Spatial Fano Resonance and its Implication for a Glass Microsphere

Fano’s resonance is not obviously that of a system parameter depending on the state energy or frequency. The spatial distribution of light intensity may experience this resonance if the continuum of eigenmodes interferes with a resonant mode. We found this spatial Fano resonance in the exact solution of a diffraction problem: a hollow Bessel impinges on a dielectric sphere with optically substantial but not very large radius. Tuning the frequency, one may engineer a very sharp Fano minimum in free space. This point at which the electromagnetic field vanishes may serve an optical trap for molecules and atoms. In accordance with our calculations, such the trap has no analogues in the available literature in what concerns its parameters and its ultimate simplicity.