Perfect optical vortex (POV) beams offer a phase-gradient route to convey small particles along a tunable circular path or belt. The traditional generalized POV method can be used to reshape the conveyor belt, but it usually worsens the orbital energy flow of the field, leading to unstable conveying speed or even creating unwanted optical traps that prevent transportation.

　　In this study, researchers proposed a method for creating shape-customizable optical conveyor belts with an orbital flow evenly distributed along the particle delivery path. By integrating random phases and the equidistant sampling method into the generalized POV generation algorithm, they sculpted the optical vortex beam to obtain a uniform distribution of phase gradient and intensity.

　　Then, researchers performed a theoretical calculation of the optical force acting on a metal particle. They experimentally achieved the transport of Au particles, approximately 1μm in diameter, on rhomboid and pentagonal conveyor belts. Long-distance transport of gold particles was also demonstrated along Archimedean spirals. 

　　Besides, researchers employed light field assembly technique to construct dual belts for the capture and delivery of larger Au particles (diameter: 4 μm) and Al particles (diameter: 7 μm), which were unrealizable with a single belt.

　　"This work will promote advanced applications of optical tweezers, paving novel avenues for medicine delivery, enantiomer separation, and microrobot assembly,” said Prof. YAO Baoli from XIOPM.

Editor: LIU Jia | Dec 03, 2024