Multi-tone driven high-power narrow-linewidth rare earth doped fiber amplifier

Abstract

A method to increase the output power of narrow-linewidth rare earth-doped fiber amplifiers by suppressing simulated Brillouin scattering. The fiber amplifier is seeded with two or more lasers having frequencies and input powers that are sufficiently different. The seed signal with the highest emission cross section (e.g., signal) initially experiences the greatest gain. If signalis also given sufficiently greater input power than signalit will be amplified to its maximum value before the seed signals have reached the midpoint of the gain fiber. Beyond that point, the signal having the lower emission and absorption cross sections (signal) and significantly lower input power will continue to experience gain by power transfer from both signaland the pump light, attaining a power output well beyond what the maximum output would have been had the amplifier been illuminated with a single frequency beam. This technique effectively reduces the Stokes light of signalwhereby higher power narrow-linewidth optical fiber amplifiers may be realized.