Characteristics of photonic nanojet generated by patchy microspheres

Photonic nanojet (PNJ), which is a kind of intense beam with wavelength-level focus, has gradually attracted the attention of researchers in recent years. Since the full-width at the half of the maximum (FWHM) of the PNJ can usually exceed the diffraction limit, and the high-intensity nanojet of wavelength-level can maintain a long working distance. Therefore, the PNJ has great research value in many optical applications, such as super-resolution imaging, micro-nano optical manipulation, micro-nano structure lithography, ultra-high-density optical storage, etc. In this paper, PNJs with different characteristics are obtained by adjusting the patchy area and patchy angle. The simulation results show that the PNJ generated by the patchy microspheres not only has the characteristics of an "S" type photon hook, but also has a FWHM beyond the diffraction limit.