3D printing technique and its application in the fabrication of THz fibers and waveguides

3D printing, also known as additive manufacturing technique, has recently found applications in various engineering fields due to its ability to produce freeform 3D structures beyond the ability of traditional subtractive manufacturing methods. In this respect, the field of THz photonics is no exception. The adoption of 3D printing technique resulted in a revolution in THz optics and device manufacturing and will continue advancing this field for years to come. In this Perspective paper, we consider, in particular, the fabrication of guided optics devices for the THz operation range using additive manufacturing. We first introduce the technical characteristics of various 3D printing techniques as well as the advantages, disadvantages, and main performance parameters. Then, various 3D printed THz waveguides and fibers and functional devices, such as metalized/metallic/dielectric rectangular waveguides, photonic crystal waveguides, hollow-core anti-resonant/Bragg waveguides, hybrid metal/dielectric waveguides, plasmonic waveguide, porous fibers, magic tee, and serpentine waveguide traveling-wave circuits, are discussed. We also highlight practical applications of 3D printed waveguides/fibers in manipulating THz waves, especially in the fields of sensing and communication, including the analyte thickness and refractive index sensors, subwavelength/suspended core fiber communication links, dispersion compensators, and add-drop multiplexers. Finally, the prospects of 3D printing techniques in the THz field are summarized.