Multiplexed photon-counting detectors

We discuss a scheme for a photon-counting detection system that overcomes the difficulties of photon-counting at extremely high rates. Our method uses an array of N detectors and a 1-by-N optical switch with a control circuit to direct input light to live detectors. Detector deadtime is significantly reduced by an active routing of single photons to the detector that has had the most time to recover from its last firing. In addition to deadtime reduction, our scheme reduces afterpulsing and background counts (such as dark counts). We present experimental results showing the advantageous performance of our system as compared to passive multi-detector detection systems. We conclude that intelligent active management of a group of N photon-counting detectors yields the highest photon counting rates, an important technological challenge for fast developing quantum metrology and quantum key distribution applications. Also, we report our experimental progress in developing an integrated device based on this scheme.