  We observe toroidal response from a planar metamaterial comprised of
asymmetric split ring resonators (ASRRs). It is showed that a toroidal-molecule
can be constructed through rational arrangement of planar ASRRs as meta-atoms
via manipulating structural symmetry of the meta-atoms. Field maps clearly
indicate that the toroidal resonance paves new electromagnetic confinement
style in a subwavelength scale. Planar scheme of manipulating the coupling
among the ASRRs may stimulate research in optical region involving toroidal
multipoles. Toroidal geometry together with the Fano resonance made high-Q
response will have enormous potential applications in low-threshold lasing,
cavity quantum electrodynamics and nonlinear processing.
