Large-area SNSPD with a high count rate enhanced by a discharge acceleration circuit

A large-area single-photon detector with a high maximum count rate (MCR) is expected by LiDAR application for a large dynamic range and high coupling efficiency. Superconducting nanowire single-photon detectors (SNSPDs) are very competitive for high quantum efficiency at near infrared wavelengths. However, it is a great challenge to balance the efficiency, area, and MCR of SNSPDs due to the long superconducting nanowire architecture. In this article, we design a large-area SNSPD with a high MCR for LiDAR applications. The SNSPD has four independent channels, and each of them is composed of four parallel nanowires. The photosensitive area has a diameter of 60 μm and can be coupled with a 200-μm multimode fiber through a lens. At the same time, we analyze the origin of the detector latching under high count rates and propose a discharge acceleration circuit to alleviate it. In the experiment, an MCR of 147 Mcps is achieved in this SNSPD. The product of area and MCR for each channel of this SNSPD is twice higher than previously reported results. We highlight that this work is of great significance for the application of SNSPD in LiDAR.