【作者】 王昌；

【导师】 姜德生； 何伟；

【作者基本信息】 武汉理工大学 ， 材料学， 2005， 博士

【摘要】 智能材料与结构是近年来在世界上兴起并迅速发展的材料技术的一个新领域。智能材料与结构具有四种主要特性，即敏感特性、传输特性、智能特性和自适应特性，它代表着21世纪先进新材料发展的一个方向。光纤传感器作为智能材料与结构理想的核心部件，正在受到越来越多的关注，而其中光纤光栅传感器是目前研究和应用的热点。 自从1995年A．M．vengsarkar等人在光纤中成功地写入长周期光纤光栅(Long-period Fiber Grating以下简称LPG)以来，LPG作为光纤器件在光纤通信和传感领域得到了越来越广泛的研究和应用。已经证实LPG可以改进掺铒光纤放大器系统，因此可以用作带阻滤波器和增益平坦滤波器，另外它也可以用作温度和压力传感器，还可以用作光纤光栅传感解调器。LPG的独特之处在于其对包层的灵敏性，这是LPG一个独一无二的特性，它的这种包层灵敏性可以用来制作生物化学传感器。 为了能使LPG广泛的应用于光通信和传感领域，本论文研究了LPG的制作、特性和其在光通信和传感领域的应用情况。文章首先采用耦合模理论模拟了长短周期光纤光栅的光谱形状基础，然后进行光纤的载氢增敏实验，采用普通单模光纤，经过载氢增敏，利用振幅掩模法和逐点法制作出LPG，并对其的传感特性进行了研究。 以三层阶跃折射率波导结构和耦合模理论为基础，考虑到氢分子引起的折射率变化，针对氢载LPG提出了一个简单的模型，对LPG的退火进行了分析和模拟，所得到的结果与实验符合得很好。 采用LPG实现了RTM工艺中的流动前沿监测。实验研究了LPG在各种工艺条件下的光谱信号响应情况，结果表明LPG能可靠地探测中-低纤维体积含量预成型体中的树脂流动前沿，在高纤维体积含量情况中以及探测三维厚度方向不同深度的树脂流动前沿时的应用受树脂折射率的限制。 采用普通单模光纤设计制作LPG，在此基础上，普通单模光纤LPG的双折射效应进行了研究，获得了很好的横向压力敏感性，证明这种LPG具有极大的用作高灵敏度的光纤横向压力传感器的潜力。 提出了一种新颖双周期光纤光栅传感器，在一段氢载光纤的相同位置上先后写入LPG、短周期布拉格光纤光栅(FBG)，这样就可以利用LPG和FBG对更多还原

【Abstract】 With four main features including sensing, information converting, automated response and self- adaptation, Smart materials and structures become the new field of materials research, and which represents a direction of advanced new material of 21th century. Because of excellent characteristic, fibers are concern by more and more researcher, thereinto fiber grating is the most important part.Since A. M. Vengsarkar et al. wrote successfully Long-Period Fiber Gratings (LPG) in optical fibers in 1995, LPG have become increasingly popular as fiber-optic devices for optical fiber communication and sensing. LPG have been demonstrated as band-rejection and gain-flattening filters for improving Er-doped fiber amplifier systems, and also used as temperature/strain sensors, as well as sensing demodulators. One of their unique characteristics is the sensitivity to the refractive index of the cladding, which can be used as biochemical sensor.This dissertation deals with the fabrication, characterization, and applications of long-period gratings in optical fiber communications and sensing systems. The aim of this project is to assess long-period gratings as fiber-optic devices for optical fiber communication and sensing. A review of the properties and characteristics of fiber gratings associated with the simple silicate fibers is provided, which includes a theoretical analysis of the principles of operation for short-period gratings (fiber Bragg gratings) and long-period gratings. The simulations of the spectral response from these two types of gratings are also presented. A number of long-period grating fabrication methods and techniques, which were reported by some researchers, are reviewed. In this project, the normal long-period gratings are fabricated by using a KrF excimer laser combined with the metal amplitude mask technique and point-by -point exposure technique. The metal mask is made of a stainless steel sheet, and the slot width (periodicity) is processed by using high quality photographic tooling.Considered the refractive index changes caused by hydrogenmoecular, this paper developed a simple model based three-layer step index wave guide and coupled mode theory to analyze and simulate the annealing of LPG inscribed in hydrogen loaded fiber. The results agree well with the experiments.更多还原