Exact expressions for vector mode cutoff in three-layer step-index fibers Charles Brunet, Pierre-André Bélanger, and Leslie A. Rusch Journal of Lightwave Technology, (Volume 13, Issue 13) (2016) Doi: 10.1109/JLT.2016.2561975 http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=7464239&isnumber =4357488 © 2016 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.