Characterization of Brillouin Scattering Properties in Erbium-Doped Optical Fibers with Different Erbium-Doping Concentrations

摘要

Brillouin distributed temperature and strain fiber-optic sensors have been widely studied for large-scale structural health monitoring. Although various methods have been developed to improve their performance, the measurement range, sensitivity, and signal-to-noise ratio are, in some cases, limited by the inherent propagation loss of the optical fibers. To overcome this problem, we have focused on utilizing Brillouin scattering in an erbium-doped fiber (EDF), which has the optical amplification capability. In this work, first, the Brillouin gain spectra of EDFs with three different concentrations are measured, and the Brillouin frequency shift dependences on temperature and strain along with their relations to erbium-doping concentration are fully investigated. Then, we measure the amplification effect of the Brillouin signal in one of the EDFs by 980-nm pumping. The Brillouin Stokes power is exponentially raised with increasing 980-nm pump power, indicating that adjusting the 980-nm pump power can control the Brillouin signal in the EDF. We also show that drastic enhancement of the Brillouin signal might be feasible by using a high-power 980-nm pump laser.