Circular waveguides with Kronig–Penney morphology as photonic band-gap filters.

Guided wave propagation in a circular waveguide filled with dielectric materials in the Kronig–Penney morphology is theoretically examined. Allowed and forbidden frequency bands in these ideal photonic band-gap (PBG) structures are obtained for the TE^z and TM^z propagation modes by invoking the Bloch theorem. Results show the many engineering possibilities for designing electromagnetic filters for ideal structures. Filtering by real PBG structures with a finite number of unit cells is also studied by using the scattering matrix technique. As the number of unit cells in a real filter increases, its transmission characteristics converge to those of its ideal analog in the forbidden frequency bands. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 37: 316–321, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10906 [ABSTRACT FROM AUTHOR]