Optical Fiber Communications 4th Edition by Gerd Keiser

Exercise 12

Consider a thermal-noise-limited analog optical fiber system that uses a pin photodiode with a responsivity of 0.85 at 1310 nm. Assume the system uses a modulation index of 0.5 and operates in a 5-MHz bandwidth. Let the mean-square thermal noise current for the receiver be 2 × 10 -23 A 2 /Hz. What is the peak-to-peak signal power to rms noise ratio at the receiver when the average incident optical power is -20 dBm