Analysis of 3D-printed metal for rapid-prototyped reflective terahertz   optics
  We explore the potential of 3D metal printing to realize complex conductive terahertz devices. Factors impacting performance such as printing resolution, surface roughness, oxidation, and material loss are investigated via analytical, numerical, and experimental approaches. The high degree of control offered by a 3D-printed topology is exploited to realize a zone plate operating at 530 GHz. Reflection efficiency at this frequency is found to be over 90%. The high-performance of this preliminary device suggest that 3D metal printing can play a strong role in guided-wave and general beam control devices in the terahertz range. 
Daniel Headland, Withawat Withayachumnankul, Michael Webb, Heike   Ebendorff-Heidepriem, Andre Luiten, and Derek Abbott
physics.optics