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The paper investigates the scattering analytical solution of arbitrary direction double zero-order Bessel beams (ZOBBs) incident on a non-uniform layered chiral sphere. Using the generalized Lorenz-Mie theory (GLMT), the electromagnetic field expansion expression of the double ZOBBs is obtained through the vector superposition of the spherical vector wave functions (SVWFs). Analytical solutions of the scattering on chiral layered particles by dual Bessel beams are derived based on the boundary condition. The iterative coefficient equations are constructed to obtain the expansion coefficients of the SVWFs in each region of the multi-layer chiral sphere. The variation of radar cross section (RCS) with angular distribution is numerically simulated, and the scattering results of layered chiral spheres degenerated into isotropic layered spheres are compared with the literature, which verifies the correctness of the theory and program. The effects of incident angle, polarization angle, cone angle and chiral parameters on the scattering characteristics of far region and internal field of the layered chiral particle are analyzed in detail. The theory and results can offer significant assistance in studying the optical properties of non-uniform chiral particles and complex biological cells irradiated by multiple beams and may also provide important practical value in the micromanipulation of multi-layered biological structures. [ABSTRACT FROM AUTHOR]

The Green function of the Biberman–Holstein integral equation, both nonstationary (instantaneous point flash) and stationary (stationary point source) is studied. The point flash produces a self-similar spherical wave of excitation in homogenous gas medium. The transfer of excitation is due to the Lévy flights of resonance line photons. The properties of the wave – its shape, time evolution and propagation – are found for arbitrary line profile. The cases of Doppler, Lorentz and Voigt profiles are considered in some detail. For the Doppler broadened line, the structure of the self-similar wave is given by a rational function. The properties of the Green function of stationary Biberman–Holstein equation are reviewed. Some unexpected parallels with non-stationary case are found. The spherically-symmetric version of the longest flight approximation is discussed and the condition of its validity is formulated. [ABSTRACT FROM AUTHOR]

An advanced light scattering model for Total Internal Reflection Microscopy (TIRM) is presented. The model considers the specific TIRM geometry and deals with the scattering by an axisymmetric particle of arbitrary orientation placed in a stratified medium and the imaging of the scattered field. The scattered field is computed by truncating the scattered and internal field expansions and by using spherical and plane wave expansions for the free-space dyadic Green's function. While the first expansion is valid outside a sphere enclosing the particle, the second one is valid outside the tangent planes bounding the particle from above and below. We demonstrate that in both cases, the results are the same, and thus, that the restrictive condition according to which the interface should not intersect the particle's circumscribed sphere is not relevant. The image of the scattered field is computed by using the Debye diffraction integral and fast Fourier transform, while for a better reconstruction of the particle orientation, an image processing step consisting in a contour extraction and ellipse fitting is considered. The numerical simulations dealing with scattering by a prolate spheroid provide evidence of the remarkably sensitivity of the geometric parameters of the image ellipse to the particle orientation angles, as well as, of the integral response of the detector to the distance between the particle and the interface. • Novel TIRM model for arbitrary particle orientation in stratified media. • High sensitivity of image ellipse in TIRM to particle orientation in simulations. • Contour extraction and ellipse fitting improve particle orientation accuracy. • Comprehensive scattering model for arbitrary particle orientation in stratified media. [ABSTRACT FROM AUTHOR]

• Using the ASR of the Gaussian beam, the blowing-up phenomenon in finite series is explained. • Blowing-up of BSCs is partly caused by catastrophic cancelation in limited precision calculations. • Blowing-up of BSCs originates from the contribution of evanescent waves. In generalized Lorenz-Mie theory, the beam shape coefficients of Gauss-like beams obtained with finite series method blow up when the wave order is high. The blowing-ups caused by the loss of significant digits may be suppressed by increasing numerical precisions. Once the elimination of such blowing-ups is carried out, blowing-up phenomena still occur whose origin is still not clear to us. The work presented here attempts to provide an explanation on this issue. Based on the angular spectrum representation of the beam field, it is found that the blowing-up originates from the contribution of evanescent waves. [ABSTRACT FROM AUTHOR]

• Objects can be places closely in T-matrix formalism. • Circumscribing spheres can intersect for non-spherical obstacles. • Transformation of spherical vector waves helps in superposition T-matrix method. • Accurate scattering results for two closely adjacent disks can be achieved. • Several scattering obstacles can be joined in a single T-matrix. This paper presents a novel method to calculate the T-matrix for two non-spherical obstacles positioned close to each other, where the individual circumscribed spheres intersect. This is achieved by translating the obstacles coordinate systems, using translation matrices for spherical vector waves. The new circumscribing spheres enables the obstacles to be positioned close to each other. A new total T-matrix of the two-obstacle system can then be calculated using methods for composite particles, i.e. , the superposition T-matrix method. This total T-matrix will generally be larger than the original ones, depending on the sizes of the circumscribing spheres used in the coordinate translation procedure. However, it is shown that the total T-matrix can be truncated after transformation to a common origin, without degrading the accuracy. The total truncated T-matrix is only slightly larger than the original individual ones. The method is demonstrated for electromagnetic scattering simulations of two metallic disks, closely adjacent to each other. [ABSTRACT FROM AUTHOR]

• The Generalized Source Method is used to develop T-matrix calculation methods: scattering matrix and scattering vector algorithms. • Scattering matrix algorithm provide a new recurrence for T-matrix calculation. • Scattering vector algorithm is highly parallelizable and yields accurate power balance. • A method for consideration of arbitrary polyhedral particles is suggested. The paper presents a scattering matrix and scattering vector methods for calculation of non-spherical particle T-matrices, which are based on the volume integral equation and the spherical vector wave function basis, and rely on the Generalized Source Method rationale. The derivation of the scattering matrix method is based on ideas previously used within the matrix operator method of the radiative transfer theory and the S-matrix method of the grating diffraction theory, and provides a new T-matrix recurrence relation being alternative to the recurrences used within the Invariant Imbedding and the Superposition T-matrix methods. The developed scattering vector algorithm for calculation of T-matrix single columns is shown to have a potential for parallelization and to yield an almost zero power balance for purely dielectric particles. Demonstrated results of electromagnetic scattering simulations include examples for spheroids and a complex non-symmetric polyhedron particle. [ABSTRACT FROM AUTHOR]

• Beam remodeling is avoided in the spherical wave expansion of the LGB. • The approximation of the ASD-BSCs under paraxial condition is consistent with the LA method. • The validity of the approximate BSC calculation is discussed, together with the distribution of the angular spectrum of the beam. • The ASD-BSCs are expressed in single integrals, which is reliable and efficient in calculation. Evaluation of the beam shape coefficients (BSC) in the spherical wave expansion of the incident beam is vital in analyzing light scattering by spherical particles. Different methods have been developed for this purpose. In this work, the formulas of the BSCs for the Laguerre-Gauss beam (LGB) are derived in the angular spectrum decomposition (ASD) method. Under the paraxial condition, these ASD-BSCs are approximated to the expressions in either series or single integrals. Besides, the BSCs for the LGB are also obtained in the localized approximation (LA) method. It is found that the approximate ASD-BSCs are same as those LA-BSCs. Numerical calculation is implemented for verifying the BSC calculations. The validity of the approximate BSC calculation is discussed, together with the distribution of the angular spectrum of the beam. The work offers another example of the shaped beams for mathematically justifying the LA method and suggests another way to discuss the validity of the LA method. [ABSTRACT FROM AUTHOR]

• TERMS is an open-source Fortran program implementing the superposition T-matrix method. • The program is described in relation to other methods. • A brief overview of the program is provided. • The theory and algorithms are reviewed. • Appendices describe the full list of arguments and subroutines. We introduce terms , an open-source Fortran program to simulate near-field and far-field optical properties of clusters of particles. The program solves rigorously the Maxwell equations via the superposition T -matrix method, where incident and scattered fields are decomposed into series of vector spherical waves. terms implements several algorithms to solve the coupled system of multiple scattering equations that describes the electromagnetic interaction between neighbouring scatterers. From this formal solution, the program can compute a number of physically-relevant optical properties, such as far-field cross-sections for extinction, absorption, scattering and their corresponding circular dichroism, as well as local field intensities and degree of optical chirality. By describing the incident and scattered fields in a basis of spherical waves the T -matrix framework lends itself to analytical formulas for orientation-averaged quantities, corresponding to systems of particles in random orientation; terms offers such computations for both far-field and near-field quantities of interest. This user guide introduces the program, summarises the relevant theory, and is supplemented by a comprehensive suite of stand-alone examples in the website accompanying the code. [ABSTRACT FROM AUTHOR]

• Cylindrical wave spectrum decomposition (CWSD) is recast for evaluating BSCs of shaped beams. • The method offers a deep insight into the effects from the beam profile and its location to the BSCs. • The method is easy to implement for beams having simple dependence on azimuth angle. • The method is flexible for shaped beams and the numerical calculation is efficient. In the analysis of light scattering by spherical particles, the incident beam is expanded into an infinite series of spherical wave functions weighted by the beam shape coefficients (BSCs). Different techniques have been developed for evaluating the BSCs in the context of generalized Lorenz-Mie theory (GLMT). In this work, the spectrum decomposition method which we call cylindrical wave spectrum decomposition (CWSD) is recast and is extended to beams having simple dependence on the azimuth angle. The method first expands the beam field in the cylindrical coordinate system and then expands the cylindrical waves into the spherical waves based on the relations between the cylindrical and spherical waves. The CWSD method offers a deep insight into the effects of the beam distribution and the beam's location to the BSCs. Numerical calculations are performed to verify the method. The CWSD method may serve as a powerful tool for studying the light scattering, in the similar way to the angular spectrum decomposition (ASD) method. [ABSTRACT FROM AUTHOR]

Abstract: Modeling of nonlinear dependences of optical properties of spherical two-layered gold core and some material shell nanoparticles (NPs) placed in water on parameters of core and shell was carried out on the basis of the extended Mie theory. Efficiency cross-sections of absorption, scattering and extinction of radiation with wavelength 532nm by core–shell NPs in the ranges of core radii r 00=5–40nm and of relative NP radii r 1/r 00=1–8 were calculated (r 1—radius of two-layered nanoparticle). Shell materials were used with optical indexes in the ranges of refraction n 1=0.2–1.5 and absorption k 1=0–3.5 for the presentation of optical properties of wide classes of shell materials (including dielectrics, metals, polymers, vapor shell around gold core). Results show nonlinear dependences of optical properties of two-layered NPs on optical indexes of shell material, core r 00 and relative NP r 1/r 00 radii. Regions with sharp decrease and increase of absorption, scattering and extinction efficiency cross-sections with changing of core and shell parameters were investigated. These dependences should be taken into account for applications of two-layered NPs in laser nanomedicine and optical diagnostics of tissues. The results can be used for experimental investigation of shell formation on NP core and optical determination of geometrical parameters of core and shell of two-layered NPs. [Copyright &y& Elsevier]

Abstract: The extinction matrices for both infinite-radius plates and finite-size particles are derived by assuming the far-field scattered waves to be either plane waves or spherical waves, and the connection between the two formalisms is discussed. In both cases, the elements of the extinction matrix are compared numerically for various incident angles and size parameters. Agreement is found between the results for the infinite-radius plates and plates with large aspect ratios and small incident angles. The differences between the two treatments provide insight into the understanding of the extinction properties of non-spherical particles illuminated by polarized incident light. [Copyright &y& Elsevier]

Abstract: This work concerns a common problem in electromagnetic scattering; calculation of the total scattering, extinction, and absorption cross sections for an arbitrary particle. Typical expressions for the cross sections are obtained in terms of the vector spherical wave function expansions for the incident and scattered waves. The unique aspect of this work is that the derivation is carried out specifically without use of the far-field zone approximation. The resulting expressions, valid at any distance, exactly match those obtained from the far-field approximation. This demonstrates that the cross sections are independent of the distance from the particle at which they are calculated as one would expect from energy conservation. Numerical simulations of the near and far-field zone energy flows due to a spherical particle are presented to illustrate several implications of this result. [Copyright &y& Elsevier]

• The scattering of a non-paraxial Bessel pincer light-sheet by a dielectric sphere of arbitrary size is investigated using GLMT. • The BSCs of the Bessel pincer light-sheet are calculated using ASDM and VSWFs. • The incident, scattering, internal and near-surface fields are numerically analyzed. • The absorption and extinction efficiencies are analyzed. • The influences of the scaling parameter and order of the Bessel pincer light-sheet are discussed. The scattering of a non-paraxial Bessel pincer light-sheet by a dielectric sphere of arbitrary size is studied in the framework of generalized Lorenz-Mie theory (GLMT). The electrical field of the Bessel pincer light-sheet is expanded using the vector angular spectrum decomposition method (VASDM), and its beam shape coefficients (BSCs) are derived using the method of multipole expansion and vector spherical wave functions (VSWF). By this way, the incident field, scattering field and near-surface field, and absorption and extinction efficiency factors are numerically calculated. Also, the effects of the beam order, scaling parameter, and polarization are mainly discussed. Numerical results represent that the intensity distribution of incident field, scattering field and near-surface field is intensely sensitive to the scaling parameters and the beam order. For the incident field, the bigger the order, the smaller the bending angle, and the closer the focus is to the source. By contrast, for the scattering and total field, the bigger the order, the larger the bending angle, and the farther the focus is to the source. Such results have potential applications in the imaging around steep corners and particle manipulation applications with minimal obstruction by particles. [ABSTRACT FROM AUTHOR]

• The T -matrix method is developed for the calculation of second-harmonic generation from clusters of particles. • The contributions of both surface and bulk nonlinear polarizations are incorporated in the formalism. • Convergence properties of the method are investigated. • We calculate the linear and nonlinear scattering cross-sections and field distributions in several generic cases. In this article, we present a T -matrix method for numerical computation of second-harmonic generation from clusters of arbitrarily distributed spherical particles made of centrosymmetric optical materials. The electromagnetic fields at the fundamental and second-harmonic (SH) frequencies are expanded in series of vector spherical wave functions, and the single sphere T -matrix entries are computed by imposing field boundary conditions at the surface of the particles. Different from previous approaches, we compute the SH fields by taking into account both local surface and nonlocal bulk polarization sources, which allows one to accurately describe the generation of SH in arbitrary clusters of spherical particles. Our numerical method can be used to efficiently analyze clusters of spherical particles made of various optical materials, including metallic, dielectric, semiconductor, and polaritonic materials. [ABSTRACT FROM AUTHOR]

• Evanescent wave scattering by a particle above a plane surface is obtained. • The projection method is applied to the scattering problem. • The normalized DSCS and SCS for the scattering problem are calculated. An exact semi-analytical solution to a scattering problem of evanescent wave incident on a particle is obtained. The evanescent wave is generated by total reflection as an electromagnetic plane wave propagates from an optically denser medium to an optically thinner one. The scattered fields by and internal fields within the particle are expanded in terms of spherical vector wave functions, and an integral representation of spherical vector wave functions over cylindrical ones is used to compute the reflection of the scattered fields on the interface between the optically denser and thinner media. By applying the boundary conditions and projection technique, the unknown expansion coefficients of the scattered fields are determined. The scattering cross sections are evaluated, and the scattering characteristics are analyzed briefly. [ABSTRACT FROM AUTHOR]

In our manuscript, we are reporting the translation criteria of scattering from Perfect Electric Conductor (PEC) sphere along three-dimensional axes using semianalytical approach. The presented scattering model is based on a generalized Lorenz-Mie theory framework and ensemble with the vector translation Addition Theorem (AT) for the Vector Spherical Harmonics (VSH). Applying extended Mie theory on a sphere leads to a set of an unknown coefficients by the use of translation AT. In the literature, there are many authors reporting different sets of the vector translation coefficients, of which we mention those calculated by Stein, Cruzan and, Mackowski in particular. We have selected the Cruzan formulation of the vector translation coefficients for its structure based on the Wigner 3-j function. As an illustration, we want to present numerical examples than simulations. of total scattered field PEC sphere using vector translation AT. We used advanced computational tools and approaches for mathematical modeling of an observation. During our numerical test, we have deeply investigated generic truncation criteria in scattered electric field using translation AT. However, we have been obtained numerical validation by using computational approach. [ABSTRACT FROM AUTHOR]

• The optical resonance scattering of a dielectric lossless sphere of arbitrary size illuminated by a polarized Airy beam is studied using the GLMT. • The BSCs of the polarized Airy beams are calculated using VASDM and VSWFs. • The influences of beam polarization, attenuation parameter γ and transverse scale ω 0 of the incident Airy beam are discussed. • The scattering and extinction, "resonance" and "interference" efficiencies are examined under different parameters. • The scattering efficiency for a perfectly conducting sphere, the normalized far-field scattering intensity and its resonance counterpart are calculated and plotted. The optical resonance scattering of a dielectric sphere of arbitrary size illuminated by a polarized Airy beam is studied using the generalized Lorenz–Mie theory (GLMT). The electric field is derived using the vector angular spectrum decomposition method (VASDM). The beam shape coefficients (BSCs) are obtained using the multipole expansion method involving vector spherical wave functions (VSWFs). The resonance scattering characteristics are calculated using the GLMT by subtracting a non-resonant background of a perfectly conducting impenetrable sphere. The effects of beam polarization (i.e., linear, circular, radial, azimuthal, and mixed), the attenuation parameter γ and the dimensionless transverse scale kω 0 of the incident Airy beam on the scattering and extinction, "resonance" and "interference" efficiencies are examined. Moreover, the scattering efficiency for a perfectly conducting sphere as well as the three-dimensional (3D) scattering directivity patterns of the normalized dimensionless far-field scattering intensity and its resonance counterpart are calculated and plotted. The analysis of the resonance scattering shows that the energy efficiency is not the mere sum of resonance and perfectly conducting background terms; there is an interference between the two denoted by Q s c a i n t e r f , which strongly affects the resonance extinction and scattering efficiencies. The results presented here are of some importance in studying the optical resonance scattering of polarized Airy beams in applications involving imaging, particle sizing, radiation forces and torques to name a few areas of research. [ABSTRACT FROM AUTHOR]

• The scattering of a non-paraxial Bessel light-sheet by a sphere of arbitrary size is investigated using GLMT. • The BSCs of the Bessel light-sheet are calculated using ASDM and VSWFs. • The incident, internal and near-surface fields are numerically calculated. • The absorption and extinction efficiencies are analyzed. • The influences of the order and half-cone angle of the Bessel light-sheet are discussed. The scattering of a non-paraxial Bessel light-sheet by a sphere of arbitrary size is studied in framework of generalized Lorenz-–Mie theory (GLMT). The electrical fields of the Bessel light-sheet are expanded using the vector angular spectrum decomposition method (VASDM), and the beam shape coefficients (BSCs) of the Bessel light-sheet are derived using the method of multipole expansion and vector spherical wave functions (VSWF). The internal and near-surface fields, and absorption and extinction efficiency factors are numerically calculated when a Bessel light-sheet is incident, and the effects of beam's order, and half-cone angle are mainly discussed. Numerical results show that there is strong point convergence in the forward scattering region under the incident of a Bessel light-sheet, and the internal and near-surface fields of Bessel light-sheet are very sensitive to the beam's order, half-cone angle, etc. Such results have potential applications in the super-resolution imaging using a light-sheet microscopy. [ABSTRACT FROM AUTHOR]

• Optical force on a sphere of arbitrary size illuminated by an Airy lightsheet is investigated using GLMT. • The BSCs of the Airy light-sheet are calculated using ASDM and VSWFs. • The negative longitudinal optical force is particularly emphasized. • The two kinds of polarizations (TE and TM) of Airy light-sheet are discussed. • The influences of the transverse scale parameter ω 0 and attenuation parameter γ of the Airy light-sheet are discussed. Based on the generalized Lorenz–Mie theory (GLMT) and the angular spectrum decomposition method (ASDM), we calculate the optical radiation force exerted on a lossless dielectric sphere of arbitrary size illuminated by an Airy light-sheet. The beam shape coefficients (BSCs) of the Airy light-sheet are calculated using the vector angular spectrum decomposition and vector spherical wave functions methods. The optical radiation force acting on the spherical particle is obtained by the integral of Maxwell's stress tensor. The transverse (F y) and longitudinal (F z) forces are numerically computed. Two kinds of polarization (TE and TM) are considered for the Airy light-sheet, and the negative longitudinal optical (pulling) force is particularly emphasized. The influence of the transverse scale parameter w 0 and attenuation parameter γ of the Airy light-sheet on the force is discussed. The results of the present theory are verified using the dipole approximation method in which the gradient force has been also computed for a Rayleigh sphere. The numerical results show that when the transverse scale parameter w 0 and attenuation parameter γ increase, the transverse and longitudinal forces decrease. Furthermore, the force caustic (i.e., maximum) shifts to the direction of y < 0 as the transverse scale parameter w 0 increases. As the dimensionless size parameter of the sphere ka increases (where k is the wavenumber and a is the radius), the resonance peaks of the optical forces become larger. The results of this paper are of practical significance for the development of Airy light-sheet based optical manipulation technologies. [ABSTRACT FROM AUTHOR]

• Gaussian beam scattering by a sphere embedded in an infinitely long circular cylinder is presented. • The projection method is applied to the scattering problem. • Total scattered field and normalized field intensity distribution are calculated. An analytical method of analyzing the electromagnetic scattering of a Gaussian beam by an infinitely long circular cylinder with a spherical inclusion is presented. The fields within different regions are expanded in terms of appropriate cylindrical or spherical vector wave functions. By applying the integral representation of spherical vector wave functions over cylindrical ones, boundary conditions and projection procedure, the unknown expansion coefficients are determined. For a localized beam model, numerical results of the total scattered field and normalized field intensity distribution are shown, and the scattering properties are discussed briefly. [ABSTRACT FROM AUTHOR]

• The lateral binding force exerted on chiral bi-sphere induced by a high-order Bessel beam with arbitrary polarization states is studied analytically. • The accuracy of the theory and codes is verified. • Numerical effects of various parameters and different properties are numerically analyzed in detail. Even more so in hindsight of these parameters with respect to optical binding clearly shows that in what case optical binding exists as a fine balance between those parameters. The generalized multi-particle Mie equation (GMM) and electromagnetic momentum (EM) theory are applied to investigate the stability and dynamics of chiral nanoparticles in lateral optical binding induced by a high-order Bessel beam (HOBB). Such non-diffracting light suppressed the influence of the axial intensity profile of the illuminating beams on the self-organization process which then depended critically upon the inter-particles interactions. The illuminating HOBB is described in terms of beam shape coefficients (BSCs) within the framework of generalized Lorenz–Mie theories (GLMT). Utilizing the addition theorem of the vector spherical wave functions (VSWFs), the interactive scattering coefficients are derived through the continuous boundary conditions on which the interaction of the chiral nanoparticles is considered. The observed lateral binding force (BF) dependence of the separation of optically bound particles on the incidence of HOBB is in agreement with earlier theoretical prediction when the chiral spheres degenerate into isotropic spheres. We discuss the influence of the different parameters of the incident Bessel beam and of the chiral body on lateral BF in detail. Linearly and circularly polarized incident Bessel beams are considered, and the corresponding lateral BFs are compared and analyzed. The polarizations of incident HOBB considerably influence the lateral BF of chiral nanoparticles. In binding chiral nanoparticles, the polarization of incident beams should be chosen in accordance with the chirality. This finding may provide a recipe to understand the light interaction with multiple chiral particles of arbitrary shapes with the aid of the analytical approach. It could be a promising avenue in controlling the optical micromanipulation on chiral structures self-arrangement. [ABSTRACT FROM AUTHOR]

• Non-orthogonal spherical Bessel functions may be used in the framework of generalized Lorenz-Mie theory. • This implies the existence of an infinite number of quadratures for evaluating the beam shape coefficients (BSCs). • This infinite number of quadratures nevertheless implies the uniqueness of BSCs, i.e. the uniqueness of the decomposition of EM fields over VSWFs. When dealing with light scattering theories such as the T-matrix methods for structured laser beams, e.g. Generalized Lorenz-Mie Theory (GLMT) or the Extended Boundary Condition Method (EBCM), EM fields are expanded over a set of Vector Spherical Wave Functions (VSWFs) involving spherical Bessel functions, with expansion coefficients expressed in terms of Beam Shape Coefficients (BSCs). Although spherical Bessel functions are orthogonal over the range (− ∞ , + ∞) , the GLMT may be expressed using a non-orthogonal set of spherical Bessel functions defined over (0 , + ∞) , allowing one to generate an infinite number of quadratures for evaluating the BSCs. This paper points out the difference between orthogonal and non-orthogonal spherical Bessel functions, establishes the infinite number of quadratures and discusses its properties. [ABSTRACT FROM AUTHOR]

• We revisit interference phenomena caused by pairs of co-propagating or counter-propagating transverse electromagnetic waves by letting the host medium be absorbing. • We first consider plane waves in an unbounded medium. • We then consider the superposition of plane and spherical waves in the context of far-field electromagnetic scattering by a particle. • The physical similarity of the two scenarios is discussed. In this semi-tutorial paper, we revisit the interference phenomena caused by pairs of co-propagating or counter-propagating transverse electromagnetic waves by letting the host medium be absorbing. We first consider plane waves in an unbounded medium, summarize the standing-wave solution of the Maxwell equations, and discuss specific effects caused by nonvanishing absorption. We then consider the superposition of plane and spherical waves in the context of far-field electromagnetic scattering by a particle. To this end we modify the classical Jones lemma by allowing nonzero absorption in the host medium and consider its most obvious consequences such as forward- and backscattering interference. The physical similarity of the two scenarios (superpositions of plane waves and superpositions of plane and spherical waves) is discussed. [ABSTRACT FROM AUTHOR]

• New algorithm for numerical simulation of laser beam backscatter in a turbulent atmosphere has been developed and implemented in study of amplification effect of atmospheric laser echo signal. • It is shown that with strengthening of the refractive turbulence the amplification factor first increases, achieves the maximum, and then begins to decrease. Amplification factor is maximal in the regime of a spherical wave and grows with an increase of the inner scale of turbulence. • Calculated data on the amplification of the mean power of the laser echo signal as a function of the refractive turbulence strength, regime of diffraction on the transmitting aperture, inner scale of turbulence, and size of the receiving aperture are reported for the first time. Laser beam backscatter in a turbulent atmosphere is analyzed. The mean intensity of radiation scattered in turbulent atmosphere is shown to increase in the backward direction in comparison with the intensity of radiation scattered in the same direction in absence of turbulence, due to the effect of backscatter amplification in random media. As the strength of refractive turbulence increases, the amplification factor first grows, achieves the maximum, and then decreases. The area of manifestation of the backscattering amplification effect in the plane, transverse to the propagation direction, increases in size with intensification of refractive turbulence. It is found that the amplification factor depends on the inner scale of turbulence and the regime of diffraction of optical radiation at the transmitting aperture. It is maximal for spherical wave and grows with an increase of the inner scale. The data on the amplification effect for the mean power of the lidar echo signal as a function of refractive turbulence strength, regime of diffraction at the transmitting aperture, inner scale of turbulence, and size of the receiving aperture are reported for the first time. [ABSTRACT FROM AUTHOR]