Fig. 1. (a) Gold nanostructures; (b) Absorption spectra of a single nanoprism

Fig. 2. (a) Absorption spectra of dimer with different gaps; (b) Charge distribution (top row) and electric field distribution (bottom row) in resonance condition, d = 60 nm; (c) The resonant wavelength versus the gap of two nanoprisms; (d) Normalized resonant peak shift versus the gap

Fig. 3. (a) Electric field distribution of incident light polarized in x direction polarization; (b) Electric field distribution of incident light polarized in y direction polarization; (c) Electric field distribution of x axis; (d) Normalized electric field distribution of x axis

Fig. 4. Distribution of electric field of x axis. (a)$l$= 80 nm, d >$l$; (b) $l$= 80 nm, d ≥ 10 nm; (c) $l$ = 40 nm, d >$l$; (d) $l$ = 40 nm, d ≥10 nm

Fig. 5. Normalized resonant absorption versus gap of two nanoprisms