Terahertz Gauss-Bessel beam generation using free electrons to drive an axicon

Gauss-Bessel beams have the attractive properties of low diffraction loss, self-reconstruction, and small energy divergence, which have promising application prospects in various fields. Here we propose and investigate a scheme to directly generate a terahertz Gauss-Bessel beam by using an electron bunch to drive an axicon, from which the focused Cherenkov radiation is obtained. Compared with the previous optical driven methods, which are all indirect methods, the proposed scheme is a direction method of generating a terahertz Gauss-Bessel beam. In addition, the focusing depth, spectrum, and field intensity of the terahertz Gauss-Bessel beam can be readily adjusted by changing the parameters of the electron bunch and axicon. This proposed scheme has potential in terahertz spectroscopy, imaging, and communication systems.