Abstract: A method to increase the output power of monolithic narrow-linewidth Yb-doped fiber amplifiers by suppressing simulated Brillouin scattering. The fiber amplifier employs a co-propagating geometry and is seeded with broad- (source 2) and narrow- (source 1) linewidth signals that are sufficiently different in wavelengths to allow for efficient gain competition and favorable temperature profile at the output end of fiber. The broadband seed signal possesses the higher emission and absorption cross sections. If source 2 is also given sufficiently greater input power than source 1, it will be amplified to its maximum value as the seed signals reach the middle portion of the gain fiber. Beyond that portion, the signal having the lower emission and absorption cross sections (signal 1) will continue to experience gain by power transfer from both signal 2 and 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.

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 2) initially experiences the greatest gain. If signal 2 is also given sufficiently greater input power than signal 1, it 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 1) and significantly lower input power will continue to experience gain by power transfer from both signal 2 and 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.