Title: Laser annealing heals radiation damage in avalanche photodiodes,
Abstract: Avalanche photodiodes (APDs) are a practical option for space-based quantum
communications requiring single-photon detection. However, radiation damage to
APDs significantly increases their dark count rates and reduces their useful
lifetimes in orbit. We show that high-power laser annealing of irradiated APDs
of three different models (Excelitas C30902SH, Excelitas SLiK, and Laser
Components SAP500S2) heals the radiation damage and substantially restores low
dark count rates. Of nine samples, the maximum dark count rate reduction factor
varies between 5.3 and 758 when operating at minus 80 degrees Celsius. The
illumination power to reach these reduction factors ranges from 0.8 to 1.6 W.
Other photon detection characteristics, such as photon detection efficiency,
timing jitter, and afterpulsing probability, remain mostly unaffected. These
results herald a promising method to extend the lifetime of a quantum satellite
equipped with APDs.