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.