Real-time time correlated photon counters for photon number resolving detectors

Abstract

In this paper, a novel Field Programmable Gate Array (FPGA) based instrument for Time Correlated Photon Counting (TCPC) is reported which takes advantage of the photon number resolving ability of newer single photon detectors technologies, such as silicon photomultipliers (SiPM). Utilizing the received photon number in the formation of the TCPC histogram will enable faster measurements in comparison to Time Correlated Single Photon Counting (TCSPC) as less information is being discarded per excitation pulse. The concept of (TCSPC) and the differences with TCPC are introduced, as the well as the advantages of using TCPC when using a number resolving photodetector such as a SiPM rather than a traditional Single Photon Avalanche Diode (SPAD). The design and performance of the system is reported. An 8-stop TCPC system is presented along with a hardware solution to handle time correlations in real-time on-chip rather than in post processing. A system accuracy of 42ps RMS has been demonstrated.