Improving maximum count rate of superconducting nanowire single-photon detector with small active area using series attenuator

Abstract

Maximum count rate is a crucial parameter of superconducting nanowire single-photon detector (SNSPD) for quantum communication and laser communication. However, when increasing the incident photon flux, the SNSPD device with small active area is apt to latch due to the AC coupling of room temperature amplifier in the readout circuit, which limits SNSPD to reach a high count rate. We proposed a simple way by inserting an electrical attenuator in series with small-active area SNSPD to avoid the latching effect, thus improving maximum count rate effectively. The count rate with the system detection efficiency reduced by half increased by 6 times for SNSPD with an active area of Φ15 μm.