Aspectos Históricos y Evolutivos de la Gimnasia

El presente ensayo presenta una reseña histórica y una referencia general acerca de la gimnasia. Esta revisión se inicia con explicación del origen de la gimnasia y la relación de los seres humanos con el medio circundante. Posteriormente hace referencia a las primeras imágenes que se han encontrado de civilizaciones antiguas en donde se observan manifestaciones gimnásticas que abarca desde los primeros indicios encontrados en las pirámides egipcias. Luego se hace una revisión a los aportes de la cultura griega y posteriormente de la cultura romana. Se distingue su evolución en el Renacimiento con la cultura de los trovadores y saltimbancos. Se destaca el aporte de Merculiaris que con su libro resalta la importancia del ejercicio físico ‘gimnástica’ para la salud, al igual que de los valiosos aportes de pedagogos famosos que exhortaban a la inclusión de la gimnasia en las clases del sistema educativo formativo. Se hace referencia a la tendencia que se dio por una época de carácter militarista a la gimnasia y se hace mención de la significativa presencia de Gutz Mutz, considerado el padre de la gimnasia con aparatos, o la gimnasia artística. Posteriormente su expansión a diversos países, las diferentes escuelas generadas hasta llegar a la creación de la Federación Internacional de Gimnasia. Igualmente se presenta la evolución en el siglo XX desde la incursión de la mujer en los Juegos Olímpicos, la puesta en escena de la gimnastrada y la evolución que este deporte ha tenido incluyendo las modificaciones del código de puntaje hasta llegar a nuestros días. Es una breve reseña de un deporte sumamente complejo, que atrae gran cantidad de practicantes y seguidores y que además tiene gran presencia en los magnos eventos deportivos del mundo

Asymmetric Shaping for Ultrafast Elliptical Bessel-like Beams

The generation of an elliptical Bessel–Gauss beam has become a topic of interest in ultrafast laser processing of transparent materials because of its nearly non-diffractive elliptical central core. These beams can show potential in generating anisotropic structures down to the nanoscale and in producing asymmetries in the induced fields of thermo-mechanical constraints relevant for material structuring. However, maintaining the central core ellipticity is a challenge that requires further analysis, notably in the propagation behavior of phase anisotropies during the conical interference. This paper presents the controlled generation and propagation of a highly elliptical Bessel–Gauss beam using asymmetric phase-modulation technique. The study involves engineering different asymmetric phase holograms and analyzing their performances in terms of the non-diffractive property and uniformity of the generated beams. We indicate the presence in specific cases of diffraction and its influence on the invariance of the beam shape. The simulation results are in excellent agreement with the experimental results, which verifies the accuracy and reliability of our approach

Multiscale Laser Written Photonic Structures in Bulk Chalcogenide Glasses for Infrared Light Transport and Extraction

International audienceDirect ultrafast laser processing is nowadays considered the most flexible technique allowing to generate complex 3D optical functions in bulk glasses. The fact that the built-in optical element is embedded in the material brings several advantages in terms of prototype stability and lifetime, but equally in terms of complexity and number of possible applications, due to the 3D design. The generated optical functions, and in particular the single mode character of the light guiding element alongside the accessibility toward different spectral windows, depend on the refractive index contrast that can be achieved within the material transparency window and on the characteristic dimensions of the optical modification. In particular, the accessibility to the infrared and mid-infrared spectral domains, and to the relevant applications in sensing and imaging, requires increasing the cross-section of the guiding element in order to obtain the desired normalized frequency. Moreover, efficient signal extraction from the transported light requires nanometer size void-like index structures. All this demands a thorough knowledge and an optimal control of the material response within the interaction with the ultrafast laser pulse. We present here an overview of some recent results concerning large-mode-area light transport and extraction in sulfur-based chalcogenide mid-infrared glasses, putting emphasis on the study of the glass response to ultrafast lasers. We then demonstrate the utilization of the achieved optimized local index modifications for building efficient and compact embedded spectrometers (linear optical functions) and saturable absorbers (nonlinear optical functions) for integrated photonic applications in the infrared and mid-infrared spectral ranges

Ultrashort Bessel beam photoinscription of Bragg grating waveguides and their application as temperature sensors

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Ultrafast laser-induced plasma anisotropy in pristine and surface pre-structured zinc telluride, probed by terahertz pulses

International audienceWe use THz probe pulses to detect and analyze the dynamics of charge transport anisotropies generated by ultrafast laser two-photon absorption in Zinc Telluride (ZnTe) semi-insulating crystal showing smooth and laser structured surfaces. The detected anisotropy consists in a modulation of the THz transmission as a function of the orientation of the  axis of ZnTe. The change in THz transmission after pump excitation is attributed to free carrier absorption of the THz field in the laser-induced electron-hole plasma. Pre-structuring the surface sample with laser-induced periodic surface structures (ripples) has strong influence on free carrier THz transmission and its associated anisotropic oscillation. Within the relaxation dynamics of the laser-induced free carriers, two relaxation times have to be considered in order to correctly describe the dynamics, a fast relaxation, of about 50 picoseconds in pristine sample (90 picoseconds in sample pre-structured with ripples), and a slow one, of about 1.5 nanoseconds. A theoretical model based on classical Drude theory and on the dependence of the two-photon absorption coefficient with the crystal orientation and with the laser polarization is used to fit the experimental results

Implementation of Embedded Antenna Functions using Periodic Bessel Nanovoids Photo-Written in Bulk Glass by Ultrafast Laser

International audienceNondiffractive ultrafast-laser-writing of scattering centers organized as groups of close periodic elongated nanovoids (antennas) in bulk glasses is demonstrated being a good solution for accessing the spectral information of optical signals transported in embedded waveguides