All-optical Hall effect by the dynamic toroidal moment in a cavity-based metamaterial

Dynamic dipolar toroidal response is demonstrated by an optical plasmonic metamaterial composed of double disks. This response with a hotspot of localized E-field concentration is a well-behaved toroidal cavity mode that exhibits a large Purcell factor due to its deep-subwavelength mode volume. All-optical Hall effect (photovoltaic) is observed numerically attributed to the nonlinear phenomenon of unharmonic plasmon oscillations, which exhibits an interesting analogy with the magnetoelectric effect in multiferroic systems. The result shows a promising avenue to explore various intriguing optical phenomena associated with this dynamic toroidal moment.