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>

Improvement of the detection efficiency calibration and homogeneity measurement of Si-SPAD detectors

“…There are two approaches mostly used for determining the detection efficiency of Si-SPAD detectors: one is based on the detector subtitution technique, which uses a strongly attenuated laser and a reference detector (López et al 2015; Dhoska et al 2015a, b; Kück et al 2014) and the other one based on the two-photon correlation technique (Polyakov et al 2006). The latter has the advantage that it does not require a reference detector; however, the effect of multiple photon events at photon-counting level has to be considered.…”

“…0.3% (López et al 2015). The major uncertainty contribution to this measurement arose from the uncertainty associated to the measurement of the filter transmission, which is obtained from the deviation between the individual and combined transmission measurement carried out with an analog standard Si-photodiode (López et al 2015; Dhoska et al 2015a, b; Kück et al 2014). …”

“…In all these fields, the detection efficiency is the main parameter, which has to be accurately known for achieving reliable measurements. In this paper we present the improvements performed on the setup described in López et al (J Mod Opt 62:S21–S27, 2015) for determining the detection efficiency of Si-SPAD detectors with a low measurement uncertainty. The improvement arises from the precise alignment of the Si-SPAD detector and the low deviation reached between the total calculated filter transmission and the individual filter transmission measurements (≤0.05%) performed with an integrating sphere with attached Si-photodiode as standard detector.…”