Influence of the fiber design and launch beam on transmission characteristics of multimode glass W-type optical fibers

Bandwidth and steady-state loss of multimode glass W-type optical fibers (doubly clad fibers with three functional layers) are evaluated for the varied fiber design and launch beam parameters. These transmission characteristics are determined from the solution of the time-dependent power flow equation by the explicit finite difference method. Results are presented in a graph form as functions either of the fiber length or loss for the varied thickness and depth of the fibers intermediate layer (inner cladding), fibers coupling strength, and input beam (mean angle and width). The trade-off relation between the bandwidth and steady-state loss for designing multimode glass W-type optical fibers is shown in graphs and highlighted the text. We found that bandwidth improves with thinner and shallower intermediate layers, narrower and more central launch-beam, and stronger mode coupling.