Gain peaking in a chain of 980 nm-pumped erbium-doped fiber amplifiers

We report the results of an experimental study of the signal-to-noise ratio and gain peaking in a chain of four 980 nm-pumped erbium-doped fiber amplifiers. Over the wavelength range 1540 nm to 1562 nm, there is less than 3 dB variation in signal-to-noise ratio and 7 dB variation in output power. Between 1544 nm and 1558 nm the signal-to-noise ratio varies by less than 1 dB. These results suggest that the high inversion resulting from the use of 980 nm pumping will mitigate the effects of gain nonuniformity and may obviate the need for gain equalization in many applications.<>