Optically trapped gold nanoparticle enables listening at the microscale.
We explore a new application of optical tweezers for ultrasensitive detection of sound waves in liquid media. Position tracking of a single gold nanoparticle confined in a three-dimensional optical trap is used to readout acoustic vibrations at a sound power level down to -60  dB, causing a ∼90  μeV increase in kinetic energy of the nanoparticle. The unprecedented sensitivity of such a nanoear is achieved by processing the nanoparticle's motion in the frequency domain. The concept developed here will enable us to access the interior of biological microorganisms and micromechanical machines not accessible by other microscopy types.
Photonics and Optoelectronics Group, Physics Department and CeNS, Ludwig-Maximilians-Universität München, Amalienstraße 54, 80799 Munich, Germany.
Alexander
A
Ohlinger
Andras
A
Deak
Andrey A
AA
Lutich
Jochen
J
Feldmann