Abstract:

Brillouin scattering in optical fiber is a nonlinear effect, i.e.scattering and frequency shift equal to the natural frequency of medium will occur when the pump light interplays with acoustic wave.Optical fiber strain can be exactly measured by Brillouin spectrum, and the longitudinal strain distribution along fiber length can also be got when pulse pump light is launched into optical fiber.In this paper, distributed optical fiber strain sensor based on Brillouin is introduced.The relationship between optical fiber strain and frequency shift of Stokes light to pump light and parameter calculation formula are published.The results show that Brillouin frequency shift caused by strain in fiber is mainly created by changing Young's modulus, Brillouin frequency shift is about several GHz, and variation of Brillouin frequency shift caused by strain is about several MHz.The theory is coincident with experiments.

Key words: B rillouin scat tering, fiber senso r, st rain senso r, parameter calculat ion