Quantitative measurement of dynamic nanostrain based on a phase-sensitive optical time domain reflectometer

• Published in: Applied optics (2004) 2016-10, Vol.55 (28), p.7810-7815
• Main Authors: Dong, Yongkang, Chen, Xi, Liu, Erhu, Fu, Cheng, Zhang, Hongying, Lu, Zhiwei
• Format: Article
• Language: English
• Subjects: Amplitudes; Dynamical systems; Dynamics; Fibers; Nanostructure; Parameters; Reflectometers; Time domain
• ISSN: 1559-128X; 2155-3165
• DOI: 10.1364/ao.55.007810

A sensing system is proposed for quantitative measurement of large-range dynamic nanostrain based on a phase-sensitive optical time domain reflectometer, where the coherent detection and I/Q demodulation methods are employed to demodulate both the phase and the amplitude of the Rayleigh scattering light in real time. A nanopositioning translation stage is utilized to apply precise nanostrain to fiber. By measuring phase differences between two adjacent sections, the quantitative nanostrain with a large measurement range is demonstrated; this is also a method to measure the strain parameter of refractive index. For the Panda polarization-maintaining fiber under test in the experiment, the strain parameter of phase difference is measured to be 8.714  mrad/(nε·m), while the strain parameter of refractive index is measured to be -0.3751ε . As a proof of the concept, the dynamic strain sensing with a range of 10-1000 nε is experimentally demonstrated, and the strain resolution is 1 or 2 nε, corresponding to 5 or 2.5 m spatial resolution, respectively. The experimental measurement also shows a triangular wave with a 12-Hz vibrating frequency and a 100-nε strain amplitude as well as a 188-Hz resonant signal of the tensile section.