Gain optimization of germanosilicate fiber Raman amplifier and its applications in the compensation of Raman-induced crosstalk among wavelength division multiplexing channels

Spectral characteristics of stimulated Raman scattering (SRS) process were theoretically investigated for step-index silica optical fibers with variou s GeO2 concentrations. Optimal-fiber lengths and germanium concentration, w here the first Stokes power reaches maximum, were calculated at various pum p power levels for application in Raman amplifiers. Based on this analysis, we proposed and experimentally demonstrated a new channel-equalizing techn ique to simultaneously compensate Raman-induced crosstalk and amplify wavel ength-division-multiplexing (WDM) signals using a discrete Raman amplifier in the 1.5-mum range. As a further application of SRS in germanosilicate gl ass fibers, we introduce an all-optical variable attenuator for channel equ alization that could be used in dynamic optical power tilt control in WDM s ystems.