Dissertations and Theses

Date of Award

2024

Document Type

Dissertation

Department

Engineering

First Advisor

Robert R. Alfano

Keywords

Optics, Photonics, Orbital angular momentum, Spin angular momentum, Optical Kerr effect, light

Abstract

Photons possess many characteristics such as wavelength, coherence, speed, polarization and wavefront. The aim of this thesis is the study of two salient properties of light exploring light carrying polarization and space degree of freedom of the wavefront. The wavefront of light is complex with different states of polarization. Special light beams are generated and characterized for interaction with liquids, solids, vapors, and bio- materials to understand fundamental processes such as Transmission, Raman scattering, and Optical Kerr Effect in steady state and temporal domains.

It has been more than hundred years since it is known that light can carry other polarizations such as circular polarization. This type of polarization is associated to the spin angular momentum (SAM) of a photon is described by , which indicates a left-handed () and right-handed () circularly polarized light respectively. Currently there are other exotic forms of polarizations described as cylindrical vector beams such as radial and azimuthal polarization, which have inhomogeneous polarization structure. These beams are best known for possessing a high degree of symmetry, for having strong longitudinal fields when tightly focused and for having a total angular momentum of . Since 1992, the other form of chirality is associated with a beam’s wavefront where in addition to the SAM; a photon can carry orbital angular momentum (OAM). This type of beam is characterized as a phase vortex and inherits a ‘donut-like’ topology. OAM beams are generated when the light bends forming a helical wavefront. These are characterized by an azimuthal phase dependence of exp (if), where f is the azimuthal coordinate in the beam’s cross section, and is an integer value, which indicates if the beam twists clockwise or counterclockwise. Also, the dictates how many intertwined helical phases front the beam has. The OAM value carried by a photon is represented by L=.

In this research proposal, various types of opto–devices are used to generate beams carrying SAM and OAM and special photons such as Majorana-like photons, which is also expanded for the generation of Majorana Supercontinuum. The beam’s SAM and OAM state are characterized by several methods. Subsequently, these beams are applied in light-matter interaction processes. We study the direct effect of OAM and SAM in these optical processes, which could possibly change the selection rules and strength of the optical interactions. The goal is to probe fundamental biological, chemical and physical processes in materials such as biological tissues, liquids, solids, and vapors. Our results will include new interpretations of the interaction and effect that OAM and SAM on chiral and non-chiral materials, where upon the multipole moment of the light (OAM) and the material affect the strength of the light matter interaction These interpretations will help to understand and expand our future work on the quantum mechanical effect of SAM and OAM involving the selection rules and multipole expansion of the light and the material involved in the process. This new research on special forms of light will also contribute and advance the fields of imaging, communications (in the classical and quantum regime), spintronics, and orbitronics.

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