Person:
Alda Serrano, Javier

First Name

Javier

Last Name

Alda Serrano

URI

https://hdl.handle.net/20.500.14352/79875

Affiliation

Universidad Complutense de Madrid

Faculty / Institute

Óptica y Optometría

Department

Óptica

Area

Optica

Identifiers

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Now showing 1 - 10 of 22

Multivariate analysis of photonic crystal microcavities with fabrication defects
(Photonic Materials, Devices, and Applications, Pts 1 and 2, 2005) Rico García, José María; López Alonso, José Manuel; Alda Serrano, Javier
Photonic crystal microcavities are defined by the spatial arrangement of materials. In the analysis of their spatial temporal mode distributions Finite-Difference Time-Domain (FDTD) methods have proved its validity. The output of the FDTD can be seen as the realizations of a multidimensional statistic variable. At the same time, fabrication tolerances induce an added and unavoidable variability in the performance of the microcavity. In this contribution we have analyzed the modes of a defective photonic crystal microcavity. The location, size, and shape of the cylinders configuring the microcavity are modelled as having a normal distribution of their parametric descriptors. A principal component analysis is applied to the output of the FDTD for a population of defective microcavities. The relative importance of the defects is evaluated, along with the changes induced in the spatial temporal distribution of electromagnetic field obtained from the calculation.
Application of tomographic techniques to the spatial-response mapping of antenna-coupled detectors in the visible
(Applied Optics, 2008) Rico García, José María; Sánchez Brea, Luis Miguel; Alda Serrano, Javier
A tomographiclike method based on the inverse radon transform is used to retrieve the irradiance map of a focused laser beam. The results obtained from multiple knife-edge measurements have been processed through a kriging technique. This technique allows us to map both the beam irradiance and the uncertainty associated with the measurement method. The results are compared with those achieved in the standard fitting of two orthogonal knife-edge profiles to a modeled beam. The application of the tomographiclike technique does not require any beam model and produces a higher signal-to-noise ratio than the conventional method. As a consequence, the quality of the estimation of the spatial response map of an antenna-coupled detector in the visible is improved.
Angular shifts of paraxial beams by refraction in a plane dielectric/dielectric interface
(Optics Communications, 2002) Alda Serrano, Javier; Rico García, José María
The longitudinal and transverse angular shifts in the refraction of a paraxial beam are calculated by using the plane-wave decomposition of the amplitude of the electric field distribution of the incident beam. The transmission coefficients are expanded into powers of the spatial frequencies. In this paper these spatial frequencies need to be within the paraxial approach around the main direction of propagation of the beam. The beam is characterized by the moments of the square of the modulus of the angular spectrum of the electric field. To compute them, it is necessary to calculate how the spatial frequencies of the beam change along the refraction. The state of polarization of the beam is also included in the analysis. Numerical results are obtained to show the dependence of the angular shifts on the polarization’s state and the symmetry of the beam.
Characterization of FDTD artifacts and modes in photonic crystals
(Proceedings of SPIE, 2004) López Alonso, José Manuel; Rico García, José María; Alda Serrano, Javier
FDTD algorithms are being used as a numeric tool for the analysis of photonic crystals. The definition of the modes associated with them is of interest for the study of the capabilities of photonic crystal devices. The Principal Component Analysis (PCA) has been applied here to a sequence of images corresponding to the electromagnetic fields obtained from the FDTD simulations. PCA has revealed and quantified the importance of the modes appearing in the photonic crystals. The capability of PCA to produce spatial structures, or maps, associated with temporal evolutions has made possible the calculation of the modulus and phase of the modes existing in the photonic crystal. Some other modes, contributing with an almost negligible amount to the total variance of the original data, are also revealed by the method. Besides, PCA has been used to quantify the contribution of the numerical noise of the algorithm and to identify the effect of artifacts related with the matching of the computational grid and the inner geometry of the photonic crystal.
Antenas ópticas y detectores de luz
(Ver y Oír, 2005) Alda Serrano, Javier; López Alonso, José Manuel; Boreman, Glenn; Rico García, José María
La investigación sobre el comportamiento de estructuras metálicas cuyo tamaño es comparable a la longitud de onda de la radiación detectada puede realizarse considerándolas como antenas detectoras de radiación óptica. El diseño, análisis y caracterización de estos dispositivos requiere el estudio de los fenómenos básicos de interacción entre la radiación y la materia. A la vez, su inclusión en sistemas con relevancia tecnológica requiere la medida y caracterización de sus propiedades. Nuestro equipo de investigación, integrado en el «Grupo Complutense de Óptica Aplicada», se ha dedicado durante los últimos años al estudio de estos dispositivos así como a la caracterización de todo tipo de detectores de luz, y a la definición de aquellas figuras de mérito que son relevantes a la hora de establecer su uso.
Principal Component Analysis of Results Obtained from Finite-Difference Time-Domain Algorithms
(Egyptian Journal of Solids, 2006) López Alonso, José Manuel; Rico García, José María; Alda Serrano, Javier
Finite-Differences Time-Domain (FDTD) algorithms are well established tools of computational electromagnetism. Because of their practical implementation as computer codes, they are affected by many numerical artefact and noise. In order to obtain better results we propose using Principal Component Analysis (PCA) based on multivariate statistical techniques. The PCA has been successfully used for the analysis of noise and spatial temporal structure in a sequence of images. It allows a straightforward discrimination between the numerical noise and the actual electromagnetic variables, and the quantitative estimation of their respective contributions. Besides, The GDTD results can be filtered to clean the effect of the noise. In this contribution we will show how the method can be applied to several FDTD simulations: the propagation of a pulse in vacuum, the analysis of two-dimensional photonic crystals. In this last case, PCA has revealed hidden electromagnetic structures related to actual modes of the photonic crystal.
FDTD analysis of nano-antenna structures with dispersive materials at optical frequencies
(Nanotechnology II. Proceedings of the Society of Photo-Optical Instrumentation Engineers, 2005) Rico García, José María; López Alonso, José Manuel; Alda Serrano, Javier
The Finite-Difference Time Domain method has encountered several difficulties when analyzing dispersive materials. This is the case of the metal structures that configure an optical antenna. These devices couple the electromagnetic radiation to conform currents that are rectified by another physical element attached to the antenna. Both elements: antenna and rectifier configures an optical detector with sub-wavelength dimensions. In this contribution we analyze the effect on the currents induced by the incident electromagnetic field using FDTD and taking into account the dispersive character of metal at optical frequencies. The analysis is done in a 2 dimensional framework and it serves as an analytical tool for the election of material and structures in the fabrication of optical antennas.
Measurement limitations in knife-edge tomographic phase retrieval of focused IR laser beams
(Optics Express, 2012) Silva López, Manuel; Rico García, José María; Alda Serrano, Javier
An experimental setup to measure the three-dimensional phase-intensity distribution of an infrared laser beam in the focal region has been presented. It is based on the knife-edge method to perform a tomographic reconstruction and on a transport of intensity equation-based numerical method to obtain the propagating wavefront. This experimental approach allows us to characterize a focalized laser beam when the use of image or interferometer arrangements is not possible. Thus, we have recovered intensity and phase of an aberrated beam dominated by astigmatism. The phase evolution is fully consistent with that of the beam intensity along the optical axis. Moreover, this method is based on an expansion on both the irradiance and the phase information in a series of Zernike polynomials. We have described guidelines to choose a proper set of these polynomials depending on the experimental conditions and showed that, by abiding these criteria, numerical errors can be reduced.
Micro- and Nano-Antennas for Light Detection
(Egyptian Journal of Solids, 2005) Alda Serrano, Javier; Rico García, José María; López Alonso, José Manuel; Boreman, Glenn
Antenna-coupled optical detectors, also named as optical antennas, are being developed as detection devices with micro- and nano-scale features for their use in the millimetre, infrared, and visible spectral range. They are optical components that couple the electromagnetic radiation in the visible and infrared wavelengths in the same way that radioelectric antennas do at the corresponding wavelengths. Optical antennas show polarization dependence, tuneability, and rapid time of response. They also can be considered as point detectors and directionally sensitive elements. So far, these detectors have been operated in the mid-infrared with positive results in the visible. The measurement and characterization of optical antennas requires the use of an experimental set-up with nanometric resolution. On the other hand, a computational simulation of the interaction between the material structures and the incoming electromagnetic radiation is needed to explore alternative designs of practical devices. In this contribution we will present the concept of optical and infrared antennas, and some experimental results of their performance, along with the experimental set-up arranged for their characterization in the visible
Finite-difference time-domain simulation of low-F# Fresnel zone plates coupled to IR antennas
(Proceedings of SPIE, 2004) Rico García, José María; López Alonso, José Manuel; Lail, Brian; Boreman, Glenn; Alda Serrano, Javier
Fresnel Zone Plate Lenses (FZPLs) have been successfully coupled to infrared (IR) antennas producing a responsivity enhancement of about two orders of magnitude. However, their lateral extension may compromise their applicability in focal-plane-arrays (FPA) IR imagers, where the dimensions of the pixel are constrained by the FPA spacing. When designing optimum-gain FZPLs for FPAs, we are lead to the requirement of FZPLs operating at very low F/#s (marginal rays propagating at a large angle in image space). In this case, Finite-Difference Time-Domain techniques (FDTD) are used to refine the physical-optics modelling results, producing a result closer to the actual case encountered in a high-fill-factor FPA. In this contribution, we analyze the FZPL designs by using FDTD techniques. The main result of the FDTD computation is the gain factor defined as the ratio of the response of the IR antennas coupled with the FZPL, compared to the same antennas without the FZPL.