The role of near-field diffraction in photonic nanojet formation

Abstract: In this paper, we show the photonic nanojet is the central bright maxima in focused near-field diffraction pattern. Using a simplified Huygens-Fresnel model, and using numerical simulations, we generate photonic nanojets from curved interfaces between media of different refractive indices and study the length, width, and peak intensity of the resultant photonic nanojet. We confirm that photonic nanojets are not sub-diffraction optical modes and are adequately described using diffraction theory. We also show how modifying the optogeometric environment can be used to tailor relevant features of the nanojets in general.