Performance of data link modules as a function of multimode fiber size

Commercial data link modules from three manufacturers were measured for transmitter launch power and receiver sensitivity when used with the five common graded-index multimode fiber types: 50 μm core/NA_mk, = 0.20; 50 μm/NA_m = 0.23; 62.5/0.275; 85/0.26: and 100/0.29. Depending on the model, transmitters launched from 2.8 to 4.4 dB more power into the 100 pm fiber than the 62.5 μm fiber, whereas receiver sensitivities decreased by up to 3.5 dB. These variations in launch power and receiver sensitivity complicate the selection of an ideal fiber and emphasize the need for specifying data link performance with the particular fiber of interest. In general, the system gain of typical transmitter/receiver pairs is less favorable to large diameter fibers than previously believed.