Study on the power transmission and light spot size of optical probes in scanning near-field optical microscopes

Abstract

The calculation principle and algorithm of boundary element method (BEM) for calculating the electromagnetic vector fields of sub-wavelength optical structures are studied. A two-dimensional computer program was developed to study the near-field and energy density distributions of the probes used in the scanning near-field optical microscopes (SNOM) and the effect of samples on the near-field light distributions. Influences of structural parameters including the probe aperture size, tip length, tapered angle and shape of the probe tip end on the power transmission and light spot size of the probes are calculated and discussed when different excitation modes of the input light are excited. Suggestions for structural parameters and operation modes of the probes are given.