Refractive index insensitive temperature sensor based on waist-enlarged few mode fiber bitapers

A refractive index insensitive temperature sensor based on waist-enlarged few mode fiber (FMF) bitapers is presented. The first section of FMF is spliced between two single-mode fibers. In fusion process, the waist-enlarged FMF bitapers can be obtained by large current discharging repeatedly. The refractive index and temperature sensing mechanisms are analyzed. For the sensors with different sizes, the refractive index and temperature experiments have been performed. The results show that in the refractive index ranges of 1.335 0—1.346 6 and 1.348 2—1.419 3, the refractive index insensitivity is verified. In a temperature range of 31.9—90 °C, the sensor sensitivity can be up to 85.57 pm/°C. In addition, it has a compact structure. Therefore, the sensor can avoid the cross sensitivity for measuring the refractive index and temperature simultaneously.     

新型光纤电压互感器信号检测系统的设计

设计了一种新型的基于椭圆芯保偏光纤模间干涉原理的光纤电压互感器,利用椭圆芯保偏光纤LP01模和LP11偶模间的干涉和石英晶体的逆压电效应来实现被测电压的测量。在阐明互感器工作原理的基础上重点研究了新型电压互感器的信号检测方法,设计了基于主动零差相位跟踪原理的传感器信号检测系统,进行了详细的理论分析,建立了系统的数学模型并利用MATLAB仿真,研究了系统稳定的建立过程,给出了系统的稳态响应和暂态响应的仿真结果。最后通过实验验证了信号检测系统具有良好的实时性和稳定性,证明该方法可以很好地应用于新型光纤电压互感器中。     

桥梁振动光纤传感系统的数学模型

本文采用在一段单模光纤两端镀膜的方法构成光纤法布里－珀罗干涉腔,导出干涉腔反射光的与被测桥梁振动之间的关系表达式,给出桥梁振动的测量方法。     

小波分析及其在土壤成分的近红外分析中的应用

用近红外光谱(NIR)对秦皇岛市昌黎地区土壤的有机质和氮含量进行了分析．光谱的预处理方法分别采用一阶微分和二阶微分,然后采用多元线性回归,以确定最佳维数．在数据处理过程中,对微分光谱数据进行了小波去噪处理,使信噪比得到了增加,从而使分析精度得到了改善．结果表明,近红外光谱分析技术与化学分析方法有很大的相关性。     

基于光电缆的分布式温度传感网络的实验研究

本文提出增加一根光纤光栅与光电缆绕制在一起,用于监测电缆中的实时温度.采用有限元分析方法,建立了光电缆温度场模型.使用可调谐脉冲激光为光源,在一根光纤上刻制多个相同中心波长的布拉格光栅,即采用全同光栅作为系统的温度传感器,当光电缆线路中温度发生异常时,反射回来的光栅中心波长发生偏移,通过检测反射光中心波长发生的偏移量可...     

基于长周期光纤光栅的成品油中乙醇含量检测

提出采用长周期光纤光栅(LPFG)测量乙醇汽油与乙 醇柴油的研究。利用耦合模理论分析了LPFG的折射率敏感特性,得到LPFG谐振波 长漂移量与外界环境折射率的关系,并将其用于乙醇汽油 和乙醇柴油中乙醇含量的检测,得到乙醇汽油与乙醇柴油中乙醇含量与LPFG谐振波长漂移量 的 关系。实验结果表明,乙醇汽油中,乙醇含量每改变1%,谐振波长平均漂移量为0. 047nm;而乙醇柴油溶 液中,乙醇含量每改变1%,谐振波长平均漂移量为1.154nm。实验测量与 理论仿真的结果基本一致,验证了LPFG用于乙醇汽油和乙醇柴油检测的可行 性。     

Analysis of the enhanced coupling efficiency for different profile curves of special optical taper

For enhancing the coupling efficiency between the beam and the photodiode, a special optical taper is proposed for receiving optical signal. Based on the circular symmetric structure of special optical taper, the profile curve equations of it are deduced, including the trigonometric function type, parabolic type and exponential type. Moreover, the coupling efficiencies for special optical tapers with different profile curves are studied. The relationships of incident position, incident angle and coupling efficiency are analyzed. Finally, the comparison of coupling efficiency analytical results is also given.     

Bending characteristics of dual-hole PM-PCF based on LP01 and LP11 modal interference

The bending characteristics of dual-hole polarization maintaining photonic crystal fiber (PM-PCF) are demonstrated in this paper. The modal interference is induced by the LP01 mode and LP11 mode propagating in a single PM-PCF with the same polarization direction. Simulation results demonstrate that the bending radius induces the phase difference between LP01 mode and LP11 mode, which leads to the change of light interference intensity on the fiber output facet. The relationship between bending radius and normalized interference intensity with three different bending angles is discussed, where the bending angle is defined as the angle between hole axis and the x axis. The bending sensitivity is obtained to be about -188.78/m around the bending radius of 1.5 cm with the bending angle of 90°. The bending characteristics can contribute for online bending detection in widespread areas.     

40倍长工作距离PCF熔接系统显微物镜设计

针对PCF熔接系统对显微物镜的长工作距离、高放大倍率和高分辨力的需要,本文设计了一组用于光子晶体光纤端面成像的特殊物镜,并通过ZEMAX仿真优化。该物镜具有40?高放大倍率、5mm长工作距离、1μm的高分辨力、500μm×500μm较大视场等特点。通过实验验证该物镜达到了设计要求。     

基于重叠光栅和啁啾光栅的双波长光纤激光器

研究光寻址电位传感器(LAPS)的器件噪声特性 。通过对LAPS半导体场效应器件的结构分析,建 立LAPS的理论模型,并进一步分析LAPS器件噪声信号的来源、种类及特性。以 pH缓冲液中H离子 浓度为检测对象,搭建基于NI采集卡和Labview环境的LAPS测试系统,对影响LAPS信号噪声 特性的光源 波长、光源调制频率、光源强度和Si衬底厚度等因素进行了仿真和实验研究。结果表明,增 大光源波长和光源强度 是提高输出信号幅值和信噪比(SNR)的最有效方法。