Metamaterial polarization converter analysis: limits of performance
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Metamaterial polarization converter analysis: limits of performance Dmitry L. Markovich • Andrei Andryieuski Maksim Zalkovskij • Radu Malureanu • Andrei V. Lavrinenko
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Received: 17 January 2013 / Accepted: 16 February 2013 / Published online: 8 March 2013 Ó Springer-Verlag Berlin Heidelberg 2013
Abstract In this paper, we analyze the theoretical limits of a metamaterial-based converter with orthogonal linear eigenpolarizations that allow linear-to-elliptical polarization transformation with any desired ellipticity and ellipse orientation. We employ the transmission line approach providing a needed level of the design generalization. Our analysis reveals that the maximal conversion efficiency for transmission through a single metamaterial layer is 50 %, while the realistic reflection configuration can give the conversion efficiency up to 90 %. We show that a double layer transmission converter and a single layer with a ground plane can have 100 % polarization conversion efficiency. We tested our conclusions numerically reaching the designated limits of efficiency using a simple metamaterial design. Our general analysis provides useful guidelines for the metamaterial polarization converter design for virtually any frequency range of the electromagnetic waves.
1 Introduction Metamaterials provide new exciting possibilities for light wave manipulations especially with operations on the wave polarization, which are on demand not only in the optical
D. L. Markovich (&) Department of Photonics and Information Technology, St. Petersburg National Research University of Information Technologies, Mechanics and Optics, 197101 St. Petersburg, Russian Federation e-mail: [email protected] A. Andryieuski M. Zalkovskij R. Malureanu A. V. Lavrinenko Department of Photonics Engineering, Technical University of Denmark, Ørsteds pl. 343, 2800 Kongens Lyngby, Denmark
and microwave range, but also in the booming field of terahertz (THz) science and technology, due to the natural limitations of the material properties. THz waves have high potential in communication systems, food quality control, defense, biomedical imaging and chemical spectroscopy [1, 2, 3]. For some THz applications, for example, magneto-optical spectroscopy [4], it is desirable to have a circularly or elliptically polarized wave, while most THz sources generate linearly polarized radiation. There are two main routes to get the polarization rotation or conversion. The ‘‘phase’’ route is to introduce eigenwaves phase offsets in birefringent or gyrotropic media with approximately equal transmitted amplitudes. The ‘‘amplitude’’ route is to play with transmission coefficients for the eigenwaves letting the output to have a polarization state of the dominating eigenwave. The unnecessary polarization is then discriminated by the higher absorption and/or higher reflection of another eigenstate. Two illustrative examples of these routes in the THz range are an achromatic quarter-wave plate made from quartz [5] and a giant Faraday effect in an electron plasma in n-
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