Optical Fiber Communications 4th Edition by Gerd Keiser

Exercise 7

Consider a long-distance transmission system containing a cascaded chain of EDFAs. Assume each EDFA is operated in the saturation region and that the slope of the gain-versus-input power curve in this region is -0.5; that is, the gain changes by ±3 dB for a 6-dB variation in input power. Let the link have the following operational parameters: ( a ) Suppose there is a sudden 6-dB drop in signal level at some point in the link. Find the power output levels after the degraded signal has passed through 1, 2, 3, and 4 succeeding amplifier stages.
( b ) Repeat part ( a ) for a signal-level drop of 12 dB.