Fig. 1. SEM image of polystyrene spheres with diameter of 450 nm

Fig. 2. SEM images of metal silver nanostructures prepared by oxygen plasma etching for different times. (a) Triangle nanoparticles array prepared by etching for 7 s; (b) connected “bow-tie” nanoparticles and triangle large nanoparticle array prepared by etching for 11 s; (c) rough nanohole array prepared by etching for 17 s; (d) ordered nanohole array prepared by etching for 21 s

Fig. 3. Optical transmission spectra of metalsilver nanostructures prepared by oxygen plasma etching for different times

Fig. 4. Simulated transmission and absorption spectra of triangle nanoparticle array and ordered nanohole array

Fig. 5. Simulated electric field distributions of metal nanostructures with x-y plane contacting glass substrate at resonant wavelength. (a) Electric field distribution of triangle nanoparticle array; (b) electric field distribution of nanohole array of metal structure