Fano Interference of Electromagnetic Modes in Subwavelength Dielectric Nanocrosses
journal contributionposted on 08.09.2016, 00:00 by Zhong-Jian Yang
The electromagnetic mode couplings in subwavelength high-index dielectric nanocrosses are theoretically investigated. The nanocross is constructed by two orthogonal rectangular silicon nanoblocks. A pronounced dip appears on the scattering spectrum of the nanocross in the visible region, which is found to be caused by the Fano interference between the broadband electric dipole mode on one nanoblock and the narrowband magnetic dipole and quadrupole modes on the other one. Near-field distributions are calculated to analyze the destructive and constructive couplings between the electric fields associated with the electric and magnetic modes in the Fano interference. By spatially separating the two blocks and varying the geometry parameters of each block, the Fano interferences can be further confirmed, and the tuning of Fano resonance line shape is also demonstrated.