本文選題：光纖布拉格光柵 + 功率解調(diào)��； 參考：《吉林大學(xué)》2017年碩士論文

【摘要】：光纖布拉格光柵(FBG)具有反射峰尖銳,布拉格波長對外界物理量敏感,體積小、耐腐蝕、響應(yīng)速度快等優(yōu)點。因此,基于FBG的光纖傳感器被廣泛的研究。本論文提出了一種基于功率解調(diào)的測量圓柱體位移的高靈敏度布拉格光柵位移傳感器。首先本文介紹了光纖傳感器的分類、應(yīng)用、傳感原理和特性;多種位移傳感器的測量原理及光纖布拉格光柵在位移傳感器中的重要應(yīng)用;對本論文所應(yīng)用的光纖器件:單模光纖、光纖布拉格光柵和光纖耦合器的分類、基本結(jié)構(gòu)、工作原理進(jìn)行了簡短的介紹。其次本文介紹了功率解調(diào)雙布拉格光柵位移傳感器的理論研究和理論模擬。本文中采用兩個完全相同的光纖布拉格光柵(FBG1、FBG2),其中FBG1的反射峰入射到FBG2中,在FBG2的透射譜出現(xiàn)雙峰結(jié)構(gòu)(左峰、右峰)。理論模擬發(fā)現(xiàn):在保持布拉格波長λB1不變,布拉格波長λB2紅移的過程中,FBG2透射譜雙峰中左峰功率增加,右峰功率減小;發(fā)現(xiàn)FBG2透射譜雙峰的功率差(左峰減右峰)與FBG2的布拉格波長紅移△λB2近似呈線性關(guān)系。這一現(xiàn)象為功率解調(diào)的光纖布拉格光柵位移傳感器提供了重要的理論依據(jù)。通過數(shù)值模擬,可以得出布拉格光柵的透射率越小,光纖布拉格光柵位移傳感器靈敏度越高的結(jié)論。再次本論文中對功率解調(diào)雙布拉格光柵位移傳感器進(jìn)行實驗研究和實驗驗證。本論文使用兩個相同的光纖布拉格光柵且布拉格波長λB1=λB2=1520nm。實驗過程中,圓柱體垂直向下壓迫FBG2,布拉格波長λB2發(fā)生持續(xù)紅移,FBG2透射譜雙峰中左峰功率不斷增加,右峰功率不斷減小。圓柱體位移在0μm~60μm范圍內(nèi),圓柱體位移與FBG2透射譜雙峰功率差(左峰減右峰)之間呈現(xiàn)良好的線性關(guān)系,位移的測量靈敏度達(dá)到了(7.46±0.17)×10-2d Bm/μm。功率解調(diào)的光纖布拉格光柵位移傳感器的實驗的結(jié)果與理論模擬是相同的,理論能夠被驗證的.然后本文對布拉格光柵位移傳感器測量范圍較小的原因進(jìn)行了分析并通過分段測量方法增大了測量范圍。當(dāng)FBG2透射譜雙峰結(jié)構(gòu)剛好不能被分辨時,軸向拉動FBG1使布拉格波長λB1紅移直至出現(xiàn)左峰和右峰功率相等的雙峰結(jié)構(gòu)時停止然后繼續(xù)測量圓柱體的位移。循環(huán)往復(fù)上述過程。最終我們在布拉格波長為1520nm附近實現(xiàn)了對圓柱體位移的分段測量,量程達(dá)到了230μm,靈敏度可達(dá)(7.46±0.17)×10-2d Bm/μm。最后本論文對實驗過程中FBG1、FBG2的波形和線寬進(jìn)行分析。發(fā)現(xiàn)在軸向牽引FBG1和垂直壓迫FBG2過程中,FBG1和FBG2的線寬基本不變,也未出現(xiàn)劈裂。結(jié)果說明,FBG1與FBG2的非均勻形變并不嚴(yán)重,不會影響實驗的測量結(jié)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 鹵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 鹵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.
【學(xué)位授予單位】：吉林大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TP212

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本文編號：1852108