单光子探测器雪崩光电二极管的低温控制系统及其温度特性

根据单光子探测系统的要求及其特点,采用半导体制冷技术,研制出了用于单光子探测的雪崩光电二极管(APD)的水循环散热制冷腔。通过配备测量精度为0.1℃的温控仪,降低了APD的工作环境温度。通过实验探讨了APD的温度特性,得到了APD的雪崩电压、暗电流、光电流、等效噪声功率与温度的关系。结果表明:降低APD的工作温度有利于减小APD的等效噪声功率,APD存在最佳工作温度。     

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.     

基于雪崩光电二极管的弱光探测技术研究

通过采用无源抑制方法对雪崩光电二极管的弱光探测技术进行了研究,分析了工作在盖革模式下的InGaAs APD的特性。利用APD两端的偏置电压VB在其雪崩后趋于稳定的特性,确定了其雪崩暗击穿电压,并且在水冷温控系统中,测得了APD雪崩暗击穿电压与温度的关系。结果表明,APD的雪崩暗击穿电压随着温度的上升而增大,光子群(弱光)到达时,APD探测到的在某一幅值处的脉冲数明显增加,其脉冲幅度也将增大。     

Zn扩散对InGaAs/InP单光子雪崩光电二极管雪崩击穿概率的影响

对InGaAs/InP单光子雪崩光电二极管进行结构设计与数值仿真,得到相应的电学与光学参数。针对雪崩击穿概率对器件光子探测效率的影响,研究了两次Zn扩散深度差、Zn扩散横向扩散因子、Zn掺杂浓度以及温度参数与器件雪崩击穿概率的关系。研究发现,当深扩散深度为2.3μm固定值时,浅扩散深度存在对应最佳目标值。浅扩散深度越深,相同过偏压条件下倍增区中心雪崩击穿概率越大,电场强度也会随之增加。当两次Zn扩散深度差小于0.6μm时,会发生倍增区外的非理想击穿,导致器件的暗计数增大。Zn扩散横向扩散因子越大,倍增区中心部分雪崩击穿概率越大,而倍增区边缘雪崩击穿概率会越小。在扩散深度不变的情况下,浅扩散Zn掺杂浓度对雪崩击穿概率无明显影响,但深扩散Zn掺杂浓度越高,相同过偏压条件下雪崩击穿概率越小。本文研究可为设计和研制高探测效率、低暗计数InGaAs/InP单光子雪崩光电二极管提供参考。     

高时间稳定性的雪崩光电二极管单光子探测器

雪崩光电二极管单光子探测器是一种具有超高灵敏度的光电探测器件,在远距离激光测距、激光成像和量子通信等领域有非常重要的应用.然而,由于雪崩光电二极管单光子探测器的雪崩点对工作温度高度敏感,因此在外场环境下工作时容易出现增益波动,继而导致单光子探测器输出信号的延时发生漂移,严重降低了探测器的时间稳定性.本文发展了一种稳定输出延时的方法,采用嵌入式系统控制雪崩光电二极管,使其处于恒定温度,并实时补偿由环境温度引起的延时漂移,实现了雪崩光电二极管单光子探测器的高时间稳定性探测.实验中,环境温度从16 ℃变化到36 ℃,雪崩光电二极管的工作温度稳定在15 ℃,经过延时补偿,雪崩光电二极管单光子探测器输出延时漂移小于±1 ps,时间稳定度达到0.15 ps@100 s.这项工作有望为全天候野外条件和空间极端条件下的高精度单光子探测应用提供有效的解决方法.     

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。     

硅雪崩二极管光子辐射特性的实验研究

利用计数统计测量的方法，对工作在击穿状态下的硅雪崩光电二极管(APD)光子辐射的暂态特性以及计数统计特性进行了实验研究.将APD辐射光子的计数统计曲线与相应Poisson、热光场进行比较，发现其在采样时间为10 ms的情况下计数统计服从Super-Poisson分布.另外实验给出了APD光子辐射的光谱特性.     

基于Royer振荡器的硅基雪崩光电二极管偏压电路

针对雪崩光电二极管（Si-APD）所加偏压需要随环境温度作调整,且偏压电路所需的低纹波低噪声等因素,构建了以Royer振荡器和微控制器为核心的偏压电路。该Si-APD偏压电路以BL8032型同步降压控制器作为Royer振荡器的输入电源,以MS5221M型DAC作为该输入电源的调整单元,以AD8606型集成运放和AD7980型ADC作为Royer振荡器输出电压采样单元,以STM32F103TBU6型微控制器作为计算与时序控制单元。本偏压电路不仅具有温度自适应性,而且具有低纹波、低噪声、低功耗和电气安全隔离的特点,能在9～36 VDC宽输入电压范围和-40～70℃环境下良好工作。     

半导体单光子雪崩光电二极管的封装发展

半导体单光子雪崩二极管可实现微弱信号的探测,在量子通讯、激光雷达和大气探测等领域具有重要应用。虽然半导体单光子雪崩二极管的性能主要取决于探测芯片设计、流片工艺和外围匹配电路的设计,但后续的封装技术对其探测性能也有重要的影响。聚焦多年来半导体单光子雪崩二极管的封装发展,简要介绍了相应封装形式和技术,以及封装对于雪崩二极管性能的影响,最后对半导体单光子雪崩二极管的封装发展前景做出了展望。     

Characteristics of InAlGaAs/InAlAs Superlattice Avalanche Photodiodes for Ultra-low Optical Power Detection in the Near Infrared

Static characteristics of two different structured InAlGaAs/InAlAs superlattice avalanche photodiodes (SLAPDs) cooled by liquid nitrogen were evaluated at a wavelength of 1.5 μm. The dark current of the SLAPD having a thick superlattice layer of 0.504 μm was 5 × 10⁻¹³ A. This was successively reduced by four orders of magnitude compared to that of the thin layer SLAPD of 0.231 μm at a breakdown voltage of around 20 V. The thickened layer was effective in suppressing tunneling dark current. An output current of 1.7×l0⁻¹² A at a bias voltage of 15 V was measured for an optical input with a wavelength of 1.5 μm and a signal power of 1 × 10⁻¹² W. This showed a sharp distinction from the dark current.     

The Asymmetric Avalanche Process

An asymmetric stochastic process describing the avalanche dynamics on a ring is proposed. A general kinetic equation which incorporates the exclusion and avalanche processes is considered. The Bethe ansatz method is used to calculate the generating function for the total distance covered by all particles. It gives the average velocity of particles which exhibits a phase transition from an intermittent to continuous flow. We calculated also higher cumulants and the large deviation function for the particle flow. The latter has the universal form obtained earlier for the asymmetric exclusion process and conjectured to be common for all models of the Kardar–Parisi–Zhang universality class.     

一个含崩塌概率的一维沙堆模型

在一维沙堆模型中加入了崩塌概率,并用元胞自动机的方法进行计算机模拟,发现该模型具有自组织临界性,其临界指数α=1.50±0.02,并且还发现只有当崩塌概率处于0.05~0.98时,系统才体现出自组织临界性.另外,根据该模型的结果,解释了一维米粒堆实验中出现的自组织临界现象.     

Theory of Cosmical Coherent Avalanche Catastrophes

Abstract

Recently pulses of the electromagnetic cosmic radiation of varies frequency ranges were detected by means of space flight equipment [1]. But so far the physical nature of the sources of these pulses are not well known. Since the generators of these pulses are at far distances obviously, the latters should have considerable power. But in this case we are forced to accepte that that the radiation is generated not only by the surface but also by the bulk mass of the distant object. It is also reasonable to propose that the objects are superdense ones [2]. In the Latter case the electromagnetic radiation cann't difused up to the surface of a superdense object from the centre and so no electromagnetic and acoustic processes can give radiation from the bulk mass of an object. On the contrary gravitational and neutrino radiation may be generated by the bulk mass of a massive object and at the surface of these objects these radiations tightly bounded to matter may be partly transformed into electromagnetic radiation [3]. And we can suppose that namely this very small part of the whole radiational energy is at time registrated at the earth and space laboratories. The mauy ask why all of the remaining purt of teh rediated energy has not been detected yet? There where made some attempts to performe neutrino astronony equipment out no solar neuttinos have been detected yet. As to the camical gravitational radiation it is pregently inveutigated only at low frequencles and no distinet conclucion about its occurence in been reached in the lilorature.     

光子雪崩上转换的四能级模型

提出了四能级耦合系统的光子雪崩上转换模型,首先从理论上分析了光子雪崩产生的条件,给出了雪崩阈值以及在低于或高于阈值条件下荧光强度随时间变化关系;再将该模型结合数值分析应用于Ｔｍ＾３＋：ＬｉＹＦ４晶体这一列,理论分析结果与实验基本一致。因此应用此模型及其理论结果将有助于探索新型光子雪崩上转换材料。     

Different Avalanche Behaviors in Different Specific Areas of a System Based on Neural Networks

Based on the standard self-organizing map (SOM) neural network model and an integrate-and-fire mecha-nism, we introduce a kind of coupled map lattice system to investigate scale-invariance behavior in the activity of modelneural populations. We find power-law distribution behavior of avalanche size in our model. But more importantly, wefind there are different avalanche distribution behaviors in different specific areas of our system, which are formed by thetopological learning process of the SOM net.     

GaN基p-i-n型雪崩探测器的制备与表征

制备和表征了p-i-n型的GaN基雪崩探测器.器件在-5V下的暗电流约为0.05 nA,-20 V下的暗电流小于0.5 nA.响应增益-偏压曲线显示,可重复的雪崩增益起始于80 V附近,在85 V左右增益达到最大为120,表明所制备的器件具有较好的质量.C-V测量用来确定载流子的分布和耗尽信息,结果显示,P型层在15 ...     

Different Avalanche Behaviors in Different Specific Areas of a System Based on Neural Networks

Based on the standard self-organizing map (SOM) neural network model and an integrate-and-fire mecha-nism, we introduce a kind of coupled map lattice system to investigate scale-invariance behavior in the activity of model neural populations. We find power-law distribution behavior of avalanche size in our model. But more importantly, we find there are different avalanche distribution behaviors in different specific areas of our system, which are formed by the topological learning process of the SOM net.     

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.