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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Fabrication and Characterization of New Phosphate Glasses and Glass-Ceramics Suitable for Drawing Optical and Biophotonic Libers
摘要： Rare earth doped phosphate glasses are attractive materials for the engineering of photonic devices, due to their easy processing, good thermal stability, excellent optical properties and high rare-earth ions solubility [1]. Besides, phosphate glasses with a P2O5 content of 50 mol% have been shown to be suitable for fiber drawing. It is well known that if the rare-earth ions are located in crystalline phase of desired nature and structure, the spectroscopic properties of the glasses can be enhanced [2]. Therefore, efforts have been focused on the development of new glass-ceramics (GCS) obtained from the heat treatment of glasses, as these engineered materials possess some of the glass properties (large flexibility of composition and geometry) but also some advantages of the RE-doped single crystals (high absorption and emission as well as long lifetimes). In this presentation, we will first discuss how new active phosphate glasses can be prepared with a bioactivity functionality and their composition tailored to enhance their spectroscopic properties. We will show that the heat treatment does not necessarily lead to the bulk precipitation of rare-earth doped crystals (see figure 1). Therefore, we will present a new route to prepare rare-earth doped crystals containing glasses using the direct doping method (schematic presented in Figure 2). We will review the main challenge with this novel route of preparing glasses, related to the survival and dispersion of the particles in the glasses. Finally, we will demonstrate that some of the promising glasses can be drawn into optical fibers with broad luminescence over 70 nm of bandwidth and also into biophotonic fiber in the prospect of developing an innovative biosensor.
关键词： glass-ceramics,biophotonic fibers,phosphate glasses,rare-earth ions,optical fibers
更新于2025-09-23 15:19:57
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Controlled synthesis and panchromatic printing of highly luminescent NaYF4:Ln3+ upconversion hollow microtubes for information encryption on various packaging substrates
摘要： Lanthanide-ion doped β-NaYF4 crystals with bright and tunable upconversion luminescence are urgently demanded in anti-counterfeiting printing. Herein, novel highly luminescent hexagonal NaYF4:Ln3+ upconversion hollow microtubes (UCHMs) were controlled synthesized by a one-pot hydrothermal method employing poly(ethylene imine) (PEI) as ligand. The surface of the synthesized UCHMs was decorated by water-soluble polymer of PEI, rendering the hydrophilic nature of UCHMs. Besides, the synthesized UCHMs exhibited bright upconversion luminescence under the irradiation of a 980 nm laser due to the unique structure and morphology. Time-dependent morphology evolution showed that the formation of UCHMs experience a morphology change from nanoparticles to hexahedron to microprisms, and ultimately to microtubes via a dissolution-reconstruction formation mechanism. Furthermore, the resulting UCHMs were used as pigments for preparation of luminescent inks and their application in anti-counterfeiting printing was explored. To realize panchromatic printing, we prepared three-primary-color (RGB) UCHMs by rational tailoring the doping pairs and molar ratio of the lanthanide ions in UCHMs. Based on the superposition principle of the red-green-blue as three primary colors, a wide array of luminescent inks with panchromatic luminescent colors were prepared. The successful creation of securely light-responsive smart encryption patterns on various packaging substrates such as art paper, aluminum sheet, polyethylene terephthalate (PET) film and cardboard by screen printing was demonstrated. Our strategy provides a new route for controlled synthesis of hydrophilic UCHMs and the as-prepared UCHMs have great potential in application of packaging anti-counterfeiting.
关键词： Rare earth ion-doped NaYF4,Anti-counterfeiting,Hollow microtube,Screen printing,Hydrothermal
更新于2025-09-23 15:19:57
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Development of a Thulium Fiber Laser for an Atomic Spectroscopy Experiment
摘要： A convenient thulium ?ber laser source is described with 3 W of output power operating at a wavelength of 2059 nm with a slope e?ciency of 49% with respect to input pump power and 60% with respect to absorbed pump power. The laser was applied in an atomic helium spectroscopy experiment to quench 3He (2058.63 nm) and 4He (2058.69 nm) meta-stable singlets (21S0), allowing for further investigation of the helium ?ne structure. The customized laser e?ectively eliminates the singlet counts to well below a background level (1%). A simpli?ed analysis describes the basic laser performance with ?tted constants in reasonable agreement with previous work.
关键词： fiber,thulium fiber laser,laser,spectroscopy,fiber laser,rare-earth elements,optics,thulium
更新于2025-09-23 15:19:57
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A Short Review on Rare Earth Doped NaYF4 Upconverted Nanomaterials for Solar Cell Applications
摘要： The enhancement of upconversion luminescence (UCL) of rare earth (RE) doped upconversion nanomaterials which facilitates anti-Stokes emission is particularly important and urgently required for a broad range of applications. The fascinating properties such as anti-Stokes shifts, long life times and sharp emissions exhibits potential application in various areas. The UC is one of the exciting processes in the RE ions in which one can get the emission of high energy ultra-violet (UV) and visible (Vis) photons with the help of low energy near infrared (NIR) photons. In this mini review, we have discussed fundamental concepts of NaYF4 host for UC emission. The NaYF4 host has been selected due to its low phonon energy and composition stability. We have also demonstrated that the introduction of core shell and plasmonic nanostructure which has a critical effect on UCL. The recent advances in plasmon-enhanced UCL in RE doped NaYF4 are also noted. Finally, the recent solar cell applications of RE doped NaYF4 nanocomposite phosphor materials are introduced.
关键词： solar cell,nanomaterials,NaYF4,Rare earth
更新于2025-09-23 15:19:57
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High-sensitive optical temperature sensing based on 5D1 emission of Eu3+ in YVO4
摘要： By studying the temperature-induced red-shift of the V-O charge transfer band (CTB) edge in YVO4:10% Eu3+, we demonstrate a high-sensitive strategy for optical temperature sensing using the combination of the temperature-induced enhancement of the excitation in the tail of the CTB and the thermal population of 5D1 state of Eu3+. Under a constant 358 nm excitation, the integrated emission intensity corresponding to 5D1 → 7F1 transition of Eu3+ exhibits drastic temperature dependence ranging from 300 to 480 K. A high relative sensitivity SR was obtained to be 3923/T2. Temperature cycling tests were performed to evaluate the reusability and feasibility as temperature sensors. Our results indicate the potential use of the proposed strategy for high performance optical thermometry.
关键词： Charge transfer band,Rare earth ions,Thermal population,Optical temperature sensing,Luminescence
更新于2025-09-19 17:15:36
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Fluorescence Studies of Dy3+ Ions in Silica Sol Gel
摘要： The fluorescence properties of Dy3+ ion are utilized to study the structural changes during the gel to glass transition of the silica xerogels. The fluorescence intensity ratio (yellow to blue, Y/B) is used as a measure of the symmetry of rare earth ion environment during the gel-glass conversion. The high value of the intensity ratio of gel heated to 1000 °C showed that the rare earth ions are embedded in the glassy silica network with an asymmetric environment. Fluorescence study is also used to characterize the effect of metal cation co-dopants on the state of aggregation of rare earth ions in silica sol gel. The addition of co-dopants inhibits the clustering of rare earth ions and promotes better dispersion. The inhibition of clustering is correlated with the generation of strong crystal field bonding sites for rare earth ions in the presence of co-dopants.
关键词： Rare earth doped materials,Luminescence,Sol gel
更新于2025-09-19 17:15:36
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APTES modified GO-PEI-Er3+/Yb3+: NaYF4 Upconverting Nanoparticles Hybrid Film Based Optical pH Sensor and NIR Photoelectric Response
摘要： The APTES modified GO-PEI-Er3+/Yb3+: NaYF4 upconverting nanoparticles hybrid film has been developed. The developed films have been structurally and optically characterized. The upconversion (UC) emission based pH dependent study to sense pH upon excitation at 980 nm diode laser radiation has been performed. The UC emission intensity is significantly reduced for pH ~ 9 and explained due to strong interaction between graphene oxide and PEI-APTES-Er3+/Yb3+:NaYF4 UC NPs. The developed film is also found more sensitive to the urine as observed from the UC emission measurement. The developed film exhibits good repeatability and high stability. The UC emission intensity for both the green and red bands arising from the Er3+ ion in the developed film shows a decreasing trend with increase in pH values (pH range of 5-9). The photocurrent response of the developed films (i.e. film 2 and film 3) coated on FTO glass plate upon excitation at 980 nm laser radiation shows the increment in current values by ~ 17% and ~ 14% respectively when the pump power density of the excitation source reaches to 1.5 W/mm2.
关键词： pH sensor,Upconversion,Rare earth,Graphene oxide,Photoelectric response
更新于2025-09-19 17:15:36
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Enhanced upconversion and downshifting emissions from Tm3+, Yb3+ co-doped CaZrO3 phosphor in the presence of alkali ions (Li+, Na+ and K+)
摘要： The Tm3+, Yb3+ co-doped CaZrO3 phosphor samples have been synthesized through solid state reaction method in the absence and presence of alkali metal ions (i.e. Li+, Na+, K+). The X-ray diffraction (XRD) study shows the formation of CaZrO3 crystal with orthorhombic phase. The Tm3+, Yb3+ co-doped CaZrO3 phosphor emits intense upconversion emission in blue (474 nm) and NIR (799 nm) regions due to 1G4 → 3H6 and 3H4 → 3H6 transitions of Tm3+ ions, respectively on excitation with 980 nm radiation. The emission intensity is significantly enhanced in the presence of alkali ions due to charge compensation and asymmetry in the crystal field. The emission intensity in the case of Na+ co-doped phosphor is maximum and at 1 W pump power, it is increased by ~ 44 and ~ 31 times in blue and NIR regions, respectively as compared to without alkali ions co-doped phosphor. The downshifting emission in blue region has been observed due to oxygen vacancy and Tm3+ ions on excitation with 277 and 360 nm radiations which is enhanced significantly in the presence of alkali ions. Thus, the intense blue emission by this material is suitable for blue and white light emitting phosphors.
关键词： Calcium Zirconate,Downshifting,Alkali ions,Upconversion,Rare earth
更新于2025-09-19 17:15:36
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Reliability of rare-earth-doped infrared luminescent nanothermometers
摘要： The use of infrared-emitting rare-earth-doped luminescent nanoparticles as nanothermometers has attracted great attention during the last few years. The scientific community has identified rare-earth-doped luminescent nanoparticles as one of the most sensitive and versatile systems for contactless local temperature sensing in a great variety of fields, but especially in nanomedicine. Researchers are nowadays focused on the design and development of multifunctional nanothermometers with new spectral operation ranges, outstanding brightness, and enhanced sensitivities. However, no attention has been paid to the assessment of the actual reliability of the measurements provided by rare-earth-doped luminescent nanothermometers. In fact, it is assumed that they are ideal temperature sensors. Nevertheless, this is far from being true. In this work we demonstrate that the emission spectra of rare-earth-doped nanothermometers can be affected by numerous environmental and experimental factors. These include the numerical aperture of the optical elements used for their optical excitation and luminescence collection, the local concentration of nanothermometers, optical length variations, self-absorption of the luminescence by the nanothermometers themselves, and solvent optical absorption. This work concludes that rare-earth-doped luminescent nanothermometers are not as reliable as thought and, consequently, special care has to be taken when extracting temperature estimations from the variation of their emission spectra.
关键词： reliability,solvent absorption,self-absorption,excitation power dependence,infrared luminescent nanothermometers,rare-earth-doped
更新于2025-09-19 17:15:36
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Rare earth-free composites of carbon dots/metal-organic framework as white light-emitting phosphor
摘要： Over the last few years, numerous efforts have been made to develop white light-emitting metal-organic frameworks (MOFs), due to the useful features of MOFs such as ultrahigh surface areas and tunable pore architecture. However, rare earth (RE) ions are most commonly applied as phosphors in these materials so far, raising device cost and environmental concerns. Here, we designed a new type of RE-free material capable of white light-emission upon excitation at 365 nm, with the photoluminescence quantum yield in solid state reaching 37%, fabricated by compositing carbon dots (CDs) with Zr(IV)-based MOF. WLEDs constructed by depositing the CDs/Zr-MOF nanocomposite on a commercial UV LED chip feature a CIE chromaticity coordinate at (0.31, 0.34), high color rendering index (CRI) of 82, and luminous efficiency of 1.7 lm/W.
关键词： carbon dots,rare-earth-free luminophores,white-light-emission,Zr-MOFs,down-conversion LEDs
更新于2025-09-19 17:15:36