Improving the peak wavelength detection accuracy of Sn-doped, H2-loaded FBG high temperature sensors by wavelet filter and Gaussian curve fitting

Abstract Fiber Bragg grating (FBG) written into Sn-doped, H 2 -loaded fiber could be used as high-temperature sensors up to 800 °C, but the peak wavelength detecting accuracy was unsatisfactory due to the low signal-noise ratio (SNR) and spectrum distortion. In this paper wavelet filter and Gaussian curve fitting were jointly applied to improve the wavelength detection accuracy of this kind of novel sensor. Firstly wavelet filter was used to suppress the noise in the noise-contaminated FBG reflection spectrum. The denoising efficiency of different wavelet functions and decomposition levels were evaluated by calculating the SNR of denoised signals, and dmey wavelet with decomposition level of 9 presented the best result. Then the denoised signals were fitted to Gaussian profile and the goodness of fit was compared with those obtained without wavelet denoising. Simulation and experimental results demonstrated that the joint application of wavelet filter and Gaussian curve fitting was a promising approach to enhance the peak wavelength detection accuracy of FBG high temperature sensors.

[1]  Chuji Wang,et al.  Fiber ringdown pressure sensors. , 2004, Optics letters.

[2]  Ajit S. Bopardikar,et al.  Wavelet transforms - introduction to theory and applications , 1998 .

[3]  Yonghang Shen,et al.  Photosensitive indium-doped germano-silica fiber for strong FBGs with high temperature sustainability , 2004, IEEE Photonics Technology Letters.

[4]  C. C. Chang.  Effects of fiber Bragg grating spectrum distortion on scanning Fabry-Perot and fiber interferometer based wavelength shift detection schemes , 1999, International Conference on Optical Fibre Sensors.

[5]  E. Brigham,et al.  The fast Fourier transform and its applications , 1988 .

[6]  Leif Bjerkan,et al.  Bragg Grating Sensor Demodulation Scheme using a Semiconductor Laser for measuring Slamming Forces of Marine Vehicle Models , 1996 .

[7]  Dongsheng Zhang,et al.  Thermal decay characteristic of fiber Bragg gratings written into Sn doped fibers loaded hydrogen and a novel encapsulation method , 2010, International Symposium on Advanced Optical Manufacturing and Testing Technologies (AOMATT).

[8]  Tong Sun,et al.  Highly photosensitive Sb/Er/Ge-codoped silica fiber for writing fiber Bragg gratings with strong high-temperature sustainability. , 2003, Optics letters.

[9]  H. N. Rourke,et al.  Thermal decay of fiber Bragg gratings written in boron and germanium codoped silica fiber , 1997 .

[10]  O. Rioul,et al.  Wavelets and signal processing , 1991, IEEE Signal Processing Magazine.

[11]  Tong Sun,et al.  High-temperature sustainability of strong fiber Bragg gratings written into Sb-Ge-codoped photosensitive fiber: decay mechanisms involved during annealing. , 2004, Optics letters.

[12]  W. Jin,et al.  Enhancement of measurement accuracy in fiber Bragg grating sensors by using digital signal processing , 1999 .

[13]  W. Jin,et al.  Improving measurement accuracy of fiber Bragg grating sensor using digital matched filter , 2003, 2002 15th Optical Fiber Sensors Conference Technical Digest. OFS 2002(Cat. No.02EX533).