Figure 20.

Experimental spectra for the phase and amplitude of reflected light under resonant plasmonic conditions: (a) Excitation of SPPs for a 50 nm gold film in the Turbadar–Kretschmann–Raether prism geometry (classical SPR). Owing to the finite roughness of the gold film surface, the Ψ value is well away from zero, leading to a smooth phase change in the minimum of the resonance curve. (b) Diffractively coupled array of gold nanodots (SLRs). The SLR is seen to be much narrower, and the value of Ψ is close to zero, leading to a very sharp jump in the phase close to the resonance minimum. Reproduced and adapted with permission from (149). Copyright 2016 The International Society for Optical Engineering.