Room temperature absolute radiometer for reproduction of terahertz radiant power

• Published in: IEEE transactions on terahertz science and technology 2023-07, Vol.13 (4), p.1-7
• Main Authors: Deng, Yuqiang, Li, Chaochen, Sun, Qing
• Format: Article
• Language: English
• Subjects: absolute radiometer; Absorption; Absorptivity; Coatings; Equivalence; Heat sinks; Holes; Irradiance; Laser beam heating; Lasers; Measurement by laser beam; Power lasers; Power measurement; Radiometers; Radiometry; Resistance heating; Room temperature; Silicon carbide; Terahertz metrology; terahertz radiometer; terahertz radiometry
• ISSN: 2156-342X; 2156-3446
• DOI: 10.1109/TTHZ.2023.3263639

We propose an electrical substitution and laser calibration technique for reproduction of terahertz radiant power. With this technique, the equivalence of terahertz absorption and electrical heating in the absorber is corrected and accurate terahertz radiant power is reproduced. A two-cavity absolute radiometer was developed for accurate reproduction of terahertz radiant power working at room temperature. The absolute radiometer has two absorptive cavities coated with different coatings. One cavity was coated with 3M Velvet-coating and used for the absolute reproduction of laser radiant power, and the other was coated with a mixture of silicon carbide particles and 3M Velvet-coating and used for the reproduction of terahertz radiant power. With the comparison of the two cavities under stable laser irradiance, the equivalence between terahertz absorption and electrical heating is calibrated, and the precision of absolute reproduction for terahertz power is improved. The reproduced power using this absolute radiometer agreed excellently with the terahertz power standard at the National Institute of Metrology, which had been used in the first international terahertz power comparison.