Optimization of parameters of photonic nanojet generated by dielectric microsphere for 'laser nanojet' SNOM

摘要

A new concept of "photonic nanojet" SNOM is proposed in this paper and the system is based on a dielectric microsphere which is mounted on a cantilever. The dielectric microsphere works as a superlens to focus the laser energy into a small volume with subwavelength spatial resolution. The numerical simulation by using Finite Element Method (FEM) has been done to optimize the parameters of the photonic nanojet of dielectic microsphere for "photonic nanojet" SNOM. The microspheres with different diameters have been investigated numerically and the results show that bigger microspheres produce higher intensity "photonic nanojets". The simulation result on the interaction between a silicon cylinder and a photonic nanojet reveals that a "hot spot" is formed inside the silicon cylinder and is confined into a small volume. Therefore a new area on high spatial resolution spectral analyzing for nanostructures is in prospect.