Search results for "Transformada de Fourier"
showing 4 items of 4 documents
Episodios de precipitación torrencial en el este y sureste ibéricos y su relación con la variabilidad intraanual de la oscilación del Mediterráneo oc…
2018
Ponencia presentada en: XI Congreso de la Asociación Española de Climatología celebrado en Cartagena entre el 17 y el 19 de octubre de 2018. [ES]La relación de la Oscilación del Mediterráneo Occidental (WeMO) con la ocurrencia e intensidad de las precipitaciones en el litoral mediterráneo ibérico ha sido demostrada en numerosos trabajos. Entre 1950 y 2016 se registraron 239 episodios de precipitación torrencial extrema (≥200 mm/24 horas) en las cuencas hidrográficas del Júcar y del Segura (3,6 casos al año). El 29,3% de estos eventos tuvieron lugar con una fase de la WeMO fuertemente negativa, el 37,5% en una fase negativa y el 28,3% en una fase ligeramente negativa. Solo el 7,9% de los epi…
Photonic fractional Fourier transformer with a single dispersive device
2013
In this work we used the temporal analog of spatial Fresnel diffraction to design a temporal fractional Fourier transformer with a single dispersive device, in this way avoiding the use of quadratic phase modulators. We demonstrate that a single dispersive passive device inherently provides the fractional Fourier transform of an incident optical pulse. The relationships linking the fractional Fourier transform order and scaling factor with the dispersion parameters are derived. We first provide some numerical results in order to prove the validity of our proposal, using a fiber Bragg grating as the dispersive device. Next, we experimentally demonstrate the feasibility of this proposal by us…
Group Delay and Spectral Phase Retrieval of Light Pulses by Spectral Intensity Measurements
2022
We discuss a method to determine both the group delay and the phase of a given pulse in the Fourier optics domain. The proposal is based on the measurement of two intensity spectra, before and after a known quadratic phase modulation. A simple analytical equation is then used to determine the group delay in one step. If necessary, the spectral phase can be determined by simple spectral integration of the determined group delay. The proposal is supported by various numerical results and an experimental measurement to prove the concept.
Influence of krypton atoms on the structure of amorphous hydrogenated carbon deposited by plasma enhanced chemical vapor deposition
2010
Hydrogenated amorphous carbon (a-C:H) films were prepared by plasma enhanced chemical vapor deposition using methane (CH4 ) plus krypton (Kr) mixed atmosphere. The depositions were performed as function of the bias voltage and krypton partial pressure. The goal of this work was to study the influence of krypton gas on the physical properties of a-C:H films deposited on the cathode electrode. Krypton concentration up to 1.6 at. %, determined by Rutherford Back-Scattering, was obtained at high Kr partial pressure and bias of -120 V. The structure of the films was analyzed by means of optical transmission spectroscopy, multi-wavelength Raman scattering and Fourier Transform Infrared spectrosco…