Light absorption in the near field around surface plasmon polaritons

Abstract

A semiclassical method is developed to calculate the energy absorption of an electronic system located in the near field of a metal nanoparticle sustaining surface plasmons. The results are found to be similar to those of photon absorption from ordinary transversal radiation. However, they are affected by a geometrical factor that can increase the absorption by several orders of magnitude. As example, we investigate ellipsoidal-shaped metal nanoparticles which, under favorable conditions, may provide near field aborption enhancements almost as large as 10 4 , and in many cases above 10.

Light concentration in the near-field of dielectric spheroidal particles with mesoscopic sizes

“…Pronounced near-field light amplification can also be achieved in the electrostatic regime using the surface plasmon resonance (SPR) of metallic nanoparticles (MNPs) much smaller than λ [5,31,[36][37][38]. As shown here, the electric intensity enhancement that can be obtained with mesoscopic spheroids is as high as that predicted at the surface of MNPs sustaining SPRs (~100E 0 2 ) in the infrared.…”

“…If the scattered electric field E S is longitudinal, energy absorption from this field cannot be determined classically such as with far-fields which are transverse [38]. A longitudinal field is a localized Coulomb field, with no associated Poynting vector [2], that transmits electrostatic energy by means of scalar photons, as described by quantum electrodynamics [40].…”

“…This is particularly suited for light trapping and concentration in novel solar cell concepts using quantum dots (e.g. intermediate band solar cells [31,38], hot carrier cells, all silicon tandem cells, etc.). DMPs should allow a significant enhancement in the absorption of a single layer of dots within a broad sunlight wavelength range.…”

Near-field scattering by dielectric spheroidal particles with sizes on the order of the illuminating wavelength

“…In this way it has been derived [18] that the rate of energy absorption from a longitudinal field, such as that in the near-field of scatterers, should be proportional to the squared magnitude of the scalar potential V(r) = -JQE • dr. Therefore, the plots of the longitudinal E r t component distributions shown in this work include a polar plot of the magnitude of V(r) at the surface of the particle.…”

“…Particular attention is drawn to the polarization characteristics in each regime. It is important to distinguish between the polarization components, longitudinal (parallel to the wavevector K) and transverse (orthogonal to K), when considering the interaction between the scattered light and a material in the near-field of the scattering particle [18], as shall be described in more detail in Subsection 3.B.…”