镀高折射率纳米薄膜长周期光纤光栅传感特性研究

发布时间：2018-01-19 16:15

本文关键词： 长周期光纤光栅原子层沉积技术折射率温度级联长周期光纤光栅温度交叉敏感　出处：《上海大学》2016年博士论文　论文类型：学位论文

【摘要】：长周期光纤光栅(Long period fiber grating,LPFG)是一种重要的光纤器件,具有体积小、重量轻、抗电磁干扰等诸多优点,在现代光纤通信与传感领域发挥着重要的作用。LPFG对多种环境参量,如温度、应力、应变等敏感,尤其是对外界环境折射率(surrounding refractive index,SRI)敏感,能够实现实时、远距离、恶劣环境下的多种参数传感,使得其在环境监测、生物医学、石油化工等众多行业应用中具有不可替代的地位。提高LPFG的传感灵敏度、拓展其应用范围、消除交叉敏感是近年来LPFG领域的研究热点。本文采用原子层沉积技术(atomic layer deposition,ALD)将高折射率Al_2O_3、TiO_2纳米薄膜镀在LPFG表面,制备出高灵敏度的折射率、温度传感器;利用级联的镀膜LPFG结构实现了对环境折射率和温度的同时测量。主要研究内容和成果包括以下方面:1、建立四层圆柱形波导模型,利用耦合模理论,采用矢量模分析法对镀高折射率纳米薄膜的LPFG进行了理论研究。讨论了镀膜LPFG对薄膜厚度、薄膜折射率、外界环境折射率的敏感特性。利用模式转换理论对镀膜LPFG增敏机制进行了详细的分析。2、采用ALD技术在LPFG表面镀高折射率Al_2O_3、TiO_2纳米薄膜。通过实验研究了不同薄膜参数条件下,硼锗共掺的光纤上写入的LPFG对SRI的敏感特性。结果表明:镀35 nm TiO_2薄膜的LPFG HE1,14模式在转换区内,SRI灵敏度达到-5000 nm/RIU,比裸LPFG提高了5倍。镀100 nm Al_2O_3薄膜的LPFG HE1,14模式在转换区内,SRI灵敏度达到-3000 nm/RIU,是裸LPFG的3倍。借助可调谐激光器和红外CCD摄像机,首次在实验中观察到了镀膜LPFG的包层模式转换现象。首次对镀膜过耦合LPFG的折射率敏感特性进行了研究。在环境折射率变化过程中,镀膜过耦合LPFG的对比度始终高于普通LPFG,这对于提高LPFG传感准确度具有重要意义。在锥形光纤上制备了LPFG,并镀Al_2O_3薄膜,与相同光栅参数、相同包层模式阶次的普通LPFG相比,镀膜锥形LPFG的SRI灵敏度提高了一个数量级。实验结果表明:拉锥与镀膜这两种工艺均能够有效的提高LPFG的SRI灵敏度。两者相结合,可以进一步提高LPFG的SRI灵敏度。3、提出了一种LPFG的温度增敏方案。在普通的通信用光纤上写入的LPFG表面镀Al_2O_3薄膜之后,采用硅橡胶和紫外固化胶对镀膜LFPG进行封装,利用封装材料的热光特性,有效地提高了LFPG的温度灵敏度。实验结果表明:镀200 nm Al_2O_3薄膜的LFPG在用硅橡胶封装后,在20℃-100℃之间,LFPG的温度灵敏度达到0.77 nm/℃,较之裸LPFG提高9倍。采用紫外固化胶作为封装材料时,在20℃-100℃之间,镀100 nm Al_2O_3薄膜的LFPG温度灵敏度达到1.26 nm/℃,比裸LPFG提高了15倍。研究了基于类似原理的LPFG磁场传感特性。将磁流体包覆在LPFG表面,使得LFPG对环境磁场敏感。用镀膜LPFG替代裸LPFG有效地提高了磁场灵敏度。实验结果表明:镀250 nm Al_2O_3薄膜的LPFG,磁场灵敏度达到120 pm/Oe,比裸LPFG提高了13倍。4、通过级联两个不同参数的镀膜LPFG,实现了温度和环境折射率的双参数同时测量。在硼锗共掺的光纤上写入双峰LPFG1,镀100 nm厚的Al_2O_3薄膜后,LFPG1的SRI灵敏度在转换区内达到-4800 nm/RIU。在普通通信用的光纤上写入LFPG2,镀100 nm厚的Al_2O_3薄膜,采用紫外固化胶封装后,在20℃-40℃之间,LFPG2的温度灵敏度达到3.2 nm/℃。LFPG1对环境折射率和温度均具有较高的灵敏度,且这两个参数(温度和环境折射率)对LPFG2共振波长的调谐作用满足良好的线性叠加特性。LFPG2对环境折射率不敏感、仅对温度具有较高的灵敏度。将上述两个LPFG级联,分别追踪各自的共振波长漂移情况,可以同时对温度和环境折射率实现高灵敏度、高分辨率、准确的测量。该传感器的温度分辨率可以达到0.0063℃;折射率分辨率可以达到64.17 10~(-6)RIU。
[Abstract]:Long period fiber grating (Long period fiber grating, LPFG) is a kind of important optical devices, has the advantages of small volume, light weight, the advantages of anti electromagnetic interference, in modern optical fiber communication and sensing areas play an important role of.LPFG on various environmental parameters, such as temperature, stress, strain and other sensitive, especially the external environment index (surrounding refractive, index, SRI) sensitive, can achieve real-time, remote sensing, various parameters under harsh environment, the biomedical in environmental monitoring, and has an irreplaceable position in many industries such as petroleum chemical application. To improve sensitivity of LPFG, and expand its scope of application, eliminate the cross sensitivity LPFG is a hot research field in recent years. This paper uses the atomic layer deposition technique (atomic layer deposition, ALD) the high refractive index Al_2O_3, TiO_2 nano thin films coated on the surface of LPFG prepared with high sensitivity The degree of refractive index, temperature sensor; realizing the measurement of refractive index and temperature at the same time using LPFG coating structure in cascade. The main research contents and results are as follows: 1, the establishment of four layer cylindrical waveguide model, using the coupled mode theory, analysis of nano film with high refractive index LPFG using the vector model. Discuss the LPFG coating on the film thickness, refractive index, sensitivity to ambient refractive index. Using mode conversion theory radiosensitizingmechanisms on coated LPFG were analyzed with.2, using ALD technology in LPFG surface with high refractive index Al_2O_3, TiO_2 nano film was studied through the experiments of different films. Parameter conditions, sensitivity of b-ge Co doped fiber writing LPFG to SRI. The results showed that: 35 nm TiO_2 plating film LPFG HE1,14 mode in the transition zone, the sensitivity of SRI nm /RIU to -5000, than the bare LPFG increased 5 times. 100 nm Al_2O_3 plating film LPFG HE1,14 mode in the transition zone, the sensitivity of SRI to -3000 nm/RIU, is 3 times the bare LPFG. Using tunable laser and infrared CCD camera, first observed the cladding mode conversion coating of the LPFG phenomenon in the experiment. The first refractive index of coating coupling LPFG rate sensitive characteristics were studied. The change of ambient refractive index in the process of coating coupled LPFG contrast is always higher than that of ordinary LPFG, which is to improve the accuracy of the LPFG sensor has important significance. The tapered fiber was prepared on LPFG and Al_2O_3 thin film plating parameters, with the same grating, the same cladding mode the order of the ordinary compared to LPFG, the sensitivity of SRI coated tapered LPFG is improved by an order of magnitude. The experimental results show that these two kinds of taper and coating process can effectively improve the sensitivity of LPFG SRI. A combination of both, can further To improve the sensitivity of SRI.3 LPFG, proposed a scheme to increase sensitivity of LPFG temperature. After plating Al_2O_3 LPFG thin film surface of common communication optical fiber written, using silicone rubber and UV curing adhesive coating on the LFPG package, the thermal properties of the packaging materials, effectively improve the high temperature sensitivity of LFPG the experimental results show that: 200. Nm Al_2O_3 LFPG plating film on the silicon rubber used for packaging, between 20 DEG -100 DEG, temperature sensitivity of LFPG was 0.77 nm/ C, compared with bare LPFG increased by 9 times. The UV curing adhesive as packaging material, between 20 DEG -100 DEG, temperature sensitivity of LFPG plating 100 nm Al_2O_3 film reached 1.26 nm/ C, LPFG was 15 times higher than bare. The effects of LPFG magnetic field sensor based on the principle of similar characteristics. The magnetic fluid is coated on the surface of LPFG, makes the LFPG sensitive to the environment. The magnetic field can effectively improve the coating with LPFG instead of naked LPFG The magnetic field sensitivity. The experimental results show that the 250 nm Al_2O_3 LPFG plating film, the magnetic field sensitivity of 120 pm/Oe,.4 was 13 times higher than that of naked LPFG, by cascading two different parameters of coated LPFG, realize the double parameters of temperature and refractive index measurement. At the same time into the Shuangfeng LPFG1 in fiber B-Ge-codoped on and with Al_2O_3 film thickness of 100 nm, LFPG1 SRI sensitivity in the transition zone within the reach of -4800 nm/RIU. LFPG2 in written communication with the ordinary fiber, Al_2O_3 film coating thickness of 100 nm, the ultraviolet curing glue packaging, between 20 DEG -40 DEG, the temperature sensitivity of LFPG2 was 3.2 nm/ C.LFPG1 it has high sensitivity to the refractive index and temperature, and the two parameters (temperature and refractive index) tuning effect on LPFG2 resonance wavelength meet.LFPG2 linear superposition of good characteristics is not sensitive to the refractive index, the temperature is only High sensitivity. The two LPFG cascade, we track the resonance wavelength shift of their own, can also on the temperature and refractive index of environment to achieve high sensitivity, high resolution, accurate measurement. The temperature resolution of the sensor can reach 0.0063 DEG C; the refractive index resolution can reach 64.17 10~ (-6) RIU.

【学位授予单位】：上海大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TN253;TP212

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