“…Erbium-doped fiber amplifiers (EDFAs) are widely used in optical fiber communication systems because of their excellent characteristics, including high efficiency, low noise, polarization insensitivity, and compatibility with optical fiber lines [1]. However, a conventional EDFA often causes significant gain variation when the input data stream has a long duration with no signal, such as a burst signal [2,3,4,5,6]. The gain variation often makes it difficult to decide the bit value in the receiver.…”