How can time delay between the different modes be reduced?
The time delay between the various modes can be reduced when
(a) the rays traveling off axis to the fiber are speeded up to catch up to the axial rays
(b) merely the axial mode is permitted to propagate that is decrease a or
(c) shift operation to very huge value of λ therefore V becomes less than 2.405. Such led to the further growth of the structure of the fiber within graded index multimode fibers and single mode fibers.