Spin-engineered 3D optical manipulation via polarization-gradient architecturing

Optical manipulation via structured light has emerged as a pivotal technique for advancing laser applications across biological and medical science and materials engineering. However, conventional optical tweezers research predominantly exploits scalar field quantities (amplitude and phase) for the orbital motion of trapped particles, while the vectorial properties of light fields (i.e., polarization states) are typically utilized to drive particle rotation. This work develops a 3D orbital control scheme in vector beams by demonstrating orbital motion driven through specially configured spatial distributions of polarization states. This polarization-gradient-induced 3D dynamical effect has not been previously investigated. Unlike traditional techniques that rely on global phase gradients, our approach synergizes freestyle 3D intensity sculpting with engineered polarization gradients, enabling flexible and versatile control over microparticle trajectories. Through comprehensive theoretical modeling and experimental validation, we demonstrate the ability to guide microparticles along complex 3D paths, including circular, elliptical, and triangular trajectories. These findings pave avenues for the development of advanced optical manipulation strategies, facilitating sophisticated microscale assembly and analysis capabilities.