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Proceedings Paper

Microwave characteristics of thin Al2O3 membranes as metasamples for optical applications
Author(s): P. Dankov; B. Tzaneva; V. Videkov
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Paper Abstract

In this paper, a complete characterization of the dielectric parameters of thin anodic Al2O3 membranes with formed nano-scale air-filled pores was performed in the frequency range 0-40 GHz by a combination of two microwave methods - a resonance method applying pair of cylindrical resonators that support excited modes with mutually perpendicular electric fields and allow evaluation of the dielectric anisotropy, and a broadband method, where planar samples cover the top surface of different transmission lines (coplanar waveguide and microstrip line). It was found that the purity of the initial aluminum foil as well as the thickness of the obtained dielectric membranes influence their optical (perpendicular transmittance through the membranes) and dielectric properties (dielectric constant and dielectric loss tangent). The main benefit of these investigations is the established dielectric anisotropy of the test samples (different dielectric parameters in parallel and perpendicular directions to the sample surface), which confirms the metamaterial-like character of anodic aluminium oxide (AAO). Three types of AAO samples' behaviour were observed due to the realized purity: 1) relatively pure dielectrics with equivalent dielectric constant ~5-7 and less; 2) lossy dielectrics with contaminations (~7-10) and 3) poor dielectrics with increased conductivity due to the metal inclusions (equivalent dielectric constant above 10 and equivalent conductivity 0.25-50 S/m). The applied microwave methods allow us to optimize the used technology for manufacturing acceptable metasamples with high final purity, suitable for optical applications.

Paper Details

Date Published: 30 December 2019
PDF: 15 pages
Proc. SPIE 11332, International Conference on Quantum, Nonlinear, and Nanophotonics 2019 (ICQNN 2019), 1133203 (30 December 2019); doi: 10.1117/12.2551892
Show Author Affiliations
P. Dankov, Sofia Univ. St. Kliment Ohridksi (Bulgaria)
B. Tzaneva, Technical Univ. of Sofia (Bulgaria)
V. Videkov, Technical Univ. of Sofia (Bulgaria)

Published in SPIE Proceedings Vol. 11332:
International Conference on Quantum, Nonlinear, and Nanophotonics 2019 (ICQNN 2019)
Alexander A. Dreischuh; Tony Spassov; Isabelle Staude; Dragomir N. Neshev, Editor(s)

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