Fig. 1. Scheme diagram of grating/nanoparticle hybrid structure. (a) Sectional view; (b) top View

Fig. 2. Simulation results for 25 nm Au nanoparticle array with different gaps. (a) Extinction spectra; (b) maximum electric field enhancement multiple within gap area under different wavelength excitation

Fig. 3. Electric field distribution of Au nanoparticle array with different gaps in xoz plane under 633 nm excitation. (a) 2 nm; (b) 4 nm; (c) 6 nm; (d) 8 nm; (e) 10 nm

Fig. 4. Schematic diagram of LSPR excited by plane wave and PSP. (a) Plane wave; (b) PSP

Fig. 5. Simulated extinction spectra. (a) Simulated extinction spectra of Au nanoparticle array with gap of 2 nm (s2), Au grating with period of 567 nm (567g) and grating/nanoparticle hybrid structure with period of 567 nm (567gs); (b) simulated extinction spectra of Au nanoparticle array with gap of 6 nm (s6), Au grating with period of 527 nm (527g) and grating/nanoparticle hybrid structure with period of 527 nm (527gs)

Fig. 6. Schematic diagram of electromagnetic coupling between PSP and LSPR

Fig. 7. Simulated electric field distribution for nano-structure in xoz plane with y=0 under 633 nm excitation. (a) Au grating with period of 567 nm; (b) hybrid structure composed of Au nanoparticle array with gap of 2 nm and Au grating with period of 567 nm