Influence of external background optical radiation on the flat view angle of silicon photomultiplier

The article presents the results of a study of the influence of external background optical radiation on the flat angle of view of silicon photomultiplier tubes (SiPMs). The relevance of the study is due to the development of open optical systems in which optical radiation is exposed to external background optical radiation, which can lead to deterioration in the quality of the recorded signal. When an object moves in space, the angle of incidence of optical radiation on the photosensitive surface of the photodetector can change, so one of its most important characteristics used in open optical communication systems is a flat angle of view. For the study, three models of silicon photomultipliers with similar structure and parameters were selected, namely KOF5-1035, Ketek RM 3325 and ON Semi FC 30035. It was found that with an increase in the illumination level of external background optical radiation, the directivity pattern of the photodetector narrows, which is associated with a decrease in the flat viewing angle. The strongest dependence of the flat viewing angle on the illumination level was observed for KOF5-1035, and the weakest – for Ketek RM 3325. It is shown that the flat viewing angle can be restored to the original va lue by increasing the overvoltage and using a light filter with a passband of 470 ± 20 nm. The maximum illumination value at which it was possible to restore the flat viewing angle to the original value was 3000 lux for all the SiPMs studied. The results obtained are potentially valuable resource for development and improvement of shared access optical communication lines.