The Nature of Accelerating Modes in PBG Fibers

Abstract

Transverse magnetic (TM) modes with phase velocities at or just below the speed of light, c, are intended to accelerate relativistic particles in hollow‐core, photonic band gap (PBG) fibers. These are so‐called “surface defect modes”, being lattice modes perturbed by the defect to have their frequencies shifted into the band gap, and they can have any phase velocity. PBG fibers also support so‐called “core defect modes” which are characterized as having phase velocities always greater than c and never cross the light line. In this paper we explore the nature of these two classes of accelerating modes and compare their properties.