Broadband absorbers for a terahertz calorimeter

Characteristics of an absorber used for power sensors is crucial for accurate terahertz (THz) power measurements. We have developed a highly sensitive THz calorimeter using a neutral-density optical filter glass as an absorber. However, the measurement accuracy deteriorated in the frequency range below 1 THz due to the reduction of absorption. In this study, broadband THz absorbers fabricated using magnetically loaded epoxy and polyurethane foam sheet were designed and evaluated for improving the measurement uncertainty of the calorimeter.