半导体上转换单光子探测技术研究进展

近年来，量子通信技术取得了卓越的进步和发展，而作为接收端的单光子探测器在其通信系统中则起着至关重要的作用.本文聚焦于当前主流的半导体单光子探测器，就其器件原理、工作模式、优势和劣势等方面进行了相关评述.在此基础上，着重介绍了本课题组所提出的一种新型半导体近红外上转换单光子探测技术（USPD）的研究进展.从USPD的器件基本原理、器件结构、性能指标等方面阐述了其优越性和可行性，并给出了USPD最新的空间光耦合实验结果.半导体上转换单光子探测技术的关键特性在于它不是采用InP雪崩层结构实现信号的放大，而是利用成熟的硅单光子雪崩二极管（Si-SPAD）器件来实现信号的放大和采集，从而规避InP结构在暗计数率和后脉冲效应方面的问题.USPD利用半导体材料，通过外加电场将近红外光子上转换为短波近红外或者可见光子，再用商用Si-SPAD进行探测的方法，也为我们提供了一种单光子探测的新思路，打开了另一扇单光子探测的窗口.

Research progress of semiconductor up-conversion single photon detection technology

Quantum communication technology has achieved remarkable progress and development in recent years, and the single photon detector, as the receiving terminal, plays a vital role in communication systems. In this paper, we focus on the current mainstream semiconductor-based single photon detectors and review their device principle, operating mode, advantages and disadvantages. Besides, the research progress of a novel semiconductor near-infrared single photon detection technology (USPD) is introduced. The feasibility and superiority of the USPD device are demonstrated from the basic principle, device structure and key performance indicators of USPD, and the latest spatial optical coupling experiment results of the USPD are also given. The design principle of the USPD device is to utilize Si multiplication layer of the Si SPAD as a multiplication layer instead of InP in conventional InGaAs-SPAD. The Si-SPAD has a much lower dark count rate and afterpulsing effect because of high-quality material of Si. Such a characteristic design of USPD can suppress the afterpulsing probability to the same level as that of the Si-SPAD and enables it to operate in the free-running regime without sacrificing photon detection efficiency. For the same reason, the dark count rate (DCR) of USPD is also very low. The operating mechanism of USPD is to convert the infrared photons into near-infrared or visible photons and the emitted near-infrared photons can be detected by a Si SPAD, which provides us with a new idea for single photon detection.