Silicon Photomultiplier (SiPM)
Silicon Photomultipliers are arrays of avalanche photodiodes operated in Geiger mode (SPADs), designed for the detection of extremely weak light, down to the single photon. Depending on the light source and application, several hundred to thousands of SPADs are connected in parallel to form an SiPM. Each SPAD includes an integrated series resistor which quenches the avalanche and resets the diode for the next incoming photon.
The SiPM signal output is an electrical current proportional to the number of photons hitting the sensor. The main signal features are: very high gain (>1 x 106), very fast response and short recovery time.
Application fields are those requiring weak light detection and/or very good timing information. Typical examples are scintillator based detectors and time-of-flight systems.