基于Lab VIEW的FBG传感解调技术的研究

结合虚拟仪器技术和光纤光栅传感技术,自行设计了一套光纤光栅传感解调系统.系统采用了基于迈克尔逊干涉技术的解调方法,将包含被测应变信息的光纤布喇格光栅(FBG)波长信号转变成相位信号,通过以Lab VIEW为核心的虚拟仪器系统检测相位的变化,从而得到被测应变的大小.该干涉解调系统避开了传统解调系统受电磁干扰和环境等方面的影响,因此使测量精度提高.虚拟仪器系统可用于静态应变和动态应变的检测,具有高分辨力、大测量范围的特点.     

新型光纤Bragg光栅振动传感系统

分析并实验研究了一种基于机械感生长周期光纤光栅(MLPFG)解调的新型光纤Bragg光栅(FBG)振动传感系统。利用机械线加工技术(MLPT)为制作周期为600μm、长为60mm的不锈钢槽板,采用机械感生法写制了中心波长1539.820nm、谐振线性边带大于6nm的MLPFG作为滤波器。选用中心波长为1542.400nm、3dB带宽为0.3nm的FBG设计振动传感器,通过附加电磁阻尼提高了稳定性,扩大了无失真频率测量范围。实验表明,该振动传感系统具有良好的动态响应特性,响应频谱与激振信号完全吻合,频率测量范围为10～3×103kHz,并具有良好的冲击振动响应。     

一种新型光纤光栅传感器解调系统

选择线性滤波法解调光纤光栅(FBG)传感信号,实现传感光栅Bragg波长微小偏移的实时检测.利用单片机取代PC机,有效实现了系统的小型化.采用锁相放大电路和24位∑-Δ高精度A/D转换模块采集有用信号,提高系统精度和动态范围.使用USB接口模块存储和传输数据,使解调系统特别适合现场测量和野外作业的要求.设计出了一种新型FBG传感器解调系统,通过实验和数据验证了该系统高精度、便携带的特点.     

基于双LPFG解调的高灵敏度振动检测系统

基于边缘滤波解调原理,提出了一种利用双长周期光纤光栅（LPFG）解调光纤布拉格光栅（FBG）振动传感信号的新方法。利用传输光谱叠加后的双LPFG作为边缘滤波器,增大了FBG传感信号解调灵敏度。静态实验结果表明,利用单、双LPFG作为滤波器解调的灵敏度分别为-1．1965dB／nm和-2．4836dB／nm,双LPFG解...     

利用高双折射光纤环镜的边缘滤波解调方法

利用由高双折射光纤所构成的Sagnac环镜作为边缘滤波器，解调制布拉格光纤光栅(FBG)传感探头所返回信号光的频率漂移，提出了一种新颖的FBG传感解调制方法。环镜滤波器具有大约6nm的准线性解调制范围。实验结果和理论分析相吻合。     

基于F-P腔滤波器的FBG温度传感器解调技术

近些年来,光纤光栅传感器成了传感领域的研究热点.对高精度的波长编码信号解调是实现光纤光栅传感的关键技术.介绍了光纤布拉格光栅(FBG)传感器的工作原理,同时对F-P腔滤波器的工作原理进行了分析,阐述了光纤光栅传感器解调技术的发展趋势,并提出了光纤光栅传感器解调技术需要解决的技术问题.     

具有温度补偿的LPFG功率解调系统的设计与实现

传统的利用光纤Bragg光栅(FBG)反射光作为长周期 光纤光栅(LPFG)入射光的解调方式,无法避免温度的影响。本文提出了一种具有温度补偿功 能的LPFG功率解调方案,将FBG的Bragg波长由压电陶瓷(PZT)的驱动电压控制,使得FBG谐振 波长始终跟随LPFG谐振波长, 以此抵消温度对传统功率解调中的影响。这种解调方案适用于LPFG透射光谱随物理量变化谱 形也发生变化的传感,如微 弯、横向负载等特性。利用本系统对LPFG的横向负载特性进行试验,结果表明,采用此解调 方案获得的实验数据具有与 光谱仪相同的功率变化趋势,能够始终监测LPFG的谐振峰幅值,实现温度补偿的功率解调, 更适合于动态解调。对LPFG 的温度特性进行功率解调实验,结果也验证了解调系统具有温度补偿功能。     

FBG光纤传感器的同步探测技术

光纤光栅传感解调系统的波长校准技术是人们关注的焦点,通常是将固定波长的FBG固定在恒温箱中,以此作为光纤光栅传感解调系统的参考元件．此方法占用了宽带光源的某个波长范围,从而制约了解调系统的波长扫描范围．构建的光纤光栅传感解调系统,将FP滤波器的驱动锯齿信号转变为方波信号,以此作为同步处理所需参考信号,省去了这个固定波长的FBG传感器,充分地利用了宽带光源的波长范围,并使得解调技术简单,同时提高了外接FBG传感器的数量．     

基于重叠多光栅的动态应变传感特性研究

利用重叠多光纤布拉格光栅(FBG)反射谱的时间同 步性,实现了动态或静态应变信号的高速传感与解调。给出了基于光纤F-P 可调谐滤波器(FFP-TF)的重叠多FBG解调系统及其时域重构的实现方法,重叠多FBG在FFP- TF 三角波扫描电压与动态应 变信号测量时产生时域上等间隔分布的传感脉冲,解调系统采用质心法硬件解算并结合平滑 滤波的方法可满足速度与解调精 度的同时测量需要。在重叠双FBG与500Hz FFP-TF扫描速率条件下 可产生2kHz的传感脉冲,动态应变信号的测量 带宽相对于单FBG解调系统提高了4倍,静态条件下的波长偏移小于±4pm。给出了影响重叠多FBG动态应变信号解调结果失真度的影响因素。     

FBG波长高精度解调的研究进展

在恶劣的环境下能准确地检测出光纤布喇格光栅(FBG)波长对工程监测非常重要。综述了在不同的解调系统中提高波长解调精度的方法和波长信号处理方法,主要介绍了基于可调谐激光器、可调谐滤波器和光谱仪的解调系统提高波长校准精确度的研究进展,分析了信号解调过程中的算法对FBG传感解调性能的影响。     

新型微带带通滤波器设计

提出一种新型微带带通滤波器设计，它是由带有J-变频器的零阶谐振ZOR（zeroth-order resonant）系统构成。零阶谐振系统以互补分裂谐振环和一系列沟道组成的左手材料LHM（Left—HandedMaterial）为基本单元，在传统设计的基础上进行改进．得到适合具有严格设计要求的滤波器设计使用模型，并给出此零阶谐振系统的共振频率和导纳斜率参数的确定方法。实验表明，该微带带通滤波器的模拟量与测量之间存在最佳关系，并具有高选择性能、对称的响应曲线以及良好的通带带宽控制性能。     

基于光子晶体光纤长周期光栅的双参数传感技术研究

利用高频CO2激光脉冲在折射率引导型的光子晶体光纤(PCF)上写制了长周期光栅(LPG),产生多个谐振峰。实验观察和理论分析均表明,这些峰是源于纤芯LP01模式向高阶纤芯LP11模式的耦合。通过研究产生的两个谐振峰随外界温度、弯曲、折射率和轴向应变的变化发现,LPG只对温度和轴向应变敏感,从而实现对弯曲和折射率均不敏感且能同时测量温度和应变的双参量传感器,减小了交叉敏感,其温度和轴向应变的灵敏度分别为10 pm/℃和-4.0 pm/με。     

光通信C波段硅基导模共振窄带滤波器的模拟

结合严格耦合波理论和遗传算法对C波段硅基导模共振滤波器进行了模拟分析.从模拟结果出发详细讨论了光栅周期、填充因子、光栅深度和入射角度对滤波器反射特性的影响.导模共振对光栅周期、填充因子、光栅深度和入射角度都有很高的敏感性,利用这一特点可以设计性能优异的硅基滤波器件.导模共振滤波器的共振波长峰值反射率达到了98.9%,峰值半高宽小于密集渡分复用(DWDM)O.8 nm的要求.

Abstract：

Simulated are silicon-based guided-mode resonant grating filters with narrow bandwidth for C-band optical communication.The effects of the characteristics of grating period,fill factor,the grating depth,the thickness of SiO_2 layer and incident angle on the reflection mechanisms of the filters are analyzed in detail based on the simulation results.Guided-mode resonant effect is very sensitive to such characteristics,which can be used to optimize silicon-based filters.The reflectance of the resonant wavelength of this filter reaches 98.9%,and the FWHM (full width at half maximum) is less than 0.8 nm limited by the DWDM (dense wavelength division multiplication) system.     

1.8GHz AlN薄膜体声波谐振器的研制

提出了基于AlN压电薄膜多层结构的1.8 GHz射频薄膜体声波谐振器(FBAR),并进行了研究。采用修正后的MBVD等效电路模型对器件的谐振特性进行了分析和模拟。给出了采用半导体加工工艺制备器件的工艺流程,并实际制做谐振器样品,样品的测试结果:器件的串联谐振频率fs和并联谐振频率fp分别为1.781和1.794 GHz,相应的有效机电耦合系数为1.8%;串联谐振频率处和并联谐振频率处的Q值分别为308和246。该谐振器样品实际尺寸为0.45 mm×0.21 mm×0.5 mm,可以用来制备高性能的滤波器、双工器和低相噪射频振荡器等。     

Study on the fir bandpass filters consisting of two resonant grids

A series of interference filters composed of two resonant grids, with resonant wavelengths λ_m <200μm, were constructed, and the dependence of the spectral characteristics on the separation of the two grids was studied experimentally in detail. The multiple-beam interference theory was applied to analyse the experimental results. The theoretical calculations and the experimental results are in good agreement. A method is presented, by which double-grid interference filters can be designed with the computer aid.     

Analysis of a novel (LCR)trap-LC-RC filter with improved performance for standalone inverters

ABSTRACT

This work introduces a new passive filter structure for a pulse width modulated inverter used in standalone applications. The proposed structure consists of an additional capacitor connected across the resistance-capacitance branch of the traditional LCR filter and an additional resistor connected across the trap filter capacitor in the traditional (LC)_trap-LCR filter configuration which helps to reduce damping power loss and increase harmonic attenuation while maintaining the same overall filter size of conventional filters. A comprehensive parameter design procedure of the proposed filter is introduced which considers inverter switching frequency and choice of damping components. Further, particle swarm optimisation algorithm is newly employed in this work to minimise resonant peaking on the premise of allowable values of overall filter inductance, capacitance and resistance. Simulation and experimental results are presented to analyse the performance of the proposed filter and a comparison is established with other passive filter topologies. A five-level inverter with the proposed filter is implemented using a SPARTAN- 6 XC6SLX25 processor on an experimental set-up. The experimental results show an attractive performance of the proposed filter in providing improved inverter output waveforms, significant harmonic reduction in the high-frequency band, reduced resonant peaking, lesser harmonic distortion and lower damping power loss.     

A novel compact ring dual-mode filter with adjustable second-passband for dual-band applications

In this letter, a novel compact ring dual-mode with adjustable second-passband for dual-band applications are presented. A ring resonator with two different geometric dimensions are derived and designed to have identical fundamental and the first higher-order resonant frequencies, and to establish appropriate couplings in the structure. Moreover, the proposed filter has smaller size as compared with the basic topology of stopband filters and stepped-impedance-resonator (SIR) filters. The measured filter performance is in good agreement with the simulated response.     

广义自对偶形态学滤波器及其在图像去噪中的应用

针对传统的自对偶形态学滤波器(SMF)是依赖于两个互为对偶的形态学滤波器,虽然能较好地保持图像的细节,但抑制噪声的效果较差。本文基于改进的形态学中值算子(MMO)和均值算子(MAO),提出了广义自对偶中值形态学滤波器(GSSMF)和广义自对偶均值形态学滤波器(GSAMF),分析并证明了两类滤波器均满足形态学滤波器的自对偶特性,分别适用于脉冲噪声和高斯噪声的去除。实验结果表明,GSMF在保持图像亮度不发生偏移的同时有效抑制了图像中的噪声,滤波后的图像具有较高的峰值信噪比(PSNR)和较小的均方根误差(RMSE)。     

Compound Bragg reflection filters made by spatial frequencydoubling lithography

A report is presented on the fabrication of complex Bragg filters with resonant wavelengths near 1.55 μm, patterned by photolithography using a high-resolution deep ultraviolet stepper. The projection of gratings with quarter-micrometer features was made possible by the use of spatial frequency-doubling lithography. A single chip, processed entirely in the silicon facility, was used to demonstrate five Bragg reflectors of different wavelengths, a quarter-wave shifted resonator, broadband stacked filters with as many as 15 uniform Bragg reflector sections of different Bragg wavelengths, and broadband stacked filters containing a passband within the reflection band. The filters exhibited nearly ideal spectral behavior     

利用智能方法进行LTCC电路的建模与优化

建模分析和优化综合是目前叠层LTCC滤波器设计的关键.建模方法一直是LTCC电路计算机辅助设计技术的主要瓶颈.利用智能方法对叠层LTCC滤波器的建模与优化的现状进行分析和讨论,即人工神经网络(ANN)、基因算法(GA)、遗传神经网络、神经网络空间映射(NSM)和知识自动模型生成(KAMG)等几种主要方法.并对以后的研究方向和发展趋势作了预测性阐述.