HTS Josephson Junction Cantilever With Integrated Near Field THz Antenna

Josephson junctions from the high-temperature superconductor YBa₂Cu₃O₇ are routinely used on a cantilever to detect microwave emission up to 762 GHz from room temperature microwave devices with spatial resolution. The Josephson junctions on the cantilever are operated in a temperature range between 40 K and 80 K cooled by a cryocooler. With this measurement setup and a 3-axis table we are able to scan the 3D half-space in the near and far field over the microwave devices. To measure the near field of a microwave source, the antenna coupled to the Josephson junction has to be smaller than the wavelength to achieve high spatial resolution but large enough to be able to detect sufficient power. Also the characteristic frequency, antenna impedance, bandwidth up to 1 THz and connection filters have to be optimized for a LaAlO₃-bicrystal substrate. We report on the first measurement at 762 GHz with a new design of the Josephson cantilever.