Controllable asymmetrical potential wells created by phase profiles of light

Abstract

Optical tweezers, which exploit laser beams to control various particles, have been widely used in many fields. However, the potential wells are typically symmetrical in optical traps, which limit the performance of manipulating particles. Herein, we report an approach for creating asymmetrical potential wells, by employing variable phase gradient profiles tailored by holograms. The depth, stiffness and location of asymmetrical potential wells can be dynamically and accurately adjusted. Moreover, the controllable collective transport of nanoparticles are experimentally demonstrated as an application example, which exhibit excellent manipulation performance. Importantly, the motion path, step distance and velocity can be easily tuned by changing the holograms, which are highly desirable in the controllable transport. This study offers a new way to optically manipulate particles, which could largely expand the capability of conventional optical tweezers.