High Accuracy Verification of a Correlated-Photon-Based Method for Determining Photon-Counting Detection Efficiency
Sergey V. Polyakov, Alan L. Migdall
We have implemented and characterized an independent primary standard method for the calibration of detection efficiency of photon counting detectors. The method is based on a light source producing correlated photon pairs. We have determined, and most importantly, verified the detection efficiency uncertainty associated with this implementation of the two-photon method by comparing the measured efficiency to a detection efficiency determined by a substitution method using a conventionally calibrated transfer detector tied to a national primary standard detector, the NIST High Accuracy Cryogenic Radiometer. We obtained an absolute uncertainty of the correlated method of 0.18% (k=1) and an uncertainty of the conventional calibration of 0.17% (k=1). From a series of measurements we found that the two independent calibration techniques differ by 0.15% b0.14%, within the established uncertainty of comparison. We believe that this is the highest accuracy verification of the two-photon method yet achieved. We describe procedures and techniques used to perform calibrations and comparisons. Also presented are procedures for determining uncertainties of the both calibration methods.