Single Photon Detection: Principles and Applications

This lecture covers the principles and applications of single photon detection, focusing on the Single Photon Avalanche Diode (SPAD). It begins with an overview of various detection technologies, including intensified CCDs and hybrid photodetectors. The instructor explains the working principle of SPADs, emphasizing the avalanche effect in PN junctions and the importance of quenching mechanisms. The lecture details the design of SPADs, including the role of quenching resistors and the significance of the Geiger mode operation. The discussion extends to the performance metrics of SPADs, such as quantum efficiency, dark counts, and afterpulses. Applications of SPAD technology are highlighted, including fluorescence correlation spectroscopy, quantum random number generation, and time-correlated single photon counting. The lecture concludes with insights into the evolution of SPAD technology and its integration into CMOS systems, showcasing advancements in pixel arrays and their implications for precision measurement in various fields.