Diffractive deformed axicon to generate terahertz diffraction-free beam

Abstract

Diffraction-free beam propagation in free space can keep the light intensity distribution constant, but the complex system and bulky devices bring inconvenience to the experiment. In this paper, we propose an effective approach to generate a terahertz diffraction-free beam from diffractive transmitted deformed axicon. The main research methods are phase folding technique and three-dimensional (3D)-printing technique. Based on the existing research, the refractive transmitted axicon is compressed into a lighter diffractive element to implement a 0.1THz beam with 344.75mm diffraction-free length. The effect of element thickness on the phase folding efficiency is investigated, and the results of the refractive axicon and diffractive deformed axicon are compared to demonstrate the advantages of diffractive optical elements in generating diffraction-free beams.