Fig. 1. Schematic of two-dimensional simulation structure (the figure shows the light incidents vertically on the device surface from the air interface). (a) Periodic array of metal nanoparticles; (b) schematic of single cycle section

Fig. 2. COMSOL simulation model xz view

Fig. 3. Absorptivity of initial model. (a) Schematic of initial model; (b) absorptivities before and after graphene addition

Fig. 4. Electric intensity distribution diagrams. (a) Pyramidal nanoparticles; (b) hemispherical nanoparticles; (c) subuliform nanoparticles

Fig. 5. Change of light absorption efficiency with wavelength under different particle radii. (a) Subuliform nanoparticles; (b) pyramidal nanoparticles; (c) hemispherical nanoparticles; (d) cube nanoparticles

Fig. 6. Variation of light absorption efficiency with wavelength under different particle shapes

Fig. 7. Change of light absorption efficiency with wavelength under different section radii. (a) Triangle; (b) trapezoid; (c) rectangle; (d) hemisphere

Fig. 8. Variation of light absorption efficiency with wavelength under different cross-section shapes

Fig. 9. Structure of nanoparticle grating array. (a) Schematic diagram of photodetector with nano particle grating structure ^[21]; (b) local distribution diagram of electric field intensity of pyramid type nano particle grating photodetector

Fig. 10. Changes of light absorption efficiency of pyramid particle and nano particle grating structure with wavelength. (a) Device Ⅰ and device Ⅲ (illustrations are 0.5-2.1 μm wavelength range); (b) device Ⅱ and device Ⅲ