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

Abstract

We apply the method of far-field matching to remodel laser beams and study light scattering from spherical particles illuminated by a Laguerre-Gaussian (LG) light beam. The optical field in the near-field region is analyzed for purely azimuthal LG beams characterized by a nonzero azimuthal mode number m LG . The morphology of photonic nanojets is shown to significantly vary, depending the mode number and the scatterer's characteristics. The cases of negative index metamaterial and metallic Mie scatterers are discussed. We also discuss the symmetry properties of laser beams and related results for the optical forces. The near-field structure of optical vortices associated with the components of the electric field, being highly sensitive to the mode number, is found to be determined by the twofold rotational symmetry.

Scattering of the Radial Polarized Beams on the Metal Spherical Particle: Plasmonic Nanojet Formation

“…In this section, we introduce all necessary notations and briefly describe computational approaches. Previously we already described most of them in our studies [24][25][26].…”

“…The far-field asymptotics for the vector spherical wave functions that enter the expansion for the incident wave (Eq. 3) are the following [24,25]:…”

“…However, there are also studies devoted to diffraction on dielectric scatterers with an inhomogeneous refractive index [20][21][22] and dielectric particles coated with metal [17,23]. In our best knowledge, the formation a nanojet by light scattering on full-metal micro particles has been not considered yet, except our brief remark about possibility of PNJ formation using strongly focused singular beams [24]. In this study, we pay attention to the case of a metallic spherical particles illuminated by a singular optical beam, i.e., carrying optical singularity in a form of an optical vortex with a helical phase front or radial or azimuthal polarization with undetermined state on the beam axis.…”

Two eccentric cylinders in a uniform electric field

“…(11) is known as the Maxwell-Garnett formula [5]. More accurate results can be obtained with the T-matrix method [13]. In the case of concentric circles and n = 2 we have [7] …”

Bound state for dielectric waveguide with high contrast inset in the core

“…Optical fibers containing inclusions with high contrast in permittivity are widely used (see, e.g., [1][2][3][4][5]). We consider a cylindrical dielectric waveguide (permittivity ߝ = ߝ 1 ) with a core (permittivity ߝ = ߝ 2 ‫ب‬ ߝ 1 ).…”