Fig. 3: Resonator response to the tungsten tip in the near field.
From: Coherent suppression of backscattering in optical microresonators
a Total linewidth (and equivalently Q-factor) and b backscattering amplitude for tip positions in the resonator plane, normalised by the intrinsic backscattering amplitude Ab,0. The black lines (r = 0) indicate the fitted resonator surface–measurements shown as r < 0 were obtained while the tip was touching the resonator surface, resulting in the tip sliding along the surface. Maximum backscattering suppression is found along the dashed line (critical tip coupling); for r < rcrit, the tip is over-coupled, reducing the suppression. c–e Fits (lines) and interpolated data (circles) along cross sections through the experimental data in panels a and b. The insets show where the cross sections were taken. c Radial tip position dependence of the linewidth and d backscattering. e Tip azimuthal position dependence of the backscattering
