contribution. As a consequence, the power absorbed by the particle in the near field is due to dissipation by fluctuating eddy currents. These results show that a number of near-field effects involving metallic particles should be affected by the fluctuating magnetic fields.

cond-mat.other↗

arXiv2006

Controlling absorption resonances from sub-wavelength cylinder arrays

The absorption and extinction spectra of sub-wavelength cylinder arrays are shown to present two different kind of resonances. Close to the Rayleigh anomalies, the diffractive coupling with the lattice periodicity leads to sharp peaks in the extinction spectra with characteristic Fano line shapes for both s and p-polarizations. When the material exhibits an absorption line or in the presence of localized surface plasmon/polaritons, the system is shown to present resonant absorption with wider and symmetric line shapes. For s-polarization our analysis predicts a theoretical limit of 50 % of absorption. Interestingly, for p-polarized light and an appropriate choice of parameters, subwavelength cylinder arrays can present perfect (100 %) absorption.

physics.optics↗