Whispering gallery mode resonance contribution in photonic nanojet simulation

Abstract

A photonic nanojet is a highly localized electromagnetic propagative beam in the shadow side of a dielectric micro-particle. This concept was introduced in a famous paper by Chen et al. in 2004. Since then, this paper has inspired numerous original developments all over the world. Several years later, we point out that whispering gallery mode (WGM) resonances, not always brought out by FDTD simulations, can coexist in addition to the photonic jet. Such WGM resonances drastically change the distribution of the electric field. Through subsequent simulations, we show how these WGM resonances are highly sensitive to parameter changes. Particle diameter change smaller than 1 nm is enough to make them disappear. This may explain why sometimes they are not observed by FDTD simulations despite high resolution spatial mesh.