Temperature and strain dependence of the power level and frequency of spontaneous Brillouin scattering in optical fibers

Abstract

The strain dependence of the optical power of Brillouin scattering in optical fibers has been measured for the first time to our knowledge. Together with measurements of the dependence of Brillouin power on temperature and the variation of Brillouin frequency with temperature and strain, we demonstrate, for what we believe to be the first time, the feasibility of a simultaneous temperature and strain sensor based on spontaneous Brillouin scattering.

Dependence of the Brillouin frequency shift on strain and temperature in a photonic crystal fiber

“…4 One could then subtract the frequency shift that resulted from any temperature effects from the combined frequency shift to determine the strain on the structure. This method was used to measure strain and temperature with a spatial resolution of 5 m. As a second solution to this problem, interest was focused on both Brillouin backscattered intensity and frequency shifts, 5,6 because they both exhibit dependence on strain and temperature. However, the spatial resolution achieved is tens of meters because of power (intensity) f luctuations induced by lasers and by the accuracy of intensity measurement.…”

Distributed discrimination of strain and temperature based on Brillouin dynamic grating in an optical fiber

“…Although the preliminary method based on a specially-designed fiber [15][16][17] is a frequencybased measurement technique prior to the power-based one [22], it is still ill-conditioned and physically limited due to the correlated relationship among multiple peaks. …”

Experimental examination of the variation of the spontaneous Brillouin power and frequency shift under the combined influence of temperature and strain

“…The Brillouin coefficients The change in Brillouin frequency and power due to strain and temperature has been represented by the matrix equation [5] …”

“…Since then there have been numerous contributions to the field of distributed sensing exploiting the dependence of the Brillouin scattering to temperature and strain [5][6][7][8][9][10] . The layout of sensing rigs for Brillouin scattering based distributed sensing to date, have comprised separate sections of sensing fiber subjected to either temperature or strain influences.…”