Strong forces in optomechanically actuated resonant mass sensor.

As resonance mass sensors shrink in order to improve the sensitivity, traditional methods of transduction and readout struggle to keep up with increasing resonance frequencies and decreasing feature sizes. In this work we demonstrate an all-photonically transduced resonant mass sensor that manages to deal with these problems. The strong optomechanical force in slot waveguides is used to drive the mechanical resonanator giving a good signal to noise ratio at low optical powers. Using 120 µW of modulated optical power we measure a frequency noise equivalent to being able to resolve 500 kDa.