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Detalhes

Detalhes

  • Nome

    Ariel Guerreiro
  • Cargo

    Responsável de Área
  • Desde

    01 maio 2007
002
Publicações

2024

Exploring new phenomena in analogue physical simulations through an optical feedback loop in paraxial light fluids

Autores
Ferreira, TD; Guerreiro, A; Silva, NA;

Publicação
NONLINEAR OPTICS AND ITS APPLICATIONS 2024

Abstract
Exploring optical analogues with paraxial fluids of light has been a subject of great interest over the past years. Despite many optical analogues having been created and explored with these systems, they have some limitations that usually hinder the observation of the desired dynamics. Since these systems map the effective time onto the propagation direction, the fixed size of the nonlinear media limits the experimental effective time, and only the output state is accessible. In this work, we present a solution to overcome these problems in the form of an optical feedback loop, which consists of reconstructing the output state, by using the off-axis digital holography technique, and then re-injecting it again at the entrance of the medium through the utilization of Spatial Light Modulators. This technique enables access to intermediate states and an extension of the system effective time. Furthermore, the total control of the amplitude and phase of the beam at the input of the medium, also allows us to explore more exotic configurations that may be interesting in the context of optical analogues, that otherwise would be hard to create. To demonstrate the capabilities of the setup, we explore qualitatively some case studies, such as the dark soliton decay into vortices with the propagation of shock waves, and the collision dynamics between three flat-top states. The results presented in this work pave the way for probing new dynamics with paraxial fluids of light.

2023

A Multi-Plasmonic Approach for Simultaneous Measurements based on a D-Shaped Photonic Crystal Fiber Sensor: from Temperature to Optical Dispersion

Autores
Romeiro, F; Cardoso, P; Silva, O; Costa, CWA; Giraldi, MR; Santos, L; Baptista, M; Guerreiro, A;

Publicação
Journal of Microwaves, Optoelectronics and Electromagnetic Applications

Abstract
The growing demand for multiparameter sensors includes compact devices accompanied by simple calibration processes to distinguish the outputs from each other. This paper evaluates a scheme to determine multiple parameters of a medium using localized surface plasmon resonances (SPR) excited on a Dshaped photonic crystal fiber (PCF) partially covered by two gold layers of different thicknesses. We demonstrate that the proposed sensing platform, once customized to characterize the possible dispersive profiles of the refractive index of the analyte, also allows interrogating the temperature of a sample from a linear relationship. Since the plasmonic resonances are excited at separated and low crosstalk spectral channels, different sensing responses can be obtained simultaneously in the same location of the D-shaped PCF. These features turn out the SPR sensor a suitable tool for simultaneous monitoring of optical dispersion and temperature. © 2023 SBMO/SBMag.

2023

Exploring the hidden dimensions of an optical extreme learning machine

Autores
Silva, D; Ferreira, T; Moreira, FC; Rosa, CC; Guerreiro, A; Silva, NA;

Publicação
JOURNAL OF THE EUROPEAN OPTICAL SOCIETY-RAPID PUBLICATIONS

Abstract
Extreme Learning Machines (ELMs) are a versatile Machine Learning (ML) algorithm that features as the main advantage the possibility of a seamless implementation with physical systems. Yet, despite the success of the physical implementations of ELMs, there is still a lack of fundamental understanding in regard to their optical implementations. In this context, this work makes use of an optical complex media and wavefront shaping techniques to implement a versatile optical ELM playground to gain a deeper insight into these machines. In particular, we present experimental evidences on the correlation between the effective dimensionality of the hidden space and its generalization capability, thus bringing the inner workings of optical ELMs under a new light and opening paths toward future technological implementations of similar principles.

2023

Deep learning-based fully automatic segmentation of whole-body [18F]FDG PET/CT images from lymphoma patients: addition of CT data has poor impact on networks performance

Autores
Constantino, CS; Oliveira, FPM; Leocádio, S; Silva, M; Oliveira, C; Castanheira, JC; Silva, A; Vaz, S; Teixeira, R; Neves, M; Lúcio, P; Joao, C; Vinga, S; Costa, DC;

Publicação
EUROPEAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING

Abstract

2022

Tunable Plasmonic Resonance Sensor Using a Metamaterial Film in a D-Shaped Photonic Crystal Fiber for Refractive Index Measurements

Autores
Cardoso, MP; Silva, AO; Romeiro, AF; Giraldi, MTR; Costa, JCWA; Santos, JL; Baptista, JM; Guerreiro, A;

Publicação
APPLIED SCIENCES-BASEL

Abstract
Subwavelength cells of metallic nanorods arrayed in a dielectric background, termed "metamaterials", present bulk properties that are useful to control and manipulate surface plasmon resonances. Such feature finds tremendous potential in providing a broad manifold of applications for plasmonic optical sensors. In this paper, we propose a surface-plasmon-resonance-based sensor with spectral response tunable by the volume fraction of silver present in a metamaterial layer deposited on a D-shaped photonic crystal fiber. Using computational simulations, we show that sensitivity and resolution can be hugely altered by changing the amount of constituents in the metamaterial, with no further modifications in the structure of the sensor. Moreover, the designed sensor can also be applied to label the average volume fraction of silver in the metamaterial layer and then to estimate its effective constitutive parameters.

Teses
supervisionadas

2023

Advances in Paraxial Fluids of Light with Photorefractive Media

Autor
Tiago David da Silva Ferreira

Instituição
UP-FCUP

2022

Optical Analogues: A Stepping Stone into Quantum Simulations and Computation

Autor
Tiago David da Silva Ferreira

Instituição
UP-FCUP

2022

Optical Extreme Learning Machines: a new trend in optical computing

Autor
Duarte José Fernandes da Silva

Instituição
UP-FCUP

2022

Towards Realtime Classification of Optically Trapped Particles

Autor
Vicente Vieira Rocha

Instituição
UP-FCUP

2021

Optical Analogues: A Stepping Stone into Quantum Simulations and Computation

Autor
Tiago David da Silva Ferreira

Instituição
UP-FCUP