【作者】 李秋顺；

【导师】 王洪艳；

【作者基本信息】 吉林大学 ， 应用化学， 2009， 博士

【摘要】 本论文利用长周期光纤光栅对折射指数的敏感性,探索了一元醇和多元醇在长周期光栅上的响应,并利用传感灵敏度分析比较了亚甲基和羟基在长周期光栅上的传感灵敏性,发现对于醇在长周期光栅上响应的影响,羟基比亚甲基有更大的贡献。研究了不同浓度的蔗糖、果糖以及苯甲醛、苯甲酸乙酯、三乙醇胺等不同折射率的化学物质在长周期光纤光栅上的敏感规律,考察了环境介质折射率变化对长周期光纤光栅波谱衰减带的影响。利用静电自组装技术,在长周期光栅表面组装了PDDA/PSS、PAH/PSS的聚电解质薄膜,研究了组装层数和厚度对长周期光栅折射率的影响和对不同折射率物质的敏感规律。研究组装了聚电解质薄膜的长周期光栅对甲醇、乙醇、异丙醇、空气和水等五种介质的响应规律。实验表明,随着组装层数的增加,衰减带的中心波长向短波方向移动;研究发现,组装了PAH/PSS薄膜的长周期光栅对异丙醇、乙醇、甲醇、水、空气依次有一个最佳灵敏度,而且它们的灵敏度顺序与在组装了PDDA/PSS薄膜的长周期光栅上的顺序不同,但都表现了对不同折射指数的敏感选择性。说明通过改变薄层表面组装物质和组装厚度可以实现对不同物质的检测。实验显示,组装了薄膜的长周期光栅对0.001-0.2mol/L浓度范围内的亚硝酸钠有较好的响应,随着浓度的增加,衰减带的中心波长向长波方向移动,并且这种响应有较好的可逆性。更多还原

【Abstract】 We mainly make some investigations to long-period fiber grating(LPFG) by using its sensitivity of refractive index. First of all, the influences of methylene and hydroxyl group on response of the polyol alcohols to LPFG were explored.the sensing sensitivity was utilized to analyse the response of alcohols to LPFG, the results showed hydroxyl group has a greater contribution than methylene in the shift of central wavelength of LPFG spectral attenuation band. Secondly, through preparing different concentrations of sucrose and fructose solutions and selecting high refractive index of benzaldehyde, ethyl benzoate, triethanolamine, the law of the sensitivity of LPFG to refractive index were studied. The experiments displayed that when the refractive index of the surrounding media is less than that of LPFG cladding, with increasing refractive index, the central wavelengths of LPFG spectral attenuation band gradually shifted toward short-wave. The more is the refractive index of environmental media close to that of grating cladding, the greater the range of movement the central wavelengths is. When the refractive index of the surrounding media is equivalent to that of cladding, there is only one attenuation band in the LPFG transmission spectrum. When refractive index of the environmental media is higher than that of the grating cladding, the central wavelengths of attenuation band gradually shifted toward long-wave, the depths of attenuation band become smaller and the response sensitivity of LPFG deseases. To further improve the sensitivity of LPFG, polyelectrolyte PDDA/PSS films were assembled on the grating surface, with increase of the assembly layers, the center wavelengths of attenuation band gradually move toward short-wave, food additive sodium nitrite was detected by using swelling of polyelectrolyte PDDA/PSS films, the experiments showed LPFG assembled thin films had a better response to sodium nitrite concentrations over the range of 0.001-0.2mol/L, the central wavelengths of attenuation bands moved to the long-wave as the concentrations increased, and the responses has a better reversibility.In order to explore the response law of LPFG assemblyed films to refractive index of ambient media, polyelectrolyte PDDA/PSS and PAH/PSS films were assembled onto the surface of LPFG cladding. Methanol, ethanol, isopropanol, air and water were used surrounding media of LPFG cladding. The experiments indicated LPFGs assembled PAH/PSS films have an optimal sensitivity following isopropanol, ethanol, methanol, water, air in order, respectively. LPFG assembled PDDA/PSS films made an appearance of the best sensitivity region following to isopropanol, ethanol, air, methanol, water, repectively, that is, there are the best sensitive regions to different refractive index of materials. Based on above appearances, we infer that the sensitivity law of LPFG assembled to different refractive index, when bilayers number is lesser, the films thickness is smaller, the average refractive index of films and media material of the higher refractive index is close to that of LPFG cladding. Under this circumstance, LPFG is sensitive to higher refractive index of material. With the rise of the assembly bilayers number, polyelectrolyte film thickness further increases, making average refractive index of films and a relatively low refractive index material approach that of LPFG cladding. In the case, LPFG is more sensitive to the lower refractive index material. LPFG assembled films incarnated selectivity of different refractive index by phenomena of the best sensitive performance in different regions to different refractive index. Therefore, by controlling assembly layers number to make LPFG have the best sensitivity to different refractive index, selectivity of LPFG to different refractive index of environmental media can be realized. This provides a good way for resolving poor specificity of LPFG, and is promising to play a larger role in the chemical and biological testing in the next step. Due to its high immunity to electromagnetic interference, low background reflection, minor insertion loss, light weight, small size, corrosion-resistant, high sensitivity, to ambient media characteristics of easily implanting and connecting with other the device, LPFG will show more and more promising prospects for applications in a wide range of nondestructive and fast on-line real-time detection of chemical and biological detection and industry measurement in the future.更多还原