Persistence of photonic nanojet formation under the deformation of circular boundary

Abstract

A photonic nanojet is a highly focused optical beam with a subwavelength waist on the shadow side of the dielectric microsphere or microcylinder. In this paper, photonic nanojets resulting from corrugated cylinders (with irregular boundaries) under normally incident plane-wave illumination are studied. Different levels of corrugations induced at the boundaries of the dielectric microcylinders produce strong light focusing as well as a photonic nanojet with unique performance compared to perfectly smooth cylinders. The spectral element method is utilized in this study for the sake of high accuracy. Interestingly, we found that under some geometrical/material parameters one may not need a highly perfect cylinder in order to obtain a photonic nanojet. In addition, resonance behavior is reported and examined under larger variations in the parameters defining corrugated cylinders when compared with circular dielectric cylinders. (C) 2016 Optical Society of America