Optical path design of Bessel beams at W band by FDTD method

Bessel beams are diffraction-free beams and have many novel properties. In this paper, we designed the optical path to generate the Bessel beams in millimeter wave band using three elements. A dielectric hybrid-mode horn is designed to generate a Gaussian beam, a lens is used to transform the Gaussian beam, and an axicon is placed behind the transform lens to convert the Gaussian beam into a Bessel beam. The designed optical path is simulated by the finite-difference time-domain method. The transversal intensity distribution of the generated Bessel beam has good agreement with the ideal Bessel beam. It can propagate longer than 50mm and suffers little diffraction.