Data for "Switchable optical trapping of Mie-resonant phase-change nanoparticles", Laser Photon. Rev. 2024

Optical tweezers revolutionized the manipulation of nanoscale objects. Typically, tunable manipulations of optical tweezers rely on adjusting either the trapping laser beams or the optical environment surrounding the nanoparticles. Here we achieve tunable and switchable trapping using nanoparticles made of a phase-change material (vanadium dioxide or VO2). By varying the intensity of the trapping beam, we induce transitions of the VO2 between monoclinic and rutile phases. Depending on the nanoparticles’ sizes, they exhibit one of three behaviours: small nanoparticles (in our settings, radius < 0.12 wavelength λ) remain always attracted by the laser beam in both material phases, large nanoparticles (> 0.22λ) remain always repelled. However, within the size range of 0.12–0.22λ, the phase transition of the VO2 switches optical forces between attractive and repulsive, thereby pulling/pushing them towards/away from the beam centre. The effect is reversible, allowing the same particle to be attracted and repelled repeatedly. The phenomenon is governed by optical Mie modes of the nanoparticles and their alterations during the phase transition of the VO2. This work provides an alternative solution for dynamic optical tweezers and paves a way to new possibilities, including optical sorting, light-driven optomechanics and single-molecule biophysics.