Abstract 

A tunable optical amplitude modulator (gate) based on a periodically corrugated two-mode waveguide made of electrooptic material is proposed. In such a waveguide, in the presence of the electrooptic Pockels effect, hybridization of the two waveguide modes and, as a result, formation of a band gap in a certain frequency range degenerate to the polarization of the waveguide mode (the so-called degenerate band gap or intra-Brillouin band gap) can be realized. For the example of a planar waveguide with a sinusoidal corrugated top surface made of a lithium niobate-like material, the characteristics of the degenerate band gap have been numerically calculated. It has been shown that the band gap was formed simultaneously for both waveguide modes. Moreover, outside the band gap, the transmission coefficient of the wave through the modulator for the polarization coinciding with the polarization of the incident wave was more than 90% by power, while the transmission coefficient for the cross-polarization was less than 0,1% by power in the presence of the mode hybridization over the entire frequency range in the vicinity of the band gap. Inside the band gap, the main reflection occurs into the cross-polarization (more than 95% by power), while the reflection into the polarization corresponding to the polarization of the incident wave was less than 2% by power over the entire frequency range in the vicinity of the band gap. The estimated efficiency of the proposed modulator (the electrical voltage providing the electrooptic effect times the waveguide length for which the transmission coefficient becomes less 10% by power) was about 2 V*cm, which corresponds to the typical efficiency values for integrated waveguide electrooptic modulators presented in the literature.

Keywords: Electrooptic modulator, Pockels effect, degenerate band gap, corrugated waveguide, polarization rotation

EFFECTIVE WAVE VECTOR OF RADIATION IN A TWO-DIMENSIONAL TWO-COMPONENT COMPOSITE MATERIAL
R.S. Puzko, A.M. Merzlikin

Abstract 

The effective wave vector of radiation propagating through a two-dimensional two-component checkerboard composite material has been studied. It is shown that in the long-wavelength limit the effective wave vector converges to the electrostatic solution for a statistically symmetric two-component composite.

Keywords: composite material, homogenization theory

ORDERED STATES IN THE SU(4)-SYMMETRIC MODEL OF AA BILAYER GRAPHENE
A.V. Rozhkov, A.O. Sboychakov

Abstract 

In this paper we discuss the classification of ordered states for model of bilayer AA graphene based on the SU(4) matrix group. Such a wide group of symmetries arises due to the unification of spin and the so-called valley degeneracy into a broad multiplet, typical for graphene and other two-dimensional materials based on it. We describe the construction of an effective theory demonstrating the SU(4) invariance, and discuss the mean field investigation of the resulting Hamiltonian. Ordered states of such a system are represented by a unifying SU(4)-invariant self-consistency equation. We will explicitly construct three different classes of solutions for the derived self-consistency equation. Using the SU(4) invariance, we generalize a previously published topological classification scheme for non-superconducting ordered states in bilayer AA graphene.

Keywords: bilayer AA graphene, ordered state, SU(4) group

Section 2. Topics on experimental electrodynamics

ASSESSMENT OF THE INFLUENCE OF THE INTERACTION OF AN OBJECT WITH A MONORAIL HOIST ON THE RESULTS OF MEASUREMENTS OF ITS RCS
N.P. Balabukha, A.S. Zubov, N.L. Menshikh, V.S. Solosin

Abstract 

The paper presents an assessment of the influence of the interaction of the measurement object with the hoist monorail during experimental studies of the scattering characteristics of objects in, as example, the Automated measuring complex - a compact range of ITAE RAS. The hoist monorail is used to install measurement objects on positioners, as well as to install the positioners themselves, and therefore passes directly above the quiet zone of the measuring complex. Model problems for measuring the scattering characteristics of an ideally conducting disk are considered, which clearly show that the signal from interaction with a monorail can exceed the measured signal from the object itself. The problems were solved in the optical approximation. To assess some of the design features of the monorail, the scattered field of the monorail was calculated using the method of integral equations. It was revealed that the results of measuring scattering characteristics can be influenced not only by re-reflections between the object and the bottom flange of the monorail, but also by re-reflections associated with the presence of a dihedral corner formed by the upper part of the channel and its vertical wall. A scheme for covering the monorail with a broadband radio-absorbing coating has been proposed to reduce this influence on the measurement results. The proposed scheme was implemented for the measuring complex under consideration.

Keywords: compact range, interference signals, anechoic chamber, radar cross section, physical optics method

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