Fig. 1

a Illustration of the circular nanodisk-nanohole hybrid nanostructure arrays on silicon substrate. b The schematics of the fabrication process for the designed nanostructures. c SEM images of the fabricated nanostructure arrays with P = 200 nm and D = 130 nm. The inset gives an enlarged view. The scale bars are 1 μm (left) and 200 nm (right)