Stimulated Raman Gain estimates for high-gain optical fibers.

The amplification of light signals by the mechanism of stimulated Raman scattering is discussed, with specific references to certain heavy-metal germanate and arsenate glasses with Raman- Gain coefficients G of up to 20 times that of fused silica. Calculations are presented of the intrinsic scattering losses from Raleigh, Brillouin and spontaneous Raman sources for these compositions which, when combined with the measured G- values, determine the potential signal-amplification capabilities as a function of pump power and fiber length L. Direct comparisons are made with an equivalent calculation for an ideally pure germania fiber. The results hinge sensitivity upon the degree to which concentration fluctuations (leading to concentration- scattering Rayleigh loss) are intrinsic in the multicomponent high-G glass compositions. In spite of this, some compositions are located which can outperform pure germania fibers even in the presence of significant concentration-scattering loss. This is particularly so for high pump powers and short fiber lengths L 2km.