NUMERICAL RESEARCH ON GAIN SPECTRUM OF STIMULATED BRILLOUIN SCATTERING IN PHOTONICS CRYSTAL FIBER

In this article, research is carried out on the characteristics of gain spectra of stimulated Brillouin scattering (SBS). Based on results reported previously, a more accurate and visualized acoustic wave equation in fiber is proposed. A mathematic model of SBS gain spectra is built using the finite element method (FEM) based on the acoustic wave equation. To prove the accuracy of the model, the numerical results of SBS gain spectra in single-mode fiber are compared with experimental results, and the maximum relative error is less than 0.13%. The gain spectra of SBS in photonics crystal fibers are also obtained with the help of the mathematic model. The influences of the size of radiuses and pitches of photonics crystal fiber, and the concentration of medium in photonics crystal fiber air-hole on the gain spectra of SBS are found. Based on the relationship between the concentration of medium in air-hole and gain spectra, a new method for optical detection of NaCl is proposed.