Gain limit in erbium-doped fiber amplifiers due to internal Rayleigh backscattering

A very high gain of 51 dB in a single Er-doped fiber is reported. A significant amount of amplified Rayleigh backscattering is also observed. This is predicted to impose an upper limit of 57-70 dB of achievable gain for the investigated fibers. By the insertion of an isolator, a gain of 54 dB is observed.<
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