Numerical solution of power flow in multimode W-type optical fibers

Transmission characteristics of multimode step-index W-type optical fibers are theoretically investigated by numerically solving the complex power flow equations. Spatial transients of power distribution and power level, as well as transmission length dependence of transmission bandwidth, are calculated for the mode-coupling condition from guided to lossy leaky modes, a characteristic of W-type fibers. The transmission characteristics of W-type fibers change from those of two singly clad reference fibers when the width of the intermediate layer is changed. The trade-off relation between the bandwidth and steady-state loss is also discussed.