Fig. 1. Metasurface with hybrid nanostructure. (a) Schematic; (b)(c) oblique- and top-view of a meta-atom

Fig. 2. Simulation results. (a) Transmission and absorption spectra of the metasurface; (b) transmittances of the metasurfaces consisting of the meta-atoms with a single Au ring and a single Au SRR; (c)(d) charge distributions of the meta-atom at the wavelengths of 1480 nm and 740 nm, respectively; (e)(f) near-field enhancements of the meta-atom at the wavelengths of 1480 nm and 740 nm, respectively

Fig. 3. Current density distribution of the metal ring and SRR combined structure and the vector direction of the current. (a) Current density distribution of fundamental frequency; (b) current density distribution of second harmonic

Fig. 4. Transmitted spectrum of the metasurface with hybrid nanostructures

Fig. 5. Relationship between pump peak intensity and SHG efficiency