Fig. 6

SPP basics. a Schematic diagram of plasmon oscillation for a sphere [192]. b Electric field contours and c Extinction efficiency of dipole mode of a silver nanosphere with r=30 nm [192]. d Schematic diagram of SPP wave at a metal-dielectric interface [17]. e The field decaying exponentially with δ_m in the metal and δ_d in the dielectric for SPP waves [17]