Traceable calibration of Terahertz detectors

The crucial point of absolute measurements of radiant power in the Terahertz spectral range is traceability to the International System of Units. PTB in Germany offers a reliable calibration of THz detectors as part of its official services as the only National Metrology Institute in the world. A dedicated calibration facility is based on a far-infrared molecular gas laser and a reference detector. Its power responsivity at 2.52 THz was originally measured in a pilot experiment using a cryogenic substitution radiometer. Actually the responsivity scale is expanded to the wider frequency range from 1 THz to 5 THz.