Josephson Cantilevers for THz Microscopy of Additive Manufactured Diffractive Optical Components

Josephson junctions can be employed as sensors to determine frequency and power of microwave and terahertz (THz) radiation. A Josephson cantilever carries at least one Josephson junction with an antenna structure to be sensitive for THz radiation. In our THz microscope, this cantilever is mounted on a 15 × 15 × 15 mm
³
positioning system in vacuum and is cooled by a cryocooler to operating temperatures between 30 and 85 K. Current-voltage characteristics are measured at every spatial position. The frequency and power of THz radiation are derived from the electrical characteristics for every spatial point and three-dimensional visualizations of the power distribution are evaluated. The THz microscope represents a versatile measuring instrument to characterize many different microwave and THz circuits and components. In this paper, Josephson cantilevers from YBa
₂
Cu
₃
O
₇
on LaAlO
₃
bicrystal substrates are employed to characterize additive manufactured diffraction gratings. The diffraction patterns of the gratings are measured and visualized with a far-infrared laser system at a frequency of 762 GHz. The obtained results are matching with calculations from a theoretical model. The presented method is capable of supporting fast prototyping processes for THz components by analyzing diffraction patterns three dimensionally.