0000000000072675
AUTHOR
Javier Abreu-afonso
showing 9 related works from this author
Control of the chromatic dispersion of photonic crystal fibers for supercontinuum and photon pairs generation
2011
The interplay between chromatic dispersion and nonlinear effects is crucial for an efficient exploitation of non linear propagation in photonic crystal fibers (PCF). Once a PCF preform has been prepared, changing the parameters that control the fabrication process it is possible to adjust the dispersion properties of the fiber. In addition, it is particularly useful to develop postprocessing techniques that enable a fine adjustment of the dispersion along a section of PCF. The tapering of PCF, using a fusion and pulling technique, has been established as a rather useful technique to engineer the dispersion properties along tens of centimeters. Some of our recent experiments demonstrate that…
Comprehensive Theoretical and Experimental Study of Short- and Long-Term Stability in a Passively Mode-Locked Solitonic Fiber Laser
2015
We demonstrate the short- and long-term stable operation of an all-polarization-maintained Fabry–Perot cavity passively mode-locked fiber laser. The laser operates in an all-anomalous-dispersion solitonic regime. Laser stability is studied by a variety of measurements, which confirm the high stability of the laser in the temporal and spectral–both optical and electrical-domains. Pulse durations of 540 fs, period-relative time jitters of $\sim$ 0.015‰, and long-term uninterrumped operation with 0.4% variation (standard deviation) in the average output power are obtained. The highly stable operation of the laser oscillator was maintained after amplifying the laser output with a conventional E…
Comparative Study of Ambient Air Particles in Patients Hospitalized for Heart Failure and Acute Coronary Syndrome
2011
Introduction and objectives: Currently air pollution is considered as an emerging risk factor for cardiovascular disease. Our objective was to study the concentrations of particulate matter in ambient air and analyze their relationship with cardiovascular risk factors in patients admitted to a cardiology department of a tertiary hospital with the diagnosis of heart failure or acute coronary syndrome (ACS). Methods: We analyzed 3950 consecutive patients admitted with the diagnosis of heart failure or ACS. We determined the average concentrations of different sizes of particulate matter (<10, <2.5, and <1 mm and ultrafine particles) from 1 day or up to 7 days prior to admission (1 to 7 days l…
Mode-locked Yb-doped all-fiber laser based on in-fiber acoustooptic modulation
2011
We show what we believe is the first demonstration of an ytterbium-doped strictly all-fiber active mode-locking laser. The active control of the laser is based on in-fiber amplitude modulation at 11 MHz, which is achieved by using an all-fiber acoustooptic superlattice modulator driven by standing acoustic waves. In our experiments, the laser was operated at 1091.3 nm and had two stable regimes producing either a train of mode-locked single pulses or a train of pulse pairs. Best results for the mode-locked train of single pulses were 740 ps of time width and 26 mW of average power, at a pump power of 480 mW.
Estudio comparativo de las partículas en aire ambiente en pacientes ingresados por insuficiencia cardiaca y síndrome coronario agudo
2011
Resumen Introduccion y objetivos Actualmente se considera la contaminacion atmosferica como un factor de riesgo emergente de enfermedades cardiovasculares. Nuestro objetivo fue comparar las concentraciones de particulas atmosfericas en aire ambiente y analizar su relacion con los factores de riesgo cardiovascular en pacientes que ingresan en un servicio de cardiologia de un hospital terciario con el diagnostico de insuficiencia cardiaca y sindrome coronario agudo (SCA). Metodos Analizamos a un total de 3.950 pacientes ingresados de forma consecutiva con el diagnostico de insuficiencia cardiaca y SCA. Se determinaron las concentraciones medias de material particulado con tamano Resultados No…
Alignment-free, all-spliced fiber laser source for CARS microscopy based on four-wave-mixing
2012
An environmentally-stable low-repetition rate fiber oscillator is developed to produce narrow-bandwidth pulses with several tens of picoseconds duration. Based on this oscillator an alignment-free all-fiber laser for multi-photon microscopy is realized using in-fiber frequency conversion based on four-wave-mixing. Both pump and Stokes pulses for coherent anti-Stokes Raman scattering (CARS) microscopy are readily available from one fiber end, intrinsically overlapped in space and time, which drastically simplifies the experimental handling for the user. The complete laser setup is mounted on a home-built laser scanning microscope with small footprint. High-quality multimodal microscope image…
Chromatic Dispersion Control in Mode-Locked Yb-Doped Fiber Lasers Based on a Microstructured Optical Fiber
2013
We present an experimental study on the use of solid core microstructured optical fibers (MOF) for managing the chromatic dispersion in an Yb-doped fiber laser passively mode-locked by a saturable absorber. The performance of the laser, in terms of pulse width and repetition rate, was investigated as a function of the net cavity dispersion.
Effects of Temperature and Axial Strain on Four-Wave Mixing Parametric Frequencies in Microstructured Optical Fibers Pumped in the Normal Dispersion …
2014
A study of the effect of temperature and axial strain on the parametric wavelengths produced by four-wave mixing in microstructured optical fibers is presented. Degenerate four-wave mixing was generated in the fibers by pumping at normal dispersion, near the zero-dispersion wavelength, causing the appearance of two widely-spaced four-wave mixing spectral bands. Temperature changes, and/or axial strain applied to the fiber, affects the dispersion characteristics of the fiber, which can result in the shift of the parametric wavelengths. We show that the increase of temperature causes the signal and idler wavelengths to shift linearly towards shorter and longer wavelengths, respectively. For t…
Relación entre exposición a corto plazo a dióxido de azufre atmosférico y lesiones obstructivas en el síndrome coronario agudo
2013
Resumen Fundamentos y objetivo Los contaminantes del aire urbano estan constituidos por una mezcla heterogenea de sustancias presentes en estado gaseoso y aerosoles. El objetivo del presente estudio fue comparar los efectos causados por la exposicion a contaminantes en fase gas y particulas atmosfericas en aire ambiente en pacientes que ingresan por un sindrome coronario agudo (SCA), en relacion con la presencia o no de lesiones obstructivas significativas (LOS) en arterias coronarias epicardicas. Pacientes y metodo Analizamos de forma prospectiva a un total de 2.110 pacientes con el diagnostico de SCA. Se determinaron las concentraciones medias de contaminantes en fase gas y particulas atm…