Effects of trap levels in single-photon optical time-domain reflectometry: evaluation and correction

Single photon detectors used in optical time-domain reflectometry (OTDR) suffer from carrier trapping phenomena. It is shown that trapping effects can result in a severe OTDR trace distortion, and that accurate measurements of trap releases open the way to the correction of the OTDR data. A simple procedure for offline correction of the experimental traces is presented. Its applicability range is analyzed, using a Monte Carlo program which simulates the actual OTDR experiments. A great improvement of signal-to-noise ratio in single-photon OTDR is expected by exploiting the technique. Requirements for the electronics to be used for these measurements are discussed.>