Improved photon-counting detector performance by intelligent management of detector deadtime

Abstract

We discuss the difficulties of photon-counting at extremely high rates and introduce a scheme for a photon-counting detection system that addresses these difficulties. The method uses an array of N detectors and a 1-by-<i>N</i> optical switch with a control circuit to direct input light to live detectors. We compare performance of our system to other, passive detection systems and show that our detection system can handle incident photon rates higher than otherwise possible by suppressing the effects of detector deadtime. To support this claim, we present results of theoretical analysis and a proof-of- concept experiment. In particular, both calculations and the experiment prove that a group of intelligently managed <i>N</i> detectors provides an improvement in operation rate that can exceed the improvement that would be obtained by either a single detector with deadtime reduced by 1/<i>N</i>, even if it were feasible to produce a single detector with such a large improvement in deadtime, or a passive beamsplitter tree system with N detectors. In addition to deadtime reduction, our scheme reduces afterpulsing as well as background counts (such as dark counts). We conclude that an intelligent active management of a group of N detectors is the best arrangement of photon-counting detectors to handle high photon rates, an important technological challenge for fast developing quantum metrology and quantum key distribution applications.