Optical Fiber Communications 4th Edition by Gerd Keiser

Exercise 5

An engineer plans to construct an in-line optical fiber data bus operating at 10 Mb/s. The stations are to be separated by 100 m, for which optical fibers with a 3-dB/km attenuation are used. The optical sources are laser diodes having a 500- µ W (-3 dBm) output from a fiber flylead, and the detectors are avalanche photodiodes with a 1.6-nW (-58-dBm) sensitivity. The couplers have a power tap-off factor of C T = 5 percent and a 10-percent fractional intrinsic loss F t The power loss at the connectors is 20 percent (1 dB).
( a ) Make a plot of P 1N in dBm as a function of the number of stations N for 2 N 12.
( b ) What is the operating margin of the system for eight stations
( c ) What is the worst-case dynamic range for the maximum allowable number of stations if a 6-dB power margin is required