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Abstract: Within the framework of the generalized Lorenz–Mie theory (GLMT), scattering from a homogeneous spheroidal particle illuminated by an on-axis Gaussian beam is formulated analytically, with more attention paid to the investigation of internal and near-surface fields. Numerical results concerning the spatial distributions of internal and near-surface fields are presented. This study may be useful to provide some physical insights to the understanding of focused beam scattering by nonspherical particles. [Copyright &y& Elsevier]

Abstract: An efficient numerical method based on the surface integral equations is introduced to simulate the scattering of Gaussian beam by complex particles that consist of an arbitrarily shaped host particle and multiple internal inclusions of arbitrary shape. In particular, the incident focused Gaussian beam is described by the Davis fifth-order approximate expressions in combination with rotation defined by Euler angles. The established surface integral equations are discretized with the method of moments, where the unknown equivalent electric and magnetic currents induced on the surfaces of the host particle and the internal inclusions are expanded using the Rao–Wilton–Glisson (RWG) basis functions. The resultant matrix equations are solved by using the parallel conjugate gradient method. The proposed numerical method is validated and its capability illustrated in several characteristic examples. [Copyright &y& Elsevier]

Abstract: A hybrid finite element-boundary integral method is applied to characterize the scattering of an arbitrarily incident-focused Gaussian beam by arbitrarily shaped inhomogeneous particles. Specifically, the Davis–Barton fifth-order approximation in combination with rotation Euler angles is used to represent the arbitrarily incident Gaussian beams. The finite element method is employed to formulate the fields in the interior region of the inhomogeneous particle, while the boundary integral equation is applied to represent the fields in the exterior region. The interior and exterior fields are coupled by means of the field continuity conditions. To reduce the computational burden, the frontal method and the multilevel fast multipole algorithm are adopted to solve the resultant matrix equation. Numerical results for differential scattering cross sections of several selected inhomogeneous particles are presented and can be served as further study on this subject. [Copyright &y& Elsevier]

Abstract: Soot particles formed in combustion processes commonly exist in the form of ensembles of randomly distributed aggregates of small, nearly spherical monomers. In this paper, these randomly distributed aggregates are numerically generated using a combination of the cluster–cluster aggregation algorithm with the Monte Carlo method. Moreover, an efficient and accurate numerical method is presented for characterizing the light scattering by these complex soot particles illuminated by plane wave and Gaussian beam. This method exploits the unique features of the hybrid finite element-boundary integral method and, more importantly, the unique features of soot aggregates. It is designed in such a manner that it first decomposes the original problem into many sub-regions, where each primary particle is regarded as a sub-region, and then it employs the edge-based finite element method to deal with each sub-region. The sub-regions communicate through the near-field Green’s function. To reduce computational burdens, an iterative domain decomposition method in combination with parallel conjugate gradient method is adopted to solve the coupling system of equations. As an illustration, we present some of our preliminary numerical results. The results are expected to provide useful insights into the optical properties of soot particles formed in combustion processes. [Copyright &y& Elsevier]

Highlights • The spheroidal beam shape coefficients are investigated by using an intrinsic method, for the case of general oblique illumination. • The analytic solution is constructed within the framework of the GLMT. • Numerical results concerning beam shape coefficients in spheroidal coordinates are presented. Abstract When dealing with T-matrix scattering, e.g. in the framework of Generalized Lorenz-Mie Theory (GLMT) or of Extended Boundary Condition Method (EBCM), the incident electromagnetic fields are expanded over a set of vectorial wave functions, with expansion coefficients expressed in terms of beam shape coefficients (BSCs). In the case of structured beams, the evaluation of these BSCs may constitute a challenging issue, particularly in the case of spheroidal coordinates. BSCs in spheroidal coordinates have been originally evaluated using an extrinsic method, i.e. they have been expressed in terms of more conventional BSCs in spherical coordinates. Later on, it has been possible to provide expressions to evaluate spheroidal BSCs using an intrinsic approach, i.e. by working only inside the spheroidal coordinate system used to deal with the scattering problem. Fairly recently, the intrinsic method for the evaluation of BSCs in spheroidal coordinates for on-axis standard configuration has been released in the archival literature. The present paper extends the intrinsic method to the case of oblique illumination. It also serves as a review devoted to GLMTs in spheroidal coordinates. [ABSTRACT FROM AUTHOR]

Abstract: A higher-order dispersive finite-difference time-domain (FDTD) method has been proposed to accurately model cloaking structures. In the proposed method, the higher-order FDTD scheme with second-order accuracy in time and fourth-order in space has combined with the shift operator algorithm. The exotic electromagnetic parameters of the cloaks are taken into account using shift operator based on dispersive FDTD method. The introduction of the higher-order algorithm would reduce the numerical dispersion of the FDTD method and guarantee a coarser grid during the simulation. Numerical results have indicated that the proposed method is more accurate than the available method maintaining the same grid size. Scattering width of different kinds of simplified cylindrical cloaks including thickness and loss is presented and this could serve for a further study on this subject. [Copyright &y& Elsevier]

Abstract: During the last decade, a strong effort has been devoted to the development of a generalized Lorenz–Mie theory for spheroids illuminated by Gaussian beams, and more generally by arbitrary shaped beams. An important issue in such a framework concerns the expanded description of the illuminating beam, and particularly the evaluation of beam shape coefficients. Unfortunately, the effort in this field is located at the bridge of three streams, each one with different conventions and notations, making the access to the literature inconveniently difficult. The aim of the present paper is to review the different approaches published, and to establish in a clear way the relationships between them. Beside being a help to the newcomer, this paper also aims to set milestones for future works, particularly concerning the development, under current investigation, of a localized beam model in spheroidal coordinates. [Copyright &y& Elsevier]