Prof. Asghar Asgari
University of Tabriz, Iran
Prof. Asghar Asgari
Research Institute for Applied Physics and Astronomy
University of Tabriz, Tabriz, Iran
The leaky and bound modes of grapheme surface plasmons for plasmonics devices
Jun Tanida and Ryoichi Horisaki
Special properties of Surface Plasmon Polaritons (SPPs) in the manipulation of light in small scales compared with the light wavelength, propose it to use for applications in sub-wavelength optics. On the other hand, graphene with special optical and electronic properties provided new potential for surface wave propagation and they are capable to propagate SPPs in the THz frequencies. Furthermore graphene SPPs (GSPPs) are tunable in characteristics by adjusting electrostatic gating or chemical doping. GSPPs have been utilized in design and improvement a variety of devices such as THz antennas, switches, sensors and waveguides. In this article the dispersion equation for TM polarized surface plasmon modes in the graphene layer embedded in a layered structure has been derived and numerically solved in THz frequencies. Our model results show that this configuration, depending on the frequency region, can support both bound and leaky surface plasmons. Investigation of the supporting frequency region, electromagnetic field distribution and propagation length of these two modes have been studied. Our investigations show that in spite of the well-known bound mode, leaky surface plasmon polaritons can be supported by such systems depending on the geometrical parameters and the frequency. Indeed, THz region of frequency is divided into two regions: leaky and bound, separated by a spectral gap. The spectral position of this gap depends on the structural parameters. Coupling the field of GSPPs to far-field radiation in the leaky region enables the detection of GSPPs via a high refractive index medium, and conversely, excitation of GSPPs by means of far field illumination is possible in this region.
Asghar Asgari is borne in Iran at 1973. He got his BSc and MSc in Solid State Physics and Electronics from University of Tabriz, Iran. He got his PhD under Prof. M. Kalafi from University of Tabriz and Prof. L. Faraone from University of Western Australia, supervisions. In 2002 he joined Microelectronics Research Group in the University of Western Australia as research associate. In 2004, he started his work in Photonics group at the University of Tabriz in Iran. Currently he is Professor in Photonics Group at University of Tabriz and also Adjunct Professor in Microelectronics Research group at the University of Western Australia.