An Electron Beam Manipulated by Laguerre-Gaussian Modes

Abstract

Manipulation of electron beam by Laguerre-Gaussian (LG) modes is investigated using finite-difference time-domain particle-in-cell (FDTD-PIC) simulations. The simulated azimuthal velocity profiles of macro-particles display a 3-D spiral pattern with the number of strands equal to a sum of the state number of spin angular momentum (SAM) and the orbital angular momentum (OAM) of LG modes. These spiral patterns move along with the electron beam like a helical traveling wave. The macro-particles also exhibit both an orbit revolution and a small rotation motion. The former is very similar to the gyromotion of electrons under an external magnetic field. The rotation motion has the same frequency as that of the LG mode while the orbit revolution frequency is far lower.