Study on the Raman gain spectrum of different GeO_2-doped silica fiber

Experiments were made to investigate how the spectrum of the stimulated Raman scatting gain changes with germania concentration and different pump power.The calculated results show that the Raman gain coefficient is determined by fiber characteristics and has nothing to do with pump power. Based on the establishment of a model of silicon dioxide structure,the effect of germania concentration across the fiber core on Raman gain spectrum was analyzed by the method of Gaussian decomposition.The decomposed spectrum showed that the dopants destroyed the silicon dioxide structure and produced some new Raman gains within the discussed(Raman) gain range,which verified the experiment conclusion for the influences of germania concentration on Raman gain coefficient and Raman gain spectrum.