Spatial State Tomography of Beams Passing Through Nanostructures

• Grant number: 25/21501-5
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate (Direct)
• Start date: February 27, 2026
• End date: June 27, 2026
• Field of knowledge: Physical Sciences and Mathematics - Physics
• Principal Investigator: Antonio Zelaquett Khoury
• Grantee: Altilano Cristino Barbosa
• Supervisor: Gabriel Molina Terriza
• Host Institution: Instituto de Física. Universidade Federal Fluminense (UFF). Niterói , SP, Brazil
• Institution abroad: Universidad Del País Vasco, Campus De Gipuzkoa, Spain
• Associated to the scholarship: 22/15035-3 - Optical communication with structured light, BP.DD

Abstract

This project proposes the realization of spatial tomography of structured light beams after their interaction with nanostructures, specifically nanoholes. The research will be carried out during a four-month internship at the Materials Physics Center of the University of the Basque Country, under the supervision of Prof. Dr. Gabriel Molina-Terriza, in collaboration with Altilano Cristino Barbosa from the group of Prof. Dr. Antonio Zelaquett Khoury (UFF).The project builds upon an ongoing collaboration between the UFF and Basque Country groups, initiated with the article "Informationally complete orbital-angular-momentum tomography with intensity measurements." This collaboration aims to experimentally characterize the effect of nanoholes on strongly focused light beams, a regime in which the paraxial approximation and the scalar description of diffraction are no longer valid. In this context, it becomes essential to account for the vectorial nature of the electromagnetic field, as degrees of freedom such as orbital angular momentum and spin angular momentum may couple during the interaction with the nanostructure.The proposed methodology consists of employing advanced modeling techniques, such as the Debye integral, to describe propagation in high-focusing regimes, and applying spatial state tomography to experimentally characterize the transformations induced by the system (objective lens - nanohole - objective lens). The experimental strategy includes assembling a tomography setup using simple optical elements (lenses, cameras, mirrors, and irises), in parallel with the development of simulation codes in Python.The work plan foresees: (i) literature review and the beginning of simulation programming in the first month; (ii) assembly of the experimental setup and adaptation of tomography methods by the third month; (iii) theoretical, computational, and experimental analysis of results during the third and fourth months.From a scientific perspective, the project will advance the understanding of the interaction between structured light and nanostructures, particularly in the non-paraxial regime, and will enable the characterization of coupling processes between different degrees of freedom of light.