Figure 6
From: Direct Measurement of Optical Force Induced by Near-Field Plasmonic Cavity Using Dynamic Mode AFM
Measured phase shift Δφ = φ(d) – φ(d = 250 nm) (relative to the non-resonant reference value obtained with d = 250 nm) as a function of gold disk diameter d.
The measurements are made in the far field with r = 5 μm (black squares) and in the near field with r = 30 nm (blue triangles). The solid line is drawn through the black squares to guide the eye. The error bars show the standard deviation of the measurements. Inset depicts a vector sum of the total force F resulting from the two forces Fo and FT with a phase delay φT. Red circles are the calculated values of Δφ using Eq. (5) with a constant value of α = (FT/Fo)T(d) = 0.17.
