Stimulated Secondary Emission of Single-Photon Avalanche Diodes

Large-area next-generation physics experiments rely on using silicon photomultiplier (SiPM) devices to detect single photons, which trigger charge avalanches. The noise mechanism of external crosstalk occurs when secondary photons produced during a charge avalanche escape from an SiPM and trigger other devices within a detector system. This work presents measured spectra of the secondary photons emitted from the Hamamatsu VUV4 and Fondazione Bruno Kessler (FBK) VUV-HD3 SiPMs stimulated by laser light, near operational voltages. This work describes the microscope for the injection and emission of light (MIEL) setup, which is an experimental apparatus constructed for this purpose. Measurements have been performed at a range of overvoltage values and temperatures from 86 to 293 K. The number of photons produced per avalanche at the source is calculated from the measured spectra and determined to be ${49}\pm {10}$ and ${61}\pm {11}$ photons produced per avalanche for the VUV4 and VUV-HD3, respectively, at 4-V overvoltage. No significant temperature dependence is observed within the measurement uncertainties. The overall number of photons emitted per avalanche from each SiPM device is also reported.