Multiplexing technology based on SQUID for readout of superconducting transition-edge sensor arrays

Multiplexing technologies based on superconducting quantum interference devices (SQUIDs) are crucial to cryogenic readout of superconducting transition-edge sensor (TES) arrays. Demands for large-scale TES arrays promote the development of multiplexing technologies towards large multiplexing factors and low readout noise. The development of multiplexing technologies also facilitates new applications of TES arrays in a wide range of frequencies. Here we summarize different types of SQUID-based multiplexing technologies including time-division multiplexing, code-division multiplexing, frequency-division multiplexing and microwave SQUID multiplexing. The advances and parameter constraints of each multiplexing technology are also discussed.     

Design,fabrication, and characterization of Ti/Au transition-edge sensor with different dimensions of suspended beams

For photon detection, superconducting transition-edge sensor (TES) micro-calorimeters are excellent energy-resolving devices. In this study, we report our recent work in developing Ti-/Au-based TES. The Ti/Au TES devices were designed and implemented with a thickness ratio of 1:1 and different suspended structures using micromachining technology. The characteristics were evaluated and analyzed, including surface morphology, 3D deformation of suspended Ti/Au TES device structure, I-V characteristics, and low-temperature superconductivity. The results showed that the surface of Ti/Au has good homogeneity and the surface roughness of Ti/Au is significantly increased compared with the substrate. The structure of Ti/Au bilayer film significantly affects the deformation of suspended devices, but the deformation does not affect the I-V characteristics of the devices. For devices with the Ti/Au bilayer (150μm×150μm) and beams (100μm×25μm), the transition temperature (T_c) is 253 mK with a width of 6 mK, and the value of the temperature sensitivity α is 95.1.     

Temperature compensation techniques for resonantly enhanced sensors and devices based on optical microcoil resonators

It is well known that environmental effects have a major influence on the optical stability of resonantly enhanced sensors and devices based on optical microfiber, namely in the configuration of a microcoil resonator. We propose a geometric design to reduce such effects by chirping the refractive index of successive paired turns in the microcoil resonator. The resistance to external effects such as temperature drifts can be considerably improved by optimizing the coupling coefficients and chirping profile, such that the wavelength span of the resonant condition is maximized without compensating its sensitivity to the desired measurand. We also demonstrate another technique based on resonant wavelength tuning using a compact piezoelectric ceramic disk measuring 3 mm in diameter and 1 mm in thickness, attaining tunability as high as 6.5 pm/100 V.     

超导转变边沿单光子探测器原理与研究进展

量子信息技术近十多年来的快速发展对单光子探测器的性能提出了更高的要求,高性能单光子探测器也因此受到了更多的关注.与传统的单光子探测器相比,超导转变边沿(TES)单光子探测器在探测效率、能量分辨、光子数分辨和暗计数等方面具有突出优势.目前,超导TES单光子探测器已经被成功地应用在量子光学实验和量子密钥分配系统中,未来在量子信息技术等研究领域具有更广泛的应用.本文从超导TES单光子探测器的工作原理、制备流程、测试系统、主要性能指标以及研究现状和进展等方面对该探测器技术进行简要综述.     

基于输出误差模型的B-Dot传感器标定方法

B-dot传感器因其频带宽, 体积小以及良好的稳定性而广泛应用于电磁脉冲(EMP)测量。任何理论模型与实际情况之间都存在差异, 因此B-dot传感器必须在实验室环境下进行标定。针对传统的时域标定方法存在的弊端, 提出一种基于输出误差(OE)模型的频域标定方法。该方法利用单输入单输出的OE模型传递函数来表征B-dot传感器的频响特性, 然后通过部分线性回归求得传感器实际工作的频率范围的灵敏度系数。经验证, 该方法能够有效避免因阻抗突变引起的过冲或振铃现象对标定精度的影响。     

全反射对混合型光纤电流传感器检测灵敏度的影响

在利用法拉第(Faraday)效应的混合型光纤传感器中,通常用全反射改变光的传递方向,以增加有效光程,并使结构紧凑。反射将改变光的偏振状态,从而影响传感的灵敏度。本文用琼斯(Jones)矩阵方法推导了有反射时传感头的传光特性,分析了反射对检测灵敏度的影响,获得了与实验一致的结果。     

基于灵敏度分析方法的光学镜架动力学模型修正

论述了理论建模与实验建模的特点,介绍了模型修正方法的相关理论,采用灵敏度分析方法,分析了光学镜架的设计参数: 材料的弹性模量、密度、内径、镜框厚度、镜架底部厚度、筋板厚度的灵敏度系数,通过镜架有限元仿真与模态实验结果的对比,建立一个以固有频率为修正目标的多变量动力学修正问题,对包含非线性连接关系的镜架动力学模型进行了修正,修正结果表明前四阶固有频率的平均误差为2.5%,满足工程要求,同时模态阶次也得到了修正。     

基于灵敏度分析方法的光学镜架动力学模型修正

论述了理论建模与实验建模的特点,介绍了模型修正方法的相关理论,采用灵敏度分析方法,分析了光学镜架的设计参数:材料的弹性模量、密度、内径、镜框厚度、镜架底部厚度、筋板厚度的灵敏度系数,通过镜架有限元仿真与模态实验结果的对比,建立一个以固有频率为修正目标的多变量动力学修正问题,对包含非线性连接关系的镜架动力学模型进行了修正,修正结果表明前四阶固有频率的平均误差为2.5%,满足工程要求,同时模态阶次也得到了修正。     

Miniature optical fiber current sensor based on a graphene membrane

The unique electronic and mechanical properties, of graphene make it an ideal material for nanoelectromechanical system (NEMS) applications. Here, a miniature optical fiber current sensor based on a quasistatic graphene NEMS with a graphene membrane covering the hole on a pre‐etched fiber tip and two gold electrodes on opposite sides of the tip has been demonstrated. The sensor overcomes the shortcomings of conventional optical fiber current sensors based on thermal effects, such as relatively low sensitivity, long response time, and huge device size; it has simultaneously a high sensitivity of 2.2 × 10⁵ nm/A², a short response time of ∼0.25 s and a compact device size of ∼15 μm, and has found practical application. Using a smaller graphene membrane with better quality can reduce the response time to submillisecond levels with a more precise measurement system. The sensor presented in this paper may pave the way for the practical usage of optical fiber current sensors based on thermal effects.

     

基于磁流体填充微结构光纤的温度特性研究

利用毛细现象将磁流体完全填充到六角形微结构光纤的空气孔中, 分析了磁流体填充长度、浓度对其传导特性的影响. 结合磁流体独特的热光效应, 并对一定浓度、长度下填充的光纤进行了温度特性的研究. 结果表明, 随着温度的升高, 透射谱1460 nm处磁流体的吸收峰逐渐变浅. 基于磁流体载液与表面活性剂对温度的不同敏感性, 吸收峰左右两个边沿表现出不同的温度响应; 在波长为1100–1700 nm之间透射损耗与温度变化成线性关系, 对于填充长度为10 cm的微结构光纤, 敏感度达到0.06 dB/℃, 且液体填充长度越长, 灵敏度越高. 该研究将微结构光纤与磁流体材料有机地结合起来, 并利用填充材料自身的热光特性, 实现了对透射谱的单边调谐, 将其作为热光可调谐器件、滤波器等相关可调谐光子器件在光通信、 光传感等领域将具有很大的应用潜力. 因此, 基于材料填充微结构光纤的研究可为探索新型全光纤光子器件的新技术和新结构提供有效的方法. 关键词： 微结构光纤 磁流体 热光效应 温度传感     

基于双面金属包覆光波导的传感器温度特性研究及实验验证

双面金属包覆波导结构(SMCW)是由一层介质波导层被两层金属膜层上下包覆的一种新型波导结构; 本文基于金属层和介质层材料的热-光效应和热膨胀作用, 研究了双面金属包覆波导结构的温度特性. 计算分析的结果表明, 金属膜层的厚度、金属的介电系数、波导层的厚度及其介电常数几乎都与温度变化成比例, 同时, 对双面金属包覆波导结构的波导功能起主要影响的是介质层的厚度值随温度的变化. 本文分别在光谱模式和角度模式下研究双面金属包覆波导结构的反射特性, 并将其应用于基于双面金属包覆波导结构的传感器, 其灵敏度约为21.89 pm/K(光谱模式)和1.449×10^-3 rad/K(角度模式). 最后, 本文对角度模式的模拟分析进行了实验验证, 实验验证结果与模拟分析结果基本一致, 实验所用SMCW样品的平均灵敏度约为0.517×10^-3 rad/K, 与模拟分析的灵敏度结果同一量级. 双面金属包覆波导结构的传感器对温度非常敏感, 且该结构的物理构造简单, 成本低, 具有非常大的潜在应用价值.     

Micro double tapered optical fiber sensors based on the evanescent field-effect and surface modification

A double tapered optical fiber sensor based on evanescent field-effect and surface modification technology was introduced in this work. Whether the liquid and gas molecules had polarities or not, they all could be detected by the sensors modified in different silane coupling agents. At the same time, the sensing characters of the single mode optical fiber with three different tapering lengths were researched, and it came to a conclusion that the optical fiber sensor had stronger evanescent field effect and higher sensitivity when length of tapered fiber was 30 mm. The functionalized tapered fibers modified by 3-aminopropyltrimethoxy silane (APTES) or 3-methylpropenylacyloxy propyltrimethoxy silane (MPAPTES), were employed to detect the polar or nonpolar molecules which had corresponding features. Further, the results of quantitative tests showed that the fiber optic sensor was sensitive to the change of the ethanol concentration and the characteristic peaks of the absorption power spectra could reach to 3–5 dB.     

触点式光纤液位传感器传感头的制作及其应用

具体描述了触点式光纤传感头的制作过程和工作原理。对传感头的微观形状与反射率的关系进行了实验研究。应用这种传感头设计了一种光纤闭环液位控制系统。应用该传感头设计的光纤液位闭环控制系统已经在实验室运行近一年 ,取得了良好的效果。由于该控制系统是本征安全型的 ,因此适用于一切易燃、易爆的恶劣环境 ,如石油、化工等领域。     

一种光电数字传声器的设计

本文介绍了一种新颖光电传声器的设计，它不采用Ａ／Ｄ转换器而直接输出数字信号，文中介绍了与传声器有关的光学扫描系统，光栅探测器的工作原理和设计参数。     

Effect of dispersion of linear birefringence upon the sensitivity of an optical current sensor

The dispersion properties of the linear birefringence inside the glass current sensing head of a bulk glass optical current sensor and its effect upon the sensitivity of the sensor are theoretically analyzed and simulated with a computer. The investigation results show that the effect is small enough to be ignored, although it can certainly affect the scale factor of the system slightly. These results might be useful for the researchers and designers working in the optical current sensing techniques area.     

Sensitivity of integrated optical sensors based on a prism coupler

Errors of registration of complex mode propagation constant increments for the sensors with a film waveguiding structure deposited on the base of the prism coupler are investigated. Possibilities for minimization of mean square errors of the registration by choosing parameters of the waveguiding structure and the exciting light beam are determined. As an example, the optimized sensor of ammonia concentration in air is analysed.     

基于光子计数的合作目标“量子”成像

在实验上研究了赝热光照明下, 基于光子计数模式的合作目标“量子”成像, 并给出理论模型和解释. 研究表明, 利用光子计数的单光子探测器代替以往光强度线性探测器作为桶探测器在“量子”成像中同样适用. 实验发现, 合 作目标的反射信号可穿透弱散射介质实现成像, 该技术在减小光学成像透镜孔径方面具有潜在的应用价值. 对比了基于强度关联成像和压缩感知算法的“量子”成像结果, 并得出实用性结论. 本文的方案为“量子”成像的实际应用提供了新方法.     

A kind of extended Korteweg——de Vries equation and solitary wave solutions for interfacial waves in a two-fluid system

This paper considers interfacial waves propagating along the interface between a two-dimensional two-fluid with a flat bottom and a rigid upper boundary. There is a light fluid layer overlying a heavier one in the system, and a small density difference exists between the two layers. It just focuses on the weakly non-linear small amplitude waves by introducing two small independent parameters: the nonlinearity ratio $\varepsilon $, represented by the ratio of amplitude to depth, and the dispersion ratio $\mu $, represented by the square of the ratio of depth to wave length, which quantify the relative importance of nonlinearity and dispersion. It derives an extended KdV equation of the interfacial waves using the method adopted by Dullin {\it et al} in the study of the surface waves when considering the order up to $O(\mu ^2)$. As expected, the equation derived from the present work includes, as special cases, those obtained by Dullin {\it et al} for surface waves when the surface tension is neglected. The equation derived using an alternative method here is the same as the equation presented by Choi and Camassa. Also it solves the equation by borrowing the method presented by Marchant used for surface waves, and obtains its asymptotic solitary wave solutions when the weakly nonlinear and weakly dispersive terms are balanced in the extended KdV equation.     

Temperature and humidity behaviour of a corona based smoke sensor

Ionization smoke sensors are amongst the best smoke sensors; however, the little radioactive source that they include is no longer desirable since recycling gets more complicated. In this paper we discuss an electrostatic system in which corona phenomena is used to generate the ions needed to smoke detection. We show how the velocity of ions is reduced in our system for a better interaction between smoke and drifting ions. Influence of smoke, temperature and moisture is studied. It is shown that the proposed sensor has a good sensitivity compared with conventional ionic and optical smoke sensors.     

Fiber-optic refractive-index sensors based on transmissive and reflective thin-core fiber modal interferometers

We present a new fiber-optic refractive-index sensor based on a fiber modal interferometer constituted by a thin-core optical fiber, whose cut-off wavelength is around three times shorter than normal single-mode fiber. In such a core diameter mismatching structure, the high-order cladding modes are efficiently excited and interfere with the core mode to form a high extinction-ratio filter (>30 dB). Both transmissive and reflective thin-core fiber modal interferometers are experimentally demonstrated, and show a high sensitivity to a small change of external refractive-index (>100 nm/R.I.U.), but a low sensitivity to the change of temperature (<0.015 nm/°C). Such a fiber device possesses an extremely simple structure, but excellent refractive-index sensing properties, and thus is an ideal candidate for fiber-optic biochemical sensing applications.