Francesc Dı́az

ORCID: 0000-0003-4581-4967
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About
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Research Areas
  • Solid State Laser Technologies
  • Luminescence Properties of Advanced Materials
  • Photorefractive and Nonlinear Optics
  • Advanced Fiber Laser Technologies
  • Laser Design and Applications
  • Glass properties and applications
  • Optical properties and cooling technologies in crystalline materials
  • Laser-Matter Interactions and Applications
  • Photonic and Optical Devices
  • Laser Material Processing Techniques
  • Solid-state spectroscopy and crystallography
  • Crystal Structures and Properties
  • Semiconductor Lasers and Optical Devices
  • GaN-based semiconductor devices and materials
  • Ferroelectric and Piezoelectric Materials
  • Acoustic Wave Resonator Technologies
  • Gas Sensing Nanomaterials and Sensors
  • Ga2O3 and related materials
  • Semiconductor materials and devices
  • Photonic Crystal and Fiber Optics
  • Optical and Acousto-Optic Technologies
  • Photonic Crystals and Applications
  • ZnO doping and properties
  • Perovskite Materials and Applications
  • Radiation Detection and Scintillator Technologies

Universitat Rovira i Virgili
2016-2025

Observatori de l'Ebre
2016-2021

Laboratoire Traitement et Communication de l’Information
2016

East Midlands Ambulance Service NHS Trust
2016

Belarusian National Technical University
2015

Centre de Recherche sur les Ions, les Matériaux et la Photonique
2013

Centre National de la Recherche Scientifique
2013

University of Southampton
2013

Université de Caen Normandie
2013

Laboratoire Matériaux Optiques, Photonique et Systèmes
2011

We demonstrated that KLu(WO<sub>4</sub>)<sub>2</sub>:Ho<sup>3+</sup>,Tm<sup>3+</sup> nanoparticles are able to combine controllable heat release and upconversion thermometry permitting estimate the thermal resistance of in air, a key parameter model transfer at nanoscale.

10.1039/c7nr08758f article EN cc-by-nc Nanoscale 2018-01-01

The development of lanthanide-doped non-contact luminescent nanothermometers operating in the biological windows spectral regions, strategies to improve their thermal sensitivities, and applications have been reviewed.

10.1039/d0nr09150b article EN Nanoscale 2021-01-01

Abstract High‐quality crystals of monoclinic KLu(WO 4 ) 2 , shortly KLuW, were grown with sizes sufficient for its characterization and substantial progress was achieved in the field spectroscopy laser operation Yb 3+ ‐ Tm ‐doping. We review growth methodology bulk KLuW epitaxial layers, structural, thermo‐mechanical, optical properties, spectroscopy, present results obtained several operational regimes both Ti:sapphire direct diode pumping using InGaAs AlGaAs diodes near 980 800 nm,...

10.1002/lpor.200710010 article EN Laser & Photonics Review 2007-05-03

We present our recent achievements in the growing and optical characterization of $\mathrm{KYb}({\mathrm{WO}}_{4}{)}_{2}$ (hereafter KYbW) crystals demonstrate laser operation this stoichiometric material. Single KYbW with optimal crystalline quality have been grown by top-seeded-solution growth slow-cooling method. The anisotropy monoclinic crystal has characterized, locating tensor indicatrix measuring dispersion principal values refractive indices as well thermo-optic coefficients....

10.1103/physrevb.65.165121 article EN Physical review. B, Condensed matter 2002-04-15

Mode locking of an Yb-doped bulk laser in the 1 μm spectral range using a single-walled carbon nanotube saturable absorber (SWCNT-SA) is demonstrated for first time, to our knowledge. Passive mode Yb:KLuW resulted nearly transform-limited pulses as short 115 fs at 1048 nm. In addition, nonlinear response SWCNT-SA was measured, yielding modulation depth 0.25% and relaxation time 750 fs.

10.1364/ol.33.000729 article EN Optics Letters 2008-03-31

Stable and self-starting mode-locking of a Tm:KLu(WO(4))(2) crystal laser is demonstrated using transmission-type single-walled carbon nanotube (SWCNT) based saturable absorber (SA). These experiments in the 2 microm regime utilize E11 transition SWCNTs for nonlinear absorption. The recovery time SWCNT-SA measured by pump-probe measurements as approximately 1.2 ps. mode-locked delivers 10 ps pulses near 1.95 with maximum output power up to 240 mW at 126 MHz repetition rate.

10.1364/oe.17.011007 article EN cc-by Optics Express 2009-06-17

We studied the temperature-dependent luminescence of GdVO4 nanoparticles co-doped with Er(3+) (1 mol %) and Yb(3+) (20 determined their thermal sensing properties through fluorescence intensity ratio (FIR) technique. also analyzed how a silica coating, in core-shell structure, affects temperature this material. Spectra were recorded range biological temperatures (298-343 K). The absolute sensitivity for determination calculated is double one bare nanoparticles, achieving resolution 0.4 K....

10.1021/acsami.6b01371 article EN ACS Applied Materials & Interfaces 2016-03-07

Non-contact thermometry is essential in biomedical studies requiring thermal sensing and imaging with high spatial resolutions. In this work, we report the potential use of Er:Yb:NaYF4 Er:Yb:NaY2F5O up-conversion nanoparticles as sensors by means lifetime based luminescent thermometry. We demonstrate how nanocrystals present a higher sensitivity than ones that their coefficient comparable to those corresponding other nano-sized systems already used for resolution fluorescence sensing....

10.1039/c4nr02305f article EN Nanoscale 2014-06-11

We studied the temperature dependence of up-conversion emission in green and red regions electromagnetic spectrum Ho,Yb:KLu(WO4)2 nanocrystals after excitation at 980 nm analyzed their possible applications as thermal sensors luminescence thermometry RT to 673 K range by using different techniques. The thermometric techniques used are fluorescence intensity ratio technique two thermally coupled Stark sublevels, between bands generated electronically linked manifolds these nanoparticles,...

10.1021/acs.jpcc.5b03766 article EN The Journal of Physical Chemistry C 2015-07-27

High-quality crystals of MgWO 4 with a significantly reduced growth time and revision the principal optical axes orientation which differs substantially from previous reports are presented.

10.1039/d4ce01168f article EN cc-by-nc CrystEngComm 2025-01-01

A diode-pumped microchip laser containing a quasi-monolithic plano-plano cavity is realized on the basis of Tm:KLu(WO₄)₂ crystal. The maximum CW output power 3.2 W (at an absorbed pump 6.8 W) and slope efficiency as high 50.4%. operating at 1946 nm in TEM₀₀ mode with M²<1.05. Microchip operation is, principle, due to special crystal cut along N(g) optical indicatrix axis. This possesses positive near-spherical thermal lens that provides required stabilization cavity. Sensitivity factors...

10.1364/ol.39.004247 article EN Optics Letters 2014-07-11

A luminescent thermometer changing from blue to red as temperature increases and based on Yb<sup>3+</sup>,Tm<sup>3+</sup>:GdVO<sub>4</sub>@SiO<sub>2</sub> nanoparticles excited at 980 nm is presented.

10.1039/c6tc01841f article EN Journal of Materials Chemistry C 2016-01-01

Multi-watt continuous-wave (CW) operation of tetragonal rare-earth calcium aluminate Yb:CaLnAlO4(Ln=Gd,Y)) crystals in plano-plano microchip lasers was demonstrated with an almost quantum-defect-limited slope efficiency. Pumped at 978 nm by InGaAs laser diode, a 3.4 mm long 8 at. % Yb:CaGdAlO4 generated 7.79 W 1057-1065 efficiency η=84% (with respect to the absorbed pump power). An even higher η=91% achieved 2.5 3 Yb:CaYAlO4 laser, from which 5.06 were extracted 1048-1056 nm. Both produced...

10.1364/ol.42.002431 article EN Optics Letters 2017-06-15

Nd:KGd(WO<sub>4</sub>)<sub>2</sub> nanoparticles were used as luminescent thermometers operating in the biological windows and NIR imaging with high penetration depth.

10.1039/c6tc01671e article EN Journal of Materials Chemistry C 2016-01-01

A series of Dy3+-doped sodium lanthanum orthosilicate oxyapatites, NaLa9−xDyx(SiO4)6O2 (NLSO:xDy, x = 0–0.3), were synthesized by the solid-state reaction method at 1100 °C, with aim developing yellow emitting phosphors for applications in w-LEDs. Their crystal structure, morphology and particle size distribution, electronic Raman spectra, concentration- temperature-dependent luminescent properties investigated first time. The structure was refined Rietveld method. Undoped NLSO is hexagonal...

10.1016/j.jallcom.2021.163109 article EN cc-by-nc-nd Journal of Alloys and Compounds 2021-12-04

Monoclinic crystals of Tm-doped KLu(WO <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$_4$</tex> ) xmlns:xlink="http://www.w3.org/1999/xlink">$_2$</tex> were grown with high crystalline quality for several dopant concentrations. The relevant spectroscopic properties the xmlns:xlink="http://www.w3.org/1999/xlink">$^3$</tex> F xmlns:xlink="http://www.w3.org/1999/xlink">$_4 rightarrow ^3$</tex> H...

10.1109/jqe.2006.881629 article EN IEEE Journal of Quantum Electronics 2006-09-13

An experimental investigation of a two-dimensional turbulent wake behind spinning cylinder at Re=9000 is carried out to determine the influence rotation on initial development flow. Spectral analysis velocity data measured in near shows that for peripheral velocities up value free-stream velocity, distinct Kármán vortex activity exists within wake, whereas greater velocities, deteriorates and disappears values excess twice velocity.

10.1063/1.864127 article EN The Physics of Fluids 1983-12-01

The crystal structure of monoclinic KLu(WO 4 ) 2 (KLuW) crystals was determined at room temperature by using single-crystal X-ray diffraction data. unit-cell parameters were a = 10.576 (7), b 10.214 c 7.487 (2) Å, β 130.68 (4)°, with Z 4, in space group C 2/ . KLu 1− x Yb (WO relation to concentration. Vickers micro-indentations used study the microhardness KLuW. linear thermal expansion tensor and principal axis maximum (\alpha_{33}' 16.72 × 10 −6 K −1 ), X_3', located 13.51° from axis....

10.1107/s0021889806004328 article EN Journal of Applied Crystallography 2006-03-12

We report on the first Tm-doped double tungstate microchip laser Q-switched with graphene using a Tm:KLu(W04)2 crystal cut along TV g dielectric axis.This generates maximum average output power of 310 mW slope efficiency 13%.At repetition rate 190 kHz shortest pulses 285 ns duration and 1.6 pj energy are achieved.

10.1364/oe.23.014108 article EN cc-by Optics Express 2015-05-20
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