Stimulated Raman scattering threshold enhancement in silica-based optical fibers via filtering techniques

Optical filtering techniques are proposed to suppress stimulated Raman scattering interactions in model optical fiber systems. First, numerical simulations are performed on the interactions of a pump with lower frequency optical noise in an optical fiber. The insertion of a high frequency pass filter is shown to effectively suppress the pump-noise interactions, leading to a significant increase in the stimulated Raman scattering threshold.; Numerical simulations of strongly pumped Raman amplifiers are also performed. A high frequency pass filter is inserted into the amplification region to eliminate the pump and signal depletion to optical noise. The simulations predict significant gain improvements through insertion of the high frequency pass filter.; Numerical simulations are carried out on WDM systems as well. The simulations demonstrate that the channel depletion due to stimulated Raman scattering in WDM systems can be eliminated by using high-frequency pass filters. These filters, when inserted appropriately into the transmission link, are shown to effectively suppress the SRS power flow from the WDM channels to lower frequency noise.; Finally, stimulated Raman scattering experiments are performed which verify that usage of a high frequency pass filter can enhance the stimulated Raman scattering threshold in an optical fiber. The measurements are performed in TrueWave optical fibers using a 1.7 Watt pump at 1500 nm. The results attest that, for a high frequency pass filter appropriately positioned in the fiber system, the SRS pump depletion can be almost entirely eliminated.