Exploring optical binding and transverse spin of microparticles trapped near optical nanofibers

Optical trapping is a ground-breaking technique for controlling the dynamics of tiny particles, from biological cells and single macromolecules to colloidal microparticles and nanoparticles. One of the main optical trapping platforms is that of optical tweezers, which has enabled a wide range of applications across biomedical research, physics, and materials science. However, to push the boundaries of particle manipulation - especially for long-distance control and for complex particles or nanoparticles - the development of new tools is essential. One solution that lets us address such challenges is the hybrid optical tweezers-optical nanofiber platform. Optical nanofibers offer several key advantages, such as easy integration with fiber-based setups, straightforward fabrication, and enhanced electric field confinement, along with intense evanescent fields at the fiber surface. These properties have facilitated the trapping, rotation, transport, and assembly of near-fiber particles. In this context, we discuss recent advances in microparticle manipulation, including Janus particle dynamics, negative torque generation, transverse spin effects, and multiparticle optical binding using the optical tweezers-nanofiber platform.