Abstract-Dual-broadband and single ultrawideband absorbers from the terahertz to infrared regime

 

Saeedeh Barzegar-Parizi, Amir Ebrahimi, and Kamran Ghorbani

https://www.osapublishing.org/josab/abstract.cfm?uri=josab-38-9-2628

This paper presents the design and analysis of broadband metamaterial absorbers with single and dual absorption bands from terahertz to infrared frequencies. The absorbers are made of a composite graphene/metallic structure. A metallic patch array is printed on a ground-plane-backed dielectric slab. A graphene patch array is stacked on top of the metallic array, whereas a dielectric spacer separates the graphene and patch spacer from each other. The tunable property of the graphene surface conductivity at terahertz frequencies together with the complex permittivity of metal at the infrared regime are used to design broadband absorbers from the terahertz to infrared regime. The design is based on the combination and excitation of the plasmon polaritons of graphene and metallic patterned arrays at terahertz and infrared frequency bands, respectively. Two broad absorption bands occur from 4.56–9.02 THz and 16.95–60.23 THz with the fractional bandwidths of 67% and 112%, respectively. Furthermore, by a proper design of the parameters, a single ultrawide absorption spectra from 6.6–58.13 THz can be achieved with a fractional bandwidth 160%. In order to validate the simulation results, a circuit model-based analysis is developed, where the patterned arrays are modeled as the surface admittances, and the dielectric spacers are modeled by transmission line stubs. The results obtained by the full-wave simulations in the high-frequency structure simulator are in good agreement with the circuit model results. The absorbers show great stability with respect to the incidence angle for both the transverse electric and transverse magnetic waves.

© 2021 Optical Society of America

Abstract-A. Ebrahimi, Miniaturised-elements frequency selective surfaces for microwave and terahertz applications,18th February 2016.

https://blogs.adelaide.edu.au/eleceng-announcements/2016/02/10/a-ebrahimi-miniaturised-elements-frequency-selective-surfaces-for-microwave-and-terahertz-applications18th-february-2016/

Frequency selective surfaces (FSSs) are usually formed by two-dimensional periodic arrangement of metallic elements on a dielectric substrate. Based on the geometry and arrangement of the metallic unit cell, the array might show different functionalities such as bandpass or bandstop spatial filter. The FSS functionality is mainly determined by its unit cell geometry and dimension. In terms of the unit cell properties, the FSSs can be divided into two major subclasses as: (i) Traditional FSSs based on resonant element unit cells, (ii) miniaturised elements FSSs based on non-resonant unit cells.

In this talk, we will present our recent research results on the design of high-performance FSSs based on miniaturised elements. The miniaturised element FSSs are considered for tunable microwave FSSs. The application of the miniaturised elements in designing a second-order bandpass terahertz FSS will also be presented and discussed.

Biography:

Amir Ebrahimi received the B.Sc. degree in electrical and computer engineering from the University of Mazandaran, Iran, in 2008, and the M.Sc. degree in electronic engineering with first class honours from Babol University of Technology, Babol, Iran. From2009 to 2012, hewas a research assistant in Integrated Circuits Research Laboratory (ICRL), Babol University of Technology. In 2012, he started his PhD degree in the School of Electrical & Electronic Engineering, The University of Adelaide. During 2014–2015, he was a visiting scholar in the School of Electrical & Electronic Engineering, Nanyang Technological University (NTU), Singapore.

During his candidature, Mr Ebrahimi received a number of awards and scholarships including, the International Postgraduate Research Scholarship (IPRS) by the Australian Government (2012), Australian Postgraduate Award (APA) (2012), Australian National Fabrication Facility (ANFF) award for fabricating high performance microwave microfluidic sensors in collaboration with the Ian Wark Research Institute, University of South Australia (2013), the University of Adelaide D. R. Stranks Traveling Fellowship (2014), the Simon Rockliff Scholarship for outstanding postgraduate mentorship from DSTO (2015), and the Yarman-Carlin best student paper award at the Mediterranean Microwave Symposium, Lecce, Italy (2015). Mr Ebrahimi has served as a reviewer for a number of recognised journals including IEEE Microwave and Wireless Components Letter, IEEE Sensors Journal, Applied Physics Letters, and Journal of Applied Physics.