Generation of Gamma-ray Beam with Orbital Angular Momentum in the QED   Regime
  We propose a scheme to generate gamma-ray photons with an orbital angular momentum (OAM) and high energy simultaneously 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 photons, and then the OAM is transferred to the gamma-ray photons from the electrons through quantum radiation. This scheme has been demonstrated using three-dimensional quantum electrodynamics particle-in-cell simulation. The topological charge, chirality and carrier-envelope phase of the short ultra-intense vortex laser can be revealed according to the pattern feature of the energy density of radiated photons. 
Chen Liu, Baifei Shen, Xiaomei Zhang, Yin Shi, Liangliang Ji, Wenpeng   Wang, Longqing Yi, Lingang Zhang, Tongjun Xu, Zhikun...
physics.plasm-ph physics.optics