LAUSR

A calorimeter based on single-mode WR-03 waveguides is developed with the aim of establishing a measurement standard for terahertz (THz)-wave power over the frequency range of 220–330 GHz. Correction factors such as the thermal leakage are estimated by actual measurements. This calorimeter measures the absolute power of the THz waves by substituting dc power, based on the isothermal temperature control technique. A commercial power meter with a WR-03 waveguide is calibrated by direct comparison with the calorimeter at a power level of 0.1 mW. The calibration factors of the commercial power meter are evaluated in the frequency range, 220–330 GHz. The associated uncertainties of the calibration factors are estimated by combining the measurement uncertainty factors using the Monte Carlo method. The relative expanded uncertainties are less than 7.2% with a coverage factor of two.