Phys.org July 8, 2024
Optical tweezers enable noncontact trapping of microscale objects using light. However, it is not known how tightly it is possible to three-dimensionally (3D) trap microparticles with a given photon budget. Reaching the limit would enable maximally stiff particle trapping for precision measurements on the nanoscale and photon-efficient tweezing of light-sensitive objects. An international team of researchers (UK, Austria) customized the shape of light fields to suit specific particles, with the aim of optimizing trapping stiffness in 3D. They showed, theoretically, that the confinement volume of microspheres held in sculpted optical traps could be reduced by one to two orders of magnitude. Experimentally, they used a wavefront shaping–inspired strategy to passively suppress the Brownian fluctuations of microspheres in every direction concurrently, demonstrated order-of-magnitude reductions in their confinement volumes. According to the researchers their work paves the way toward the fundamental limits of optical control over the mesoscopic realm… read more. Open Access TECHNICAL ARTICLE
Light intensity in conventional optical tweezers (left) and a custom-tailored optical trap (right). Credit: University of Exeter.