Figure 10

Self-mixing voltage obtained from demodulation of the laser voltage at the \({\varvec{n}} =\) 3 harmonic of the tip tapping frequency, measured as a function of laser driving current (blue circles). Also shown is a fit to the L–K model (Eq. 1), in which \({\varvec{\beta}} =\) 0.76 mV and \(\phi =\) 14.7°.