Optical properties of surface plasmons induced by the plan of a periodically arranged dielectric spheres on the metal slab

Optical properties of a system composed of a metal slab with two planes of periodically arranged dielectric spheres on the metal surface have been investigated.The results obtained from multiple scattering method show that the periodic dielectric spheres on the upper surface of the metal could induce surface plasmons on the metal-dielectric interface.For a very thick metal slab,the existence of the surface plasmons can be observed by corresponding peaks in absorption spectrum.The position of the absorption peak is mainly determined by the periodicity ofdielectric spheres,and is consistent with the analytic theory very well.For the limited thickness of metal slab,there exist two surface plasmon modes,corresponding to symmetric and antisymmetric modes,respectively,and the absorption peak that occurs in the thick metal slab splits into a double-peak strurcture.For a symmetric or antisymmetric surface plasmon,the magnitudes of the electric and magnetic fields are the same on both sides of the metal slab,thus these surface plasmons can results in a strong transmittance.The plane of periodically arranged dielectric spheres beneath the metal slab can lead the surface field out of the metal,and form a transmission plane wave.The results obtained from multiple scattering method show that the transmittance is fairly high when surface plasmons exist.The fundamental physical mechanism is studied in detail,and the occurrence of the surface plasmons,and hence the position of the peak of absorbance or transmittance,can be controlled by adjusting corresponding parameters in the system.