High sensitivity micro-displacement sensor based on fiber Bragg grating and amplification substrate

Abstract

A micro-displacement sensor based on fiber Bragg grating (FBG) is proposed. The device consists of a pair of FBGs with different central wavelengths fabricated by femtosecond laser phase mask method and a metal substrate with lever structure. The displacement is amplified by lever structure and it converts into axial tension of FBG, which has a high displacement sensitivity. The amplification factors obtained by theoretical analysis and finite element simulation are 2.67 and 2.50, respectively. The experimental results show that in the range of 0–50 µm the shift of FBG center wavelength is linearly related to the displacement of measured object and displacement sensitivity reaches 121 pm/µm. In addition, the cascaded FBG is used to compensate the temperature.

Keywords

fiber Bragg grating / femtosecond laser / micro-displacement sensor / lever structure

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