取样光纤Bragg光栅特性及其通信应用的研究

用传输矩阵法对取样均匀光纤Bragg光栅进行了理论分析,并依据此方法对取样光栅的反射谱进行了数值仿真.研究表明:随着光栅长度的增加和采样率、折射率调制深度的减少,反射峰的均匀性得到了改善,旁瓣的反射率变小,带宽明显变窄,而反射峰间隔保持不变.反射峰的间隔由光栅周期决定,与采样率无关.基于取样光栅的独特反射谱特性,对其作...     

双波长FBG折射率变化平均值的研究

光纤Bragg光栅(FBG)是发展最为迅速的光测量器件.为解决光纤光栅传感器温度应变交叉敏感的问题,使用双波长FBG替代传统FBG是实用性较好的方案之一.通过数值计算双波长FBG的反射谱,着重分析了双波长FBG的折射率变化平均值对中心波长及其反射率的影响.     

光纤Bragg光栅的反射特性研究

阐述了由耦合模理论得到的光纤Bragg光栅的反射率的表达式 ,并且由此表达式导出了光纤Bragg光栅的反射特性 ,反射中心波长为λB=2 ·neff·Λ。进而理论分析了反射波长λ、光栅栅距Λ ,折射率微扰的最大值Δnmax、光栅区长度L和反射率Rg 之间的关系。     

光纤Bragg 光栅的温度传感研究􀀁

本文分析了光纤 Bragg光栅在受到温度调制时的滤波特性。与温度对光纤光栅反射谱波长的影响相比 ,对其带宽的影响可忽略。实验中 ,光纤光栅受温度的调制 ,并且其反射谱由光谱仪记录。结果表明该光纤 Bragg光栅对温度产生的波长偏移是 0 .0 0 991nm/℃。值得注意的是实验中最大标准误差为 0 .0 3nm,能满足目前波分复用技术所需的信道精度。     

光纤光栅应变传感特性的研究

叙述光纤Bragg光栅的反射率与栅距，有效折射率和入射波长的关系，用Matlab描述有效折射率和栅距的变化对反射波长的影响。以此为基础阐述光纤Bragg光栅的应变传感原理，并对光纤Bragg光栅的应变传感特性进行实验研究，实验结果与理论分析结果相一致。     

基于相关分析的光纤光栅Bragg波长偏移值测量

在分析光噪声对光纤光栅Bragg波长偏移量测量影响机理的基础上,利用数字信号处理技术中信号的互相关分析对信号噪声的抑制及其在信号时延长度测量中的应用,将光纤Bragg光栅反射功率谱序列等效为信号的一个时间抽样序列,在较强噪声条件下,对基于光纤Bragg光栅的测力传感探头受拉后Bragg波长的偏移量,使用相关分析的方法进行了测量;结果显示,该方法将光纤光栅Bragg波长偏移值的测量波动最大差值由一般方法的90pm降低到了28pm,有效减小了由噪声引起的Bragg波长偏移值的测量误差.     

常用光纤Bragg光栅特性分析

结合光纤Bragg光栅在通信与传感领域应用的特性,利用传输矩阵法分析了均匀光栅、啁啾光栅、切趾光栅的反射率、时延特性、边模抑制比和反射带宽示意图.分析得到了不同光栅的特性规律,这些规律对光栅在通信与传感领域应用具有参考的价值.     

光纤Bragg光栅传感器高速冲击试验研究

光纤Bragg光栅是一种性能优良的敏感元件,光纤Bragg光栅传感器在很多领域得到了应用.通过霍普金森压杆上的冲击试验研究了光纤光栅的动态响应能力.试验表明Bragg光栅能够正确响应不同频率的冲击信号,解调仪能够正确并快速解调出高速动态激励信号,同时Bragg光栅在受拉和受压时以及动态和静态灵敏度基本一致.光纤光栅传感器能够应用于武器侵彻爆炸等强冲击、恶劣环境下动态应力应变的测试.     

基于回归分析的取样光栅传感特性分析

基于耦合模理论,采用传输矩阵法分析了取样光栅反射谱.取样光纤光栅在受到外界环境应变和温度影响时,其反射光谱的反射率和波长会发生变化.通过测量反射光谱的反射率变化和波长漂移,就能够实现用单根的取样光纤光栅同时测量应变和温度.取样光纤光栅的光弹系数为P11=0.121,P12=0.27.纤芯材料的泊松比0.17.热膨胀系数为5.5×10-7/℃,光纤材料的热光系数为8.3×10-6/℃.通过仿真实验获得了取样光纤光栅的应变和温度传感数据.采用回归分析的方法得到系数矩阵中A,B,C,D分别为-0.00033/ε,-0.00011/℃,-0.00055nm/ε,0.013 nm/℃.应变测量范围为0 με～1800 με,温度测量范围为0℃～180℃.     

结构健康监测用光纤Bragg光栅温度补偿研究

阐述了光纤Bragg光栅及多光栅温度补偿法基本原理,推导出温度补偿公式。在光纤Bragg光栅应变灵敏系数标定及钢架静力试验过程中进行温度补偿,试验结果显示光纤Bragg光栅温度计能够准确测量温度干扰。     

Sensitivity optimization of surface plasmon sensors for detection of intermediate layers

A sensitivity optimization method for the detection of an intermediate layer using a surface plasmon sensor is presented. The dependence of detection sensitivity on distance from the metal surface and the average refractive index over the sensing region are considered. Based on the calculated results, the sensitivity for detecting an intermediate layer in a multilayered sample is determined by varying the refractive index and thickness of each layer. It is shown that, in particular cases, controlling the refractive index and thickness increases the detection sensitivity. The proposed method is useful for designing multilayered samples.     

基于光电传感器精确测量透明溶液浓度的研究

根据液滴对光具有会聚的特点,以及溶液浓度与其折射率有定量的对应关系,提出了用origin7．0软件精确计算透明溶液浓度的光电测量方法。实验结果表明溶液浓度分辨率可达0．1％,该方法还可能用于溶液其他性质的判别与测量。此方法具有非接触、在线动态测量,判别迅速,装置简单等特点。     

表面等离子共振传感器的研究进展

表面等离子体是在金属和电介质交界面上所形成的电荷层,在电磁波的激励下表面等离子体发生共振现象,影响电磁波的传播。根据这一原理制作的表面等离子共振传感器可对化学和生物等量进行探测。介绍了表面等离子共振传感器的工作原理和最新研究进展。由于具有体积小、准确度高、抗电磁干扰能力强和可用于遥测等优点,SPR传感器将有广泛的应用前景。     

低折射率液芯光纤特性的研究

研究了以低折射率液体（ｎ≥１．３４６）及乙醇等水溶液的液芯光纤的传输特性和光谱特性，分析了影响芯光传输特性的因素及其对光强调制型芯光纤传感器的影响。     

Analysis of optical cavities in the presence of negative refractive index materials

We introduce the ABCD matrix for negative refractive materials (NRM) and investigate the optical properties of (NRM), according to the matrix method. The propagation of a Gaussian beam inside a NRM slab is also investigated. It is demonstrated that for n = −1, the waist of the transmitted Gaussian beam is the same as the waist of incident beam, which leads in the perfect lens. Further the optical resonator in the presence of NRM is studied and the stable condition is introduced. The article is published in the original.     

A compact reconfigurable bandpass/lowpass filter with independent transmission zeros based on generalized NRI metamaterial

This article introduces a new design and analysis of a compact reconfigurable bandpass/lowpass filter based on compact negative refractive index metamaterial transmission line. The filter equivalent circuit has been designed as a cascade of three cells of bisected‐Π/Π configuration. The reconfigurable function was achieved using inserted switches in ON and OFF modes within the cells. The filter works as bandpass when all switches are in ON condition and for lowpass switch‐1 is in OFF and switch‐2 in ON condition. The low pass filter has 3‐dB cutoff frequency of 3.25 GHz with a selectivity of 170 dB/GHz. The bandpass filter is cantered at 3.65 GHz and has a well‐matched pass band with insertion loss of 0.2 dB and wide stop band with two transmission zeros (TZs). The frequency positions of TZs are independently varying with series and shunt loading elements. The filter performance has been validated through circuit model, electromagnetic simulation, and experimental measurements. The electrical size of bandpass filter excluding feed line is 0.22 λ_g × 0.20 λ_g (12 × 11 mm²) at center frequency of 3.65 GHz and for lowpass filter is 0.19 λ_g × 0.18 λ_g at cutoff frequency of 3.25 GHz. The filter can be applied in suitable for different wireless applications.     

大气折射对合成孔径雷达(SAR)成像距离向漂移和信号延迟的影响

推导了大气折射引起合成孔径雷达成像点距离向漂移及视线向测量距离与真实距离的误差表达式,并通过实测的北京地区对流层折射率剖面和我国电离层中等电子浓度剖面,对ERS成像点距离向漂移以及视线向测量距离与真实距离的误差进行了模拟计算。计算结果表明在一般的研究中成像点距离向漂移可以忽略不计;而测量距离与真实距离之间的误差显著,在高精度的地表形变和数字高程提取研究中应予以考虑。最后讨论了雷达电磁波在色散介质电离层中折射率对频率的响应。     

岩石矿物的偏振反射光谱与物质折射率的关系研究

研究岩石矿物的偏振反射光谱特征,并研究岩石矿物的偏振度与物质折射率的关系问题。在理论上给出了一种利用偏振度计算物质折射率的方法。同时进行相应的实验,测定了十几种岩石、晶体在2π空间上的偏振反射光谱,讨论这些矿物晶体的偏振反射光谱特征。     

Gain enhancement of the ultra‐wideband tapered slot antenna using broadband gradient refractive index metamaterial

In this article, a broadband gradient refractive index (GRIN) metamaterial is designed and used to enhance the gain of the tapered slot antenna (TSA). The proposed GRIN is implemented using nonresonant parallel‐line unit cell with different refractive index values. GRIN lens are placed in front of the tapered slot direction in the direction of x‐axis. The designed GRIN metamaterials have broad bandwidth (2‐12 GHz) characteristics due to the nonresonant parallel‐line elements which is suitable for the ultra‐wideband frequency band. The measurement results indicates that the radiated beam becomes more directive with narrow beam width. The measured reflection coefficient is below ?10 dB over the frequency bandwidth of 3‐11 GHz. The peak gain of TSA is obtained up to 14 dB at 10 GHz using GRIN lens.     

利用线阵CCD测量液体的折射率

根据光线穿过厚度均匀的液体介质时所产生的横向偏移量,提出了一种利用CCD和计算机测量液体介质折射率的新方法。实验结果验证了此方法的有效性和实用性。