Squared-field amplitude modulus and radiation intensity nonequivalence within nonlinear slabs

This paper presents a novel approach to wave propagation inside the Fabry-Perot framework. It states that the time-averaged Poynting vector modulus could be nonequivalent with the squared-field amplitude modulus. This fact permits the introduction of a new kind of nonlinear medium whose nonlinearity is proportional to the time-averaged Poynting vector modulus. Its transmittance is calculated and found to differ with that obtained for the Kerr medium, whose nonlinearity is proportional to the squared-field amplitude modulus. The latter emphasizes the nonequivalence of these magnitudes. A space-time symmetry analysis shows that the Poynting nonlinearity should be only possible in noncentrosymmetric materials.Comment: 5 pages, 4 figures, added space-time symmetry analysis and reference

Patrones de distribución de los Carabidae ibéricos (Insecta, Coleoptera)

We have categorised the 1336 species and subspecies of the Iberian Peninsula according to the chorotype classification proposed by Vigna Taglianti et al. (1992), modified by the addition of new chorotypes. The Iberian Peninsula is noticeable among the different European and Circum-Mediterranean regions by the high proportion of endemic taxa (43.1%). The old age and stability of the northern half, the extreme position of the Peninsula within the Eurasiatic continent, alpine tectonics and abundance of caves are among the factors that have probably contributed to the origin of a distinctive fauna. Taxa with a large distribution pattern are predominant at a regional scale; the proportion of endemic taxa increases to the North and in mountain regions; Mediterranean elements are more frequent in the South whereas European elements increase in the northern half. Adaptation to a Mediterranean climatic regime and dispersal are two of the factors causing these patterns. The Peninsula is poor in Afrotropical elements, probably because of the strong isolation derived from the Sahara Desert. The Balearic Islands have high proportions of widely distributed and Mediterranean taxa, what suggests a main role of dispersal in the colonisation of the archipelago. The proportion of endemic taxa in Mallorca (7.8%) is intermediate between that of Sardinia and Sicily; in spite of a relatively long isolation, the Balearic Islands are small in size and moderately rich in caves, what explains that most endemic taxa are found in the lowlands.Se han categorizado las 1336 especies y subespecies de la fauna ibérica de Carabidae, usando los corotipos propuestos por Vigna Taglianti et al. (1992), los cuales se han completado con algunos otros adicionales. La Península Ibérica destaca entre las diversas regiones europeas y circunmediterráneas por la elevada proporción de elementos endémicos (43,1%). La antigüedad y estabilidad de la mitad norte peninsular, el aislamiento de la región, los plegamientos alpinos y la abundancia de cuevas, son factores que probablemente han contribuido a su singularidad faunística. Los elementos de amplia distribución predominan a la escala regional; las proporciones de endemismos son mayores hacia el Norte y en las zonas de montaña; la de los elementos mediterráneos se incrementa hacia el Sur, al contrario de lo que ocurre con los elementos europeos. La adaptación al régimen climático mediterráneo y la dispersión son dos de los factores que probablemente causan estos patrones. La Península es pobre en elementos afrotropicales, posiblemente debido al aislamiento causado por la barrera natural del Sahara. Las Islas Baleares tienen altas proporciones de elementos de amplia distribución y mediterráneos, lo que sugiere el papel relevante de la dispersión en la colonización de las islas. La proporción de endemismos de Mallorca (7,8%) es intermedia entre la de Cerdeña y Sicilia; a pesar de su aislamiento las Baleares son de tamaño pequeño y tienen un abundancia moderada de medios favorables para la especiación, como ocurre con las cuevas, lo que explica que la mayoría de los endemismos se encuentren en zonas abiertas de baja altitud

Caustics, catastrophes, and symmetries in curved beams

In this paper, a meaningful classification of optical caustic beams in two dimensions is presented. It is demonstrated that the phase symmetry of the beam's angular spectrum governs the optical catastrophe, which describes the wave properties of ray singularities, for cusp (symmetric phase) and fold (antisymmetric phase) caustics. In contrast to the established idea, the caustic classification arises from the phase symmetry rather than from the phase power, thus breaking the commonly accepted concept that fold and cusp caustics are related to the Airy and Pearcey functions, respectively. Nevertheless, the role played by the spectral phase power is to control the degree of caustic curvature. These findings provide straightforward engineering of caustic beams by addressing the spectral phase into a spatial light modulator or glass plate.Centro de Investigaciones Óptica

Medidas experimentales de desplazamientos micrométricos basadas en vórtices ópticos

In this work, a system for measuring micrometer-displacements based on the characteristics of optical vortices is presented. In the proposal, a binary vortex-producing lens (BVPL) programmed to generate optimized optical vortices is transversally displaced from the optical axis, inducing perturbations on the optical characteristics of the vortices that are used as transduction parameters. Specifically, the method proposed theoretically by Anzolin et al. [18], which is based on the asymmetry of the intensity patterns of the off-axis optical vortices, is studied experimentally by using BVPLs. Experimental implementation is completely described and compared with theoretical results, likewise, metrological characteristics of the experimental metrological system are analyzed. Based on the results, we experimentally confirm the possibility of creating high sensitivity metrological systems by using optical vortices, opening the door for new vortex metrology techniques.En este trabajo, un sistema para medir desplazamientos micrométricos basados en las características de vórtices ópticos es presentado. En la propuesta, una lente productora de vórtices binaria (BVPL) programada para generar vórtices ópticos optimizados es desplazada transversalmente del eje óptico, induciendo perturbaciones en las características ópticas de los vórtices que son usadas como parámetros de transducción. Específicamente, el método propuesto por Anzolín et al [18], el cuál es basado en la asimetría de los patrones de intensidad de los vórtices ópticos fuera del eje, es estudiado experimentalmente usando BVPLs. Se describe completamente la implementación experimental y se compara con los resultados teóricos, así mismo, se analizan características metrológicas del sistema metrológico experimental. En base a los resultados, confirmamos experimentalmente la posibilidad de crear sistemas metrológicos de alta sensibilidad utilizando vórtices ópticos, abriendo la puerta para nuevas técnicas de metrología de vórtices.Centro de Investigaciones Óptica

Analytical description of optical vortices generated by discretized vortex-producing lenses

In this article, a general analytical treatment (any topological charge - any number of discretization levels) for the diffraction of a Gaussian beam through a discretized vortex-producing lens is presented. In the proposal, the field is expressed as a sum of Kummer beams with different amplitudes and topological charges, which are focalized at different planes on the propagation axis. Likewise, it is demonstrated that characteristics of diffracted light can be modified by tuning the parameters of the setup. Vortex lines are analyzed to understand the internal mechanism of measurable topological charges that appear in specific planes, apparently violating topological charge conservation. Conservation of the topological charge is verified and theoretical predictions are supported by experiments.Fil: Rumi, Gonzalo Agustín. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Ópticas. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones Ópticas. Universidad Nacional de La Plata. Centro de Investigaciones Ópticas; ArgentinaFil: Actis, Daniel Guillermo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Ópticas. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones Ópticas. Universidad Nacional de La Plata. Centro de Investigaciones Ópticas; ArgentinaFil: Amaya Robayo, Dafne Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Ópticas. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones Ópticas. Universidad Nacional de La Plata. Centro de Investigaciones Ópticas; ArgentinaFil: Gomez, Jorge A.. Politécnico Colombiano Jaime Isaza Cadavid; ColombiaFil: Rueda, Edgar. Universidad de Antioquia; ColombiaFil: Lencina, Alberto Germán. Universidad Nacional del Centro de la Provincia de Buenos Aires; Argentin

Analytical description of optical vortices generated by discretized vortex-producing lenses

In this article, a general analytical treatment (any topological charge - any number of discretization levels) for the diffraction of a Gaussian beam through a discretized vortex-producing lens is presented. In the proposal, the field is expressed as a sum of Kummer beams with different amplitudes and topological charges, which are focalized at different planes on the propagation axis. Likewise, it is demonstrated that characteristics of diffracted light can be modified by tuning the parameters of the setup. Vortex lines are analyzed to understand the internal mechanism of measurable topological charges that appear in specific planes, apparently violating topological charge conservation. Conservation of the topological charge is verified and theoretical predictions are supported by experiments.Facultad de Ciencias ExactasCentro de Investigaciones Óptica