Photonic nanojets generated by single microspheres of various sizes illuminated by resonant and non-resonant focused Gaussian beams of different waists

Abstract

We report theoretical simulations on the photonic nanojet (PNJ) of single dielectric microspheres of various sizes illuminated by focused Gaussian beams (FGBs), using analytical theory developed by Gouesbet et al. based on the Bromwich formalism. The radius of the microsphere ( R ) is varied from 1 to 45 µm. The effect of the beam waist ( ω 0 ) on characteristic parameters such as maximum electric field enhancement ( η m a x ) of the PNJ, the focal length of the microsphere ( f ), effective length, and width of the PNJ is studied in detail. The effect of the refractive index of the microsphere ( n p ) and R on the η m a x for different values of ω 0 is studied. The dependence of (i) the f value on R and (ii) the η m a x value on λ is investigated systematically.