阶跃折射率多模光纤包层等离子体共振传感器

光纤表面等离子体共振(SPR)传感器通常以纤芯为共振基底,需要采用腐蚀、侧抛、研磨等复杂的加工工艺将光纤包层去除,存在倏逝波不易泄露,传感探针制作困难的问题。本文提出一种以光纤包层为SPR共振基底的阶跃折射率多模光纤包层SPR传感器。采用单模光纤与阶跃折射率多模光纤偏芯熔接结构,将单模光纤纤芯中的光直接注入多模光纤包层,并在阶跃折射率多模光纤包层外镀50nm金膜。在探针传感段,光场能量全部分布在阶跃折射率多模光纤包层中,发生SPR效应充分。与传统光纤包层SPR传感结构相比,该传感器能够获得更深的共振谷,折射率测量范围为1.333~1.385RIU时,传感器的平均灵敏度可达2307nm/RIU,本文亦对传感段多模光纤纤芯直径与长度不同参数的影响进行了探究。本文提出的阶跃折射率多模光纤包层SPR传感器制作简单,有效解决了光纤包层与空气界面不易获得倏逝波的问题。     

待测介质折射率对光纤SPR光谱的特性研究

为提高光纤传感器的灵敏度和检测精度,达到精确测量的目的。基于表面等离子体共振(SPR)理论及TFCalc软件,仿真研究光纤表面等离子体共振传感器的反射光谱特性,考查待测介质折射率在一定范围内变化对反射光谱特性的影响。研究结果表明,当入射角一定时,表面等离子体共振的最佳膜厚随待测介质折射率的减小而减小;当膜厚和入射角度不变时,表面等离子体共振波长随待测介质折射率的减小向短波长方向移动。共振吸收峰随待测介质折射率的减小移动的距离越小,且逐渐变窄,传感器的灵敏度逐渐提高。     

多通道光纤表面等离子体波共振传感器研究

研究了一种采用2×n型特种耦合器构建的多通道光纤表面等离子体波共振(SPR)传感器模型.应用空分复用原理和多层膜反射理论分析了SPR共振效应在若干光纤探针中连续被激励的基本原理.数值模拟和实验结果表明,研制的双通道光纤SPR探针能够达到与常规单通道探针相同的检测灵敏度.这种新型多通道传感模型的特点在于,各通道探针特性可根据待测检测目标进行选择替换,通道数目可以根据实际待测参量进行调节,并适用于对处于不同空间位置目标液体参量进行检测的情况.     

光纤表面等离子体共振传感器理论仿真研究

为了考查光纤表面等离子体共振传感器的传感特性,基于单层膜表面Snell反射公式,利用MatLab软件仿真研究光纤表面等离子体共振(SPR)传感器的反射光谱特性,系统考查金膜厚度、待测介质介电常数以及入射到纤芯—金膜界面的入射角对反射光谱特性的影响.仿真结果表明:光纤SPR的共振波长随金膜厚度的增大而增大,随外界介质介电...     

基于Au-Ag复合膜的光纤表面等离子体共振传感器理论仿真研究

为增强基于Ag膜光纤表面等离子体共振(SPR)传感器的抗氧化能力,可将Au膜镀于Ag膜表面.利用TFCalc软件对不同厚度Ag膜和Au-Ag复合膜的光纤SPR传感特性进行理论仿真研究.仿真结果表明:光纤SPR吸收峰显著依赖于Ag膜厚度,当Ag膜厚度由40 nm逐渐增加到80 nm时,共振吸收峰的半峰全宽逐渐减小,且共振波长随Ag膜厚度的增大而减小,共振波长变化范围较小,仅为7nm左右;Au膜的引入对共振吸收峰反射率影响不大,不同厚度Au-Ag复合膜的SPR共振波长随Au膜厚度的增大而增大.     

光纤电压传感器温度特性研究

本文介绍了光纤电压传感器温度特性和实验结果,提出了改善传感器温度特性的措施。     

光纤表面等离子体共振光谱对待测介质折射率的响应特性研究

基于表面等离子体共振理论, 利用TFCalc软件仿真研究待测介质折射率在1.2到1.37范围内的光纤表面等离子体共振反射光谱特性。研究表明,入射角一定时,表面等离子体共振的最佳膜厚随待测介质折射率的减小而减小;当银膜厚度和入射角度不变时,表面等离子体共振波长随待测介质折射率的减小向短波长方向移动,共振吸收峰逐渐变窄,传感灵敏度提高。     

液体折射率测定方法分析

折射率是反映介质光学性质的一个重要参数,对其精确测定有重要的意义。文章对液体折射率测量方法做了归纳和分类,并对几种主要测定方法做了介绍,分析了各自的特点和存在的问题。尤其对基于表面等离子体波共振效应的新型光纤传感系统的结构、工作原理及其在液体折射率测定等方面应用做了具体的分析和介绍。     

表面激元共振(SPR)传感器理论分析

在基于ATR方法的SPR传感器设计和制作的工作中，为了得到更加优化的性能，对其原理进行了较为深入的分析。从表面激元波和全反射消逝波的数学模型入手，得到了共振角的数学关系及几个结论，并以金膜为例进行了计算机仿真。     

Sensitivity-optimized long-period fiber gratings for refractive index and temperature sensing

A long-period fiber grating sensor was fabricated by periodically changing the structure of single-mode fiber with an electric arc discharge technique. After the fabrication, the refractive index and temperature sensitivities were optimized by etching the cladding with hydrofluoric acid solution. The experimental results illustrate that the thinner cladding shows relatively higher refractive index and temperature sensitivities for the same order cladding mode, which are accordant with that of numerical simulation. After the long-period fiber grating was etched for 15?min, average refractive index sensitivities of 214?nm/refractive index unit (RIU) (1.3333?–?1.3931) and 1987?nm/RIU (1.4115–1.4555) were achieved. An extremely higher refractive index sensitivity of 2731?nm/RIU appears near 1.4555. By systematically studying the temperature sensing characteristic of cladding-etched long-period fiber grating in this work for the first time, the temperature sensitivity can reach as high as 144.23?pm/°C when the ambient temperature changes from 30 to 80°C. This work provides a theoretical reference for the fabrication of a high-sensitivity refractive index and temperature sensor based on arc-induced long-period fiber grating.     

基于噪声分析的波长表面等离子体共振分析仪的数据处理

波长SPR（表面等离子体共振）分析仪的分辨率主要取决于仪器的灵敏度和噪声水平决定的波长分辨率两部分,但高波长分辨率的光谱仪往往以牺牲波长探测范围为代价。因此,为了在保证波长SPR分析仪的动态范围的同时,提高其分辨率,降低波长SPR分析仪噪声的影响,分析了分析仪的噪声来源：与光强有关的光源本身产生的噪声和入射光光子噪声;与光强无关的信号后处理电路、温度等引起的噪声两部分噪声对SPR分析仪探测力的影响。以波长SPR分析仪的信噪比为目标,对波长SPR的数据处理进行了优化。其优化结果：最佳的处理曲线部分为SPR信号最强波长所对应的反射系数R1与信噪比最大波长所对应的反射系数R2之间前半部分的SPR曲线。基于这段最佳的处理曲线,提出了一种部分质心法的数据处理算法。实验结果表明,经优化后波长SPR分析仪,其分辨率提高了将近10倍,动态范围扩大了2倍,采用此种算法测得的折射率在1.3325-1.3600甘油溶液的线性相关系数大于0.99,说明此种算法对测试结果的线性度不会产生不利的影响。     

High-resolution wide-field surface plasmon microscopy

This paper describes the application of a Köhler illuminated high‐resolution wide‐field microscope using surface plasmons to provide the image contrast. The response of the microscope to a grating structure in both the Fourier and the image planes is presented to demonstrate image formation by surface waves. The effect of spatial filtering in the back focal (Fourier) plane to enhance image constrast is described. We also discuss how the surface wave contrast mechanism affects the imaging performance of the microscope and discuss factors that can be expected to lead to even greater improvements in lateral resolution and sensitivity.     

Refractive index sensor based on fiber loop ring-down spectroscopy

An optical fiber refractive index sensor based on fiber loop ring-down spectroscopy and a tapered fiber was fabricated using an ordinary single mode fiber with an arc fusion splicer. The performance of the sensor was controlled by the parameters of the tapered fiber. A fiber loop ring-down spectroscopy system was employed to enhance the sensitivity and demodulate the transmission spectrum. The results showed that a sensor with a waist diameter of 14 m and a length of 1.2 mm had good optical performance. By monitoring the ring-down time of the system, relatively high sensitivity of 411.576 s/ RIU was achieved with refractive index values from 1.333 to 1.412. This sensor offers few interferences, high sensitivity, easy fabrication, and low cost.     

光纤荧光温度传感器用于高压设备温度在线监测的研究

设计了一种基于荧光寿命的光纤温度传感器,用于高压开关柜触头温度的监测。采用稀土作为敏感材料,将其粘贴到被测体表面,实现了非接触测温。     

Two-photon fluorescence surface wave microscopy

This paper demonstrates the principle of two-photon surface wave microscopy with a view to applications on biological samples. We describe a modified scanning optical microscope, which uses specially prepared coverslips. These coverslips are designed to support the propagation of surface waves capable of large field enhancements. We also discuss the beam conditioning necessary to ensure efficient use of the available illumination. Two-photon surface wave fluorescent excitation is demonstrated on fluorescent nanospheres, demonstrating a point spread function width of ≈220 nm at an illumination wavelength of 925 nm. The potential of non-linear surface wave excitation for both fluorescence and harmonic imaging microscopy is discussed.