纠缠光子法绝对定标光电探测器量子效率的研究

Research on Absolute Calibration of Photodetector Quantum-Efficiency Using Entangled Photons

为了应对国际上"坎德拉"新定义的动向,开展了利用纠缠光子法测量光电探测器量子效率的研究,并建立了测量装置。装置采用351.1nm连续激光抽运BBO晶体产生纠缠光子场,然后通过双通道门控计数器组成的符合测量系统在702.2nm和788.7nm两个波长点对光电倍增管的量子效率进行了测量。同时对单光子脉冲信号获取、噪声抑制及提取、符合时间特性、偶然符合、暗背景计数和器件透过率等影响测量结果的关键因素进行了实验分析并给出了修正分量,最终在两个波长点量子效率测量不确定度小于0.7%。

In response to the new definition of ＂Candela＂, the research on measurement of photodetector quantum efficiency （QE） with entangled photon method is carried out, and a complete QE measurement setup is established. From a Type-I phase match BBO crystal pumped by a 351. 1 nm CW laser, the correlated photons are generated, potomultiplier tube （PMT） QE is calibrated at 702.2 nm and 788.7 nm based on the coincidence count system which is realized with a dual-channel gated photon counter. At the same time, the key factors which influence the QE measurement are analyzed, including single-photon pulse acquisition, noise suppression and extraction, time related character about coincidence, accidental coincidence counts, dark counts, transmittance of optics. In the end, the measurement uncertainty of QE at the two wavelengths is less than 0.7 % .