Toroidal dipolar excitations in all-dielectric nanostructures

We have numerically investigated toroidal dipolar excitation at optical frequencies in Si nanostructures. Our results show that, through either special structured pump illumination, or by adding an additional layer associated with geometric tuning, we are able to excite strong toroidal dipolar responses with suppressed electric dipolar excitations. These findings may further pave the way to exploit future applications of toroidal resonances including optical nonlinear enhancement, induced transparency for narrow-band filter, etc