Figure 7

The structure parameters and extinction of the concentric nanoring. (a) The structure parameters of the NDNR. The polarization (E) and propagation (k) directions of incident light are denoted. (b) The extinction of the concentric nanoring with r _R1/r _R2/r _R3/d _R = 0 nm/90 nm/135/0 nm (black line), asymmetric nanoring with r _R1/r _R2/r _R3/d _R = 0 nm/90 nm/135 nm/42 nm (red line), the NDNR with r _R1/r _R2/r _R3/d _R = 66 nm/90 nm/135 nm/42 nm (blue line), and the NDNR with r _R1/r _R2/r _R3/d _R = 75 nm/90 nm/135 nm/42 nm (cyan line). (c) The charge density distributions of the dipolar antibonding mode (832 nm) and the dipolar bonding mode (1,368 nm) of the NDNR with r _R1/r _R2/r _R3/d _R = 75 nm/90 nm/135 nm/42 nm.