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Research On Refractive Index Sensing Technology Based On Liquid-filled Hollow Bragg Fiber

Posted on:2019-11-13Degree:MasterType:Thesis
Country:ChinaCandidate:K J ZhengFull Text:PDF
GTID:2438330548966384Subject:Circuits and Systems
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The refractive index of liquid is closely related to the factors such as composition,concentration and temperature of liquid.The change of liquid refractive index can effectively reflect the biochemical information of the liquid.Therefore,the measurement of liquid refractive index is the basis of biochemical sensor analysis.In recent years,with the emergence of all kinds of new microstructured optical fibers,refractive index sensing technology based on liquid filled hollow core fiber shows great potential in biochemical sensing applications.Hollow Core Bragg fiber(HCBF)is a new type of microstructured optical fiber which using one-dimensional photonic bandgap effect(1DPBG)to guide light.It has novel guided wave mechanism and excellent low loss transmission characteristics.This dissertation is oriented to the application requirements of biochemical sensing to the measurement of liquid refractive index,and the research of refractive index sensing based on liquid filled HCBF is carried out.The work done in this paper includes the following two parts:1.We investigate the transverse resonance effect and the band rejection filter characteristics caused by the introduction of the defect layer in Hollow Core Bragg fiber with defect layer(DHCBF)and mainly analyze the influence of the thickness,refractive index and location of defect layer,periodic number of cladding and the diameter of fiber core on the band rejection filter characteristics of DHCBF.Based on that,we utilize the resonant wavelength caused by the transverse resonance effect of DHCBF as the refractive index sensing characteristic wavelength and study the influence of defect layer structure parameters on the relationship between the characteristic wavelength and the refractive index of the core filled liquid.The numerical simulation results show that the linear correlation between the resonant wavelength and the refractive index of liquid filled core can be significantly improved through the optimized design of structure parameters of the defect layer,and this principle can be applied to the design of liquid refractive index sensor based on the low refractive index contrast DHCBF filled liquid.In the liquid refractive index range of 1.324-1.432,the sensitivity that DHCBF liquid refractive index sensors acquired is about 2062nm/RIU,and the measurement of liquid refractive index with high sensitivity and large dynamic range is realized.2.As for high refractive index contrast HCBF,the transmission properties of the first and second order PBG of HCBF are studied and compared.The results show that the second order band gap with narrowband transmission spectrum is more beneficial to improve the accurate demodulation of the characteristic wavelength of the refractive index sensing process;We mainly analyze the influences of the cladding material dispersion on the first and second order PBG structure and on the relationship between the sensing characteristic wavelength and the refractive index of the filled liquid.We verify the dispersion of cladding material is also significant for improving the linear relationship between the characteristic wavelength based on the second order PBG and the refractive index of the liquid.Aiming at the application of high refractive index liquid measurement,it is found that HCBF liquid refractive index sensors based on second order PBG can get higher sensitivity than that based on first order PBG by comparing the refractive index sensing performance based on the first and second order PBG.On this basis,in order to reduce the dependence on the dispersion characteristics of cladding materials,liquid filled DHCBF refractive index sensor based on the second order band gap is designed and the sensitivity of it is about 679nm/RIU in the refractive index range of 1.46-1.66.
Keywords/Search Tags:Hollow Core Bragg fiber, liquid refractive index sensing, photonic band gap effect, transverse resonance effect
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