Application Note: Single Photoelectron Resolution

The SPM is a high gain photodetector that is sensitive to single photons. In particular, the signals due to different numbers of photons can be easily resolved i.e. the signal corresponding to two photons is clearly distinguishable from that corresponding to a single photon detection. This is due to the devices high gain, low multiplication noise and process uniformity across the SPM. The noise that is inherent in SPM detector single photoelectron spectrum is due to statistical variations in the gain, which are low in the SPM because of the high number of carriers that are generated for each detected photon (~106). Additional factors that ensure a good SPM photoelectron resolution are minimal gain variations between microcells, bias and temperature stability, low system noise and a low dark count rate.

This technical note will detail the experimental procedure for acquiring a spectrum with resolved peaks corresponding to the photon number, and show examples with the sensL products.