Overcoming the difficulties in numerical analysis of surface plasmon polaritons on noble metals at nanometer wavelengths

Experiments show that thin metallic (Ag, Au) films with periodic irregularities exhibit super-transmission phenomenon. At optical frequencies these metals have plasma dispersive properties. Resonant excitation of plasma surface waves is known as the surface plasmon polariton (SPP) effect. Even though theoretical formulations for the numerical analysis using periodic Green's functions exist, no rigorous models have been actually used to analyze SPP. Difficulties include: (i) complex permittivity with negative real part make the Green's functions no longer smooth in space; (ii) regular surface and volume equivalence principle schemes require very fine discretization for electrically large 3D structures; (iii) periodic formulation drastically slows down computational efficiency. Integral-equation based schemes with accelerated layered-media, periodic Green's functions, developed in our computational laboratory at Michigan State University promise significant advantage in accurate and efficient numerical analysis.