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In this paper, we investigate photonic nanojets (PNJs) generated from silicon-based cuboids and grating structures. The cuboid structure consists of a base microcuboid and a nanocuboid sitting on top. By tuning the parameters of cuboids and surrounding medium, we show that ultra-narrow PNJs with spot sizes between 82 nm (~ λ /7.8) and 86 nm (~ λ /7.4) can be achieved under a 638 nm TE-polarized light illumination. These results are comparable to the solid immersion resolution limit of λ /7.8 for silicon lenses, but significantly exceeding the half wavelength limit in air. By arranging an array of hybrid-cuboids structures into a grating structure, we show that the PNJ resolution can be pushed beyond the solid immersion limit, reaching λ /8.3 with spot size ~77 nm. This is one of the highest optical resolutions reported to date for a visible light PNJ array generated by a grating and may find applications in sensing and lithography. [ABSTRACT FROM AUTHOR]

Recently, tunable photonic nanojets (PNJs) utilizing a mask have been investigated to produce narrow PNJs and curved PNJs (photonic hooks, PHs). Herein, a dielectric nano-layer is employed to tune the PNJs from a micro-cylinder. Symmetric and asymmetric illumination caused by the nano-layer are studied separately with finite element method. The results show that, for the symmetric illumination, narrow PNJs and twin PNJs (t-PNJs) can be generated through controlling the width of the layer. For the asymmetric illumination, it has the ability to produce PHs and asymmetric t-PNJs by changing the thickness of the nano-layer. Based on these results, an optical switch for light-route selection depending on the incident light wavelength is presented. This work may have great potential in the fields of optomechanical manipulation, super-resolution imaging and optical nanolithography. [ABSTRACT FROM AUTHOR]

In this paper, we report the realization of Mie resonances in air using eccentric hollow metallic cylinders. Our numerical results show that electric resonances/magnetic resonances can be selectively generated in a properly-designed eccentric hollow metallic cylinder under TE-/TM-polarization plane wave illuminations, respectively. We find that the critical dimension for Mie resonance generation is the radius of the hollow hole. Finally, two resonant modes supported by a dual-hole cylinder are presented. This study can be highly favorable to various applications, including optical sensing and nonlinear optics. [ABSTRACT FROM AUTHOR]