Optical Fiber Communications 4th Edition by Gerd Keiser

Exercise 3

Consider the cutback attenuation measurement technique described by Eq. (14.2) using a photodetector, the power measurements are proportional to the detector output voltage. If the uncertainty in the voltage readings for the two power measurements are ±0.1 percent each, what is the uncertainty in the attenuation accuracy How long must the fiber be to get a sensitivity better than ±0.05 dB/km