High performance single photon counting and timing with single photon avalanche diodes

Single Photon Avalanche Diodes (SPADs) have been proven to be extremely powerful sensors for single photon detection. Thanks to the advantages of solid state devices (ruggedness, small size, low supply voltage, high reliability) combined to photon detection efficiency inherently higher than PMTs, especially in the red and near-infrared regions of the spectrum, SPADs have become the detectors of choice in a steadily increasing number of applications, such as Förster Resonance Energy Transfer (FRET), Laser Imaging Detection and Ranging (LIDAR) and Quantum Key Distribution (QKD). The development of specific fabrication processes, usually referred to as custom technologies, has given the designers the degrees of freedom necessary to pursue the best device performance. Nevertheless, custom processes do not easily allow the integration of complex front-end and processing electronics on the same chip of the detector. Therefore, external high-performance electronics is required to extract the best performance from these sensors. We report the latest results we achieved with a fully-planar custom technology process, that allows the fabrication of SPAD arrays, and specifically designed external front-end and timing electronics with particular focus on solutions to achieve high speed in counting and timing applications.