Optical Fiber Communications 4th Edition by Gerd Keiser

Exercise 2

An engineer wants to find the attenuation at 1310 nm of an 1895-m long fiber. The only available instrument is a photodetector, which gives an output reading in volts. Using this device in a cutback-attenuation setup, the engineer measures an output of 3.31 V from the photodiode at the far end of the fiber. After cutting the fiber 2 m from the source, the output voltage from the photodetector now reads 3.78 V What is the attenuation of the fiber in dB/km