Optomechanical measurement of single nanodroplet evaporation with millisecond time-resolution

Tracking the evolution of an individual nanodroplet of liquid in real-time remains an outstanding challenge. Here a miniature optomechanical resonator detects a single nanodroplet landing on a surface and measures its subsequent evaporation down to a volume of twenty attoliters. The ultra-high mechanical frequency and sensitivity of the device enable a time resolution below the millisecond, sufficient to resolve the fast evaporation dynamics under ambient conditions. Using the device dual optical and mechanical capability, we determine the evaporation in the first ten milliseconds to occur at constant contact radius with a dynamics ruled by the mere Kelvin effect, producing evaporation despite a saturated surrounding gas. Over the following hundred of milliseconds, the droplet further shrinks while being accompanied by the spreading of an underlying puddle. In the final steady-state after evaporation, an extended thin liquid film is stabilized on the surface. Our optomechanical technique opens the unique possibility of monitoring all these stages in real-time

Efficient optical coupling to gallium arsenide nano-waveguides and resonators with etched conical fibers

We explore new methods for coupling light to on-chip gallium arsenide nanophotonic structures using etched conical optical fibers. With a single-sided conical fiber taper, we demonstrate efficient coupling to an on-chip photonic bus waveguide in a liquid environment. We then show that it is possible to replace such on-chip bus waveguide by two joined conical fibers in order to directly couple light into a target whispering gallery disk resonator. This latter approach proves compliant with demanding environments, such as a vibrating pulse tube cryostat operating at low temperature, and it is demonstrated both in the telecom band and in the near infrared close to 900 nm of wavelength. The versatility, stability, and high coupling efficiency of this method are promising for quantum optics and sensing experiments in constrained environments, where obtaining high signal-to-noise ratio remains a challenge

Multifrequency Nanomechanical Mass Spectrometer Prototype for Measuring Viral Particles Using Optomechanical Disk Resonators

Nanomechanical mass spectrometry allows characterization of analytes with broad mass range, from small proteins to bacterial cells, and with unprecedented mass sensitivity. In this work, we show a novel multifrequency nanomechanical mass spectrometer prototype designed for focusing, guiding and soft-landing of nanoparticles and viral particles on a nanomechanical resonator surface placed in vacuum. The system is compatible with optomechanical disk resonators, with an integrated optomechanical transduction method, and with the laser beam deflection technique for the measurement of the vibrations of microcantilever resonators. The prototype allows the in-vacuum alignment of resonators thanks to a dedicated visualization system. Finally, in this work, we have demonstrated the detection of gold nanoparticles, polystyrene nanoparticles and phage G viruses with optomechanical disks and microcantilever resonators.Peer reviewe