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

The general concept of Fano resonance is considered so as to show the possibility of this resonance in space. Using a recently found solution for a Bessel wave beam impinging on a dielectric sphere, we analyze the electromagnetic fields near a microsphere with different optical sizes and permittivity values. We theoretically reveal 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 on 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 submicrometer optical trap with unusual and useful properties.