Reflection insensitive erbium-doped fiber amplifier

It is experimentally and theoretically examined how the insertion of an isolator within the erbium-doped fiber influences the sensitivity of the fiber amplifier to external reflections. We examined the EDFA in various regions of saturation, and compared the configuration with the isolator to the traditional configuration without an isolator. The most significant improvements were found in the small-signal region, where the requirements to reflections may be relaxed by as much as 13 dB. This, together with an improved gain and noise figure, makes the configuration with the isolator very attractive for preamplifier applications.<>