We demonstrate the photon-number resolution (PNR) capability of a 1.25 GHz gated InGaAs single-photon avalanche photodiode (APD) that is equipped with a simple, low-distortion ultra-narrowband interference circuit for the rejection of its background capacitive response. Through discriminating the avalanche current amplitude, we are able to resolve up to four detected photons in a single detection gate with a detection efficiency as high as 45%. The PNR capability is limited by the avalanche current saturation, and can be increased to five photons at a lower detection efficiency of 34%. The PNR capability, combined with high efficiency and low noise, will find applications in quantum information processing technique based on photonic qubits.

对InGaAsP/InP单光子雪崩探测器（SPADs）进行了总剂量为10 krad（Si）和20 krad（Si）的γ辐照，并进行了原位和移位测试。辐照后，暗电流和暗计数率有轻微的下降，而探测效率和后脉冲概率基本不变。经过一定时间的室温退火后，这些退化基本恢复，这表明瞬态电离损伤在γ辐照对InGaAsP/InP单光子雪崩探测器的损伤中占主导地位。

我们描述了一种高性能平面InGaAsP/InP单光子雪崩二极管（SPAD），该二极管具有单独的吸收、分级、电荷和倍增（SAGCM）异质结构。通过电场调节和缺陷控制，SPAD在293 K的门控模式下工作，光子探测效率（PDE）为70%，暗计数率（DCR）为14.93 kHz，后脉冲概率（APP）为0.89%。此外，在死区时间为200 ns的主动淬灭模式下工作时，室温下实现了12.49%的PDE和72.29 kHz的DCR。

The influence of the virtual guard ring width (GRW) on the performance of the p-well/deep n-well single-photon avalanche diode (SPAD) in a 180 nm standard CMOS process was investigated. TCAD simulation demonstrates that the electric field strength and current density in the guard ring are obviously enhanced when GRW is decreased to 1 μm. It is experimentally found that, compared with an SPAD with GRW = 2 μm, the dark count rate (DCR) and afterpulsing probability (AP) of the SPAD with GRW = 1 μm is significantly increased by 2.7 times and twofold, respectively, meanwhile, its photon detection probability (PDP) is saturated and hard to be promoted at over 2 V excess bias voltage. Although the fill factor (FF) can be enlarged by reducing GRW, the dark noise of devices is negatively affected due to the enhanced trap-assisted tunneling (TAT) effect in the 1 μm guard ring region. By comparison, the SPAD with GRW = 2 μm can achieve a better trade-off between the FF and noise performance. Our study provides a design guideline for guard rings to realize a low-noise SPAD for large-array applications.

近年来，单光子探测技术在激光雷达等方面的应用越来越受到研究人员的关注。研制了基于InGaAs负反馈雪崩二极管（Negative Feedback Avalanche Diode, NFAD）的自由运转式集成型近红外单光子探测器。设计将被动淬灭原理的NFAD与主动淬灭技术结合，针对NFAD的信号读出电路易受电磁干扰的问题，创新地提出了无前级放大器的雪崩信号高阻抗差分提取电路，并采用吸波材料对关键电路部分进行了屏蔽，同时提高了淬灭性能和稳定性。此外，为了降低暗噪声计数率，针对集成制冷型NFAD器件的散热进行了详细的热设计，对集成热电制冷的NFAD器件和高速淬灭电路发热量较大的特点进行了电路和散热结构设计优化。通过实验对淬灭电路性能、散热设计和抗干扰设计进行了验证。结果表明：无前置放大器设计的探测器性能稳定，对1550 nm波长光子的最高探测效率可达33%，在−50 ℃、10%探测效率时可用死时间低至120 ns，此时暗计数率890 Hz，后脉冲概率10.6%。探测器散热性能良好，环境20 ℃风冷下的最低制冷温度可稳定在−58 ℃。上述结果表明这一低噪声计数、高集成度的通信波段近红外单光子探测器尤其适用于对性能和环境空间要求更严苛的应用场合。