Comparison of two methods for predicting the bandwidth of multimode graded-index optical fibers

Two methods for predicting the bandwidth of multimode graded-index optical fibers are studied. Each method is based on measurements of the profile of the refractive index in the preform. The first method is the α-approximation method. The second method is based on a model of a quasiregular fiber and uses the Petermann equation to calculate the mode delay times. Experiments show that the second of these methods is more accurate by a factor of 3.5.