多芯长周期光纤光栅制备及其应用研究

Long period fiber grating is one of the important passive optical fiber devices, which has a good application prospect in optical communication and optical sensing field. At present, it is one of the hot topics in optical device research. The project aims to explore a preparation method and carry out a study about transmission mechanism and application of a new type multicore long period fiber grating .The main idea is based on FBT(fused biconical taper) with an electrical heater, through the mini graphite heating element to make the fiber physical deformation. Meanwhile, it also can write long period fiber grating in each waveguide core of optical fiber. The resonance wavelength of each core is related to the core position, tapering process parameters, optical fiber refractive index distribution and other factors. Using controllability can be made into a variety of optical passive devices, such as: filter, eliminating temperature crosstalk of optical fiber sensor, wavelength division multiplexer. The main research contents include: 1. Study the structure optimization design and the key fabrication technology of the multicore special optical fiber ; 2. Study the write methods and mechanism of multicore long-period fiber grating; 3. Study the asymmetric multicore fiber bending sensor based on long-period fiber grating.

长周期光纤光栅是一种重要的光纤无源器件，在光通信、光传感领域都具有良好的应用前景，是目前光器件研究热点之一。本项目旨在探索一种新型多芯长周期光纤光栅制备方法，并开展其传输机理和应用研究，其主要思路是基于电加热式熔融拉锥的方法，通过微型石墨发热元件使光纤发生物理变形，在光纤各个波导芯中同时写入长周期的光纤光栅。各纤芯的光栅谐振波长与纤芯位置、拉锥工艺参数、光纤折射率分布等因素有关，利用这种可控性，可制成多种光纤无源器件，如：滤波器、消温度串扰的光纤传感器、波分复用器等。项目拟开展的主要研究内容包括：1、多芯特种光纤结构优化设计和关键制备技术研究；2、多芯长周期光纤光栅制备与机理研究；3、基于长周期光纤光栅的非对称多芯光纤弯曲传感器研究。

多芯光纤光栅在传感领域中具有重要意义，项目针对多芯光纤光栅的制备及弯曲特性进行研究。搭建了光纤端面对准平台，实现了多芯光纤纤芯分别注光和探测，分析了多芯光纤光栅在不同角度的弯曲特性。具体内容为：通过热力学方法仿真了在熔融拉锥下非对称多芯光纤的变形情况，实验表明位于非对称多芯中心的纤芯变形程度小于位于边缘纤芯变形程度。通过单芯光纤与多芯光纤的耦合模型，进行了光纤端面对准的方法研究。构建了光纤图像形貌分析的实验平台，实现了所有光栅锥区的显微观察，并利用图像处理技术，计算LPFG的锥腰直径、周期大小等参数，在此基础上，完成了多芯光纤光栅弯曲特性的分析与探测。