Scattered field formulation of finite difference time domain for a focused light beam in dense media with lossy materials

Abstract

Using the scattered field finite difference time domain (FDTD) formalism, equations for a plane wave incident from a dense medium onto lossy media are derived. The Richards-Wolf vector field equations are introduced into the scattered field FDTD formalism to model an incident focused beam. The results are compared to Mie theory scattering from spherical lossy dielectric and metallic spheres.

Plasmon spectra of nanospheres under a tightly focused beam

“…Nevertheless, since the NP is very small compared to the wavelength, the measured plasmon spectrum is usually only compared to theory based on plane wave (PW) illumination [1]. While the effect of supporting films and substrates has been extensively investigated [18,19,20,21,22], to the best of our knowledge, there is no detailed study on the spectrum of metal NPs under tight illuminations [23,24].…”

“…Less attention has been given to the case of a high-numerical-aperture (high-NA) beam incident upon a metal NP [23,24]. Török et al [23] and Challener et al [24] have described the high-NA beam by PW expansion [33].…”

“…Török et al [23] and Challener et al [24] have described the high-NA beam by PW expansion [33]. Subsequently, the scattering problem was solved using classical Mie theory [23] or the finite-difference time-domain method [24].…”

FDTD Simulations of Surface Plasmons Using the Effective Permittivity Applied to the Dispersive Media

“…Around this time, Ritchie reported the abnormal behavior of metal gratings in terms of excited surface plasmon resonance modes [6].In the same year, Otto [7], Kretschmann and Raether [8] presented methods to optically excited surface plasmon on metal surfaces. Since this pioneer study, various metallic nanostructures are reported for nano-plasmonic devices [3,9,10,12,13,14].…”

An Equivalent Circuit Modeling of an Equispaced Metallic Nanoparticles (MNPs) Plasmon Wire

“…However, light cannot propagate along the conventional waveguide if it is smaller than the wavelength of the optical signal [2]. As an alternative to solving the diffraction limit of optical signals, surface plasmon (SP) is now being extensively pursued for fabricating nanoscale photonic devices [3]. Notably, a metal has a negative dielectric permittivity in the optical spectrum, thereby enabling 1-D or 2-D SP wave to be propagated over subwavelength metallic structures [2], [4].…”