Cross Conversion between Surface Plasmon Polaritons and Quasicylindrical Waves

The optical properties of textured metallic surfaces are governed by the scattering of surface plasmon polaritons (SPPs) and of quasicylindrical waves (CWs), which are both excited by the nano-objects located on the surface. We study here a fundamental scattering process of these fields, namely, the cross conversion of a CW into a SPP. We first show that this inelastic process is inevitable in multi-nano-object ensembles and then propose a procedure enabling a rigorous calculation of the cross conversion scattering coefficients. Additionally, by mapping this intricate process to a much simpler one, we derive general and simple expressions for the cross conversion efficiency. All predictions are carefully supported by fully vectorial computational results.