Developments in single photon avalanche photodiodes with fast timing resolution

Until very recently Single Photon Avalanche Diodes (SPAD), which yield high detection efficiency in the visible spectrum, provided poor timing performance. This paper will review the current state of the SPAD technology and review new SPAD developments that provide: sub 50ps-timing resolution, are stable with count rate, and yield high detection efficiency. Examples will be provided; comparing timing resolution of PMT's and solid-state photon counting modules, effect of count rate on timing resolution, thus illustrating the stability of these newly developed SPAD's. In addition, the paper will review the basics of photon counting using SPAD's and illustrate how these SPAD's are used in Time-Correlated Single Photon Counting (TCSPC) and the results from these experiments.