Chiro-ferrites for low-loss magnetic photonic crystals Conference

Yarga, S, Sertel, K, Volakis, JL. (2005). Chiro-ferrites for low-loss magnetic photonic crystals . 2015 IEEE INTERNATIONAL SYMPOSIUM ON ANTENNAS AND PROPAGATION & USNC/URSI NATIONAL RADIO SCIENCE MEETING, 2 B 208. 10.1109/APS.2005.1551975

cited authors

  • Yarga, S; Sertel, K; Volakis, JL

authors

abstract

  • Magnetic photonic crystals (MPCs) display exotic propagation characteristics in the form of a frozen mode (A. Figotin and I. Vitebskiy, Phys. Rev. E, Vol. 63, 066609, pp. 1-17; see also Phys. Rev., B, 67, 165210, pp. 1-20). Among them is low reflectivity (high coupling) and significant wave slow-down. These properties hold the potential for a variety of novel applications, ranging from high quality isolators to highly-directive miniature antenna arrays (G. Mumcu, K. Sertel, J.L. Volakis, I. Vitebskiy and A. Figotin, IEEE APS Symposium, 2004, pp. 1395-1398 Vol.2). However, as is well known, ferrites are associated with losses at microwave frequencies. Such losses are further exacerbated due to resonant wave behavior (frozen mode) within the crystal. To minimize losses, it is therefore necessary to minimize the ferrite layer thickness while still attaining sufficient Faraday rotation to preserve the frozen mode phenomenon. For practical designs, very low-loss ferrite materials such as Calcium Vanadium Garnets (CVG) or Yttrium Iron Garnets (YIG) can be used, but it is still important to reduce the thickness of these layers in forming the crystal. Towards this goal, we investigate the performance of (1) Chiral inclusions within a ferrite medium, and (2) Chiral (handed) ferrite inclusions within a possibly non-magnetic medium host medium. Our preliminary analysis demonstrated that much thinner periodic MPC layers can be designed using chiro-ferrite layers. Concurrently, the MPC frozen mode and reflectivity properties are maintained. More specifically, the inflection point in the band diagram is achievable using only a fraction (lower than 1%) of the original ferrite material, implying a significant loss reduction in practice. For our analysis, we assumed a reasonable chirality admittance ζc to model the chiro-ferrite material having the constitutive relations D = εE + iζcB and H = iζcE + μ-1B). However, the actual value of ζc depends on various geometrical and material parameters, including the handedness of the inclusions. Hence, the computation of ζc requires a full wave analysis of the actual "molecular" geometry. Assuming a three-dimensional periodic array of handed ferrite inclusions, we can generate the Bloch diagram from the eigenvalues of the finite element matrix of the unit cell. We will discuss how this band diagram provides all the information pertaining to the modes supported within the structure and can be used to extract the equivalent chirality parameter ζc through homogenization. Our goal is to demonstrate this homogenization process and to develop optimization tools to enable the design of artificial material having pre-specified chirality. © 2005 IEEE.

publication date

  • December 1, 2005

published in

Digital Object Identifier (DOI)

International Standard Book Number (ISBN) 10

International Standard Book Number (ISBN) 13

start page

  • 208

volume

  • 2 B