Trajectory-based unveiling of angular momentum of photons

In this talk, we devote to explore the the average photon trajectories (APTs) under the paraxial circumstance. The APTs provide an intuitive picture for unveiling the angular momentum of photons, involving the SAM and the OAM as well as the coupling between them. The results reveal that the SAM and the OAM result both in the helical three-dimensional APTs. Due to the presence of the helical path caused by the SAM and/or the OAM, the actual traveling distance of the photons might be much longer than the geometric distance. The APT concept is very helpful for unveiling the angular momentum of photons and for understanding the behavior of the motion of the trapped particles in the tweezer experiment, and can also be promised to elucidate other physical systems.