Publication in Nature Microsystems & Nanoengineering
Our manuscript is now published in Nature Microsystems & Nanoengineering!
Here, we demonstrate a very-high-frequency ring-shaped AFM probe, operated fully optically thanks to optomechanical effects, which senses forces exerted on its nanoscale tip. The probe uses a stiff and very-high-frequency bulk mechanical mode, strongly coupled to light, and reaches in resonant force sensing operation a frequency two decades above the fastest AFM cantilevers (130 MHz), with a motion amplitude four orders below (sub-picometer).
In the paper, we not only introduce the concept of these probes for AFL with silicon optomechanics: we go through the design, the technical realization, the characterization, the calibration, and up to the concrete experimental operation in a dedicated scanning probe instrument. The reported results fully prove the operability of the concept, and experimentally show that the mechanical interaction with a sample can be probed, both at ultra-low amplitude of motion and at uncommon very high frequency. Moreover, we demonstrate the stable closed-loop operation of the instrument, where the probe-sample distance is adjusted to stabilize the force gradient between the tip and the sample surface. The understanding and modeling of our results also elucidate the regime of the local interaction that is mediated in air by a stretched water meniscus between the tip apex and the sample surface.