Estudo sobre geração e manipulação de feixes de luz com Momento Angular Orbital

Abstract

Given that light can carry orbital angular momentum (OAM), in this doctoral dissertation we investigated, in an experimental and theoretical manner, several aspects of optical beams with this property that could somehow contribute to advances in optical communications (OCs). Our investigations include beam generation with new geometries, conservation of OAM, separation and classification of multiplexed OAM states in the coherent and incoherent light scenario and incoherent vortex characterization via coherence function geometry. In our first work we show, theoretically and experimentally, a new method of generating non-diffractive beams that carry OAM with arbitrary geometric shapes through the parameterization of simple curves. The nondiffractive behavior makes these beams more resistant to atmospheric turbulence, which makes them good channels for sending information in a communication system besides being potentially applicable in micromanipulation . We then study the conservation of topological charge (TC) in Laguerre-Gauss (LG) modes diffracted by arbitrary openings. The conservative character of TC implies the conservation of OAM. Thus, knowing that it is possible to encode information in OAM states, the importance of this study for OCs is observed, since the data sent in a OC system is expected to be robust in propagation. In another of our investigations, coherent multiplexed OAM states were separated and classified using a high-resolution classification scheme. This same scheme was used to classify incoherent pure OAM states. In the OC scenario, this research contributes to the efficient decoding of information, increased data sending capacity and security of an optical communication system. Finally, we explore geometric aspects of the coherence function of autocorrelation of incoherent optical vortices in order to determine the CT of a given scattered OAM state. This study also contributes to the efficient decoding of information and the security of an optical communication system.