Figure 2.

(a) Top view of a unit cell of the infinite array employed in numerical simulations. A dimer consists of two pillars separated by 20 nm gap. The dimer is illuminated with electric field polarized along the direction of separation of the two pillars. The two pillars are symmetrically displaced with respect to the center of the unit cell. (b) Side view of a unit cell. The substrate is made out of 100 nm thick layer of gold, on top of which there is a 10 nm thick SiO₂ spacer. Also plotted in dashed line, the projection of the surface used for the integration of the average EF (see Methods).