Photon Temporal Distribution Extraction Based on Event-Refreshed TDC

This letter presents an efficient method for photon temporal distribution extraction based on an event-refreshed time-to-digital converter (TDC). The extraction method is applied to evaluate the average detected photons. The operation mode of the event-refreshed TDC is to reset and wait for a restart only when one event is detected after being started. The requirement of the TDC resolution in this method can be chosen flexibly, which is advantageous to simplify the design. In this manner, one can obtain the probability distribution of the light-induced single- photon signals that spread across many periods, which results in several histogram peaks. Then the average detected photons can be accurately determined by fitting the period peaks. The principle of the method is analyzed based on inhomogeneous Poisson process. Experimental validation is also implemented by using a commercial single-photon avalanche diode detector, which indicates the proposed method is effective and practical for photon number detection, especially in small number of incident photons or low photon detection efficiency applications.