Fig. 1. Optical responses of a single gold split-ring resonator under x-polarized incidence that propagating along the z-axis. (a) Scattering spectrum of the split-ring resonator, and the inset denotes a schematic view of the split-ring resonator; near-field distributions at the center cross section of (b) electric quadrupole and (c) magnetic dipole resonances

Fig. 2. Optical response of split-ring resonator arrays. (a) Extinction spectra of perpendicular incidence of x polarization when the period along the y-axis is 1300 nm; (b) relation of extinction spectrum with periodic change along x direction

Fig. 3. Electric field amplitude distribution and the components of electric field intensity in x and y directions at different wavelengths. (a) 1972 nm; (b) 1968 nm; (c) 1995 nm

Fig. 4. Optical response of split-ring resonator arrays. (a) Extinction spectra of perpendicular incidence of x polarization when the period along the y-axis is 720 nm; (b) relation of extinction spectrum with periodic change along x direction

Fig. 5. Electric field amplitude distribution and the components of electric field intensity in x and y directions at different wavelengths. (a) 1095 nm; (b) 1088 nm; (c) 1128 nm