Figure 6
From: Free-field characterization via directional transmission through a nanoaperture
Transmission efficiency. (a) Variation of the zero-order efficiency η0 (red line, left-hand scale) and the total transmission efficiency η (black line, right-hand scale) as a function of the Al film thickness h. (b) Angular dependence of transmission efficiency: surface corrugation optimized for SPP coupling (green line), the final design without (blue line) and with (black line) the TiO2 layers.