Dual Photonics Nanojets Interference Achieves Sub-Diffraction Limit Beam Size for Micro/nanostructures Detection

Optical sensing for surface micro/nanostructures detection is widely applied in broad research fields, such as biomedical, environmental monitoring, micro/nano optics, and so on. However, the diameter of the detection light is difficult to break through the diffraction limit, which limits the improvement of detection resolution. Here, a photonics nanojet (PNJ) interference method to reduce the size of detection light is proposed. The interference field is generated by the overlap of two individual PNJs peaks which are induced by dual microspheres. The simulation results show that for polystyrene microspheres with a diameter of 20 μm, the full width at half maximum (FWHM) of the PNJ produced by a single microsphere is 600 nm, while the FWHM of the interference field induced by the dual microspheres is 210 nm, realized a reduction in spot size to nearly one-third. This method shows great potential for application in semiconductor, biosensing, medical testing and other fields.