An L-band-cascaded erbium-doped fiber amplifier for uniform gain without gain equalizing filter

In the letter, a high gain-naturally flattened L-band erbium-doped fiber amplifier (EDFA) is demonstrated. The system uses two bidirectionally pumped lasers for exciting Er3+ in three cascaded fiber amplifiers. The maximum gain of ∼36.4 dB and equalized gain of over 26 dB in the absence of any gain flattening filter with ∼2.5-dB variation over 35 nm (1572–1608 nm) was obtained. Studies for varying amplifier lengths; signal power and pump powers have also been reported. The proposed EDFA has a noise figure below 5 dB and was found to be stable at extreme temperatures. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2053–2055, 2014