同轴电缆反射方案单光子探测器的特性研究

分析了用于消除门控单光子探测器电尖峰噪声的同轴电缆反射方案的特性.重点分析了该方案中,雪崩光电二极管的偏置电压和输出信号的变化特性.根据理论分析的结果,给出了不同的单光子信号与两个门控脉冲的时序关系的确定依据,以及该方案对电尖峰噪声的消除效果,同时给出了探测系统的最小探测周期.并对理论分析的结果进行了实验验证,实验中测得尖峰噪声的抑制比为25.1dB,实验结果与理论分析相符.这些分析结果将有助于红外单光子探测器的设计和性能的优化.     

测量软X射线脉冲信号的门控积分器

 研制了满足ICF诊断中软X射线能量测量精度要求的具有限定时间积分功能的门控积分器。测试结果表明, 门控积分器的门有效导通时间约为7.8ns; 用信号源做被积信号, 门控积分器与示波器同时测量, 积分非线性小于3%; 门控积分器与示波器测量对比, 最大误差小于门控积分器满量程的5%。     

用于红外单光子探测的雪崩光电二极管传输线抑制电路模型的理论分析

结合利用雪崩光电二极管(APD)进行红外单光子探测电路模型的工作原理和特点以及传输线瞬态电脉冲产生的过程,提出了将传输线瞬态过程脉冲发生电路模型用于APD雪崩抑制的一种新方法,该方法可以实现利用APD门模工作方式进行红外单光子探测的过程.主要从理论上计算了红外单光子信号入射APD时,传输线脉冲发生电路模型中负载电阻输出电脉冲的特点,讨论了传输线终端不同边界条件对输出电脉冲的影响,通过理论计算确定了这种利用APD进行红外单光子探测新模型的电路结构与参数,证明了该电路模型用于红外单光子探测APD门模工作方式的 关键词： 红外单光子探测技术 雪崩光电二极管(APD) 抑制电路 传输线瞬态过程     

量子通信中单光子探测器的实验研究

为了提高单光子探测系统的灵敏度,实验采用InGaAs/InP雪崩光电二极管作为量子通信中的单光子探测器件,以门控脉冲模式实现了更高精度的单光子探测器的偏压生成电路、单光子信号放大电路、单光子信号检测电路和温度控制模块,并通过选用高精度前置放大器OP37和精密比较器AD8561,将量子效率提高到18.3%,暗计数控制小于4.1%×10~(-6)/ns.     

基于单光子探测及脉冲位置调制的激光通信关键技术研究

为了实现高灵敏度的空间激光通信,并提高传输信道的抗干扰能力,将单光子探测技术和脉冲位置调制技术相结合,采用门控电路与反馈淬灭电路相结合的方式淬灭单光子探测器雪崩,设计了插入帧头法用于脉冲位置调制解调。用现场可编程门阵列进行了脉冲位置调制解调过程的仿真,验证了插入帧头法的有效性与可行性。在此基础上搭建了1 550 nm的脉冲位置调制激光通信实验,同时测试了单光子探测器在不同参数下的性能。结果表明,当探测效率为25%,触发延时为8.00 ns,门宽为5.0 ns,死时间为0.1μs时,单光子探测器性能最佳。最后测试了不同调制速率下单光子探测器的探测灵敏度,结果表明,当通信码速率为1 Mbps时,通信灵敏度为-51.8 dBm;当通信码速率为4 Mbps时,通信灵敏度为-41.0 dBm,实现了高灵敏度的空间激光通信。     

Balanced, gated-mode photon detector for quantum-bit discrimination at 1550 nm

A photon detector that combines two avalanche photodiodes (APDs) has been demonstrated for quantum-bit discrimination at 1550 nm. Spikes accompanied by signals in a gated mode were canceled by balanced output from the two APDs. The spike cancellation enabled one to reduce the threshold in the discriminators and thus the gate pulse voltage. The dark count probability and afterpulse probability were reduced to 7x10(-7) and 7x10(-4) , respectively, without affecting the detection efficiency (11%) at 178 K.     

通讯波段单光子探测器的研制

将InGaAs/InP雪崩光电二极管应用于盖革模式下,采用门脉冲模式淬灭雪崩,并使用魔T混合网络抑制尖峰噪声,实现了通信波段1550 nm的单光子探测.在APD工作温度为223 K时,测得暗计数率与探测效率的比值为0.035.     

InGaAs单光子探测器传感检测与淬灭方式

针对InGaAs单光子雪崩光电二极管(SPAD)的光电感应特性,研究了基于门控主动式淬灭的SPAD动态偏置控制和电路实现的策略.采用门控主动淬灭控制可降低淬灭时间,有效抑制暗计数和后脉冲效应.接口感应检测电路采用标准互补金属氧化物半导体(CMOS)工艺进行制造,而SPAD则采用非标准CMOS工艺.利用铟柱互连混合封装工艺实现SPAD与感应接口电路的协同工作.在低温-30?C的条件下,实现了SPAD光触发雪崩电流信号的提取和快速淬灭.研究了感应电阻和临界检测电压对传感检测电性能的影响,并采用简单电路结构实现状态检测,实测得到的SPAD恢复时间、传输延时分别为575,563 ps,淬灭时间为1.88 ns,满足纳秒级精度传感检测应用的需要.     

基于APD线列的单光子探测计数研究

单光子探测系统可以对单个光子进行探测;探测系统含有探测部分、淬灭电路部分和计数部分;探测部分主要由工作在盖革模式下的雪崩光电二极管组成;在盖革模式下的雪崩光电二极管发生雪崩后不能自然停止,淬灭部分主要为了主动抑制雪崩电流,快速降低雪崩电压,以达到提高探测效率,降低错误计数的目的;APD线列产生多个光子脉冲信号,计数部分的主要功能是对多路光子脉冲信号进行计数、显示并且可以控制每路APD的比较电压,保证每路APD淬灭电路的正常工作。     

硅雪崩光电二极管单光子探测器

将硅雪崩光电二极管应用于盖革模式下,制作出高量子效率、低噪音、短死时间的单光子探测器.设计并制作了雪崩抑制电路,获得探测器特性参量为无源抑制方式下死时间1μs,有源抑制下60～80ns,输出脉冲宽度15～20ns.并详细检测了探测器直到液氮温度下的特性.观察到一些新现象.     

Measuring the photon distribution with ON/OFF photodetectors

Reconstruction of photon statistics of optical states provides fundamental information on the nature of any optical field and helps with various relevant applications. Nevertheless, no detector that can reliably discriminate the number of incident photons is available. On the other hand, the alternative of reconstructing the density matrix by quantum tomography leads to various technical difficulties that are particularly severe in the pulsed regime (where mode matching between a signal and local oscillator is very challenging). Even if on/off detectors, as usual avalanche photodiodes operating in Geiger mode, seem useless as photo-counters, it was recently shown how reconstruction of photon statistics is possible by considering a variable quantum efficiency. Here we present experimental reconstructions of photon number distributions of both continuous-wave and pulsed light beams in a scheme based on on/off avalanche photodetection assisted by maximum-likelihood estimation. Reconstructions of the distribution for both semiclassical and quantum states of light (as single photon, coherent, pseudothermal, and multithermal states) are reported for single-mode and multimode beams. The stability and good accuracy obtained in the reconstruction of these states clearly demonstrate the interesting potentialities of this simple technique.     

单光子探测技术

近年来,以量子密钥分配为代表的各种量子信息技术应用获得了飞速发展,这些应用对单光子探测器的性能提出了非常苛刻的要求,以光电倍增管和雪崩光电二极管为代表的传统单光子探测器件已经无法满足需求。在此背景下,出现了以超导单光子探测器为代表的新型低温单光子探测器件,其性能比现有商用单光子探测器有了本质性的提升。本文综述了迄今为止各种类型的单光子探测器,并指出各自在量子信息技术应用中的优势和不足之处以及发展方向。     

On the passive probing of fiber optic quantum communication channels

Avalanche photodetectors based on InGaAs:P are the most sensitive and only detectors operating in the telecommunication wavelength range 1.30–1.55 μm in the fiber optic quantum cryptography systems that can operate in the single photon count mode. In contrast to the widely used silicon photodetectors for wavelengths up to 1 μm operating in a waiting mode, these detectors always operate in a gated mode. The production of an electron-hole pair in the process of the absorption of a photon and the subsequent appearance of an avalanche of carriers can be accompanied by the inverse processes of the recombination and emission of photons. Such a backward emission can present a potential serious problem for the stability of fiber optic quantum cryptography systems against passive probing. The results of analyzing the detection of backscattered radiation are reported. The probability of such an emission has been estimated.     

红外通信波段SAGM APD单光子探测应用技术研究

研究采用由过度层间隔吸收区与倍增区的InGaAs/InP雪崩光电二极管(SAGM APD)在红外通信波段实现单光子探测的方法,包括管型的选择、特性分析、工作参数以及根据实验结果提出的对这类APD设计制作的改进建议.特别研究目前市售的APD器件用作单光子探测时的实用技术.     

基于门控积分的光电导探测器标定方法

 为了用同步辐射光源完成对光电导探测器的标定工作，用门控积分方法代替基于高性能宽带示波器的高灵敏测量系统，改进了前端放大器，带宽达到了2.9 GHz，改进后的门控积分系统灵敏度达到2.8×10^-18 C/bit。在北京同步辐射装置进行了金刚石探测器的灵敏度动态标定实验，针对碳、铝、镍、铁多种薄滤波片进行了测量，获得了具有比较好的信噪比结果。从试验结果可以初步得出样品探测器在长波段响应（50～280 eV）比较灵敏，在原理上验证了这种方法的可行性。     

Detection efficiency characteristics of free-running In Ga As/In P single photon detector using passive quenching active reset IC

In Ga As/In P avalanche photodiodes(APD) are rarely used in a free-running regime for near-infrared single photon detection. In order to overcome the detrimental afterpulsing, we demonstrate a passive quenching active reset integrated circuit. Taking advantage of the inherent fast passive quenching process and active reset to reduce reset time, the integrated circuit is useful for reducing afterpulses and is also area-efficient. We investigate the free-running single photon detector's afterpulsing effect, de-trapping time, dark count rate, and photon detection efficiency, and also compare with gated regime operation. After correction for deadtime and afterpulse, we find that the passive quenching active reset free-running single photon detector's performance is consistent with gated operation.     

High performance of gated-mode single-photon detector at 1.55 μm

High performances of single-photon detection at 1.55 μm were achieved by operating InGaAs/InP avalanche photodiodes in the gated mode at the optimized temperature. As short pulses used in the gated-mode detection produce strong spikes, a transformer-based method was invented to cancel the spikes, which makes it possible to reduce the dark counts by using short-gate pulse durations, and to discriminate the avalanche signals at low thresholds. The spike-cancellation single-photon detection at the optimized temperature produced a detection efficiency of 20% with a dark-count probability of 3.4 × 10⁻⁷ per pulse. With such a single-photon detector, a stable single-photon routing was realized in 155 km optical fibers with the average photon number 〈n〉 = 0.1 per pulse, exhibiting a fringe contrast of 87%.     

盖革模式下反偏压对雪崩光电二极管贯穿特性的影响

利用无源抑制技术,研究了盖革模式下雪崩光电二极管（APD）的电流一电压特性。发现光电流和暗电流的一个显著区别是暗电流不反映贯穿特性,这是光生栽流子和热载流子有不同统计分布的实验证据,也说明在盖革模式下,暗计数增加比光子探测效率增加更快的原因是由于载流子收集效率不同引起的。根据其贯穿特性适当选择盖革模式下APD的反偏压可提高单光子探测器的信噪比。     

高触发信号和功率合成的高峰值功率皮秒脉冲源

对于目标的攻击、干扰和探测,超宽带时域脉冲源的幅值直接影响其攻击、干扰和探测的强度和效果。基于雪崩晶体管的Marx电路被广泛应用在产生此类信号源上,传统的Marx电路可以一定程度上提高输出电压的幅值,但由于雪崩晶体管功率容量较低等原因,雪崩晶体管的Marx电路输出电压幅度会随级数增加而达到饱和。针对此类问题,为了产生更高幅值的脉冲信号,综合采用提高触发信号和使用宽带功率合成器的手段。最终利用26级Marx电路作为触发信号,4路40级Marx电路进行功率合成的方法,实现了输出电压幅值为8.7 kV、上升沿约为180 ps的技术指标,并通过机理分析了高触发信号对雪崩晶体管Marx电路的影响,通过实验得到了印证。     

非制冷红外探测器读出电路的非均匀性研究

对于长线列的非制冷红外探测器组件, 不同探测元之间的非均匀性是衡量电路设计的关键指标. 为了实现长线列非制冷红外探测器的高性能读出, 本文设计了一种基于电流镜方式的非制冷红外探测器160线列读出电路, 电路由电流镜输入模块、电容负反馈互导放大器模块及相关双采样输出模块组成. 电路采用0.5 μm工艺制作完成. 通过合理设置电路中MOS管的参数和布局电流镜版图, 电路的非均匀性有了明显地改善. 通过测试, 电路的非均匀性小于1%, 器件总功耗约为100 mW, 并具有良好的低噪声特性, 输出噪声小于1 mV, 输出摆幅大于2 V. 该电路与160线列非制冷红外探测器互连后, 能较好地完成红外信号的读出, 在积分时间为20 μups的情况下, 器件的响应为0.294 mV/Ω, 整体性能良好. 该电路的研制对超长线列的非制冷红外冷探测器读出电路研制奠定了重要的技术基础.