Single-TM-mode Bragg fibers made of magnetic materials.

Single-mode fibers are advantageous over multi-mode fibers in many aspects, e.g., much smaller loss, much longer transmission distance, much greater bandwidth, and higher bit rates. We propose a kind of single-TM-mode Bragg fiber in which magnetic materials are introduced. The idea for designing this kind of Bragg fiber comes from the symmetry of TE modes and TM modes when permittivity and permeability are replaced by each other. Through the transfer matrix method, we demonstrated a special kind of single-TM-mode Bragg fiber in a wide frequency range. Guiding modes may be in the bandgaps, at the edges of bandgaps, and in some region in conduction bands, but much more strongly confined guiding TM modes are inside the bandgaps. In addition, the optimization of the structure is also discussed.