Advantages and demonstration of gated-mode passive quenching with active reset circuit

Synchronized detection is one of the major areas of photon counting applications, e.g., the quantum key distribution (QKD). With single photon avalanche diodes (SPADs), gated-mode operation has the advantage of reduced dark count probability thanks to the limited detection windows. On the other hand, passive quenching with active reset (PQAR) circuits can confine the afterpulsing probability with reduced charge, which enables high bit rate operation. To take the benefits of both, a gated-PQAR circuit is designed, which is also demonstrated with 10X reduction in afterpulsing probability compared to the gated quenching circuit with similar dark count probability under the same photon detection efficiency.