微型化自由运行InGaAs/InP单光子探测器(特邀)

Miniaturized free-running InGaAs/InP single-photon detector(invited)

单光子探测器具有最高的光探测灵敏度,在激光雷达系统中使用单光子探测器可以极大提升系统的综合性能。近红外二区(1.0~1.7μm)激光具有大气透过率高、散射弱、太阳背景辐射弱等优势,是大气遥感、三维成像等激光雷达系统的理想工作波段。研制了一种基于InGaAs/InP负反馈雪崩光电二极管的微型化自由运行单光子探测器。该探测器长宽高为116 mm×107.5 mm×80 mm,在1.5μm最大探测效率超过35%,时间抖动(半高宽)低至80 ps。为满足激光雷达系统对光子飞行时间测量的需求,探测器内部集成时间数字转换(TDC)功能,时间精度100 ps。同时,探测器集成一套后脉冲修正及计数率修正算法,可以有效降低探测器所引起的雷达信号畸变。

Objective Single-photon detectors have the highest sensitivity of light detection.The utilization of single-photon detectors in LiDAR system can greatly improve the comprehensive performance of the system.Laser in the second near-infrared region(1.0-1.7μm)has the advantages of high atmospheric transmittance,weak scattering and weak solar background radiation,which is the ideal working band of aerosol remote sensing and three-dimensional imaging LiDAR system.Therefore,a high-performance miniaturized free-running single-photon detector is designed in this paper.Methods The single-photon detector is based on InGaAs/InP negative feedback avalanche photodiode(NFAD),allowing it to operate in the free-running mode(Fig.1).A precise bias circuit and a precise temperature control circuit provide the bias voltage and cooling for the NFAD,respectively(Fig.2,Fig.3).In order to meet the needs of photon time-of-flight measurement for LiDAR system,the time-to-digital converter(TDC)function is realized by FPGA based on carry delay chain(Fig.4).Through the built-in micro controller unit(MCU)with integrated counting rate and afterpulse correction algorithm,it can make real-time correction of TDC data and output via USB interface.Results and Discussions The detector has dimensions of 116 mm×107.5 mm×80 mm(Fig.5).The maximum detection efficiency is more than 35%at 1.5μm(Fig.6),and the time jitter(full width at half maxima,FWHM)is as low as 80 ps(Fig.7).The time measurement accuracy of internal TDC can reach 100 ps.The miniaturized LiDAR product using this single-photon detector can detect up to 15 km with a range resolution of less than 30 m(Fig.8).Conclusions The QCD600 series miniature free-running InGaAs/InP single-photon detector provides a compact and real-time data post-processing single-photon detection solution for LiDAR systems in the near infrared band with high efficiency,low noise,low time jitter.In the future,free-running single-photon detector will be developed in the direction of miniaturization using integrated refrigeration technology and ultra-low noise using deep refrigeration technology,which will provide more powerful technical support for LiDAR,QKD and other applications.