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.
Citation: Optics Express
Pub Type: Journals
correlated photons, detector, down-conversion, high accuracy calibration, primary standard verification, single photon detector