Single-Photon Detectors: From Traditional PMT to Solid-State SPAD-Based Technology

Solid-state photomultipliers (SSPM) made by multi-element SPAD (single-photon avalanche detector) are nowadays jousted to replace the traditional, vacuum-tube photomultipliers (PMT) based on the photocathode and dynode-chain technology. We revisit the milestones and the conceptual steps leading to single-photon detectors, from the PMT to the SSPM. Then, we discuss state-of-the-art performances of the two detectors and point out that SSPMs are equalling or even surpassing PMTs for response time and sensitivity, while are still lagging for acceptance area, linearity and dark current. We finally compare the detectors in applications to pulse spectrometry, fast waveform analysis, and photon counting.