The Correction of Nonlinearity in Wavelength Scanning Based on Long-OPD Interferometer for Fiber Bragg Grating Demodulation in Environment With Variable Temperature

Abstract

Fabry-Perot (F-P) filter based fiber Bragg grating (FBG) demodulation has been widely applied in many areas. However, the F-P filter suffers from random fluctuation in wavelength scanning when the ambient temperature changes severely, which reduces the demodulation accuracy inevitably. In this paper, a demodulation method based on an etalon and a fiber-optic Michelson interferometer is proposed to improve the demodulation accuracy in an environment with variable temperature. The experiment is carried out by constructing an interferometer with long-optical path difference (OPD). When the environment temperature increases from 20 °C to 60 °C in 30 minutes, the results show that the error of the proposed method is reduced from ± 20.39 pm to ± 6.89 pm. The standard deviation is 3.11 pm, which is reduced by 43.92% compared with the etalon-based demodulation method.

Keywords

• Michelson interferometer
• optical fiber sensor
• filter nonlinearity
• variable temperature environment demodulation