Optical Longitudinal-Lateral Force Directed in Arbitrary Directions by a Linearly Polarized Beam

Optical forces arise from the transfer of linear momentum between light and objects, while the tailoring schemes for longitudinal and lateral forces are always complicated and incompatible, which prevents them from achieving the same configuration. Here it is demonstrated that the exclusive longitudinal and lateral forces can be harnessed collaboratively, i.e., optical longitudinal-lateral force (OLLF), which can scan the whole 2π space by solely rotating the half-wave plate to switch the linear polarization of the incident beam. It is found that, through the interplay between s- and p-polarized light induced by a particle on the interface, the longitudinal force can be altered from pushing to pulling, while the lateral force can be altered from left to right independently. Due to the merit of large amplitude and flexible tunability, the OLLF can act as the engine to drive a micro vehicle along the arbitrary direction in a 2D plane. This work paves a new way for versatile applications of optical manipulation in theory and applications.