Computational and experimental microfluidics: Total analysis system for mixing, sorting, and concentrating particles and cells.

Body fluids can potentially indicate the presence of non-small cancer cells. Studying these fluids is an emerging field that could be crucial for cancer detection and monitoring treatment effectiveness. Meanwhile, the examination of fluids on a microscopic level is part of the field of microfluidics.

Cascade laser optimization for H → H and F → H sequent transitions in Tm-doped materials.

We study a cascade laser scheme involving the H → H and F → H consecutive transitions in Tm-doped materials as a promising technique to favor laser emission at 2.3 µm. We examine the conditions in terms of the Tm doping levels for which the cascade laser is beneficial or not.

Structure and luminescence properties of Dy doped quaternary tungstate LiBaGd(WO) for application in wLEDs.

Quaternary tungstates with the composition LiBaGd(WO) doped with different concentrations of Dy (from 0.5 to 10 at%) were prepared by the solid-state reaction method at 900 °C. Their structural, spectroscopic and optical properties were studied systematically in this work.

Excited-state absorption and upconversion pumping of Tm-doped potassium lutetium double tungstate.

We report on a bulk thulium laser operating on the H → H transition with pure upconversion pumping at 1064 nm by an ytterbium fiber laser (addressing the F → F excited-state absorption (ESA) transition of Tm ions) generating 433 mW at 2291 nm with a slope efficiency of 7.4% / 33.2% vs.

Tailoring Wettability Properties of GaN Epitaxial Layers through Surface Porosity Induced during CVD Deposition.

Porous GaN epitaxial layers were prepared using single-step chemical vapor deposition (CVD) through the direct reaction of ammonia with gallium. The degree of porosity and pore diameters in the resulting GaN were analyzed by means of SEM and AFM and were found to depend on the GaN deposition time. Furthermore, the evolution of the contact angle of a droplet of water located on the surface of these GaN epitaxial layers with the deposition time was investigated.

Lanthanide doped luminescence nanothermometers in the biological windows: strategies and applications.

The development of lanthanide-doped non-contact luminescent nanothermometers with accuracy, efficiency and fast diagnostic tools attributed to their versatility, stability and narrow emission band profiles has spurred the replacement of conventional contact thermal probes. The application of lanthanide-doped materials as temperature nanosensors, excited by ultraviolet, visible or near infrared light, and the generation of emissions lying in the biological window regions, I-BW (650 nm-950 nm), II-BW (1000 nm-1350 nm), III-BW (1400 nm-2000 nm) and IV-BW (centered at 2200 nm), are notably growing due to the advantages they present, including reduced phototoxicity and photobleaching, better image contrast and deeper penetration depths into biological tissues. Here, the different mechanisms used in lanthanide ion-doped nanomaterials to sense temperature in these biological windows for biomedical and other applications are summarized, focusing on factors that affect their thermal sensitivity, and consequently their temperature resolution.

Effect of the Size and Shape of Ho, Tm:KLu(WO) Nanoparticles on Their Self-Assessed Photothermal Properties.

The incorporation of oleic acid and oleylamine, acting as organic surfactant coatings for a novel solvothermal synthesis procedure, resulted in the formation of monoclinic KLu(WO) nanocrystals. The formation of this crystalline phase was confirmed structurally from X-ray powder diffraction patterns and Raman vibrational modes, and thermally by differential thermal analysis. The transmission electron microscopy images confirm the nanodimensional size (~12 nm and ~16 nm for microwave-assisted and conventional autoclave solvothermal synthesis) of the particles and no agglomeration, contrary to the traditional modified sol-gel Pechini methodology.

Tm and Ho colasing in in-band pumped waveguides fabricated by femtosecond laser writing.

We report on the first, to the best of our knowledge, in-band pumped , codoped waveguide (WG) laser. A depressed-index surface channel WG (type III) with a 50 µm half-ring cladding is fabricated in a 5 at. % , 0.

Spectroscopy and diode-pumped laser operation of transparent Tm:LuAlO ceramics produced by solid-state sintering.

A transparent Tm:LuAlO ceramic is fabricated by solid-state reactive sintering at 1830 °C for 30 h using commercial α-AlO and LuO/TmO powders and sintering aids - MgO and TEOS. The ceramic belongs to the cubic system and exhibits a close-packed structure (mean grain size: 21 µm). The in-line transmission at ∼1 µm is 82.

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.

Low-loss fs-laser-written surface waveguide lasers at >2 µm in monoclinic Tm:MgWO.

Surface channel waveguides (WGs) based on a half-ring (40-60-µm-diameter) depressed-index cladding (type III) geometry are fabricated in monoclinic Tm:MgWO by femtosecond (fs) laser writing at a repetition rate of 1 kHz. The WGs are characterized by confocal laser microscopy and -Raman spectroscopy. A Tm:MgWO WG laser generates 320 mW at ∼2.

Bifunctional Tm,Yb:GdVO@SiO Core-Shell Nanoparticles in HeLa Cells: Upconversion Luminescence Nanothermometry in the First Biological Window and Biolabelling in the Visible.

The bifunctional possibilities of Tm,Yb:GdVO@SiO core-shell nanoparticles for temperature sensing by using the near-infrared (NIR)-excited upconversion emissions in the first biological window, and biolabeling through the visible emissions they generate, were investigated. The two emission lines located at 700 and 800 nm, that arise from the thermally coupled F and H energy levels of Tm, were used to develop a luminescent thermometer, operating through the Fluorescence Intensity Ratio () technique, with a very high thermal relative sensitivity . Moreover, since the inert shell surrounding the luminescent active core allows for dispersal of the nanoparticles in water and biological compatible fluids, we investigated the penetration depth that can be realized in biological tissues with their emissions in the NIR range, achieving a value of 0.

Single crystal growth, optical absorption and luminescence properties under VUV-UV synchrotron excitation of type III Pr:KGd(PO).

Scintillator materials are widely used for a variety of applications such as high energy physics, astrophysics and medical imaging. Since the ideal scintillator does not exist, the search for scintillators with suitable properties for each application is of great interest. Here, Pr-doped KGd(PO) bulk single crystals with monoclinic structure (space group: P2) are grown from high temperature solutions and their structural, thermal and optical properties are studied as possible candidates for scintillation material.

Spectroscopy and high-power laser operation of a monoclinic Yb:MgWO crystal.

Monoclinic (wolframite-type) monotungstate crystals are promising for rare-earth doping. We report polarized room- and low-temperature spectroscopy and efficient high-power laser operation of such a ${{\rm Yb}^{3 + }}{:}\,{{\rm MgWO}_4}$Yb:MgWO crystal featuring high stimulated emission cross section (${\sigma _{\rm SE}}\; = \;{6}.{2}\; \times \;{{10}^{ - 20}}\;{{\rm cm}^2}$σ=6.

Laser operation of cleaved single-crystal plates and films of Tm:KY(MoO).

We report on the crystal growth, spectroscopy and first laser operation of a novel double molybdate compound - Tm:KY(MoO). This orthorhombic (sp. gr.

Ultrafast laser inscribed waveguide lasers in Tm:CALGO with depressed-index cladding.

Depressed-index buried and surface channel waveguides (type III) are produced in a bulk 3.5 at.% Tm:CALGO crystal by femtosecond direct-laser-writing at kHz repetition rate.

Optimization of the Synthesis and Physical Characterization of Praseodymium-Doped Type III KGd(PO) Nanocrystals.

Scintillator materials are used as detectors in the ray imaging techniques for medical diagnosis. Because the ideal medical scintillator material does not exist, many efforts are being made to find new materials that satisfy a greater number of properties. Here, the synthesis conditions of Pr:KGd(PO) nanocrystals by the modified Pechini method are optimized to obtain a single crystalline phase of those that form the polymorphism of KGd(PO).

Investigation of antireflective and hydrophobic properties in polycrystalline GaN films with dual porosity produced by CVD.

We optimized the deposition conditions of polycrystalline nanoporousGaN coatings produced by Chemical Vapor Deposition on Si substrates, by exploring the effect produced by the Ga holder shape, the initial amount of Ga, the reaction deposition time and the metallic catalyst used. Such polycrystalline films probed to act as antireflective coatings by reducing the reflectance of Si substrates by 50% or more, and that of flat GaN samples by 40% in the UV and 83% in the visible, at the same time that they exhibit an almost constant reflectance from 400 to 800 nm, important to develop UV sensors with enhanced sensitivity. Furthermore, the polycrystalline nanoporous coatings we developed exhibit hydrophobic behaviour, with a static contact angle of 119°, and a contact angle hysteresis of 4.

KLu(WO)/SiO Tapered Waveguide Platform for Sensing Applications.

This paper provides a generic way to fabricate a high-index contrast tapered waveguide platform based on dielectric crystal bonded on glass for sensing applications. As a specific example, KLu(WO) crystal on a glass platform is made by means of a three-technique combination. The methodology used is on-chip bonding, taper cutting with an ultra-precise dicing saw machine and inductively coupled plasma-reactive ion etching (ICP-RIE) as a post-processing step.

Ytterbium calcium fluoride waveguide laser.

Calcium fluoride is a well-known material for optical components. It is also suited for doping with rare-earth ions, e.g.

Fs-laser-written thulium waveguide lasers Q-switched by graphene and MoS.

We report the generation of mid-infrared (~2 µm) high repetition rate (MHz) sub-100 ns pulses in buried thulium-doped monoclinic double tungstate crystalline waveguide lasers using two-dimensional saturable absorber materials, graphene and MoS. The waveguide (propagation losses of ~1 dB/cm) was micro-fabricated by means of ultrafast femtosecond laser writing. In the continuous-wave regime, the waveguide laser generated 247 mW at 1849.

"Mixed" Tm:Ca(Gd,Lu)AlO - a novel crystal for tunable and mode-locked 2 µm lasers.

We report on the crystal growth, spectroscopy characterization and first laser operation of a new tetragonal disordered "mixed" calcium aluminate crystal, Tm:Ca(Gd,Lu)AlO. The introduction of Lu leads to an additional inhomogeneous broadening of Tm absorption and emission spectra compared to the well-known Tm:CaGdAlO. The maximum stimulated-emission cross-section for the F → H Tm transition is 0.

Femtosecond-laser-written Ho:KGd(WO) waveguide laser at 2.1 μm.

We report on efficient laser operation of the first holmium monoclinic double tungstate waveguide laser fabricated by femtosecond direct laser writing. A depressed-index buried channel waveguide with a 60 μm diameter circular cladding was inscribed in 5 at.% Ho:KGd(WO).

Diamond saw dicing of thulium channel waveguide lasers in monoclinic crystalline films.

A surface channel waveguide (WG) laser is produced by diamond saw dicing of a 15 μm thick 10 at. % Tm:KYGdLu(WO) monoclinic double tungstate thin film grown by liquid phase epitaxy on an undoped KY(WO) substrate. The WG propagation losses are 1.

Mapping Temperature Distribution Generated by Photothermal Conversion in Graphene Film Using Er,Yb:NaYF Nanoparticles Prepared by Microwave-Assisted Solvothermal Method.

This study analyzes the mapping of temperature distribution generated by graphene in a glass slide cover after illumination at 808 nm with a good thermal resolution. For this purpose, Er,Yb:NaYF nanoparticles prepared by a microwave-assisted solvothermal method were used as upconversion luminescent nanothermometers. By tuning the basic parameters of the synthesis procedure, such as the time and temperature of reaction and the concentration of ethanol and water, we were able to control the size and the crystalline phase of the nanoparticles, and to have the right conditions to obtain 100% of the β hexagonal phase, the most efficient spectroscopically.