中文摘要：

研究了超导单光子探测器器件超导纳米线的多光子响应特性．在温度3．5K实验测量了纳米线器件直流特性和光子响应概率对多光子脉冲信号的响应特性．实验表明，器件超导转变电流随光辐照强度的增加而减小；在多光子脉冲信号下，器件响应的光子数随偏置电流减小而增加．同时基于量子光学和器件Hotspot理论半定量分析了该多光子响应的机制．

英文摘要：

In this paper, we study the response properties of multi-photon of NbN superconductor nanowire in superconducting single pho- ton detector （SSPD）. We measure the NbN nanowire device＇s DC characteristics and detection probability for single and multi-photon light pulse signal at a temperature of 3.5 K. The measured results show that the superconducting transition current of superconduc- tor nanowire decreases as light irradiation intensity increases. The photon number detected by SSPD is derived from the slope of detection probability versus light intensity. We find that the detected photon number increases as superconducting nanowire bias cur- rent decreases. Moreover, based on quantum optics and hotspot theory, we analyze the mechanism of the multi-photon response of superconducting nanowire semi-quantitatively. This result may be of benefit to understanding SSPD and developing the SSPD with the capability of resolving photon number.