Zihan Yi, Sylvain Lecler
Opt Express. 2021 Nov 22;29(24):39249-39255. doi: 10.1364/OE.443546.
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.
光子纳米喷流是电介质微粒阴影侧的一种高度局域化电磁传播光束。这一概念由陈等人在2004年发表的一篇著名论文中提出。自那时起，该论文激发了全球众多原创性的研究进展。几年后，我们指出，除了光子喷流外，还可能共存有回音壁模式（WGM）共振，而这种共振并不总是能由时域有限差分（FDTD）模拟得出。这种WGM共振会极大地改变电场分布。通过后续模拟，我们展示了这些WGM共振对参数变化是多么敏感。粒径变化小于1纳米就足以使其消失。这或许可以解释为什么尽管采用了高分辨率空间网格，FDTD模拟有时仍观测不到它们。
