Development of Superconductor-Insulator-Superconductor (SIS) Terahertz Receiver With Mechanical and Thermal Vibration-Reduced Cryocooler

We are developing a superconductor-insulator-superconductor (SIS) mixer receiver to realize a highly sensitive and easy-to-use terahertz (THz) spectrum analyser, which measures both the frequency and the power of a terahertz signal. Although commercially available cryocoolers can cool the SIS mixer to a cryogenic temperature without troublesome cooling operations, the mechanical and thermal vibrations of a cryocooler can impede the sensitive detection of terahertz signals. We have developed a reduced-vibration cryostat that produces less than 10-μm peak-to-peak mechanical vibration at the 4-K stage; the temperature fluctuations are as small as 6 mK, which have negligible effects on the measurements of our SIS mixer receiver.