Advanced Materials, Vol.28, No.37, 8206-8211, 2016
Sharp Toroidal Resonances in Planar Terahertz Metasurfaces
A toroidal dipole in metasurfaces provides an alternate approach for the excitation of high-Q resonances. In contrast to conventional multipoles, the toroidal dipole interaction strength depends on the time derivative of the surrounding electric field. A characteristic feature of toroidal dipoles is tightly confined loops of oscillating magnetic field that curl around the fictitious arrow of the toroidal dipole vector.