Optimal frequency scanning range for parameters extraction from Brillouin scattering spectrum

Abstract

To improve the accuracy in temperature and strain measurement based on Brillouin scattering, Brillouin scattering spectra with different values of Signal to Noise Ratio (SNR), full width at half maximum (ΔvB) and the number of frequencies scanning are numerically generated. The influence of frequency scanning range on the accuracy in parameters extraction is systematically investigated and the optimal frequency scanning ranges in different cases are obtained. The results reveal that the frequency scanning range has a big influence on the accuracy in parameters extraction of Brillouin scattering spectrum. If the number of frequencies scanning remains unchanged, the error initially decreases with increasing frequency scanning range. Once the minimum error is reached, it increases with increasing frequency scanning range. The SNR, ΔvB and the number of frequencies scanning have little effect on the optimal frequency scanning range. For the cases with SNR ranging from 10 dB to 40 dB and the other parameters falling within the typical range, the optimal frequency scanning ranges are calculated and presented. The systematical investigations reveal that the frequency scanning range can be set to a value ranging from 1.2ΔvB to 1.6ΔvB within which it has little influence on the parameters extraction accuracy. A distributed fiber sensing system based on Brillouin scattering has been set up and the above results are fully validated by the parameters extraction from the measured Brillouin scattering spectra.