Microfiber knot resonator based electric field sensor

An optical fiber electric field sensor was constructed by coating a microfiber based knot resonator with propylene carbonate, a liquid electrooptic material. The Kerr electrooptic effect of propylene carbonate changed the refractive index of the liquid in the presence of an electric field and shifted the fringe pattern of the resonator. The electric field was demodulated by monitoring the fringe shift. The sensor was used to characterize sinusoidal electric fields with magnitudes from 200–4000?V/cm and a pulsed field with a 200?µs duration time. This work may provide practical applications for the characterization of electric fields.     

基于微纳光纤Sagnac环结构的光学电流传感器的响应特性研究

磁流体具有固体物质磁性及液体流动性的特性,且无本征矫顽力,无剩磁,磁场响应速度快,灵敏度高,将微纳光纤Sagnac环特殊的光传输性能与磁流体独特的磁光特性相结合,提出了一种基于磁流体包覆微纳光纤Sagnac环的全光纤电流传感器.理论推导了传感器的电流传感机理,设计了传感器的封装方法,并对传感器的温度特性和传感特性进行了...     

Design and optimization of slab coupled microfiber sensors

We investigated the sensing performance of a tapered microfiber, which was in evanescent contact with a multimode slab waveguide. The effects of the sensor configuration parameters on its transmission features and sensitivity were found for both the resonant-wavelength-shift scheme and light-intensity-variation scheme through theoretical and numerical calculations. On the basis of these results, we propose rules for optimizing geometrical parameters of the slab coupled microfiber sensors. With this approach, the slope of resonant spectra and resonant wavelength shift were increased. As a result, the sensitivity was substantially improved. It was shown that the potential device sensitivity can be as high as approximately 20,000?nm/RIU by matching optimal geometrical parameters. These results may provide beneficial references in optimally designing and fabricating slab coupled microfiber sensors to satisfy the requirements in applications.     

马赫-曾德尔干涉集成化的全光纤磁场与温度传感器

为了简化光纤磁场与温度传感器的结构并提高传感器灵敏度,设计并制作了马赫-曾德尔干涉集成化的全光纤磁场与温度传感器。将单根光纤的马赫-曾德尔模间干涉结构和双臂马赫-曾德尔干涉结构结合:将总长度为1.2m的单模光纤部分制备成长度为2.7cm、锥腰直径为30.1μm的锥形微纳光纤,并得到了拉锥时间与锥腰直径的关系。将锥形微纳光纤放置尼龙槽内并包覆磁凝胶构成传感头,实现模间干涉的马赫-曾德尔磁场传感器;将磁场传感器通过两耦合比为50%∶50%的耦合器并联带有可调谐光衰减器的单模光纤形成马赫-曾德尔干涉的温度传感器。从理论上分析了光谱漂移对磁场和温度传感的特性关系,实验测得室温下磁场强度在25~50mT时,磁场传感的灵敏度为0.301 14nm/mT;在磁场强度为0,温度由25℃升高到30℃时,温度传感的灵敏度为0.518 86nm/℃。该传感器可广泛应用于电力系统放电检测、材料加工、安全监控等领域。     

Etched multimode microfiber knot-type loop interferometer refractive index sensor

We propose a novel refractive index sensor based on multimode microfiber knot-type loop (NL) interferometer. The middle portion (~5 cm) of a 15 cm long multimode fiber is etched in 48% hydrofluoric acid to reduce its diameter to ~12 μm. A NL of diameter <1 mm is made from the etched fiber. The ends of etched fiber are spliced with single-mode fibers for launching and detecting light from the NL interferometer. The NL introduces path differences to produce interferometric spectra with free spectral range ~16 nm. The spectrum shifts as the surrounding refractive index of the loop is changed by adding chemicals. We observe the highest sensitivity of the NL interferometer ~172 nm/RIU (refractive index unit) at a refractive index value 1.370 as obtained experimentally using commonly available chemicals. The design could be used as simple, low cost, and highly sensitive biological and chemical sensor.     

丙酮对碳纳米管薄膜微纳光纤传输光的能量分布影响

基于薄膜微纳光纤中传播光能量分布的理论,在实验研究基础上,进一步用模场分析仪观察微纳光纤在表面镀有碳纳米管薄膜包层后,与丙酮气体接触时,其传输光的能量分布规律和倏逝场的变化。实验可知,在一定浓度的丙酮环境下,没有碳纳米管薄膜包层时,微纳光纤中传输光能量呈对称分布,当有碳纳米管薄膜包层时,其能量分布不再对称,并且能量分布的直径宽度增加。     

一种差动压磁式扭矩传感器的研究与设计

为提高压磁式扭矩传感器的测试精度和灵敏度，设计了一种三磁极差动式压磁扭矩传感器。论述了这种传感器的工作原理并导出了其感应电压输出方程和电流灵敏度计算式。通过试验，分析了传感器励磁电流强度、频率以及测试磁隙等对其输出特性的影响，也证明了这种传感器比传统交叉铁心压磁式扭矩传感器有更高的测试精度和灵敏度。     

INVESTIGATION OF THE THERMAL PROPERTIES OF OPTICAL MICROFIBER KNOT RESONATORS

The dependence of optical microfiber knot resonators (MKRs) thermal properties on the geometry parameters is theoretically and experimentally investigated in this article. According to the simulated and experimental results, the thermal properties of MKRs are synthetically determined by the microfiber diameter, refractive index, and thermo-optic coefficients of the external medium. Also, the rules for reinforcing or suppressing the thermal effects of MKRs and MKR-based devices by selecting matched configuration parameters are presented. A good agreement between the simulated and experimental results is obtained. The conclusions derived from our work would provide helpful guidelines in designing MKR-based devices with desired thermal properties to satisfy different requirements in applications.     

聚烯烃超细纤维的制备技术

聚烯烃超细纤维特有的结构与性能使其研究与生产技术发展迅速,生产量也在飞速地增长。本文综述了聚烯烃超细纤维的制备技术,详细介绍了直接纺丝法、复合纺丝法、高压静电纺丝法、熔喷非织造技术、模板合成法等聚烯烃超细纤维制备方法。迄今为止,国内及国际对于超细纤维的概念并没有公认的定义,一般认为单纤维线密度为0．1～1．0dtex的纤维属于超细纤维,而线密度〈0．1 dtex的纤维一般称为极细纤维。     

环形差动压磁式非接触动态扭矩传感器的研究与设计

为了提高动态扭矩非接触测量的精度和灵敏度,对一种基于非晶态合金压磁效应的环形差动式扭矩传感器进行了研究。介绍了传感器的结构和原理,推导出了传感器的输出方程。通过试验,分析了这种扭矩传感器探头与轴表面的气隙对输出信号的影响,得出了最佳气隙范围。分别对轴表面附着和不附着非晶态合金层进行了动态转矩测量,对比分析了两种情况下的测量精度和灵敏度。试验显示,采用所设计的传感器,在轴表面附着非晶态合金层时,最大非线性误差为2.14%（满量程）,最大重复性误差为1.54%（满量程）,最大灵敏度为2.09mV/（N.m）。     

Photonic crystal lattice strain anisotropy as a basis of highly sensitive selective optical chemosensors

An experimental study of the effect of asymmetric strain of a photonic crystal in the form of changes in the slope of crystal planes during its filling with a gas analyte is performed. This effect is used as a basis for creating a model of a relatively inexpensive selective highly sensitive fast-response sensor of ammonia sensor.     

一种微型隧道效应磁强计的设计

隧道效应传感器是一种灵敏度很高的位移传感器,其原理已经被用于微加速度计和红外传感器的设计。文中介绍了基于这一原理的微型磁强计,对传感器的固有频率和驱动电压进行了分析和计算。     

Direct exit-wave reconstruction from a single defocused image

We propose a direct, non-iterative method for the exact recovery of the complex wave in the exit-surface plane of a coherently illuminated object from a single defocused image. The method is applicable for a wide range of illumination conditions. The defocus range is subject to certain conditions, which if satisfied allow the complex exit-surface wave to be directly recovered by solving a set of linear equations. These linear equations, whose coefficients depend on the incident illumination, are obtained by analyzing the autocorrelation function of an auxiliary wave which is related to the exit-surface wave in a simple way. This autocorrelation is constructed by taking the inverse Fourier transform of the defocused image. We present an experimental proof of concept by recovering the exit-surface wave of a microfiber illuminated by a plane wave formed using a HeNe laser.     

Design and Analysis of a Gain-scaling Controller Applied to a Chain of Integrator System with Measurement Noise on Feedback Sensor

A control problem of a chain of integrator system with measurement noise on feedback sensor is considered.We propose a gain-scaling controller for compenasating measurement noise of feedback sensor.Because control systems operate via feedback sensor' s signal,the measurement noise in sensor' signal results in performance degradation or even system failure.Therefore,control systems often demand on compensating measurement noise.Our controller is equipped with a compensator and gain-scaling factor in order to reduce the effect of measurement noise on feedback sensor.     

Research on the parallel load sharing principle of a novel self-decoupled piezoelectric six-dimensional force sensor

This paper presents a novel integrated piezoelectric six-dimensional force sensor which can realize dynamic measurement of multi-dimensional space load. Firstly, the composition of the sensor, the spatial layout of force-sensitive components, and measurement principle are analyzed and designed. There is no interference of piezoelectric six-dimensional force sensor in theoretical analysis. Based on the principle of actual work and deformation compatibility coherence, this paper deduces the parallel load sharing principle of the piezoelectric six-dimensional force sensor. The main effect factors which affect the load sharing ratio are obtained. The finite element model of the piezoelectric six-dimensional force sensor is established. In order to verify the load sharing principle of the sensor, a load sharing test device of piezoelectric force sensor is designed and fabricated. The load sharing experimental platform is set up. The experimental results are in accordance with the theoretical analysis and simulation results. The experiments show that the multi-dimensional and heavy force measurement can be realized by the parallel arrangement of the load sharing ring and the force sensitive element in the novel integrated piezoelectric six-dimensional force sensor. The ideal load sharing effect of the sensor can be achieved by appropriate size parameters. This paper has an important guide for the design of the force measuring device according to the load sharing mode.     

A displacement sensor combining cavity tuning of a laser with a piezoelectric transducer's subdivision technique for a bidirectional sampling on the rising and falling flanks

A displacement sensor combining cavity tuning of a laser with a piezoelectric transducer's subdivision technique is presented. Because of the low gain, the measuring range of the displacement sensor based on the orthogonally polarized dual-frequency He-Ne laser at 633 nm is limited. The gain coefficient is proportional to the cube of the wavelength, so the He-Ne laser at 1.15 μm is adopted in research. A subdivision technique using a piezoelectric transducer enhances the resolution and the bidirectional sampling of the actuated voltage on its rising and falling flanks effectively amends the hysteresis and nonlinearity effect. The displacement sensor achieves the resolution of 10 nm in the range of 100 mm.     

一种新型浓度传感器的实验研究

介绍一种新型测量气／固两相流固相浓度的螺旋极板电容传感器，并通过实验得出提高传感器检测场灵敏度空间分布均匀性及克服边缘效应对检测精度影响的方法。     

Application of excilamps in a flow reactor for recovery of stable toxic compounds

The preliminary results of the development and tests of a prototype of a small flow reactor for utilizing stable compounds are presented. A specific feature of the reactor is the use of two excilamps with different radiation wavelengths (λ ～ 222 nm, λ ～308 nm) and a polypropylene microfiber material. Then, design of the test bench allows studying the degradation of organic compounds before their mineralization. In accordance with the described technique, the experimental dependences of the decrease in organic compounds on the irradiation time are measured. The energy consumption is within 100 W. The reactor has been developed for training purposes, but it can be used when developing industrial reactors. The proposed design of the reactor equipped with a unit for photocatalytic degradation allows its application for recovery of a wide class of compounds.     

Capacitance Transducers with a Correction in the Feedback Circuit that Are Based on Self-Excited Oscillators

It is shown that the introduction of a parallel oscillatory circuit into the feedback circuit of a self-excited oscillator makes it possible to reduce the effect of the conductance of the measured sensor on the accuracy of the conversion of the sensor capacitance by approximately two orders of magnitude.     

Frequency shift of a nanomechanical sensor carrying a nanoparticle using nonlocal Timoshenko beam theory

The frequency shift of a nanomechanical sensor carrying a nanoparticle is studied. A bridged single-walled carbon nanotube (SWCNT) carrying a nanoparticle is modeled as a clamped micro-beam with a concentrated micro-mass at any position. Based on the nonlocal Timoshenko theory of beams, which incorporates size effects into the classical theory, the natural frequencies of the nanomechanical sensor are derived using the transfer function method. The effects of the mass and position of the nanoparticle on the frequency shift are discussed. In the absence of the nonlocal effect, the frequencies are reduced to the results of the classical model, in agreement with those using the finite element method. The obtained results show that when the mass of the attached nanoparticle increases or its location is close to the beam center, the natural frequency decreases, but the shift in frequency increases. The effect of the nonlocal parameter on the frequency shift is significant. Decreasing the length-to-diameter ratio also increases the frequency shift. The natural frequencies and shifts are strongly affected by rotary inertia, and the nonlocal Timoshenko beam model is more adequate than the nonlocal Euler-Bernoulli beam model for short nanomechanical sensors. The obtained results are helpful in the design of SWCNT-based resonator as nanomechanical mass sensor.