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.     

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.     

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.     

门控下InGaAs/InP单光子探测器用于符合测量的时域滤波特性研究

基于砷化镓/磷化铟雪崩光电二极管(InGaAs/InP APD)的半导体单光子探测器因工作在通信波段,且具有体积小、成本低、操作方便等优势,在实用化量子通信技术中发挥了重要作用.为尽可能避免暗计数和后脉冲对单光子探测的影响,InGaAs/InP单光子探测器广泛采用门控技术来快速触发和淬灭雪崩效应,有效门宽通常在纳秒量级.本文研究揭示了门控下单光子探测器可测量的最大符合时间宽度受限于门控脉冲的宽度,理论分析与实验结果良好拟合.该研究表明,门控下InGaAs/InP单光子探测器用于双光子符合测量具有显著的时域滤波特性,限制了其在基于双光子时间关联测量的量子信息技术中的应用.     

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。     

近红外单光子探测器

该单光子探测器在实验中使用半导体制冷器制冷，雪崩二极管工作于盖革模式下，使用交流耦合方式提供门脉冲信号，通过延迟补偿和采样门控消除尖脉冲干扰，采用反馈门控减小后脉冲影响，优化电路参数减小暗计数.经实验测试与分析，温度在-62.5℃，门脉冲宽度为50ns，采样门控为10ns的条件下，最佳工作点的暗计数率小于4×10^-6ns^-1，量子效率约18%，噪声等效功率为2.4×10^-19W/Hz^1/2.     

Single-Photon Detection at Telecom Wavelengths

A single-photon detector based on an InGaAs avalanche photodiode has been developed for use at telecom wavelengths. A suitable delay and sampling gate modulation circuit are used to prevent positive and negative transient pulses from influencing the detection of true photon induced avalanches. A monostable trigger circuit eliminates the influence of avalanche peak jitter, and a dead time modulation feedback control circuit decreases the afterpulsing. From performance tests we lind that at the optimum operation point, the quantum efficiency is 12% and the dark count rate 1.5 × 10^-6 ns^-1, with a detection rate of 500 kHz.     

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。     

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.     

The analysis of the integral gated mode single photon detector

This paper critically analyses and simulates the circuit configuration of the integral gated mode single photon detector which is proposed for eliminating the transient spikes problem of conventional gated mode single photon detector. The relationship between the values of the circuit elements and the effect of transient spikes cancellation has been obtained. With particular emphasis, the bias voltage of the avalanche photodiode and the output signal voltage of the integrator have been calculated. The obtained analysis results indicate that the output signal voltage of the integrator only relates to the total quantity of electricity of the avalanche charges by choosing the correct values of the circuit elements and integral time interval. These results can be used to optimize the performance of single photon detectors and provide guides for the design of single photon detectors.     

New protocols for non-orthogonal quantum key distribution

Combining the passive decoy-state idea with the active decoy-state idea, a non-orthogonal (SARG04) decoy-state protocol with one vacuum and two weak decoy states is introduced based on a heralded pair coherent state photon source for quantum key distribution. Two special cases of this protocol are deduced, i.e., a one-vacuum-and-one-weak-decoy-state protocol and a one-weak-decoy-state protocol. In these protocols, the sender prepares decoy states actively, which avoids the crude estimation of parameters in the SARG04 passive decoy-state method. With the passive decoy-state idea, the detection events on Bob’s side that are non-triggered on Alice’s side are not discarded, but used to estimate the fractions of single-photon and two-photon pulses, which offsets the limitation of the detector’s low efficiency and overcomes the shortcoming that the performance of the active decoy-state protocol critically depends on the efficiency of detector. The simulation results show that the combination of the active and passive decoy-state ideas increases the key generation rate. With a one-vacuum-and-two-weak-decoy-state protocol, one can achieve a key generation rate that is close to the theoretical limit of an infinite decoy-state protocol. The performance of the other two protocols is a little less than with the former, but the implementation is easier. Under the same condition of implementation, higher key rates can be obtained with our protocols than with existing methods.     

单光子探测器APD无源抑制特性研究

为了选择高性能单光子探测器件，采用无源抑制方法对工作在盖革模式下的雪崩光电二极管（APD: avalanche photodiode）特性进行了测量。利用APD两端的电压在雪崩后趋于稳定的特性，获得了一种确定暗击穿电压的方法。特性测量实验结果表明：降低温度能加宽APD的最佳工作区域范围，并提高最佳增益值，从而使APD具有更高的灵敏度。通过对EG&;G系列APD和外延APD暗电流和信噪比特性进行比较，发现外延 APD具有良好的噪声性能和信噪比性能，适用于单光子探测。     

超短光脉冲波形对门模单光子探测的影响

采用两种不同的皮秒光脉冲波形进行了门模单光子探测实验.测量了单光子探测效率随探测器和超短脉冲光源之间的同步延迟细微调节时的变化曲线.结果表明：光脉冲波形直接影响光子到达时间与门脉冲时间窗口之间的精确同步和探测效率,使用其中一种脉宽较短的皮秒光脉冲时探测效率比使用另一种脉冲提高了约9%.     

Photon statistics measurement for coherent fields

An efficient scheme for photon statistics measurement is presented based on the Hanbury-Brown-Twiss configuration. We set the sampling time Ts to satisfy the relationship of Ts 〈 Td 〈 Tm, where Td is the dead time of each detector and Tm is the laser pulse repetition period. And each single photon detector cannot detect more than one photon in each pulse. The approach can sufficiently eliminate the influences of the detector＇s dead time on photon statistics. At last, the photon statistics of coherent field is experimentally determined.     

Efficient single-photon counting at 1.55 microm by means of frequency upconversion

We demonstrate efficient single-photon detection at 1.55 microm by means of sum-frequency mixing with a strong pump at 1.064 microm in periodically poled lithium niobate followed by photon counting in the visible region. This scheme offers significant advantages over existing InGaAs photon counters: continuous-wave operation, higher detection efficiency, higher counting rates, and no afterpulsing. We achieved single-photon upconversion efficiency of 90% at 21.6 W of circulating power in a resonant pump cavity with a 400-mW Nd:YAG laser. We observed high background counts at strong circulating pump powers due to efficient upconversion of pump-induced fluorescence photons.     

Single photon sources with single semiconductor quantum dots

In t.his contribution, we briefly recall the basic concepts of quantum optics and properties of semicon- ductor quantum clot. （QD） which a.re necessary to the nnderstanding of the physics of single-photon generation with single QDs. Firstly, we address the theory of quantmn emitter-cavity system, the fluorescence and optical properties of semiconductor QDs, and the photon statistics as well as opti- cal properties of the QDs. We then review the localizatioll of single semiconductor QDs in quantum confined optical microcavity systems to achieve their overall optical properties and perfornances in terms of strong coupling regime, elfieiency, directionality, and polarization control. Furthermore, we will discuss the recenl, progress on the fabrication of single photon sources, and various a.pproaehes for embedding single QDs into mieroca,vities or photonic crystal nanoeavities and show how to ex- tend the wavelength range. We focus in part;icular on new generations of electrically driven QD single photon source leading to high repetition rates, efficiencies at elevated temperature operation. Besides strong eoupling regime, and high collection new development;s of room temperature sin- gle photon emission in the strong coupling regime are reviewed. The generation of indistinguishable photons and remaining challenges for pract ical single-photon sources are also discussed.     

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     

Coupled Mach-Zehnder interferometer memory element

Two active Mach-Zehnder interferometers are integrated in a monolithic InP/InGaAsP photonic integrated circuit. Together they form a crucial component for optical signal processing: an optical memory element or set-reset flip-flop. The switching time for this initial device is approximately 200 ps. The photonic integrated circuit contains active and passive optical components, including electro-optic phase shifters.     

红外InGaAs/InP单光子探测器暗计数的研究

在开发探测器灵敏度极限实现单光子探测时,暗计数是影响探测效率的主要原因.本文分析了在红外波段采用InGaAs/InP雪崩光电二极管工作于雪崩击穿电压之上(盖革模式),进行单光子探测时暗计数的三个主要来源,指出隧穿效应对暗计数的贡献是很小的,并且针对热噪声和后脉冲分析了减小暗计数的有效方法.     

两个独立全光纤多通道光子纠缠源的Hong-Ou-Mandel干涉

独立光子源的干涉是实现复杂量子体系应用(比如多光子纠缠态产生和量子隐形传态等)的核心技术.利用100 GHz密集波分复用技术,实现了1.55μm全光纤多通道独立纠缠光子源的Hong-Ou-Mandel干涉,在不去除暗符合(随机符合计数)的情况下,可见度为53.2%±8.4%,去除暗符合可见度可达到82.9%±5.3%.给出了关于色散位移光纤中基于自发四波混频过程产生的单光子光谱纯度严格的理论描述,模拟了抽运脉冲宽度和滤波器带宽对单光子光谱纯度的影响,并给出了理论上的最佳条件(最佳的抽运脉冲宽度为8 ps,高斯滤波器带宽为40 GHz及以下).在测量Hong-Ou-Mandel干涉之前,先测量了液氮冷却状态下的色散位移光纤关联光子源的符合和随机符合比率,在抽运功率为23μW的情况下,最大比率可以达到131.Hong-Ou-Mandel干涉在高精度光学测量、测量装置无关的量子密钥分配等应用中扮演着极为重要的角色.