Comprehensive characterization of deadtime in single-photon avalanche photodiode-based detectors

Abstract Single-photon avalanche photodiode-based detectors (SPADs) are largely used in applications that require sensitivity to low-intensity radiation down to a single photon, as quantum communications. Operation in Geiger mode renders the devices infinite gain, but avalanche quenching imposes an intrinsic deadtime after each detection event. This parameter must be characterized for correcting the detection count rate, especially when operated in free-running mode under continuous-wave illumination. Here a set of SPADs of different models are characterized using a methodology based on time interval analysis and their deadtime parameters are compared. Results indicate distinct behavior between devices as a function of input photon flux, thus photon counting rate. Misleading evaluation of the deadtime dependence on the photon counting rate may result in a sixfold correction error, indicating that a comprehensive characterization of the SPAD as reported is required to avoid miscorrection of the measured count rate.