Study on the Plasmonic Properties of Ag-coated Spherical Dielectric Nanoparticles by Finite-Difference Time-Domain Calculations

The optical properties of nanostructures are rather important for designing plasmonic devices. In this work, the Ag-coated spherical dielectric nanoparticles (NPs), namely, Ag-SiO2-NPs, Ag-ZnO-NPs, and Ag-TiO2-NPs, were studied using a method finite-difference time-domain calculations. It was found that NPs start to exhibit unique different from Ag-NPs as thickness Ag shells is reduced be less than critical value, which basically determined by penetration depth light in silver. On other hand, core–shell structures benefit resonance high-efficiently coupled with incident light. extinction spectra sufficient thin shells, dipole predominant exhibits pronounced red-shift up infrared band increasing NP sizes. addition electromagnetic waves emission towards outside, field inside uniformly enhanced well both quadrupole resonances identified. suggested have great potential devices working band, such emitters SERS substrates biosensing.