Preparation method of sapphire fiber grating temperature and stress sensor with u-shaped structure

Abstract

The invention discloses a sapphire optical fiber grating temperature and stress sensor with a U-shaped structure and a preparation method thereof. A section of sapphire optical fiber end face is a microhole structure, forming a low-refractive-index cladding structure similar to photonic crystal optical fiber; a section of long-period optical fiber grating Electromagnetic sputtering is used to dope MgO on the side of the optical fiber, and the reaction forms a MgAl2O4 crystal, which changes the mechanical strength of the optical fiber. After writing the optical fiber grating, the two gratings have different stress responses, which can realize temperature and stress. simultaneous measurement. The invention has the advantages of simple structure, large temperature measurement range and high measurement accuracy, and can be applied to temperature stress measurement of rocket engines, optical fairings, ultra-high temperature environments and the like.

Description

Technical field: [0001] The invention relates to an optical fiber sensor device in the field of optical fiber, in particular to a U-shaped structure optical fiber grating temperature stress sensor capable of simultaneously measuring dual parameters of temperature and stress and a preparation method thereof. Background technique: [0002] Fiber Bragg Grating sensors have attracted widespread attention due to their advantages such as simple structure, electrical insulation, anti-electromagnetic interference and resistance to harsh environments. Simultaneous sensing of temperature and stress is currently a hotspot in the study of FBG sensing, but FBG is sensitive to temperature and stress at the same time, that is, both temperature and stress can cause FBG peak wavelength sensitivity. Therefore, the key to simultaneously realize the sensing of temperature and stress is to solve the problem of cross-sensitivity of temperature and stress. [0003] People have done a lot of resea...

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Problems solved by technology

This solution solves the problem that the two gratings need to be coupled, but it is difficult to ensure the adhesion between the fiber grating and the metal in ultra-high temperature, so the measurement in a specific environment is limited

[0005] In addition, Stephen.J.Mihailov et al. used the response of the peak wavelength of the fiber Bragg grating to temperature and stress, put the fiber Bragg grating into a micro furnace, and realized the measurement of temperature and stress respectively. This method achieved a temperature measurement value of 1290 ° C, but This method cannot realize the simultaneous measurement of temperature stress, and the single-mode transmission in sapphire fiber is difficult to control. This is a report on the use of sapphire fiber for high temperature stress sensing

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