Spatial Fano resonance of a dielectric microsphere impinged by a Bessel beam

Abstract

General concept of Fano resonance is considered so that to show the possibility of this resonance in space. Using a recently found solution for a Bessel wave beam impinging a dielectric sphere, we analyze the electromagnetic fields near a microsphere with different optical size and permittivity values. We theoretically reveal a spatial Fano resonance when a resonant mode of the sphere interferes with {an amount of } non-resonant modes. This resonance results in a giant jump of the electric field behind the sphere impinged by the first-order Bessel beam. The local minimum of the electromagnetic field turns out to be noticeably distanced from the rear edge of the microsphere. However, this is a near-field effect and we prove it. We also show that this effect can be utilized for engineering a submicron optical trap with unusual and useful properties.