Energy flow around a small particle investigated by classical Mie theory

Abstract

The field lines of Poynting vector around a small particle are investigated on the basis of classical Mie theory. A particle can effectively absorb incident energy near the optical resonance, where its optical absorption cross-section becomes much greater than its geometrical cross-section. It is shown that absorbed energy flows into the particle through some limited portion of its surface ("input window") instead of the whole surface as it follows from the dipole approximation. This "input window" expands with the increasing value of the imaginary part Љ of the dielectric function of the particle. For a small Љ the absorbed energy is released by the plasmon radiation. Interference of this radiation with the incident wave creates complex patterns of energy flux in the near-field region. These patterns cannot be understood within the frame of a dipole approximation and the terms of higher orders with respect to size parameter q =2a / (a is the radius of the particle and is radiation wavelength) should be taken into account.

Suppression of scattering for small dielectric particles: anapole mode and invisibility

“…The physical reason for this effect can be explained from the Poynting vector field 16,17 , which indicates that the cross-section of separatrix tubes for the energy flow into the particle can greatly exceed the geometrical cross-section. Near plasmonic resonances with .…”

Aggregated Silver Sols as SERS Substrates

“…The illustration shows a few interesting phenomena occurring in the vicinity of plasmon resonance, in particular, the existence of singularities and the formation of optical vortices. These phenomena are discussed in detail in [19]. From point of view of this paper the most interesting is the fact that close to the resonance condition lines of energy ux can enter into the nanoparticle not only from the front (with respect to a power source) but also from the shadow side.…”

Magnetic-Dipolar-Mode Oscillations for Near- And Far-Field Manipulation of Microwave Radiation

“…It was shown recently that anomalous light scattering with quite unusual scattering diagrams and enhanced scattering cross sections near plasmon (polariton) resonance frequencies is nonRayleigh scattering. The observed power-flow patterns cannot be understood within the frame of a dipole approximation and the terms of higher orders with respect to size parameter q = 2πa/λ should be taken into account [35][36][37]. At microwave frequencies, the eigenvalue problem for magnetostatic resonances in small ferrite particles is quite different.…”