3-D Printed Circularly Polarized Terahertz Lens for Bessel Beam Generation

A novel circularly polarized (CP) Bessel beam launcher fed by a standard linearly polarized (LP) pyramidal horn at 300 GHz is proposed in this paper. The design adopts a bilayer structure, with the upper layer being a discrete dielectric lens antenna that transforms a quasi-Gaussian beam into a well confined and collimated pseudo-Bessel beam, and the lower layer being a uniform dielectric grating that converts diagonally incident LP waves into transmitted CP waves. In house developed three-dimensional (3-D) printing techniques are adopted to fabricate the design for process simplification and cost minimization. Experimental results reveal that the proposed lens can realize right-hand circular polarization (RHCP) and generate a Bessel beam with constant spot size and constant axial intensity over a considerable range, all these achieved at 0.3 THz.