Within the framework of generalized Lorenz–Mie theory, the properties of three-dimensional photonic jets emerging from spheroidal particles illuminated by a focused Gaussian beam are studied. The intensity, focal distance, and transverse and longitudinal dimensions of a photonic jet depending on the ellipticity of the spheroidal particle are numerically investigated. The simulation results show that, by simply varying the ellipticity, it is possible to obtain localized photon fluxes having different power characteristics and spatial dimensions. This can be of interest for several applications, such as high-resolution (nanometer scale) optical sensors, subdiffraction-resolution optical virtual imaging, and ultradirectional optical antennas.

In this paper we investigate the integral version of the localized approximation (ILA)—a powerful technique for evaluating the beam shape coefficients in the framework of the generalized Lorenz–Mie theory—as applied to ideal scalar Bessel beams (BBs). Originally conceived for arbitrary shaped beams with a propagating factor $\exp (\pm ikz)$, it has recently been shown that care must be taken when applying the ILA for the case of ideal scalar BBs, since they carry a propagating factor $\exp (\pm ikz\cos \alpha )$, with $\alpha$ being the axicon angle, which cannot be smoothly accommodated into its mathematical formalism. Comparisons are established between the beam shape coefficients calculated from both ILA and exact approaches, assuming paraxial approximation and both on- and off-axis beams. Particular simulations of radiation pressure forces are provided based on the existing data in the literature. This work helps us in elucidating that ILA provides adequate beam shape coefficients and descriptions of ideal scalar BBs up to certain limits and, even when it fails to do so, reliable information on the physical optical properties of interest can still be inferred, depending on specific geometric and electromagnetic aspects of the scatterer.

Based on the recent results in the generalized Lorenz–Mie theory, solutions for scattering problems of a sphere with an eccentrically located spherical inclusion illuminated by an arbitrary shaped electromagnetic beam in an arbitrary orientation are obtained. Particular attention is paid to the description and application of an arbitrary shaped beam in an arbitrary orientation to the scattering problem under study. The theoretical formalism is implemented in a homemade computer program written in FORTRAN. Numerical results concerning spatial distributions of both internal and external fields are displayed in different formats in order to properly display exemplifying results. More specifically, as an example, we consider the case of a focused fundamental Gaussian beam (${\mathrm{TEM}}_{00}$ mode) illuminating a glass sphere (having a real refractive index equal to 1.50) with an eccentrically located spherical water inclusion (having a real refractive index equal to 1.33). Displayed results are for various parameters of the incident electromagnetic beam (incident orientation, beam waist radius, location of the beam waist center) and of the scatterer system (location of the inclusion inside the host sphere and relative diameter of the inclusion to the host sphere).