Generation of diffraction-free Bessel beams based on combined axicons

Bessel beams are of great interest because of their unique diffraction-free properties and broad potential applications. In this paper we investigate the generation of diffraction-free Bessel beams by combined axicons. We found that such beams can propagate up to 9.63 km in free space. Longer propagation distance can be achieved by utilizing the angular spectrum reconstruction theory that is proposed here for the first time, to rectify the distortion caused by diffraction and extend the propagation distance up to 15 km from the emission plane. Additionally, the self-healing property of the Bessel beam is demonstrated by initially removing the main lobe and reconstructing the beam after 9.63 km. Finally, we demonstrate that the Bessel beam has outstanding performance in weak and moderate turbulence atmosphere. The results obtained provide an effective way for optical communication in deep space and may inspire new ideas for wireless energy transmission in the microwave range.