Abstract-Graphene layered systems as a terahertz source with tuned frequency

K. Batrakov and S. Maksimenko

https://journals.aps.org/prb/abstract/10.1103/PhysRevB.95.205408

The propagation of an electron beam over a graphene/dielectric sandwich structure is considered assuming the distance between the graphene layers in sandwich is large enough to prevent interlayer tunneling. A dispersion equation for the surface electromagnetic modes propagating along graphene sheets is derived and Čerenkov synchronism between a surface wave and a nonrelativistic electron beam is predicted at achievable parameters of the system. Generation frequency tuning is proposed by varying the graphene doping, the number of graphene sheets, the distance between sheets, etc.

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Abstract-F Electromagnetic and thermal properties of three-dimensional printed multilayered nano-carbon/poly(lactic) acid structures

A. Paddubskaya1,2, N. Valynets1, P. Kuzhir1,3,a), K. Batrakov1, S. Maksimenko1,3, R. Kotsilkova4, H. Velichkova4, I. Petrova4, I. Biró5,b),K. Kertész6,c), G. I. Márk6,c), Z. E. Horváth6,c) and L. P. Biró6,c)


a) Author to whom correspondence should be addressed. Electronic mail: polina.kuzhir@gmail.com. Tel.: +375 17 200 7410.
b) URL: http://3dkivansag.blog.hu/
c) URL: http://www.nanotechnology.h
http://scitation.aip.org/content/aip/journal/jap/119/13/10.1063/1.4945576?TRACK=RSS

A new type of light-weight material produced by 3D printing consisting of nano-carbon doped polymer layer followed by a dielectric polymer layer is proposed. We performed temperature dependent characterization and measured the electromagnetic (EM) response of the samples in the GHz and THz range. The temperature dependent structuralcharacteristics, crystallization, and melting were observed to be strongly affected by the presence and the number of nano-carbon doped layers in the sandwich structure. The electromagnetic measurements show a great potential of such a type of periodic materialfor electromagnetic compatibility applications in microwave frequency range. Sandwich structurescontaining only two nano-carbon layers already become not transparent to the microwaves, giving an electromagnetic interference shielding efficiency at the level of 8–15 dB. A sandwich consisting of one nano-carbon doped and one polymer layer is opaque for THz radiation, because of 80% of absorption. These studies serve as a basis for design and realization of specific optimal geometries of meta-surface type with the 3D printing technique, in order to reach a high level of electromagnetic interference shielding performance for real world EM cloaking and EM ecology applications.

Abstract-Enhanced microwave-to-terahertz absorption in graphene

K. Batrakov1,a), P. Kuzhir1, S. Maksimenko1, N. Volynets1, S. Voronovich1, A. Paddubskaya2, G. Valusis2, T. Kaplas3, Yu. Svirko3 andPh. Lambin4
 HIDE AFFILIATIONS
1 Research Institute for Nuclear Problems, Belarusian State University, Minsk 220030, Belarus
2 Center for Physical Sciences and Technology, A. Gostauto 11, Vilnius LT-01108, Lithuania
3 Institute of Photonics, University of Eastern Finland, Joensuu FI-80101, Finland
4 Physics Department, Universite de Namur, 61 Rue de Bruxelles, B-5000 Namur, Belgium
a) Electronic mail: kgbatrakov@gmail.com.
Appl. Phys. Lett. 108, 123101 (2016); http://dx.doi.org/10.1063/1.4944531

Fresnel equations predict that an ultrathin free standing conductive film, thousands times thinner than skin depth, is capable to absorb up to 50% of incident electromagnetic radiations. In the microwave range, the same holds true for a free standing graphene sheet. We demonstrate theoretically and prove experimentally that microwave absorptance of graphene can be enhanced considerably by depositinggraphene on a dielectric substrate. On the experimental side, we obtain 80% and 65% absorptance at 30 GHz and 1 THz, respectively. Theory predicts that higher absorptance can be achieved with a suitable choice of the dielectricpermittivity and the thickness of the substrate. Absorption can also be maximized by choosing the optimum incidence angle for s-polarized waves in free space or by working in the vicinity of the cut-off frequency of the transverse electric mode in waveguide configuration. The polarizationsensitivity of the transmittance and reflectance of graphene layers can be used to tune the polarizationstate of the transmitted and reflected radiations.