Transverse-electric surface plasmon polaritons in homogeneous and periodic graphene systems

Ahmad, Zeeshan 2022. Transverse-electric surface plasmon polaritons in homogeneous and periodic graphene systems. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

Metamaterials making use of conductors have been shown to manipulate light in ways difficult for dielectric photonic devices, owing to the dispersive conductivity response. For example, light can be “sqeezed” through subwavelength metallic apertures, which is not possible for a dielectric aperture. This allows optical metamaterial devices to be augmented by plasmon polariton devices, increasing their capability whilst minimising design complications. One particular subject matter of interest is the existence of surface plasmon polariton (SPP) in the transverse electric (TE) polarisation in graphene. The terahertz frequency range of this mode makes this mode a suitable candidate for devices operating in the infrared frequencies. The contribution of this thesis is that of showing that the TE SPP electromagnetic modes can exist outside the earlier reported range of frequency between 1.667 and 2, normalised with respect to the chemical potential, in graphene. We find that these electromagnetic modes may have either evanescent or exponentially growing field profile perpendicular to graphene, depending on the mode frequency. The dispersion of these TE SPP modes lies below the light cone, not allowing resonant excitation, meaning that an incident beam of light in a dielectric can not have the frequency and wavenumber matching that of the TE modes. We propose a graphene grating, in which TE SPPs can produce sharp and prominent transmission spectra resonances, showing that excitation is possible. The position of the sharp features can be tuned for desired frequency and in-plane wavenumber, by choosing the chemical potential, temperature, and period of the grating. Thus the TE SPP mode in graphene is a prospective for optical devices that would benefit from the tunability, high in-plane velocity, and terahertz frequency range of the mode.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Physics and Astronomy
Subjects:	Q Science > QC Physics
Uncontrolled Keywords:	Surface plasmon polariton, plasmons, graphene, Plasmonics, carbon-based systems, optical grating, surface plasmon, scattering matrix
Funders:	EPSRC
Date of First Compliant Deposit:	8 June 2023
Last Modified:	09 Jun 2023 10:33
URI:	https://orca.cardiff.ac.uk/id/eprint/160263

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