基于变刚度结构的光纤布拉格光栅低温环境下的温度増敏方法研究

光纤布拉格光栅采用非电磁信号测试方式，具有显著的抗电磁干扰以及可嵌入被测结构内部等特性，已成为近些年广受关注的光学应变、温度传感与测试新技术。但在极端条件下(如超低温环境)，光纤由于受到其自身材料特性的局限，传感特性不明显甚至限制了其应用。基于结构变刚度的力学増敏方法，本文提出了一种适用于低温区的光纤布拉格光栅温度传感増敏的结构设计方法。研究结果表明：该传感结构可有效感应低温下的温度变化，増敏效果明显；并获得増敏效果随结构材料与几何特性的依赖关系，经过优化可使得光栅区对温度和应变的敏感性大大提高，甚至提高1个数量级。最后，完成了这一増敏结构的设计和制备，实验验证了所提方法的有效性和可靠性。

Method of Enhancement of temperature Sensitivity for Fiber Bragg Grating at Low Temperature Based on A Variable Stiffness Structure

Fiber Bragg Gratings (FBG) have been widely used in optical strain, temperature measurements as one of non-electromagnetic signal testing methods. They have advantage of significant anti-electromagnetic interference and can be embedded inside of the structure. However, under extreme conditions (such as cryogenic temperature), the optical fibers due to the limitations of the material characteristics, their sensing characteristics are invalid which even limit applications. Based on the method of changing structural stiffness, this paper presents a structural design of enhancement of temperature sensitivity for the fiber Bragg grating sensor in low-temperature region. The results show that the FBG can effectively work at low temperature, and the temperature sensitivity is obviously enhanced. The sensitivity dependence on structural material and geometrical properties is obtained, and the sensitivities of the grating region related to temperature and strain are optimized to even increase an order of magnitude. Finally, we completed the design and manufacture of this structure to validate the proposed method.