An analysis of Rayleigh backscattering (RBS) and amplified spontaneous emission (ASE) in strongly pumped ytterbium fiber amplifiers is presented. The ytterbium (three-level) system is compared with four-level systems that were studied previously. Both approximate expressions and exact numerical solutions for ASE and RBS as well as for the amplifier noise figure are examined. The results suggest that ASE is apparently stronger in three-level systems, which implies a preferable pumping strategy.
© 1999 Optical Society of America
Ram Oron and Amos A. Hardy, "Rayleigh backscattering and amplified spontaneous emission in high-power ytterbium-doped fiber amplifiers," J. Opt. Soc. Am. B 16, 695-701 (1999)