Optical Fiber Communications 4th Edition by Gerd Keiser

Exercise 10

Suppose an avalanche photodiode has the following parameters: I L = 1 nA, I D = 1 nA, = 0.85, F=M 1/2 , R L = 10 3 W, and B e = 1 kHz. Consider a sinusoidally varying 850-nm signal, which has a modulation index m = 0.85 and an average power level P₀=-50 dBm, to fall on the detector at room temperature. Plot the signal-to- noise ratio as a function of M for gains ranging from 20 to 100. At what value of M does the maximum signal-to-noise ratio occur