Theses and Dissertations

Zhangjin Xu

Issuing Body

Mississippi State University

Advisor

Arnoldus, Henk F.

Committee Member

Wang, Chuji

Committee Member

Pierce, Donna M.

Committee Member

Pradhan, Prabhakar

Committee Member

Koshka, Yaroslav

Date of Degree

5-1-2020

Document Type

Dissertation - Open Access

Major

Engineering/Applied Physics

Degree Name

Doctor of Philosophy

College

College of Arts and Sciences

Department

Department of Physics and Astronomy

Abstract

In this dissertation we have studied nearield phenomena in dipole radiation. We have studied first the energy flow patterns of the radiation emitted by an electric dipole located in between parallel mirrors. The field lines of the Poynting vector have intricate structures, including many singularities and vortices. For a dipole parallel to the mirror surfaces, vortices appear close to the dipole. Vortices are located where the magnetic field vanishes. Also, a radiating electric dipole near the joint of two orthogonal mirrors is considered, and also here we find numerous singularities and vortices in the energy flow patterns. We have also studied the current density in the mirrors. Next we have studied the reflection of radiation by and the transmission of radiation through an interface with an  -near-zero (ENZ) material. For p polarization, we find that the reflection coefficient is -1, and the transmission coefficient is zero for all angles of incidence. The transmitted electric field is evanescent and circularly polarized. The transmitted magnetic field is identically zero. For s polarization, the transmitted electric field is s polarized and the transmitted magnetic field is circularly polarized. The next topic was the study of the force exerted on the dipole by its own reflected field near an ENZ interface. We found that, under certain circumstances, it could be possible that the dipole would levitate in its reflected field. This levitation is brought about by evanescent reflected waves. Finally, power emission by an electric dipole near an interface was considered. We have derived expressions for the emitted power crossing an interface. The power splits in contributions from traveling and evanescent incident waves. We found that for an ENZ interface, only evanescent dipole waves penetrate the material, but there is no net power flow into the material.

URI

https://hdl.handle.net/11668/16683

Comments

Dipole radiation||Energy flow||Epsilon-near-zero (ENZ) material||Reflection and transmission of radiation||Levitation force||Power emission

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