${\pi}$-Phase-Shifted FBG for High-Resolution Static-Strain Measurement Based on Wavelet Threshold Denoising Algorithm

We propose a high-resolution static-strain sensor based on a π-phase-shifted Bragg grating (π-FBG) combined with a wavelet threshold denoising algorithm. The Pound-Drever-Hall (PDH) technique based on a narrow-linewidth fiber laser is used to interrogate the sensor. A reference FBG-based Fabry-Perot interferometer (FBG-FP) is used to compensate the temperature and laser source frequency fluctuation. As the reflect spectrums of π-FBG have a higher SNR than FBG-FP, the SNR of PDH signals from FBG-FP and π-FBG is increased from 18.1 to 35.6 dB. Wavelet threshold denoising algorithm is used to further improve the SNR of the PDH signals (about 8 dB). As a result, a static-strain resolution of 1.0 nε is obtained in the laboratory test.

[1]  Zuyuan He,et al.  Ultra-high-resolution large-dynamic-range optical fiber static strain sensor using Pound-Drever-Hall technique. , 2011, Optics letters.

[2]  Genda Chen,et al.  Measurement accuracy improvement of Brillouin signal using wavelet denoising method , 2009, Smart Structures and Materials + Nondestructive Evaluation and Health Monitoring.

[3]  Gang-Ding Peng,et al.  Demodulation of Fiber Bragg Grating Sensor Using Cross-Correlation Algorithm , 2007 .

[4]  Yong Chen,et al.  Research on FBG sensor signal wavelength demodulation based on improved wavelet transform , 2013 .

[5]  Kazuo Hotate,et al.  An ultra-high-resolution FBG static-strain sensor for geophysics applications , 2010, European Workshop on Optical Fibre Sensors.

[6]  Stéphane Mallat,et al.  A Theory for Multiresolution Signal Decomposition: The Wavelet Representation , 1989, IEEE Trans. Pattern Anal. Mach. Intell..

[7]  Xiaoyi Bao,et al.  Wavelet Denoising Method for Improving Detection Performance of Distributed Vibration Sensor , 2012, IEEE Photonics Technology Letters.

[8]  Minho Song,et al.  Noise reduction of FBG sensor signal by using a wavelet transform , 2011, Optics + Optoelectronics.

[9]  Stephen W. James,et al.  Pressure measurements on aircraft wing using phase-shifted fibre Bragg grating sensors , 2009, International Conference on Optical Fibre Sensors.

[10]  Dobryna Zalvidea,et al.  Effective length of short Fabry-Perot cavity formed by uniform fiber Bragg gratings. , 2006, Optics express.

[11]  M Tur,et al.  Highly sensitive dynamic strain measurements by locking lasers to fiber Bragg gratings. , 1998, Optics letters.

[12]  E. Black.  An introduction to Pound–Drever–Hall laser frequency stabilization , 2001 .

[13]  J. Greenleaf,et al.  Time delay estimation using wavelet transform for pulsed-wave ultrasound , 1995, Annals of Biomedical Engineering.

[14]  E. Pettit,et al.  Measurement of vertical strain and velocity at Siple Dome, Antarctica, with optical sensors , 2002, Journal of Glaciology.

[15]  Malcolm B. Gray,et al.  Quasi-static fiber strain sensing with absolute frequency referencing , 2008, International Conference on Optical Fibre Sensors.

[16]  Qingwen Liu,et al.  An ultra-high-resolution large-dynamic-range fiber optic static strain sensor using Pound-Drever-Hall technique , 2011, 2011 International Quantum Electronics Conference (IQEC) and Conference on Lasers and Electro-Optics (CLEO) Pacific Rim incorporating the Australasian Conference on Optics, Lasers and Spectroscopy and the Australian Conference on Optical Fibre Technology.

[17]  P. Laporta,et al.  Fiber strain sensor based on a pi-phase-shifted Bragg grating and the Pound-Drever-Hall technique. , 2008, Optics express.

[18]  N. Djilali,et al.  In-fibre Bragg grating sensors for distributed temperature measurement in a polymer electrolyte membrane fuel cell , 2009 .

[19]  Moshe Tur,et al.  Static fiber-Bragg grating strain sensing using frequency-locked lasers , 1999 .