Optical Trapping of High-Aspect-Ratio NaYF Hexagonal Prisms for kHz-MHz Gravitational Wave Detectors

Abstract

We present experimental results on optical trapping of Yb-doped β−NaYF sub-wavelengththickness high-aspect-ratio hexagonal prisms with a micron-scale radius. The prisms are trapped in vacuum using an optical standing wave, with the normal vector to their face oriented along the beam propagation direction, yielding much higher trapping frequencies than those typically achieved with microspheres of similar mass. This plate-like geometry simultaneously enables trapping with low photon-recoil-heating, high mass, and high trap frequency, potentially leading to advances in high frequency gravitational wave searches in the Levitated Sensor Detector, currently under construction. The material used here has previously been shown to exhibit internal cooling via laser refrigeration when optically trapped and illuminated with light of suitable wavelength. Employing such laser refrigeration methods in the context of our work may enable higher trapping intensity and thus higher trap frequencies for gravitational wave searches approaching the several hundred kHz range.

Inert Shell Coating for Enhanced Laser Refrigeration of Nanoparticles: Application in Levitated Optomechanics

“…Although of particular interest to the field of levitodynamics, this work also shows the potential of a bottom-up nanoengineering approach for optimizing optical cryocooling materials. Ultimately, it allows for more versatility for integration with other nanostructures , as well as for the study of different materials, crystal phases, morphologies, , designs, and dopant concentrations compared to a bulk crystal approach with stringent requirements on the quality and purity of the crystal.…”

Levitation and controlled MHz rotation of a nanofabricated rod by a high-NA metalens

“…Structured light enables novel control of particle's rotational dynamics through OAM transfer 17 and facilitates stable trapping using a doughnutshaped beam 18 . In the aspect of engineering nanoparticle's geometry, unique structures such as prisms make it possible to search for high-frequency gravitational waves 19 and polarization-based inverse optical torque 20 .…”

Optical levitation using an LG01 vortex beam

“…These systems can be highly sensitive to external forces and be further isolated from thermodynamical influence when in vacuum, providing a means of detecting very weak forces due to their high Qfactor, however active position stabilization may also be required to counteract photophoretic forces at low pressure. Examples include searches for dark matter [7], gravitational wave detection [8,9], and ultra-weak force sensing [10].…”