A Simulation Study of Photonic Nanojet Generated by a Combination of a Dielectric Microsphere and a Hemisphere Lens

Photonic nanojet (PNJ) is a highly focused light beam generated on the shadow side surface of a plane-wave-illuminated dielectric microcylinder, microsphere or hemisphere lens. Compound microsphere lenses allow image magnification and better resolution. Here, we report the PNJ generated by using a combination of a dielectric microsphere lens and a hemisphere lens. The numerical simulation results demonstrate that full width at half-maximum (FWHM) and working distance (WD) show a decreasing trend with the increases of the distance between the microsphere and the hemisphere. Compared with the hemisphere lens of smaller radius, the hemisphere lens with larger radius has greater FWHM and WD. The minimum FWHM is ~0.82λ and the corresponding WD is ~2λ.