Figure 7: Toroidal metamaterial and its properties under traveling-wave excitation.
From: Coherent selection of invisible high-order electromagnetic excitations
Schematic of the metamaterial. Unit cell dimensions: periodicity in the x direction Px = 220 nm, that in the y direction Py = 120 nm, thickness of the dielectric cavity D = 500 nm, bar base length L = 80 nm, bar arm length A = 60 nm, bar width W = 20 nm, bar thickness t = 30 nm, gap g = 20 nm. (b) Traveling-wave spectra of the sample. (c) The contribution of different multipoles in radiation, including the electric dipole (E-Dip), magnetic dipole (M-Dip), toroidal dipole (T-Dip), electric quadrupole (E-Quad), magnetic quadrupole (M-Quad), toroidal quadrupole (T-Quad), electric octupole (E-Oct), and magnetic octupole (M-Oct).
