Reduction of Laser Pulse Diffraction by Magnetized Electron–Positron Plasma Lens

The main goal of this paper is to focus a laser beam with a thin axially magnetized electron-positron (EP) plasma lens in the area outside the plasma region. A thin plasma slab is used as an optical element as long as the focal length is larger than the thickness of the lens. The focal length is defined as the distance between the plasma lens and the laser-beam focus point. The external magnetic field is applied along the direction of the laser field propagation. The theoretical investigation reveals not only that the circularly polarized beam focuses very effectively compared with the linear case but also that the magnetized EP plasma lens more sufficiently decreases the minimum spot size and increases the focal length of a laser beam compared with the magnetized purely electron plasma lens.