We study the applicability of the weakly guiding approximation (WGA) to the modal analysis of an M-type optical fiber in which a ring-shaped core lies between two uniform cladding layers. Besides being dependent on the refractive indices, the accuracy of the approximation is shown to be substantially affected by the transverse dimensions of the core. The accuracy is characterized by calculating an overlap integral between the exact and WGA-approximated modal fields. Fibers that have an inner cladding similar to the outer cladding, or similar to vacuum, are considered in detail. The feasibility of the WGA in determining the fiber parameters for single-mode guidance is also discussed.
© 2005 Optical Society of America
(060.2310) Fiber optics and optical communications : Fiber optics
(060.2340) Fiber optics and optical communications : Fiber optics components
(060.2430) Fiber optics and optical communications : Fibers, single-mode
(260.2110) Physical optics : Electromagnetic optics
Markus Hautakorpi and Matti Kaivola, "Modal analysis of M-type-dielectric-profile optical fibers in the weakly guiding approximation," J. Opt. Soc. Am. A 22, 1163-1169 (2005)