Classification and Properties of Modes in Bragg Fibers

Modes supported in air-core Bragg fibers with infinite number of H/L (high/low) layers are modeled and simulated which provide a solid foundation for the analysis of modes supported in air-core Bragg fibers with finite number of H/L layers. Three types of modes supported in Bragg fibers with a finite number of H/L layers are well defined and divided into branches in the mode spectrum. The three types of modes can be identified as quasi-guided modes, leaky modes and PML modes and their different characteristics are shown by the corresponding field patterns.