Abstract
The light transmission in a weakly guided cylindrical step-index waveguide, containing a section of the double cladding with an anisotropic or metallic outer cladding, is theoretically investigated. Instead of formulating the dispersion relationship in the doubly-clad section, the throughput power of a guided ray in such a waveguiding structure is estimated from the viewpoints of the ray propagation and its tunneling phenomenon. Illustrated examples and calculations clearly show the filtering properties of the waveguide. Advantages of the present method and comparisons with other approaches are also discussed.