Optical Fiber Communications 4th Edition by Gerd Keiser

Exercise 4

Consider an SCM system having 120 channels, each modulated at 2.3 percent. The link consists of 12 km of single-mode fiber having a loss of 1 dB/km, plus a connector having a 0.5-dB loss on each end. The laser source couples 2 mW of optical power into the fiber and has RIN = -135 dB/Hz. The pin photodiode receiver has a responsivity of 0.6 A/W, B e = 5 GHz, I D = 10 nA, R eq = 50 , and F t = 3 dB. Find the carrier-to-noise ratio for this system.