Fig. 1. (a) Numerical simulation result of the scattering spectra. The inset shows a schematic diagram of the problem. (b) Electromagnetic field distribution at MD resonance (λ=1105  nm). (c) Electromagnetic field distribution at ED resonance (λ=821  nm). (d) Electromagnetic field distribution at MQ resonance (λ=730.8  nm).

Fig. 2. Scattering spectra of the nanocuboid with different h, l, and w ranging from 160 to 30 nm. The inset shows the schematic diagram of the problem.

Fig. 3. (a) Scattering spectra of the nanocuboid with l=w=160  nm and h=72  nm. The inset shows the schematic diagram of the geometry. The far-field scattering pattern at (b) the resonance frequency (λ=693  nm) and (c) the off-resonance frequency (λ=800  nm).

Fig. 4. (a) Scattering spectra of the nanocuboid with h=w=160  nm and l=32  nm. The inset shows the schematic diagram of the geometry. The far-field scattering pattern at (b) the resonance frequency (λ=354  nm) and (c) the off-resonance frequency (λ=343  nm).

Fig. 5. (a) Transmittance of forward scattering (red line) and backward scattering (blue line) of 30 nm gap. (b) Ratio of forward scattering to total scattering. Red solid line corresponds to the case of the 30 nm gap, the dark blue corresponds to the 20 nm gap, the light blue to the single isolated nanocuboid, and the dashed line to the ratio of 95%. Far-field scattering pattern at 777.4 nm in (c) xz-plane and (d) yz-plane. The inset shows the schematic of the problem.