Mie scattering of Laguerre-Gaussian beams: Photonic nanojets and near-field optical vortices

Abstract

We study Mie light scattering of Laguerre-Gaussian (LG) beams remodelled using the method of far-field matching. The theoretical results are applied to examine the optical field in the near-field region for purely azimuthal LG beams characterized by the nonzero azimuthal mode number m LG . The mode number m LG is found to have a profound effect on the morphology of photonic nanojets and the near-field structure of optical vortices associated with the components of the electric field.

Light scattering of Laguerre-Gaussian beams: near-field structures and symmetries

“…As opposed to the case with m LG = 2 discussed in Ref. [38], at m LG = 1, the central vortex of the x component, E x , is structurally stable and cannot be destroyed.…”

“…[10,38] to study the light scattering problem for optically isotropic spherical scatterers illuminated with LG beams that represent optical vortex laser beams. Our approach uses the remodelling procedure in which the far-field matching method is combined with the results for nonparaxial propagation of LG beams.…”

“…It can be shown [38] that the vector spherical harmonics (3) can also be recast into the well-known standard form [44]:…”

“…Then, the vector version of the well-known Rayleigh expansion (see, for example, [2,10,38]) immediately gives the expansion coefficients for the plane wave:…”

“…[10,38] and use the T -matrix approach in which the far-field matching method is combined with the results for nonparaxial propagation of LG beams [29,30]. Our goal is to examine the near-field structure of optical field depending on the parameters characterizing both the beam and the scatterer.…”