基于光纤传感的森林资源环境检测关键技术研究
发布时间：2018-08-31 14:39
【摘要】：森林资源环境的健康检测是保护生态环境和提高国民生产总值的重要需求，但是现有森林资源环境检测方法存在费用昂贵与信息不完整等问题。光纤传感技术具有抗电磁干扰、灵敏度高、耐腐蚀、远距离传输、可工作在严重污染的恶劣环境中、对测量对象无污染等优点。基于此，本论文首次提出结合光纤传感技术的独特优势，将光纤传感器应用至森林资源环境检测中，具有广泛的应用价值。本论文主要开展了基于光纤传感的森林资源环境检测关键技术中光纤湿度传感器、光纤折射率传感器和光纤多参量传感器的研制工作，提出并制作了多种新型光纤传感器，对它们进行了理论分析和实验研究。论文的主要工作如下： （1）理论分析和数值模拟了微纳光纤布拉格光栅(MFBG)的折射率传感特性。利用化学腐蚀法制作了MFBG样品，实验研究了MFBG的折射率和湿度响应特性。实验结果表明表明直径为8.9μm的MFBG在折射率变化范围为1.335-1.381RIU内，折射率灵敏度为1.70nm/RIU；在折射率变化范围为1.389-1.403RIU内，折射率灵敏度为10.91nm/RIU，折射率实验结果与理论计算相符。在55%-80%RH湿度变化范围内，MFBG的湿度灵敏度为0.003nm/%RH，拓宽了MFBG的应用领域。 （2）设计并制作了一种基于单模-多模纤芯-单模(SMS)光纤结构与光纤布拉格光栅(FBG)的传感器。利用光束传播法理论模拟并分析了多模纤芯长度、直径、模式阶次和外界环境折射率对SMS光纤结构内部光场分布的影响。实验结果表明传感器在1.335-1.404RIU折射率变化范围内，折射率灵敏度为193.55dBm/RIU；在50%-85%RH湿度变化范围内，湿度灵敏度为0.07dBm/%RH；在20-80℃温度范围内，温度灵敏度为0.008nm/℃。研究表明该传感器可实现基于能量检测的折射率和湿度的传感测量，而且可以消除温度对测量结果的影响。 （3）提出并实现了一种利用熔接机制作光纤锥的方法。制作了三种基于该光纤锥的马赫-曾德干涉仪(MZI)样品，并对传感器进行了理论分析和实验研究。实验结果表明，基于双光纤锥的MZI型湿度传感器在50%-95%RH湿度范围内，湿度灵敏度为-0.047nm/%RH，且响应线性，无需镀制湿敏膜；基于多模光纤嵌入两个光纤锥的MZI型湿度传感器在35%-90%RH湿度范围内，湿度灵敏度为0.12dBm/%RH。在20-100℃温度范围内，温度灵敏度为0.003nm/℃。表明该传感器可实现湿度与温度的区分测量；基于多模纤芯嵌入两个光纤锥的MZI型折射率传感器在1.335-1.394RIU折射率范围内，折射率灵敏度最高可达430.934nm/RIU。 （4）提出了一种单模-细芯-多模纤芯-单模(STMS)光纤结构。利用光束传播法理论模拟了STMS光纤结构的内部光场分布，讨论了细芯光纤长度、多模纤芯长度和直径、外界环境折射率对光场分布及输出耦合系数的影响。制作了多个传感器样品并对其进行传感实验研究，，实验结果表明传感器在折射率变化范围为1.333-1.403RIU内，折射率灵敏度为148.27nm/RIU；在55%-90%RH湿度范围内，湿度灵敏度为0.207nm/%RH；在20-80℃温度范围内，温度灵敏度为0.007nm/℃。传感器具有制作简单、灵敏度高、线性响应等优点。 （5）提出并制作了一种基于长周期光纤光栅(LPFG)嵌入保偏光纤萨格纳克(Sagnac)环的传感器。利用保偏光纤Sagnac环透射光谱被LPFG调制的特性，监测透射谱中谐振峰的波长与能量随外界温度、折射率和应变的变化，获取外界环境参量的信息。实验结果表明传感器在23-93℃温度范围内，温度灵敏度为0.128nm/℃；在1.32-1.40RIU折射率变化范围内，折射率灵敏度为49.38dBm/RIU；LPFG区的应变灵敏度为0.005dBm/με；保偏光纤Sagnac环区的应变灵敏度为0.015nm/με。传感器不仅可以实现温度与折射率或应变的同时测量，消除温度与与折射率或应变的交叉灵敏，而且可以区分出应力施加区域。 上述传感器具有制作简单、结构紧凑、成本低廉、灵敏度高等优点，可满足森林资源环境检测中对湿度传感器、折射率传感器、多参量传感器的需求，有一定的应用潜力。
[Abstract]:The health detection of forest resources and environment is an important requirement to protect the ecological environment and improve the gross national product. However, the existing methods of forest resources and environment detection have some problems, such as high cost and incomplete information. Based on the advantages of non-polluting in the environment, this paper firstly puts forward the application of optical fiber sensor in forest resources and environment detection, which combines the unique advantages of optical fiber sensing technology. In this paper, several new types of optical fiber sensors are proposed and fabricated, and their theoretical analysis and experimental research are carried out.
(1) The refractive index sensing characteristics of micro-nano fiber Bragg grating (MFBG) are analyzed and simulated theoretically. The samples of MFBG are fabricated by chemical etching method. The refractive index and humidity response characteristics of MFBG are studied experimentally. The experimental results show that the refractive index sensitivity of MFBG with diameter of 8.9 micron is 1.335-1.381 RIU. 70 nm/RIU; in the refractive index range of 1.389-1.403 RIU, the refractive index sensitivity is 10.91 nm/RIU, and the experimental results are in agreement with the theoretical calculation.
(2) A sensor based on single-mode-multi-mode core-single-mode (SMS) fiber structure and fiber Bragg grating (FBG) is designed and fabricated. The effects of the length, diameter, mode order and external refractive index of the multi-mode core on the optical field distribution in the SMS fiber structure are simulated and analyzed by using beam propagation method. In the range of 1.335-1.404 RIU, the refractive index sensitivity is 193.55 dBm/RIU; in the range of 50% -85% RH, the humidity sensitivity is 0.07 dBm/% RH; and in the range of 20-80 C, the temperature sensitivity is 0.008 nm/ C. The research shows that the sensor can realize the sensing measurement of refractive index and humidity based on energy detection, and it is feasible. To eliminate the effect of temperature on measurement results.
(3) A method of fabricating optical fiber cone by welding mechanism is proposed and realized. Three samples of Mach-Zehnder interferometer (MZI) based on the optical fiber cone are fabricated, and the theoretical analysis and experimental study of the sensor are carried out. The experimental results show that the humidity sensitivity of the MZI humidity sensor based on the double optical fiber cone is - 0 in the range of 50% - 95% RH humidity. The MZI humidity sensor based on multi-mode fiber embedded in two fiber cones has a humidity sensitivity of 0.12 dBm /% RH in the range of 35% - 90% RH. The temperature sensitivity of the sensor is 0.003 nm / C in the temperature range of 20 - 100 C. The MZI type refractive index sensor with two fiber cones embedded in the core has a maximum refractive index sensitivity of 430.934 nm/RIU in the range of 1.335-1.394 RIU.
(4) A single-mode-fine-core-multi-mode-single-mode (STMS) fiber structure is proposed. The internal light field distribution of STMS fiber structure is simulated by using beam propagation theory. The effects of the length of the fine-core fiber, the length and diameter of the multi-mode fiber core, the refractive index of the external environment on the light field distribution and the output coupling coefficient are discussed. The experimental results show that the sensor has a refractive index sensitivity of 148.27 nm/RIU in the range of 1.333-1.403 RIU, a humidity sensitivity of 0.207 nm/%RH in the range of 55%-90% RH, and a temperature sensitivity of 0.007 nm/C in the range of 20-80 ~C. It has the advantages of linear response.
(5) A sensor based on long-period fiber grating (LPFG) embedded in polarization-maintaining fiber Sagnac (Sagnac) ring is proposed and fabricated. The experimental results show that the temperature sensitivity of the sensor is 0.128 nm/C in the temperature range of 23-93 C, 49.38 dBm/RIU in the refractive index range of 1.32-1.40 RIU, 0.005 dBm/u_ E in the LPFG region and 0.015 nm/u_ E in the Sagnac ring region of the polarization-maintaining fiber. Simultaneous measurement with refractive index or strain eliminates cross-sensitivity between temperature and refractive index or strain, and distinguishes stress-applied regions.
These sensors have the advantages of simple fabrication, compact structure, low cost and high sensitivity. They can meet the requirements of humidity sensors, refractive index sensors and multi-parameter sensors in forest resources and environment detection, and have certain application potential.
【学位授予单位】：西北工业大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：S757.2;TN253
本文编号：2215293
[Abstract]:The health detection of forest resources and environment is an important requirement to protect the ecological environment and improve the gross national product. However, the existing methods of forest resources and environment detection have some problems, such as high cost and incomplete information. Based on the advantages of non-polluting in the environment, this paper firstly puts forward the application of optical fiber sensor in forest resources and environment detection, which combines the unique advantages of optical fiber sensing technology. In this paper, several new types of optical fiber sensors are proposed and fabricated, and their theoretical analysis and experimental research are carried out.
(1) The refractive index sensing characteristics of micro-nano fiber Bragg grating (MFBG) are analyzed and simulated theoretically. The samples of MFBG are fabricated by chemical etching method. The refractive index and humidity response characteristics of MFBG are studied experimentally. The experimental results show that the refractive index sensitivity of MFBG with diameter of 8.9 micron is 1.335-1.381 RIU. 70 nm/RIU; in the refractive index range of 1.389-1.403 RIU, the refractive index sensitivity is 10.91 nm/RIU, and the experimental results are in agreement with the theoretical calculation.
(2) A sensor based on single-mode-multi-mode core-single-mode (SMS) fiber structure and fiber Bragg grating (FBG) is designed and fabricated. The effects of the length, diameter, mode order and external refractive index of the multi-mode core on the optical field distribution in the SMS fiber structure are simulated and analyzed by using beam propagation method. In the range of 1.335-1.404 RIU, the refractive index sensitivity is 193.55 dBm/RIU; in the range of 50% -85% RH, the humidity sensitivity is 0.07 dBm/% RH; and in the range of 20-80 C, the temperature sensitivity is 0.008 nm/ C. The research shows that the sensor can realize the sensing measurement of refractive index and humidity based on energy detection, and it is feasible. To eliminate the effect of temperature on measurement results.
(3) A method of fabricating optical fiber cone by welding mechanism is proposed and realized. Three samples of Mach-Zehnder interferometer (MZI) based on the optical fiber cone are fabricated, and the theoretical analysis and experimental study of the sensor are carried out. The experimental results show that the humidity sensitivity of the MZI humidity sensor based on the double optical fiber cone is - 0 in the range of 50% - 95% RH humidity. The MZI humidity sensor based on multi-mode fiber embedded in two fiber cones has a humidity sensitivity of 0.12 dBm /% RH in the range of 35% - 90% RH. The temperature sensitivity of the sensor is 0.003 nm / C in the temperature range of 20 - 100 C. The MZI type refractive index sensor with two fiber cones embedded in the core has a maximum refractive index sensitivity of 430.934 nm/RIU in the range of 1.335-1.394 RIU.
(4) A single-mode-fine-core-multi-mode-single-mode (STMS) fiber structure is proposed. The internal light field distribution of STMS fiber structure is simulated by using beam propagation theory. The effects of the length of the fine-core fiber, the length and diameter of the multi-mode fiber core, the refractive index of the external environment on the light field distribution and the output coupling coefficient are discussed. The experimental results show that the sensor has a refractive index sensitivity of 148.27 nm/RIU in the range of 1.333-1.403 RIU, a humidity sensitivity of 0.207 nm/%RH in the range of 55%-90% RH, and a temperature sensitivity of 0.007 nm/C in the range of 20-80 ~C. It has the advantages of linear response.
(5) A sensor based on long-period fiber grating (LPFG) embedded in polarization-maintaining fiber Sagnac (Sagnac) ring is proposed and fabricated. The experimental results show that the temperature sensitivity of the sensor is 0.128 nm/C in the temperature range of 23-93 C, 49.38 dBm/RIU in the refractive index range of 1.32-1.40 RIU, 0.005 dBm/u_ E in the LPFG region and 0.015 nm/u_ E in the Sagnac ring region of the polarization-maintaining fiber. Simultaneous measurement with refractive index or strain eliminates cross-sensitivity between temperature and refractive index or strain, and distinguishes stress-applied regions.
These sensors have the advantages of simple fabrication, compact structure, low cost and high sensitivity. They can meet the requirements of humidity sensors, refractive index sensors and multi-parameter sensors in forest resources and environment detection, and have certain application potential.
【学位授予单位】：西北工业大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：S757.2;TN253
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