Simulation of light scattering in large, disordered nanostructures using a periodic T-matrix method

Abstract

To model and design light propagation in disordered optical nanostructures and materials, any applicable simulation technique has to cope with enormous computational challenges in a bearable time frame. To circumvent these, the introduction of an artificial periodicity to the disordered particle structure allows to rely on computational techniques that exploit periodic boundary conditions. Choosing a rather large periodicity promises to preserve randomness in form of a close-range disorder but can introduce false interferences. So far, it remains open how the artificial periodicity has to be chosen to minimize its detrimental influence. Here, we combine the superposition T-matrix scheme with an Ewald sum formulation to account for light scattering in periodic particle arrangements that contain hundreds to thousands of individual scatterers per unit cell. Simulations reveal that the periodicity’s influence cannot be minimized by simply choosing one single period much longer than the excitation wavelength. The excitation of lattice induced resonances prevents so. However, choosing a periodicity that does not sustain such detrimental features allows for reliable predictions. With that, the presented approach is suitable to derive spectral information about wave-optical phenomena in large, random particle arrangements with a spatial extend beyond those accessible with other full-wave solvers.