Fractal graphene patch plasmon-polariton nanoantenna for near infrared and optical frequency ranges

Background. Due to their multi- and broadband,miniaturization and planar design, fractal patch nanoantennas are widely used in wireless communication system in the gigahertz frequency range. There are successful attempts to use then also at terahertz and optical frequencies. In this case, graphene is very promising material for the patch due to its of high electrical conductivity and the convenience of exciting surface plasmon-polariton waves. In this regard, the purpose of the study is to design a fractal graphene plasmonpolariton patch nanoantenna for operation in the near IR and optical part of the electromagnetic wave spectrum and mathematical modeling of its characteristics. Materials and methods. A graphene patch in the form of a triangular Sierpinski carpet in the 4th iteration on a dielectric substate of silicon carbide, gallium arsenide or quartz deposited on a metal ground electrode is proposed. A gate voltage is applied between the patch and the grounded electrode to shift the Fermi level in graphene relative to the Dirac point. In the theoretical part of the work, well-known provisions from graphene physics, fractal theory and microwave electronics and antenna-feeder technology are used. The simulation was performed using the Microwave Studio software package. Results. For the reference model of a nanoantenna with a graphene fractal patch in the form of a Sierpinski triangle in the 4th iteration with a side of a large triangle of 625 nm on the a dielectric substrate of silicon carbide with a thickness of 10 nm, the following results were obtained: resonant frequencies is – 204 THz, 356 THz, 583 THz, 912 THz, 1294 THz; VSWR – no higher than 1.7; the input impedance is from 29 to 42 ohms. The maximum gain (at the frequency of 583 THz) reaches a value of 7.43 dB, the angular width of the main lobe is 91.8 º, the level of the side lobes is 9.1 dBm less than the level of the main lobe. In order to optimize the material and thickness on them has been studied. Conclusion. The possibility of creating fractal patch nanoantennas on graphene for operation in the near-infrared and optical part of electromagnetic radiation is shown. The results of the work can be used in the design of these antennas and the calculation of their characteristics.