Physikalisch-Technische Bundesanstalt

Recent technological progress in THz generation and detection paves the way to applications of THz radiation in fields like security, material inspection and process monitoring and, on the long term, medical science and communication technology. Radiometry in the THz spectral region has to be developed as established radiometric techniques from radio-frequency or optical metrology do not sufficiently cover the THz region.

PTB operates a detector based measurement facility for characterization and calibration of THz-detectors at 2.52 THz. The available spectral range for detector calibration will be expanded to 1 THz to 5 THz in the future. The core instrument of the calibration facility is a molecular gas laser pumped by a frequency stabilized CO₂ laser. This gas laser delivers monochromatic THz-radiation tuneable to several rotational transitions of the molecules in use. Tuneability and high power of the THz laser allow for a large step closing the metrological gap in radiometry between radio-frequency and optical frequencies in the far infrared.