Analysis and Comparison of Demodulation Methods for Distributed Fiber-optic Sensing Based on Optical Frequency-Domain Reflectometry

Distributed fiber-optic sensing based on optical frequency-domain reflectometry (OFDR) can quantitatively obtain the information of environmental parameters along the optical fiber by analyzing the phase changes or spectral shifts of the Rayleigh backward scattering (RBS) signals when a linear frequency-modulated continuous wave signal is used as the probing signal. In view of the differences in the two approaches for the extraction of the optical parameters of the RBS, we have analyzed the mechanisms of two demodulation methods through theoretical modeling, revealing their differences in accuracy, dynamic range, spatial resolution, and sensing spatial resolution. In addition, experimental comparisons for the performances of the two methods under the same OFDR system parameters through distributed temperature sensing have been conducted, testifying the differences in accuracy. These results can be useful for the design and optimization of the distributed sensing systems based on OFDR.