为了提高超导纳米线单光子探测系统(SNSPD)的探测效率，搭建了超导纳米线单光子探测系统，研究了该系统的光耦合结构及该结构随温度降低而发生的变化。首先，测量了SNSPD在不同电流下的量子效率，确定了器件的性能。然后，提出了两种不同的光纤直接对准的器件封装方法，这些方法可以在室温下自主控制光纤端面与器件表面的距离(gap)。考虑封装材料的热胀冷缩，gap在温度变化时有很明显的变化，研究了温度变化对gap的影响。最后，提出通过改变入射光的波长来观察器件表面反射光光强的周期性波动，从而精确测量不同温度下gap的大小。实验结果表明，对于两种不同的光耦合结构，gap在温度降低270 K以后分别减小了4.1 μm和17 μm。理论计算和实验数据基本吻合，可为未来器件封装和新型封装结构的设计提供参考依据。

In order to investigate the characteristics of the package and fiber coupling of a Superconducting Nanowire Single-photon Detector (SNSPD), the SNSPD was successfully built up in our laboratory. Experiments show that the quantum efficiencies of the detector under different light wavelengths are 6%@1310nm and 3%@1550nm when the dark count rate is 100 Hz. Then, as the distance(gap) between SNSPD and optical fiber would be changed due to the thermal stress during cooling, and would cause a misalignment, two kinds of fiber coupling methods to modulate the gap at room temperature were proposed. Finally, by altering the wavelength of the input light, the exact values of the gap at different temperatures were measured and then the influence of temperature on the gap were figured out by an experiment. The experimental results indicate that decreases of the gap for the two packages are 4.1 μm and 17 μm when the temperature dereases 270 K. Based on the analysis of package material and structure, the gaps at both room and low temperature were calculated theoretically. The result fits well with that of the experiments and it may offer some references to the design of new package and fiber coupling in the future.