Modal propagation characteristics of radially stratified and D-shaped metallic optical fibers

The eigenvalue equation is formulated for a general three-layered radially stratified metallic optical fiber waveguide and solved numerically using the zoom search method. The result is shown to be applicable to the common D-shaped fiber, which bears no similarity to a concentric stratum but may be converted as such through the Mobius conformal representation. The theoretical prediction agrees well with our experimental measurements, and the method should be proved valuable for optimizing metallic fiber design relationships.