Electromagnetic interpretation of the quarter-wave stack condition by means of the phase calculation in Bragg fibers

摘要

This paper presents an expression for the eigenvalue equation and fields in a Bragg fiber by calculating the phase change that is based on geometrical optics. The quarter-wave stack condition makes it possible to consider that the Bragg fiber has approximately no cladding from the electromagnetic point of view, despite the fact that the Bragg fiber has a periodic cladding. As a result, its eigenvalue equation can be represented in terms of the zeros of Bessel functions and only the core parameters, for a specific case. The eigenvalue equations for HE and EH modes in the Bragg fiber have a formal equivalence to those for TE and TM modes, respectively, in the circular metallic waveguide. Results obtained are in agreement, under a specific limit, with those derived by an asymptotic expansion method. (c) 2006 Optical Society of America.