Realization of Optical Power Scale Based on Cryogenic Radiometry and Trap Detectors

We report the realization of the Brazilian optical power scale based on cryogenic radiometry. The electrical-substitution cryogenic radiometer (ESCR) national primary standard is characterized and used for measurement of the optical power at specific laser lines. The scale is transferred to silicon detectors arranged in a reflection-trap configuration through the direct calibration of their spectral power responsivity. These devices are then characterized and used as standards for radiometry and photometry. The experimental results for the spatial nonuniformity, polarization dependence, and spectral responsivity are shown and discussed. The external quantum efficiency of the detectors is modeled to extend the optical power scale over the visible spectral range. The results are validated by comparing the modeled scale with a calibration certificate for the spectral power responsivity of one of the standards. A bilateral international comparison of ESCRs using the characterized trap detectors was additionally performed to link the optical power scale to the Consultative Committee for Photometry and Radiometry intercomparison of cryogenic radiometers. The set of results establishes the Brazilian optical power scale traced to the cryogenic radiometer.