Fig. 1. Preparation process of bow tie type nanosilver metal array. (a) Polystyrene nanosphere templates are laid on substrate by self－organizing method; (b) silver film is grown on template by evaporation; (c) template is removed by toluene immersion and ultrasound, leaving neat bow tie type nanosilver metal array

Fig. 2. Simulation model of bow tie type silver nanoparticles. (a) Simulation model of extinction characteristics of bow tie type silver nanoparticles; (b) simulation model of electric field distribution of bow tie type silver nanoparticles

Fig. 3. SEM images of polystyrene nanosphere template and bow tie type silver metal array. (a) SEM image of monolayer polystyrene nanospheres with diameter of 500 nm; (b) SEM image of polystyrene nanospheres after evaporation of silver with thickness of 30 nm; (c) SEM image of bow tie type silver metal array after removing polystyrene nanosphere template; (d) local magnified SEM image of bow tie type silver metal array

Fig. 4. Extinction spectra of bow tie type silver nanoparticles with different sizes. (a) Extinction spectra of bow tie type silver nanoparticles with different side lengths; (b) extinction spectra of bow tie type silver nanoparticles with different thicknesses

Fig. 5. Extinction spectrum and electric field distribution of bow tie type silver nanoparticles. (a) Extinction spectrum of bow tie type silver nanoparticles without substrate, and electric field distribution in x－z plane corresponding to extinction peak; (b) extinction spectrum of bow tie type silver nanoparticles with GaN substrate, and electric field distribution of two extinction peaks corresponding to bow tie type silver nanoparticles in x－z plane

Fig. 6. Hybrid modes of local surface plasmons. (a) Charge mainly concentrates on upper surface of nanoparticles after coupling of dipole mode and quadrupole mode; (b) charge mainly concentrates on lower surface of nanoparticles after coupling dipole mode and quadrupole mode

Fig. 7. Electric field distribution of bow tie type silver nanoparticles with different sizes in 370 nm band. (a) L＝30 nm, H＝30 nm; (b) L＝120 nm, H＝30 nm; (c) L＝160 nm, H＝30 nm; (d) L＝30 nm, H＝50 nm; (e) L＝120 nm, H＝50 nm; (f) L＝160 nm, H＝50 nm; (g) L＝30 nm, H＝70 nm; (h) L＝120 nm, H＝70 nm；(i) L＝160 nm, H＝70 nm

Fig. 8. Electric field distribution of bow tie type silver nanoparticles with different sizes in 425 nm band. (a) L＝30 nm, H＝30 nm; (b) L＝120 nm, H＝30 nm; (c) L＝160 nm, H＝30 nm; (d) L＝30 nm, H＝50 nm; (e) L＝120 nm, H＝50 nm; (f) L＝160 nm, H＝50 nm; (g) L＝30 nm, H＝70 nm; (h) L＝120 nm, H＝70 nm；(i) L＝160 nm, H＝70 nm

Fig. 9. Electric field distribution of bow tie type silver nanoparticles with different sizes in 525 nm band. (a) L＝30 nm, H＝30 nm; (b) L＝120 nm, H＝30 nm; (c) L＝160 nm, H＝30 nm; (d) L＝30 nm, H＝50 nm; (e) L＝120 nm, H＝50 nm; (f) L＝160 nm, H＝50 nm; (g) L＝30 nm, H＝70 nm; (h) L＝120 nm, H＝70 nm；(i) L＝160 nm, H＝70 nm

Fig. 10. Photoluminescence spectra of bow tie type silver metal arrays in different bands. (a) Near ultraviolet band (370 nm); (b) blue band (425 nm); (c) green light band (525 nm)

Fig. 11. Photoluminescence spectra of bow tie silver nanoparticles with different thicknesses in different bands. (a) Near ultraviolet band (370 nm); (b) blue band (425 nm); (c) green light band (525 nm)

Fig. 12. SEM image of defective bow tie type silver metal array

Fig. 13. FDTD simulation model of defect particle

Fig. 14. Extinction spectrum of bow tie type silver nanoparticles and defect particles. (a) Bow tie type silver metal array; (b) defective particles

Fig. 15. I－V curves of LEDs integrating bow tie type silver metal arrays of different sizes at 370 nm. (a) H＝50 nm, d is 200, 500, 900 nm, respectively; (b) d＝200 nm, H is 30, 50, 70 nm, respectively

Fig. 16. I－V curves of LEDs integrating bow tie type silver metal array of different sizes at 425 nm. (a) d＝200 nm, H is 30, 50, 70 nm, respectively; (b) H＝50 nm, d is 200, 500，900 nm, respectively

Fig. 17. I－V curves of LEDs integrating bowtie nanosilver metal arrays of different sizes at 525 nm. (a) H＝50 nm, d is 200, 500, 900 nm, respectively; (b) d＝500 nm, H is 30, 50, 70 nm, respectively