A Broadband Suspended Hollow Vivaldi Antenna for THz Quantum Cascade Lasers

Terahertz (THz) Quantum Cascade Lasers (QCLs) based on double metal waveguides have been of large interest as compact sources of broadband THz radiation, including frequency comb operation [1] . Their far-field patterns, however, are highly divergent. There have been several approaches to mitigate this drawback [2] , [3] , and recently we have shown [4] that the far-field can be improved using an antipodal Vivaldi antenna [5] , [6] . It was based on a double-sided photolithography process on a transparent polymer. Here, we present a suspended hollow Vivaldi antenna with improved far-field properties, as well as a more straightforward fabrication and mounting procedure.