Alignment position method for SPAD detector calibration and homogeneity

Abstract

<p><strong>Background:</strong> Over the last decade have seen a drastically increase of interest in the Single photon avalanche diode (SPAD) detectors applications at many variety of quantum experiments where the detection efficiency at single-photon level is required. The calibration of such detectors involves predominantly the determination of the detection efficiency.</p><p><strong>Methods:</strong> The present study was carried out at Department of Photometry and Applied Radiometry, Physikalisch-Technische Bundesanstalt (PTB), National Metrology Institute of Germany. This work is focused in a reproducible and close-to-ideal alignment position method of the SPAD detectors to the incident beam for achieving low measurement uncertainty.</p><p><strong>Results:</strong> A dominantly Gaussian profile is obtained when the diameter of the detector is smaller than the beam diameter, whereas in case then the detector is larger than the beam, a dominantly rectangular scan is obtained. The optimal position (X/Y/Z) for setting the SPAD detector correspond to X<sub>center</sub> = 235.11 mm, Y<sub>center</sub><em> </em>= 6.28 mm and Z<sub>position</sub> = 14.6 mm. Homogeneity of the detection efficiency depends on the beam size and evaluated regions.</p><p><strong>Conclusions:</strong> The experimental set-up and experimental results needed for optimization of the SPAD detector position were described. This analysis gives important information in how to carry out the optimization of the detector position for the calibration of the SPAD and analysis of quantum detection homogeneity.</p>