Inverse design on terahertz multilevel diffractive lens based on 3D printing[Invited]

Terahertz(THz)lenses have numerous applications in imaging and communication systems.Currently,the common THz lenses are still based on the traditional design of a circular convex lens.In this work,we present a method for the design of a 3D-printed multilevel THz lens,taking advantage of the benefits offered by 3D printing technology,including compact size,lightweight construction,and cost-effectiveness.The approach utilizes an inverse design methodology,employing optimization methods to promise accurate performance.To reduce simulation time,we employ the finite-difference time-domain method in cylindrical coordinates for near-field computation and couple it with the Rayleigh-Sommerfeld diffraction theory to address far-field calculations.This technology holds great potential for various applications in the field of THz imaging,sensing,and communications,offering a novel approach to the design and development of functional devices operating in the THz frequency range.