The breakdown flash of Silicon Avalance Photodiodes - backdoor for eavesdropper attacks?

Silicon avalanche photodiodes are the most sensitive photodetectors in the visible to near infrared region. However, when they are used for single photon detection in a Geiger mode, they are known to emit light on the controlled breakdown used to detect a photoelectron. This fluorescence light might have serious impacts on experimental applications like quantum cryptography or single-particle spectroscopy. We characterized the fluorescence behaviour of silicon avalanche photodiodes in the experimentally simple passive quenching configuration and discuss implications for their use in quantum cryptography systems.