Un mes de jazz a Sa Nostra

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Broner en el país del cinema

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Emission cross sections and spectroscopy of Ho3+ laser channels in KGd(WO4)2 single crystal

The spectroscopic properties of Ho3+ laser channels in KGd(WO4)2 crystals have been investigated using optical absorption, photoluminescence, and lifetime measurements. The radiative lifetimes of Ho3+ have been calculated through a Judd-Ofelt (JO) formalism using 300-K optical absorption results. The JO parameters obtained were Ω2=15.35×10-20 cm2, Ω 4=3.79×10-20 cm2, Ω6 =1.69×10-20 cm2. The 7-300-K lifetimes obtained in diluted (8·1018 cm-3) KGW:0.1% Ho samples are: τ(5F3)=0.9 μs, τ( 5S2)=19-3.6 μs, and τ(5F5 )=1.1 μs. For Ho concentrations below 1.5×1020 cm-3, multiphonon emission is the main source of non radiative losses, and the temperature independent multiphonon probability in KGW is found to follow the energy gap law τph -1(0)=βexp(-αΔE), where β=1.4×10-7 s-1, and α=1.4×103 cm. Above this holmium concentration, energy transfer between Ho impurities also contributes to the losses. The spectral distributions of the Ho3+ emission cross section σEM for several laser channels are calculated in σ- and π-polarized configurations. The peak a σEM values achieved for transitions to the 5I8 level are ≈2×10-20 cm2 in the σ-polarized configuration, and three main lasing peaks at 2.02, 2.05, and 2.07 μm are envisaged inside the 5I7→5I8 channel.This work was supported by Comisión Interministerial de Ciencia y Tecnología under Projects MAT99-1077 and 2FD97-0912.Peer reviewe

Femtosecond laser-written double-cladding waveguides in Nd:GdVO4crystal: Raman analysis, guidance, and lasing

We report on waveguide lasers at 1064.5 nm in femtosecond laser-written double-cladding waveguides in Nd∶GdVO4 crystals. The cladding waveguides guide both transverse electric (TE)- and transverse magnetic (TM)-polarized modes with considerably symmetric single-modal profiles and show good transmission properties (propagation loss as low as 1.0 dB∕cm). The detailed structure of the single and double claddings has been imaged by means of μ-Raman analysis, and the observed slight fabrication asymmetries with respect to an ideal circular cladding are in well agreement with the observed differences in TE/TM propagation losses. Importantly, the Raman imaging shows the complete absence of lattice defect at the laser active volume. Under the optical pumping at 808 nm, a maximum output power up to 0.43Wof the continuous wave waveguide laser with a slope efficiency of 52.3% has been achieved in the double-cladding waveguide, which is 21.6% and 23% higher than that from a single-inner cladding waveguide. Furthermore, the maximum output power of the waveguide laser is 72% higher than that of the double-line waveguide due to the double-cladding designThe work is supported by the National Natural Science Foundation of China (No. 11274203), the Specialized Research Fund for the Doctoral Program of Higher Education of China (No. 20130131130001), and Junta de Castilla y León under project SA086A12-2. Support from the Centro de Láseres Pulsados (CLPU) is also acknowledged. This work was supported by the Spanish Government under project MAT2011- 29255-C02-02 and by the Generalitat de Catalunya under project 2014SGR1358

Hypertension prevalence in active working population in the Balearic Islands: gender and age socioeconomic inequalities and differences

Introducción: La clase social a partir de la ocupación constituye uno de los determinantes sociales de la salud más importantes. Muchos estudios confirman la influencia de las condiciones del trabajo sobre la salud de los individuos así como la prevalencia de determinados factores de riesgo cardiovascular como la hipertensión arterial. Objetivos: Determinar la prevalencia de hipertensión arterial en población laboral activa y analizar si las diferencias por clase social varían según edad y sexo. Material y método: Estudio transversal sobre una muestra de 1.910 trabajadores de entre 20 y 65 años de las Islas Baleares. Las variables de estudio fueron: clase social, medidas antropométricas, perfil lipídico, glucosa y presión arterial. Resultados: En general el grupo formado por las clases sociales más favorecidas tenía menor prevalencia de hipertensión arterial que el grupo formado por las clases sociales más desfavorecidas. En cuanto al sexo, según el análisis estratificado por clase social, los hombres pertenecientes a las clases sociales más favorecidas presentan una prevalencia de hipertensión arterial similar a la de los hombres de clases sociales más desfavorecidas. Las mujeres de clase social favorecida, en cambio, presentan menos hipertensión que las pertenecientes a las clases sociales más desfavorecidas. En relación a la edad, se obtiene que a mayor edad aumenta la prevalencia de hipertensión arterial. Conclusiones: Las desigualdades por clase social en la prevalencia de hipertensión arterial fueron mayores entre las mujeres que entre los hombres. La edad juega un papel crucial en la prevalencia de hipertensión arterial en cualquier estrato social.Background: Social class determined from occupation is one of the most important social determinants of health. Many studies confirm the influence of working conditions on the health of individuals and the acquisition of cardiovascular risk factors such as arterial hypertension. Aims: To determine the prevalence of hypertension in active working population and to analyze whether social class differences change with age and gender. Material and methods: A cross-sectional study in a sample of 1,910 workers aged 20-65 years in the Balearic Islands. The following study variables were collected: social class, anthropometric measurements, lipid profile, glucose and blood pressure. Results: Participants belonging to higher social classes presented, in general, lower prevalence of hypertension than participants belonging to lower social classes. When participants in the study were stratified by gender and social class, men belonging to the highest social classes showed similar prevalence of hypertension than men located in the lower social classes. However, women belonging to the higher social classes presented lower prevalence of hypertension than those belonging to the lower social classes. Regarding the effect of age, it was found that hypertension prevalence increases with aging. Conclusions: Social class inequalities in the prevalence of hypertension were higher among women than among men. Age plays an essential role in the prevalence of hypertension in any social class

Optical and structural characterisation of epitaxial nanoporous GaN grown by CVD

Producción CientíficaIn this paper we study the optical properties of nanoporous gallium nitride (GaN) epitaxial layers grown by chemical vapour deposition on non-porous GaN substrates, using photoluminescence, cathodoluminescence, and resonant Raman scattering, and correlate them with the structural characteristic of these films. We pay special attention to the analysis of the residual strain of the layers and the influence of the porosity in the light extraction. The nanoporous GaN epitaxial layers are under tensile strain, although the strain is progressively reduced as the deposition time and the thickness of the porous layer increases, becoming nearly strain free for a thickness of 1.7 μm. The analysis of the experimental data point to the existence of vacancy complexes as the main source of the tensile strain.Ministerio de Economía, Industria y Competitividad (Projects No. TEC2014-55948-R and MAT2016-75716-C2-1-R (AEI/FEDER, UE)Junta de Castilla y León (programa de apoyo a proyectos de investigación – Ref. Projects VA293U13 and VA081U16)Comisión Interministerial de Ciencia y Tecnología (Proyect CICYT MAT2010-20441-C02)Ministerio de Economía, Industria y Competitividad (Projects No.ENE2014-56069-C4-4-R

Transition of pulsed operation from Q-switching to continuous-wave mode-locking in a Yb:KLuW waveguide laser

We report on the diverse pulsed operation regimes of a femtosecond-laser-written Yb:KLuW channel waveguide laser emitting near 1040 nm. By the precise position tuning of a carbon-nanotube-coated saturable absorber (SA) mirror, the transition of the pulsed operation from Q-switching, Q-switched mode-locking and finally sub-GHz continuous-wave mode-locking are obtained based on the interplay of dispersion and mode area control. The Q-switched pulses exhibit typical fast SA Q-switched pulse characteristics depending on absorbed pump powers. In the Q-switched mode-locking, amplitude modulations of the mode-locked pulses on the Q-switched envelope are observed. The radio-frequency spectrum represents the coexistence of Q-switching and mode-locking signals. In the purely mode-locked operation, the waveguide laser generates 2.05-ps pulses at 0.5 GHz.National Research Foundation of Korea (2018H1A2AA1061480, 2019R1A2C3003504, 2020R1A4A2002828); Spanish Government (FIS2017-87970-R, MAT2016-75716-C2-1-R (AEI/FEDER,UE)); Junta de Castilla y León (SA287P18); Generalitat de Catalunya (2017SGR755)

Plasmonic enhancement of second harmonic generation from nonlinear RbTiOPO4 crystals by aggregates of silver nanostructures

We demonstrate a 60–fold enhancement of the second harmonic generation (SHG) response at the nanoscale in a hybrid metal-dielectric system. By using complex silver nanostructures photochemically deposited on the polar surface of a ferroelectric crystal, we tune the plasmonic resonances from the visible to the near-infrared (NIR) spectral region, matching either the SH or the fundamental frequency. In both cases the SHG signal at the metal-dielectric interface is enhanced, although with substantially different enhancement values: around 5 times when the plasmonic resonance is at the SH frequency or up to 60 times when it matches the fundamental NIR radiation. The results are consistent with the more spatially-extended near-field response of complex metallic nanostructures and can be well explained by taking into account the quadratic character of the SHG process. The work points out the potential of aggregates of silver nanostructures for enhancing optical nonlinearities at the nanoscale and provides an alternative approach for the development of nanometric nonlinear photonic devices in a scalable way.This work has been supported by the Spanish Ministry of Economy and Competitiveness (MINECO) under projects MAT2013-43301-R, FIS2013-41184-P, MAT2013-47395-C4-4-R and TEC2014-55948-R. The authors also acknowledge Comunidad de Madrid under grant S2013/MIT-2740, Dept. of Industry of the Basque Country under project nanoGUNE’14, and Catalan Authority under project 2014SGF1358. F.D. acknowledges additional support through the ICREA Academia awards 2010ICREA-02 for excellence in research. LSG acknowledges FPU13/02476 grant from the Spanish Ministry of Education.Peer reviewe

Oriented zinc oxide nanorods: A novel saturable absorber for lasers in the near-infrared

Zinc oxide (ZnO) nanorods (NRs) oriented along the crystallographic [001] axis are grown by the hydrothermal method on glass substrates. The ZnO NRs exhibit a broadband (1–2 µm) near-IR absorption ascribed to the singly charged zinc vacancy VZn−1. The saturable absorption of the ZnO NRs is studied at ≈1 µm under picosecond excitation, revealing a low saturation intensity, ≈10 kW/cm2, and high fraction of the saturable losses. The ZnO NRs are applied as saturable absorbers in diode-pumped Yb (≈1.03 µm) and Tm (≈1.94 µm) lasers generating nanosecond pulses. The ZnO NRs grown on various optical surfaces are promising broadband saturable absorbers for nanosecond near-IR lasers in bulk and waveguide geometries