Fig. 1. Schematic diagram of the preparation procedure for fabricating patterned aluminum templates and Ag nanosphere arrays: (a) Purity aluminum; (b) AAO nanotube arrays after the first anodization; (c) AAO nanobowl arrays after the removal of the porous alumina layer; (d) Ag nanoparticles; (e) Ag nanosphere arrays.

Fig. 2. Schematic diagram of vacuum evaporation apparatus.

Fig. 3. View of simulation model in FDTD Solution (a) x-y; (b) x-z.

Fig. 4. SEM images of the (a) AAO nanobowl arrays and (b) periodic arrays of Ag nanospheres.

Fig. 5. (a)−(n) SEM images of Ag nanosphere arrays/Ag film and (i)−(x) their related size distribution histograms: (a)D = 73.5 nm; (b) D = 78.2 nm; (c) D = 83.2 nm; (d) D = 85.5 nm; (e) D = 87.7 nm; (f) D = 90.1 nm; (g) D = 91.3 nm; (h) D = 91.7 nm; (i) D = 93.1 nm; (j) D = 94.2 nm; (k) T = 17.5 nm; (l) T = 18.2 nm; (m) T = 19.0 nm; (n) T = 19.7 nm.

Fig. 6. Experimental UV-vis-NIR absorption spectra of (a) Ag nanosphere arrays deposited on AAO-nanobowl with different sizes; (b) silver composite structure fabricated on different substrates.

Fig. 7. UV-Vis absorption spectra of Ag nanosphere arrays with different sizes: (a) Experimental results; (b) FDTD simulation results

Fig. 8. (a) UV absorption spectra of Ag nanosphere arrays (black dashed line is experimental results; red line corresponds to σ_t obtained by fitting the Eq. (3); (b) polarized field distributions on the x-y plane (z = 0) of the Ag nano-sphere array excited 437 nm.

Fig. 9. NIR absorption spectra of Ag nanosphere arrays with different sizes: (a) Experimental results; (b) FDTD simulation results.