Abstract
Accurate measurement of strain is one of the most important issues for high temperature environments. We present a highly integrated all-fiber sensor to achieve precise measurements of strain/high-pressure, which consists of a fiber Bragg grating (FBG) inscribed by an 800 nm femtosecond laser cascaded with a micro extrinsic Fabry–Perot (FP) cavity fabricated by the 157 nm laser micromachining technique. FBG is sensitive to temperature, but insensitive to strain/pressure, whereas the FP is sensitive to strain/pressure, but has a small dependence on temperature. Therefore, such a cascaded sensor could be used for dual-parameter measurement and can work well at high temperatures. Experimental results indicate that this device exhibits a good strain characteristic at high temperatures and excellent high-pressure performance at room temperature. Due to its highly sensitive wavelength response, the proposed sensor will have remarkable potential applications in dual parameter sensing in harsh environments.
Highlights
Accurate measurement of strain under high temperatures is one of the most important issues for many industrial applications, such as downhole and aero-engine monitoring, etc. [1,2,3]
The fiber Bragg grating (FBG) is sensitive to temperature, but insensitive to strain/pressure
Conclusions femtosecond laser cascaded with an FP cavity fabricated by a 157 nm laser was proposed and
Summary
Accurate measurement of strain under high temperatures is one of the most important issues for many industrial applications, such as downhole and aero-engine monitoring, etc. [1,2,3]. It is quite challenging to achieve accurate measurement of strain under high temperatures as the thermal-induced drift of the sensor would be significant and cause a relatively large measurement error under high temperatures. Many configurations based on hybrid fiber gratings and an FP interferometer (FPI) have been reported for simultaneous strain and temperature, such as a fiber grating cascaded with an FP [8,9,10], and a fiber grating overlapped on an FP cavity [11,12,13] Among these sensors, FBGs are inscribed by an ultraviolet (UV) laser, which has low thermal stability under high temperatures, and regenerated. The integrated FP/FBG sensor shows excellent characteristics for accurate measurement of strain under high temperatures of up to 500 ◦ C and high-pressures of up to 23 MPa at room temperature. The FBG and the FP, fabricated using laser micromachining technology, can work well at high temperatures, and have good consistency for mass production, making them quite promising to be used in high temperature, harsh environments
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