功率解调的高灵敏度光纤布拉格光栅位移传感器的研究

发布时间：2018-05-06 11:18

本文选题：光纤布拉格光栅 + 功率解调　；参考：《吉林大学》2017年硕士论文

【摘要】：光纤布拉格光栅(FBG)具有反射峰尖锐,布拉格波长对外界物理量敏感,体积小、耐腐蚀、响应速度快等优点。因此,基于FBG的光纤传感器被广泛的研究。本论文提出了一种基于功率解调的测量圆柱体位移的高灵敏度布拉格光栅位移传感器。首先本文介绍了光纤传感器的分类、应用、传感原理和特性;多种位移传感器的测量原理及光纤布拉格光栅在位移传感器中的重要应用;对本论文所应用的光纤器件:单模光纤、光纤布拉格光栅和光纤耦合器的分类、基本结构、工作原理进行了简短的介绍。其次本文介绍了功率解调双布拉格光栅位移传感器的理论研究和理论模拟。本文中采用两个完全相同的光纤布拉格光栅(FBG1、FBG2),其中FBG1的反射峰入射到FBG2中,在FBG2的透射谱出现双峰结构(左峰、右峰)。理论模拟发现:在保持布拉格波长λB1不变,布拉格波长λB2红移的过程中,FBG2透射谱双峰中左峰功率增加,右峰功率减小;发现FBG2透射谱双峰的功率差(左峰减右峰)与FBG2的布拉格波长红移△λB2近似呈线性关系。这一现象为功率解调的光纤布拉格光栅位移传感器提供了重要的理论依据。通过数值模拟,可以得出布拉格光栅的透射率越小,光纤布拉格光栅位移传感器灵敏度越高的结论。再次本论文中对功率解调双布拉格光栅位移传感器进行实验研究和实验验证。本论文使用两个相同的光纤布拉格光栅且布拉格波长λB1=λB2=1520nm。实验过程中,圆柱体垂直向下压迫FBG2,布拉格波长λB2发生持续红移,FBG2透射谱双峰中左峰功率不断增加,右峰功率不断减小。圆柱体位移在0μm~60μm范围内,圆柱体位移与FBG2透射谱双峰功率差(左峰减右峰)之间呈现良好的线性关系,位移的测量灵敏度达到了(7.46±0.17)×10-2d Bm/μm。功率解调的光纤布拉格光栅位移传感器的实验的结果与理论模拟是相同的,理论能够被验证的.然后本文对布拉格光栅位移传感器测量范围较小的原因进行了分析并通过分段测量方法增大了测量范围。当FBG2透射谱双峰结构刚好不能被分辨时,轴向拉动FBG1使布拉格波长λB1红移直至出现左峰和右峰功率相等的双峰结构时停止然后继续测量圆柱体的位移。循环往复上述过程。最终我们在布拉格波长为1520nm附近实现了对圆柱体位移的分段测量,量程达到了230μm,灵敏度可达(7.46±0.17)×10-2d Bm/μm。最后本论文对实验过程中FBG1、FBG2的波形和线宽进行分析。发现在轴向牵引FBG1和垂直压迫FBG2过程中,FBG1和FBG2的线宽基本不变,也未出现劈裂。结果说明,FBG1与FBG2的非均匀形变并不严重,不会影响实验的测量结果。
[Abstract]:Fiber Bragg grating (FBG) has the advantages of sharp reflection peak, sensitive Bragg wavelength to external physical quantity, small volume, corrosion resistance and fast response speed. Therefore, fiber optic sensors based on FBG are widely studied. In this paper, a high sensitivity Bragg grating displacement sensor based on power demodulation is proposed. Firstly, this paper introduces the classification, application, sensing principle and characteristics of fiber optic sensor, the measuring principle of various displacement sensors and the important application of fiber Bragg grating in displacement sensor. This paper briefly introduces the classification, basic structure and working principle of the fiber devices used in this paper: single mode fiber, fiber Bragg grating and fiber coupler. Secondly, this paper introduces the theoretical research and theoretical simulation of double Bragg grating displacement sensor with power demodulation. In this paper, two identical fiber Bragg gratings are used, in which the reflection peak of FBG1 is incident to the FBG2, and the transmission spectrum of FBG2 has two peaks (left peak and right peak). The theoretical simulation results show that the left peak power increases and the right peak power decreases during the red shift of the Bragg wavelength 位 B1 and the Bragg wavelength 位 B2 transmission spectrum. It is found that the power difference between the two peaks of FBG2 transmission spectrum (left peak minus right peak) is approximately linear with the Bragg wavelength red shift 位 B2 of FBG2. This phenomenon provides an important theoretical basis for the fiber Bragg grating displacement sensor with power demodulation. Through numerical simulation, it can be concluded that the smaller the transmittance of the Bragg grating, the higher the sensitivity of the fiber Bragg grating displacement sensor. Thirdly, the power demodulation double Bragg grating displacement sensor is experimentally studied and verified. In this paper, two identical fiber Bragg gratings are used and the Bragg wavelength 位 B _ 1 = 位 _ B _ 2N _ (1520nm) is used. In the process of experiment, the cylinder compresses FBG2 vertically down, and the power of left peak increases and the power of right peak decreases continuously when the Bragg wavelength 位 B2 shows a continuous red shift in the transmission spectrum of FBG2. In the range of 0 渭 m ~ 60 渭 m, there is a good linear relationship between the cylinder displacement and the double peak power difference (left peak minus right peak) of FBG2 transmission spectrum. The sensitivity of displacement measurement is up to 7.46 卤0.17 脳 10 ~ (-2) d Bm/ 渭 m. The experimental results of the power demodulated fiber Bragg grating displacement sensor are the same as the theoretical simulation, and the theory can be verified. Then the reason of the small measurement range of Bragg grating displacement sensor is analyzed and the measurement range is enlarged by the method of subsection measurement. When the double peak structure of FBG2 transmission spectrum is just unable to be distinguished, the axial pull of FBG1 makes the Bragg wavelength 位 B1 red shift until the double peak structure with the same power of left and right peak stops and then continues to measure the displacement of the cylinder. Cycle the above process. Finally, we have realized the segmental measurement of the displacement of the cylinder near the Bragg wavelength of 1520nm. The measurement range is 230 渭 m and the sensitivity is 7.46 卤0.17 脳 10 ~ (-2) d Bm/ 渭 m. Finally, the waveforms and linewidths of FBG _ 1 and FBG _ 2 are analyzed. It is found that the line widths of FBG1 and FBG2 are almost unchanged and no splitting occurs in the process of axial traction FBG1 and vertical compression FBG2. The results show that the inhomogeneous deformation of FBG1 and FBG2 is not serious and will not affect the experimental results.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TP212

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