Experimental characterization of the photon statistics of four-wave mixing photon source

We discuss the statistics of Poissonian and thermal sources, and verify that as an approximation to a single-photon source, both Poissonian and thermal sources can be used, when the average number of photons per pulse is of the order of 0.1. An experimental characterization of the photon statistics of a single-photon source obtained from the four-wave mixing (FWM) process in optical fibers is presented. We employ an on/off avalanche photodetector operating in the Geiger mode, and use the maximum-likelihood estimation (MLE) method and the expectation-maximization (EM) algorithm to reconstruct the data. We find that the statistics of the source goes from thermal, at a low signal power regime, to Poissonian, in a high signal power regime.