超高温环境下蓝宝石光纤光栅多参量一体化传感技术

针对航空发动机中1800℃超高温环境下温度和压力测量的重大需求，在利用飞秒激光制备光纤光栅与微结构传感器的工作基础之上，本项目提出一种基于螺线型蓝宝石相移光纤光栅的多参量一体化传感技术，研究内容包括：飞秒激光在蓝宝石光纤中的折射率调制机理；单模螺线型蓝宝石光纤光栅的制备工艺及模式耦合机制；蓝宝石相移光纤光栅的设计、制备与测试；蓝宝石光纤光栅的高可靠低损耗连接及耐高温一体化封装；蓝宝石相移光纤光栅的温度、压力同时传感及解调技术。预期获得超高温、高压多参量一体化蓝宝石光纤光栅传感器样品、解调系统样机及配套软件1套，实现测温范围-50～1800℃，测温精度±1%，测压量程5MPa，测压精度±2%，温度、压力响应时间100ms。本项目的研究有利于填补该领域空白，最终实现一种新颖并具有实用化前景的超高温多参量传感技术，满足航空发动机状态监控的迫切需求。

In order to meet the demand of measuring temperature and pressure in aero-engines under the harsh ultra-high temperature conditions at 1800℃, we propose an integrated multi-parameter sensing technology based on helical sapphire phase-shifted fiber gratings. In this project, we will first study the mechanism of refractive index modulation induced by femtosecond laser in sapphire optical fiber. We will fabricate an annular waveguide layer with low refractive index, which aims to achieve single-mode transmission in sapphire optical fiber. And then, we will study the fabrication process and mode coupling mechanism for single-mode helical sapphire fiber Bragg gratings. Subsequently, we will study the design, fabrication, and characterization of sapphire phase-shifted fiber gratings by using femtosecond laser spiral inscription method and micro channel machining. Researches will then be carried out on the high-reliability and low-loss connection technology for connecting the sapphire optical fiber and the traditional quartz-glass optical fiber, and an integrated package with high temperature resistance will be done for the sapphire fiber grating by using corundum casing. Finally, we will research the multi-parameter sensing techniques for detecting ultra-high temperature, high pressure, and vibration, and the wavelength demodulation for phase-shifted fiber grating. After finishing the project, we could expect novel sapphire fiber gratings samples, integrated multi-parameter sensors for ultra-high temperature, high pressure, and vibration, and the prototype of demodulation system. The project aims to realize a temperature measurement range of -50 to 1800℃, a temperature measurement accuracy of ±1%, a pressure measurement range of up to 5 MPa, a pressure measurement accuracy of ±2%, and a response time of 100 ms. The project has proposed a practical and promising high-temperature and multi-parameter sensing technology, and should be helpful to fill in the blank of this field, and could finally be used to meet the urgent demands of conditions monitoring in advanced aero-engines.