Numerical simulation of DC equivalent factor of THz calorimeter

We have developed a calorimeter for a metrology standard for measuring the power of terahertz (THz) waves. Since the THz calorimeter is based on the thermal balance between heat produced by THz waves and direct current (DC), it requires an equivalent factor for converting from THz to DC power. The DC equivalent factor, which is defined as the ratio between the thermal efficiency of THz and DC powers, was calculated with a thermal simulator based on the finite element method. This factor was estimated to be approximately 1 with a maximum error of 0.7 %, which implies a good equivalence between DC and THz powers, enabling accurate measurement of the absolute power of THz waves.