In this work we review in part of our recent theoretical study on the electrical intensity enhancement in the dielectric medium surrounding metallic nanoparticles due to the effect of their localized surface plasmon resonance (LSPR). The known results in the case of a simple metallic spherical nanoparticle are presented and then extend them to the general case of complex network of the identical spherical metallic nanoparticles. For illustration, several typical lattices of identical spherical metallic nanoparticles will be treated. The findings of electrical intensity enhancements and plasmonic resonance wavelengths of the single and the network of the metallic nanoparticles are obtained based on the analytical expressions. The theoretical results were compared and shown the good agreement with simulation results. The simulation of the LSPRs and the electrical intensity enhancements was performed using the boundary element method.

This paper presented the design, calculation and simulation of the Fano-like guidedmode resonances (GMRs) in the visible spectrum range based on the interference of the two in-plane waves oscillate towards the opposite directions with a phase difference in two-dimensional photonic crystal slabs (2D-PhCs). Narrowing linewidth or enhancing Q-factor of the GMR in 2D-PhC slab was based on the innovative PhC lattice, which was formed by introducing an additional cylinder or rectangular in each unit cell to enhance the light confinement in the waveguide slab. As such the induced Fano-like GMRs’ Q-factor was significantly increased about two orders of magnitude compared to the traditional PhC without additional cylinder or rectangular. The Finite-Difference Time-Domain (FDTD) method was used to determine the reflection spectra and simulated optical characteristics of the GMRs. The simulated spectra had Fano forms and were fitted to the theoretical model to determine precisely the resonant characteristics such as Qfactor and asymmetric factor (q-factor). The results showed that the resonant spectrum, optical properties, and characteristics influenced the shape and size of the addition elements. As a result, the innovative 2D-PhC slab excited Fano-like GMRs in this work would find fascinating applications in efficient free-space optic devices.