Scattering of an electromagnetic beam by a radially inhomogeneous sphere

A method to calculate the scattering intensities of a multilayered sphere or a radially inhomogeneous sphere is presented. The sphere is illuminated with an electromagnetic wave of an arbitrary spatial distribution. The radially inhomogeneous sphere is modeled by a multilayered sphere. The method uses the technique presented by Wu and Wang (1991) and by Johnson (see Appl. Opt., vol.35, p.3285-96, 1996) to calculate the scattering coefficients of a multilayered sphere and a method that represent an arbitrary incident beam in terms of vector spherical harmonics (VSH). The presented method is used to calculate the backscattered and angular scattering intensities of a multilayered and a radially inhomogeneous spheres illuminated with a Gaussian beam. The method is capable of calculating the scattered field of any scatterer as long as its scattering coefficients are known. Also the method can be used for a tightly focused incident beam. The beam can be focused to an arbitrary position with respect to the sphere.