Generation of gamma-ray beam with orbital angular momentum in the QED regime

We propose a scheme to generate high-energy gamma-ray photons with an orbital angular momentum (OAM) from laser-plasma interactions by irradiating a circularly polarized Laguerre–Gaussian laser on a thin plasma target. The spin angular momentum and OAM are first transferred to electrons from the driving laser, and then the OAM is transferred to the gamma-ray photons from the electrons through quantum radiation. This scheme has been demonstrated by using three-dimensional quantum electrodynamics particle-in-cell simulations. The topological charge, chirality, and carrier-envelope phase of the short ultra-intense vortex laser can be revealed according to the energy distribution of gamma-ray emission.