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About


Maria Inês Carvalho graduated in Electrical and Computer Engineering from the University of Porto in 1990 and received her M.S. and Ph.D. degrees in Electrical Engineering from Lehigh University, USA, in 1994 and 1996, respectively. She joined the Electrical and Computer Engineering Department at the University of Porto in 1996 as an assistant professor, where she is presently an associate professor. In 2009 she joined INESC TEC as a researcher. Her main research area has been the propagation of light in nonlinear media. Her work includes both the theoretical modeling of these phenomena and their numerical simulation and has addressed, among others, soliton beams in photorefractive media, incoherent solitons and microstructured optical fibers. She is a member of the Optical Society of America.

Interest
Topics
Details

Details

003
Publications

2019

Estimation of atmospheric turbulence parameters from Shack-Hartmann wavefront sensor measurements

Authors
Andrade, PP; Garcia, PJV; Correia, CM; Kolb, J; Carvalho, MI;

Publication
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY

Abstract
The estimation of atmospheric turbulence parameters is of relevance for the following: (a) site evaluation and characterization; (b) prediction of the point spread function; (c) live assessment of error budgets and optimization of adaptive optics performance; (d) optimization of fringe trackers for long baseline optical interferometry. The ubiquitous deployment of Shack-Hartmann wavefront sensors in large telescopes makes them central for atmospheric turbulence parameter estimation via adaptive optics telemetry. Several methods for the estimation of the Fried parameter and outer scale have been developed, most of which are based on the fitting of Zernike polynomial coefficient variances reconstructed from the telemetry. The non-orthogonality of Zernike polynomial derivatives introduces modal cross coupling, which affects the variances. Furthermore, the finite resolution of the sensor introduces aliasing. In this article the impact of these effects on atmospheric turbulence parameter estimation is addressed with simulations. It is found that cross-coupling is the dominant bias. An iterative algorithm to overcome it is presented. Simulations are conducted for typical ranges of the outer scale (4-32 m), Fried parameter (10 cm) and noise in the variances (signal-to-noise ratio of 10 and above). It is found that, using the algorithm, both parameters are recovered with sub-per cent accuracy.

2019

Dissipative solitons for generalizations of the cubic complex Ginzburg-Landau equation

Authors
Carvalho, MI; Facao, M;

Publication
PHYSICAL REVIEW E

Abstract
We found stable soliton solutions for two generalizations of the cubic complex Ginzburg-Landau equation, namely, one that includes the term that, in optics, represents a delayed response of the nonlinear gain and the other including the self-steepening term, also in the optical context. These solutions do not require the presence of the delayed response of the nonlinear refractive index, such that, they exist regardless of the term previously considered essential for stabilization. The existence of these solitons was predicted by a perturbation approach, and then confirmed by solving the ordinary differential equations, resulting from a similarity reduction, and also by applying a linear stability analysis. We found that these solitons exist for a large region of the parameter space and possess very asymmetric amplitude profiles as well as a complicated chirp characteristic.

2018

Evaluation of SAR induced by a planar inverted-F antenna based on a realistic human model

Authors
Vieira, VF; Pessoa, LM; Carvalho, MI;

Publication
IFMBE Proceedings

Abstract
In this paper the absorption by the human body of electromagnetic (EM) radiation generated by a Planar Inverted-F Antenna (PIFA) from a modern mobile phone is investigated through the evaluation of the Specific Absorption Rate (SAR) in head, brain and hand regions using Sim4Life (S4L) and a realistic anatomical model. Several scenarios were evaluated, by varying the distance between the antenna and the head, the feeder position and the orientation of the antenna. The effect of the presence of the hand was also studied and, finally, different communication bands were considered. The main results show that the presence of the hand is determinant to reduce SAR on head and brain, while bottom orientations of the antenna reduce the SAR on the brain, but increase the SAR in other tissues. © Springer Nature Singapore Pte Ltd. 2018.

2018

Skeletal muscle dispersion (400-1000?nm) and kinetics at optical clearing

Authors
Oliveira, LM; Carvalho, MI; Nogueira, EM; Tuchin, VV;

Publication
Journal of Biophotonics

Abstract

2017

Plain and oscillatory solitons of the cubic complex Ginzburg-Landau equation with nonlinear gradient terms

Authors
Facao, M; Carvalho, MI;

Publication
PHYSICAL REVIEW E

Abstract
In this work, we present parameter regions for the existence of stable plain solitons of the cubic complex Ginzburg-Landau equation (CGLE) with higher-order terms associated with a fourth-order expansion. Using a perturbation approach around the nonlinear Schrdinger equation soliton and a full numerical analysis that solves an ordinary differential equation for the soliton profiles and using the Evans method in the search for unstable eigenvalues, we have found that the minimum equation allowing these stable solitons is the cubic CGLE plus a term known in optics as Raman-delayed response, which is responsible for the redshift of the spectrum. The other favorable term for the occurrence of stable solitons is a term that represents the increase of nonlinear gain with higher frequencies. At the stability boundary, a bifurcation occurs giving rise to stable oscillatory solitons for higher values of the nonlinear gain. These oscillations can have very high amplitudes, with the pulse energy changing more than two orders of magnitude in a period, and they can even exhibit more complex dynamics such as period-doubling.

Supervised
thesis

2017

Effect of electromagnetic fields induced by mobile devices in the human brain

Author
Vânia Filomena Madureira Vieira

Institution
UP-FEUP

2016

Optical characterization of atmospheric turbulence

Author
Paulo Alexandre Paiva de Andrade

Institution
UP-FEUP