  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) due to this optical toroidal moment is
demonstrated numerically, in mimicking the magnetoelectric effect in
multiferroic systems. The result shows a promising avenue to explore various
optical phenomena associated with this intriguing dynamic toroidal moment.
