Versatile Optical Tweezer by Geometric Metalens with Phase-Tailored Focusing Trajectory

A geometric metalens is presented that can achieve a three-dimensional focusing curve embedded with on-trajectory tailored phase distribution. The proposed design strategy is highlighted by flexible modulations on both the focusing trajectory and the on-trajectory gradient phase and by the independent designability between them. The coexisting intensity gradient force and phase gradient force are numerically investigated, which can jointly provide the versatile abilities to push particles along the curve in the direction of phase increasing. This design strategy offers more controllability degrees of freedom on a complex optical field and is promising to miniaturize the contactless system of multifunctional optical manipulation on tiny particles. A geometric metalens is presented that can create a three-dimensional focusing curve embedded with independently tailored phase distribution. Numerical calculations demonstrate that coexisting intensity-gradient and phase-gradient forces can propel particles along the curve. This design strategy of such metalens tweezers is able to miniaturize the contactless system of multifunctional optical manipulation on tiny particles.image