Darvehi, Pegah (2021) Vector field patterning of light: methods and applications. [Tesi di dottorato]
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| Item Type: | Tesi di dottorato |
|---|---|
| Resource language: | English |
| Title: | Vector field patterning of light: methods and applications |
| Creators: | Creators Email Darvehi, Pegah pegah.darvehi@unina.it |
| Date: | 14 July 2021 |
| Number of Pages: | 102 |
| Institution: | Università degli Studi di Napoli Federico II |
| Department: | Fisica |
| Dottorato: | Fisica fondamentale ed applicata |
| Ciclo di dottorato: | 33 |
| Coordinatore del Corso di dottorato: | nome email Capozziello, Salvatore salvatore.capozziello@unina.it |
| Tutor: | nome email Marrucci, Lorenzo UNSPECIFIED |
| Date: | 14 July 2021 |
| Number of Pages: | 102 |
| Keywords: | orbital angular momentum of light, spin angular momentum, optical fibers, structured light, polarization, singularity |
| Settori scientifico-disciplinari del MIUR: | Area 02 - Scienze fisiche > FIS/03 - Fisica della materia |
| Date Deposited: | 15 Jul 2021 08:43 |
| Last Modified: | 07 Jun 2023 11:17 |
| URI: | http://www.fedoa.unina.it/id/eprint/13603 |
Collection description
Light (electromagnetic field in general) is a main form of energy in nature. Thanks to centuries of scientific investigations, we nowadays possess a fairly complete knowledge of its properties and behavior. In particular, conserved quantities, such as energy and momentum of light, have been the subject of experimental and theoretical activities leading to a great advancement of science and technology. The momentum of light can be distinguished in two different kinds, that is, linear momentum and angular momentum. The main focus of this work is on the angular momentum of light and its manipulation in order to control the vectorial pattern of the light field. The angular momentum of the electromagnetic field expresses two different forms of rotation called spin angular momentum and orbital angular momentum. We focus on the cases in which these two rotations can be considered independent. The first is related to the state of the polarization, and the second to the spatial distribution of the beam. Since they are independent, each of these two rotations can be studied separately and used in different applications. The interaction between them, however, attracts great attention, since a beam may possess both at the same time. The device called q-plate is one possible technique which results in spin-orbit coupling. In this work, we present the importance of the interaction of spin and orbital angular momentum for certain applications. For this purpose, we have designed devices (e.g., q-plates) that combine both forms of angular momentum. This thesis consists of four chapters as follows: • Chapter 1: In this chapter, we give an introduction about light angular momentum, in particular orbital angular momentum. Various methods for generating helical modes, in particular q-plates, are discussed. • Chapter 2: In this chapter, we discuss the optical fibers and the coupling efficiency in the fundamental mode of a single-mode step-index fiber. The main focus of this chapter is on amplitude matching to increase the coupling efficiency. • Chapter 3: Reaching the highest possible coupling efficiency cannot be achieved by amplitude matching alone. Another important factor is polarization matching, which is the interest of this chapter. We present a novel application for q plates to improve the coupling efficiency by manipulating the polarization structure of the input beam. • Chapter 4: In this last chapter, we investigate the possibility of beam tailoring and polarization singularity generation using Spatially Varying Axes retardation wave Plates (SVAPs), devices which generalize the q-plates. Finally, we conclude this work by presenting the results and possible prospects for future work.
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