Research Article The Terahertz Controlled Duplex Isolator: Physical Grounds and Numerical Experiment Konstantin Vytovtov, 1 Said Zouhdi, 2 Rostislav Dubrovka, 3 and Volodymyr Hnatushenko 1 1 Department of Physics, Electronics and Computing Systems, Oles Honchar Dnipropetrovsk National University, Gagarina 72, Dnipropetrovsk 49010, Ukraine 2 Laboratoire de G´ enie Electrique de Paris, SUPELEC, 91192 Gif-sur-Yvette, France 3 Queen Mary University of London, UK Correspondence should be addressed to Volodymyr Hnatushenko; vvgnatush@gmail.com Received 27 June 2015; Revised 23 November 2015; Accepted 24 December 2015 Academic Editor: Dmitry Kholodnyak Copyright © 2016 Konstantin Vytovtov et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Electromagnetic properties of an anisotropic stratifed slab with an arbitrary orientation of the anisotropy axis under an oblique incidence of a plane harmonic wave are studied. Te dependence of the eigenwave wavenumbers and the refection coefcient on an anisotropy axis orientation and frequency is investigated. For the frst time, the expression for the translation matrix is obtained in the compact analytical form. Te controlled two-way dual-frequency (duplex) isolator based on the above described slab is presented for the frst time. It is based on the properties of the anisotropic structure described here but not on the Faraday efect. 1. Introduction Te terahertz domain actively developed in the last decades [1–5]. Various devices have been created and numerous electromagnetic structures have been used in this frequency range. One of the most interesting classes of terahertz devices is the class of nonreciprocal devices [1–10]. Usually, the Faraday rotation efect itself is exploited naturally to achieve desired nonreciprocal performance [1]. Te electrically tun- able Faraday efect in a HgTe thin flm has been reported in [2]. Faraday rotation has also been studied for pump pulse of terahertz radiation [3]. In [4], the heterostructures based on the piezoelectric and semiconductor layers have been proposed for radio frequency applications. Other examples of nonreciprocal properties of nonlinear devices in terahertz range have been presented in [5] where a Faraday isola- tor operating on the coupled microwave resonators circuit has been proposed. A theoretical study of the refection of infrared radiation from antiferromagnets and -type barium hexagonal ferrite using an attenuated total refection geometry has been presented in [6]. Nonreciprocal devices using attenuated total refection and thin flm magnetic layered structures have been described in [7]. Tus, we can clearly see that this topic is quite relevant in modern microwave science. In this paper, we consider nonreciprocal properties of an anisotropic structure based on dependence of the refection coefcient on an incident wave direction and an anisotropy axis orientation, but not on the Faraday efect. Te physical grounds and numerical simulations of a controlled bidi- rectional dual-frequency isolator not based on the Faraday efect are presented. For this, the analytical investigation and numerical calculations of a stratifed anisotropic structure are carried out. At frst, the elements of the translation matrix are written in the compact analytical form (4) for the general case of an anisotropic medium for the frst time. It is important that these elements are expressed in elementary algebraic functions. Te obtained form is very useful in subsequent numerical experiments. In this work, it also is found that the refection coefcients are diferent for diferent incidence angles  and −. Tus, a structure shows nonreciprocal properties. Tese properties allow us to build nonreciprocal elements in the terahertz domain. Te physical principles of construc- tion of a two-way double-frequency (duplex) isolator are described here. Tese principles are based on dependence Hindawi Publishing Corporation International Journal of Microwave Science and Technology Volume 2016, Article ID 1468508, 7 pages http://dx.doi.org/10.1155/2016/1468508