Invariant Imbedding Theory for the Scattering and Absorption of Electromagnetic Waves by Spherical Bodies

We develop an invariant imbedding method for the computation of the electromagnetic scattering cross-section from three-dimensional spherical bodies. We demonstrate that we can precisely calculate quantities of interest in the scattering and the absorption of an incident plane wave in various situations, such as propagation through arbitrarily inhomogeneous media and multilayered structures. Examples include scattering by a Luneburg lens and by a spherical cavity enclosed in a spherical photonic crystal structure, the layers of which satisfy the Bragg conditions for the incident wavelengths. In the latter case, light confinement in a very small core with a radius of 1.55 mu m with high quality factors at a level of 1.7 x 10(6) could be achieved.