Ultrahigh electric and magnetic near field enhancement based on high-Q whispering gallery modes in subwavelength all-dielectric resonators

Abstract

Here, we show that whispering gallery modes of subwavelength dielectric resonators can exhibit ultrahigh electric and magnetic field enhancements due to their high-quality factors. The resonators are dielectric disks. The field enhancements are dependent on the height of the disk, the refractive index n and the azimuthal mode index, and they can reach ∼102 inside a subwavelength disk of n = 3.5. For a disk dimer of n = 3.5, the electric field enhancement reaches ∼103 in the small gap. The Purcell factor of an electric and magnetic dipole emitter in the dimer can reach ∼105 and ∼104, respectively.