Fluoride Glasses Research Articles

Prediction of mid-infrared 2.72 μm lasing in heavily Er3+-doped fluorotellurite glass

Fluorotellurite glasses heavily doped with Er3+ are prepared in less demanding conditions as compared with fluoride glasses. Specifically, the effects of PbF2 added in the system of AlF3–MgF2–CaF2–SrF2–BaF2–TeO2 (AMCSBYT) are systematically studied on the correlation between glass structure and mid-infrared (MIR) luminescent properties of Er3+. These PbF2-modified glasses with an improved thermal stability and a noticeably reduced phonon energy as compared with telluride glasses exhibit an intense MIR emission at 2.72 μm and a long radiative decay lifetime. Calculation and analysis based on the Judd-Ofelt theory provide deeper insights into the interdependence of luminescent properties and glass structure. Numerical simulation is conducted for a MIR fiber laser based on the experimental data derived from the proposed glass. The 2.72 μm lasing output of 0.68 W is predicted with a slope efficiency of 3.38 %. It is expected that the performance of the fiber laser can be further optimized such that the output power can be increased over 1.0 W. The results emphasize the potential of the PbF2-modified fluorotellurite glass as a promising gain material for 2.72 μm fiber lasers.

Mid-infrared interferometry with non-adiabatic tapered ZBLAN optical fiber

This work illustrates, to the best of our knowledge, the first non-adiabatic tapered single-mode zirconium fluoride optical fiber sensor in the mid-infrared spectral range. It is designed and fabricated via pulling and heating technique. A waist diameter d w = 25 µm with no visible crystallization is achieved, overcoming the typical fluoride glass challenges associated with crystallization, narrow temperature fabrication window, and low glass transition temperature. The performance of the non-adiabatic tapered optical fiber is theoretically and experimentally investigated, demonstrating its high potential for a wide range of sensing applications in the mid-infrared spectral range.

Histological analysis of laser-enabled tissue coring with a novel 2910 nm erbium-doped fluoride glass fiber laser.

There remains an unmet need for a laser-enabled tissue coring device that can effectively improve face and neck skin laxity and rhytides. We investigate a novel 2910 nm erbium-doped fluoride glass fiber laser (2910 nm fiber laser) (UltraClear; Acclaro Medical) for laser-coring of submental tissue. Five subjects, Glogau scale III-IV, were treated with a single pulse of the laser-coring mode of the 2910 nm fiber laser in the submentum. A 4 mm punch biopsy was immediately performed. Biopsy specimens were sectioned and stained with hematoxylin and eosin and placed on glass slides. All sections were reviewed, and sections containing the center of the transected core were analyzed for depth and diameter of the ablative microchannel and width of the surrounding zone of coagulation. A total of 15 intact micro-cores were analyzed. Histological analysis revealed an average ± standard deviation microchannel diameter of 242.5 ± 65.2 µm, an average ablative depth of 980 ± 318.8 µm, and an average zone of coagulation of 104 ± 32 µm. Laser-enabled tissue coring with a novel 2910 nm fiber laser can safely achieve a wider microchannel diameter with ablative depth extending to the mid and deep dermis, which has the potential for collagen contraction and tissue tightening. Laser-coring to this ablation diameter and depth and with the surrounding zone of coagulation was found to be safe without adverse effects of post-inflammatory erythema or scarring in our study.

High power and high efficiency yellow laser in Dy3+-doped single-mode double-clad structured waterproof fluoro-aluminate glass fiber

We demonstrated a single-mode yellow fiber laser using a Dy3+-doped single-mode double-clad structured weatherproof fluoro-aluminate glass fiber (Dy3+:SM-DC-WPFGF) and a 450-nm GaN laser diode (LD) as the excitation light. The power of 445 mW and the slope efficiency of 51.2% were achieved for the single-mode yellow fiber laser. The power level was approximately 20 times higher than our previous result due to improved efficiency of the focusing optics and increased Dy3+ doping concentration (10,000 ppm) in the fiber core. This yellow fiber laser shows particular promise for use in the medical field, e.g., for the treatment of melasma and telangiectasia.

Erbium(III)-Doped Fluorozirconate Phosphate Glasses and Glass Ceramics: Visible and NIR Luminescence

Erbium(III)-Doped Fluorozirconate Phosphate Glasses and Glass Ceramics: Visible and NIR Luminescence

Mechanochemical synthesis of fluoride-ion conducting glass and glass–ceramic in ZrF4–BaF2 binary system

Fluoride glasses in the binary system ZrF4–BaF2 were prepared via mechanochemical treatment. The glass-forming region of the ZrF4–BaF2 system obtained using the mechanochemical method was wider than that obtained using the conventional melt-quenching method. The glass–ceramic 60ZrF4·40BaF2 (mol%) sample was obtained by heat treatment and shows a higher conductivity of 1.2 × 10–6 S cm−1 at 200 °C than the pristine glass. This study revealed that mechanochemical treatment was effective for the synthesis of fluoride glasses.

Tailoring fluoride networks to precipitate hexagonal Ln1-yMyF3-y nanocrystals in glass: Towards short-wavelength upconversion PL of lanthanides

The AlF3-MF2-LnF3 (M = Ca; Sr; Ba; Ln = Yb/Tm) based pure fluoride GCs are essentially ideal candidates for the realization of PL in UV and VIS spectral region. However, the pure fluoride glasses are prone to precipitation of undesired nano-crystals while quenching and post annealing due to their poor chemical stability. Therefore, the development of such glass systems requires strict adherence to composition control right from the outset. This research employed extensive molecular dynamics (MD) simulations and incorporated the results into the experimental design to develop an efficient multicomponent fluoride glass system. Vivid simulation of M-F-Ln and M-F-Al nano-cluster formation via MD are observed in the glass matrix. These nano-clusters serve as the structural origins of the precipitated nano-crystals in GCs post heat treatment. Through meticulous manipulation of the Al/M ratio, it became feasible to theoretically forecast the transformation of the glass matrix from a cubic M1-xLnxF2+x to a hexagonal Ln1-yMyF3-y nano-crystal precipitated GCs, which could conceivably be manufactured experimentally. This transformation offers superior luminescent performance for Ln1-yMyF3-y containing GCs enabling short-wavelength PL realisation in near UV (∼361 nm with 8-fold enhancement) and VIS (∼478 nm with 1.7-fold enhancement) from Yb3+/Tm3+ transitions, in comparison to its cubic M1-xLnxF2+x counterpart. Hence, we propose an effective fluoride glass system for short-wavelength upconversion luminescent applications through the integration of MD simulations and experimental research.

All-fiber-coupled mid-infrared quartz-enhanced photoacoustic sensors

Infrared laser-based gas sensors are mature to take the leap from laboratory prototype to outdoor operation. Considering the demand of high robustness and compactness, the reliability of the optical alignment in a sensor is the top priority. This paper proposes a solution designing an optical system embedded within a sealed metallic cylinder containing an aspheric micro-lens to couple a single-mode interband cascade laser with an indium fluoride glass fiber. The fiber output is plug & play connected to an acoustic detection module of a quartz-enhanced photoacoustic sensor (QEPAS) equipped with a fiber port, avoiding the use of any free-space optics, from the source to the detection module. To demonstrate the operability, three all-fiber-coupled QEPAS sensors were realized for detection of CH4, CO2 and NO reaching sub-ppm ultimate detection limits with a signal integration time of 100 ms.

Dual-wavelength lasing at ∼1.2 μm and ∼2.0 μm in a Ho3+-doped fluoroaluminate glass microsphere

This study presents the experimental realization of a microsphere laser resonator designed to operate within the approximate wavelength range of 1.2 μm and 2.0 μm. This resonator, employing a Ho3+-doped fluoroaluminate glass microsphere, was stimulated by a 1150 nm laser, marking the first demonstration of its kind. The observed laser emissions at ∼1.2 μm and ∼2.0 μm were ascribed to the transitions of Ho3+ ions, specifically 5I6 → 5I8 and 5I7 → 5I8, respectively. The fabrication of the microsphere, possessing a characteristic diameter of approximately 50 μm, entailed the controlled melting of a fluoroaluminate glass filament through the application of a focused CO2 laser beam. Concurrently, a tapered fiber with a waist diameter of ∼2 μm was created by subjecting a standard silica single-mode fiber to a process of controlled heating and stretching. The findings of this investigation suggest promising prospects for the development of multi-wavelength lasers utilizing fluoroaluminate glass microspheres, particularly in intricate environmental settings.

The effect of combined use of resin infiltration with different bioactive calcium phosphate-based approaches on enamel white spot lesions: An in vitro study

ObjectivesThis in vitro study aimed to evaluate the effect of resin infiltration combined with casein phosphopeptide-amorphous calcium phosphate with fluoride (CPP-ACPF) or bioactive glass (BAG) on the stability of enamel white spot lesions (WSLs) treatment. Materials and methodsEighty-four enamel blocks were prepared from the buccal surfaces of sound human premolars. All enamel blocks were placed in a demineralisation solution for 3 days to establish the artificial enamel WSLs. Enamel blocks with WSLs were randomly divided into three groups (n = 28 each group): RI/B: one-off resin infiltration followed by twice daily BAG treatment; RI/C: one-off resin infiltration followed by twice daily CPP-ACPF treatment; RI: one-off resin infiltration treatment only (as control) and subjected to pH cycling for 7 days. Surface morphology, elemental analysis, crystal characteristics, surface roughness and microhardness of enamel surfaces were investigated by scanning electron microscopy and energy-dispersive spectrometry observation, X-ray diffraction (XRD), atomic force microscope and Vickers’ hardness testing, respectively. ResultsMean values of the surface roughness (mean±standard deviation (nm)) were 24.52±5.07, 27.39±5.87 and 34.36±4.55 for groups RI/B, RI/C and RI respectively (p = 0.003). The calcium to phosphate ratios were 1.32±0.16, 1.22±0.26 and 0.69±0.24 for groups RI/B, RI/C and RI respectively (p < 0.001). XRD revealed apatite formation in all three groups. The mean enamel surface microhardness (kg/mm2) of the groups were 353.93±28.49, 339.00±27.32 and 330.38±22.55 for groups RI/B, RI/C and RI respectively (p = 0.216). ConclusionsResin infiltration combined with CPP-ACPF or BAG remineralisation appears to improve the surface properties of WSLs. Clinical SignificanceThe combination of resin infiltration and CPP-ACPF/BAG remineralisation may be a potential treatment for the management of the WSLs.

Direct generation of multicolor Bessel beams from a Pr3+: WPFG fiber laser.

Multicolor visible high-order Bessel (Bessel-vortex) beams which have a helical wavefront and a long confocal length have garnered significant interest for applications in materials processing and biomedical technologies. In this paper, we demonstrate the direct generation of multicolor (523, 605 and 637 nm) Bessel-vortex beams from a Pr3+-doped water-proof fluoro-aluminate glass (Pr3+: WPFG) fiber laser with an intracavity lens which induces chromatic and spherical aberration. The handedness of the generated Bessel-vortex beam is selectively controlled through lateral displacement of the intra-cavity lens.

Full-face and neck resurfacing with a novel ablative fractional 2910 nm erbium-doped fluoride glass fiber laser for advanced photoaging.

Ablative fractional lasers have long been considered the gold standard for facial resurfacing for advanced photoaging. These lasers offer an improved safety profile compared to traditional ablative lasers but typically require more treatment sessions given their fractional approach. In this study, we evaluate a new novel 2910 nm erbium-doped fluoride glass fiber laser (2910 nm fiber laser) (UltraClear; Acclaro Medical) for full-face and neck resurfacing for the treatment of advanced photoaging. Twenty-two healthy subjects aged 44-80 years presenting for advanced facial photoaging and rhytides were enrolled in the study. All subjects received three full-face and neck, multipass treatments utilizing the 2910 nm fiber laser spaced 6-8 weeks apart. Subjects were asked to rate the average level of pain during the treatment. At 90 days following subjects' third treatment subjects evaluated their improvement using a Global Aesthetic Improvement Scale (GAIS) and rated their satisfaction with the treatment. Evaluation of pretreatment and posttreatment photos was completed by two blinded physician reviewers. Reviewers were asked to identify the pretreatment and posttreatment photographs and to rate the degree of improvement utilizing a GAIS. Fifteen participants completed the study; six were exited from the study (withdrew or lost to follow-up). The average subject GAIS score for overall appearance was 3.8. The average subject satisfaction level at follow-up was 4.8. The average subject pain score was 4.9. One blinded physician reviewer correctly identified 100% of subjects' posttreatment photographs, while the second blinded reviewer correctly identified 93%. Blinded evaluation of digital photographs revealed an average GAIS score of 3.2. Posttreatment skin responses included pin-point hemorrhage, erythema, edema, and soft tissue crusting lasting 5-7 days. There were no instances of infection, scarring or hypopigmentation. There were two instances of temporary hyperpigmentation. Treatment with the novel 2910 nm fiber laser is safe and effective in treating advanced photoaging and rhytides. Three treatments produced moderate to marked improvement with high patient satisfaction and treatment was associated with less discomfort and downtime compared to conventional fractional ablative lasers.

Short review and prospective: chalcogenide glass mid-infrared fibre lasers

Rare-earth ion doped, silica glass, optical fibre amplifiers have transformed the world by enabling high speed communications and the Internet. Fibre lasers, based on rare-earth ion doped silica glass optical fibres, achieve high optical powers and are exploited in machining, sensing and medical surgery. However, the chemical structure of silica glass fibres limits the wavelength of laser operation to < 2.5 µm, which excludes the mid-infrared longer wavelength range of 3–50 µm. Rare-earth ion doping of fluoride glasses enables manufacture of fibre lasers up to a limiting 3.92 µm wavelength, but the fluoride glass chemical structure again prevents operation at longer wavelengths. Optical fibre lasers that are constructed from different rare-earth ion doped chalcogenide glass fibres will potentially operate across the 4–10 µm wavelength range, where suitable high-power lasers currently do not exist. We present a short review here of our recent work in achieving first time, continuous wave, mid-infrared fibre lasing beyond 5 μm wavelength in Ce3+-doped selenide chalcogenide fibre. We place this disruptive breakthrough into the wider fibre laser context, and also present the unprecedented advances in new cross-sector applications that will be enabled by mid-infrared fibre lasers in the 4–10 µm wavelength range. To surpass the few mW power output of the Ce3+-doped chalcogenide glass fibre lasing achieved to date, the glass quality of the doped chalcogenide fibres must now be improved, similar to the challenges originally facing the first glass fibre lasers based on silica.

Modified Chalcogenide Glass Equations for the Activation Energy of Crystallization

For over six decades, chalcogenide glasses (ChGs) have played a pivotal role in the optical community, fostering innovations and new applications in photonics, electronics, and electro-optics. In the last decade, the exploration of novel applications, such as Gradient Index (GRIN) ChGs, has underscored the need for a nuanced comprehension and precise control of nucleation and crystallization kinetics in emerging infrared glass compositions. This article explores the activation energy of crystallization in amorphous materials, particularly focusing on ChGs. It identifies long-standing challenges associated with existing models used for crystal growth in nucleated glasses. Employing carefully outlined mathematical logic, our study critiques conventional models and introduces innovative equations centering around the need for balanced units and proper physical trends. These new models overcome some shortcomings of the established framework and provide a more accurate depiction of crystallization kinetics. To validate the efficacy of our proposed models, we conducted a comparative analysis using differential scanning calorimetry data from a recently published Sb-Te-Se chalcogenide glass composition. The numerical and graphical results clearly illustrate the improvements inherent in our models and their practical utility. Beyond ChGs, our models and equations have broader applications. They may extend to oxide, halide, oxy-halide, and fluoride glass compositions, as well as polymers, contributing new tools to the understanding of crystallization kinetics across diverse materials. Received: 29 November 2023 | Revised: 9 January 2024 | Accepted: 18 January 2024 Conflicts of Interest The authors declare that they have no conflicts of interest to this work. Data Availability Statement Data sharing not applicable – no new data generated. All data used in calculations was extracted from Elabbar et al. (2008).

RESEARCH AND DEVELOPMENT OF TECHNOLOGY FOR PRODUCTION OF SODIUM FLUORIDE, AMORPHOUS SILICA AND LIQUID GLASS FROM A MIXTURE OF FLUOROSILICIC AND HYDROFLUORIC ACIDS

In article presents the results of processing of a mixture of fluorosilicic and hydrofluoric acids – a by-product of fluoride salts and phosphate fertilizers production in order to obtain sodium fluoride, silica gel (amorphous silicon oxide) and liquid glass. On this basis, the optimal technological parameters of the interaction of a mixture of FSA and hydrofluoric acid with sodium hydroxide were determined depending on temperature, process duration and sodium hydroxide concentration. It was found that at temperature 25 ºC, process duration 15 min, sodium hydroxide concentration 45% wt. the degree of sodium fluoride extraction reaches more than 93%. Also, sodium fluoride dissolved during the reaction after hydrolysis of sodium metasilicate with precipitation and filtration of silica gel is returned back to the production cycle for preparation of the required sodium hydroxide solution. It was determined that treatment of amorphous silica forming with 10 % sodium hydroxide solution for 60 min. and temperature 85-90 ºC yields liquid glass. The results of the conducted research are confirmed by chemical and X-ray phase analyses, which gives grounds for the introduction of this technology in the industry. In addition, on the basis of the conducted researches the basic technological scheme of processing of the mixture of FSA and hydrofluoric acid was developed in order to obtain sodium fluoride, amorphous silica and liquid glass.

Synthesis, optical and magnetic properties of Nd2O3/borate strontium fluoride glasses

The present work conducts the synthesis, thermal, optical, and magnetic characterization of (60-x)B2O3+20Li2O+20SrF2+ x Nd2O3 where x = 0, 0.5, 1, 1.5, 2 mol% glass samples. The samples were investigated via X-ray diffraction (XRD), Raman spectroscopy, differential scanning calorimetry (DSC), UV–Vis absorption spectroscopy, and vibrating sample magnetometry (VSM). XRD patterns for borate strontium fluoride glass samples doped with Nd2O3 showed broad humps around 30 and 43°, indicating their amorphous structure. Raman spectra of glass samples indicated that as Nd3+ ions were added to the host matrix, there was an increase in Raman intensity due to bond breakdown and the development of more non-bridging oxygen (NBO) species. The DSC data of the borate strontium fluoride glass samples doped with Nd2O3 demonstrated that the glass transition temperature (Tg) generally increased. UV–Vis absorption spectra showed transitions in Nd3+ ions doped borate glasses that are associated with the bands at different wavelengths, attributed to 4G5/2+2G7/2, 2H11/2, 4F9/2, 2H9/2 +4F5/2, and 4F3/2. The refractive index of borate strontium fluoride glass samples doped with Nd2O3 increased. The saturation magnetization values decreased from 0.9 to 0.29 upon increasing the Nd2O3 percentage (0–2 mol%). These low saturation magnetization glass samples can be used in spintronic devices to effectively reduce switching current density and lower the damping constant.

The Effect of Formulated Dentin Remineralizing Gel Containing Hydroxyapatite, Fluoride, and Bioactive Glass on Dentin Microhardness: An In Vitro Study.

This study aimed to develop a gel with dentin-remineralizing properties, integrating nano-hydroxyapatite (nHA), sodium fluoride (NaF), and bioactive glass (BG). The enamel layer of 40 bovine incisors was removed. The samples were allocated into four groups of 10 each, based on varying concentrations of nHA, BG, and NaF in the gel compositions (wt%): (1) 2.5%-7.5%-0.05%, (2) 5%-5%-0.05%, (3) 7.5%-2.5%-0.05%, and (4) a control group with a base gel lacking remineralizing agents. After 8 hr of demineralization, the dentin surface microhardness was measured at depths of 30, 60, and 140 µm. After a 20-day pH cycling, the percentage of surface microhardness recovery (SMHR%) was measured and compared among the groups using the ANOVA and Tukey HSD post hoc tests (α = 0.05). Scanning electron microscopy analysis evaluated each specimen's superficial morphology. At all depths, the SMHR% of the Group 2 and Group 3 was significantly higher than the control group (p < 0.05). The SMHR% Group 1 (67.39% ± 29.34%) was significantly higher than the control group (-21.24% ± 51.72%) only at the depth of 30 μm (p = 0.047). Group 3 had higher SMHR% than Group 2 at all depths; however, the difference was not statistically significant. Moreover, the SMHR% of Group 3 was significantly higher than that of Group 1 at depths of 30 μm (187. 94% ± 68.95% vs. 67.39% ± 29.34%; p = 0.005) and 60 μm (179.55% ± 75.96% vs. 64.34% ± 41.96%; p = 0.043). Surface deposition and tubule occlusion were observed in the Groups 2 and 3 samples, which was more prominent in the latter. Combining 7.5% nHA, 2.5% BG, and 0.05% NaF could potentially remineralize primary carious lesions.

Developments in Research on Mid‐Infrared Fiber Lasers Based on Fluoroaluminate Glass (Invited)

Developments in Research on Mid‐Infrared Fiber Lasers Based on Fluoroaluminate Glass (Invited)

Multi-mode mechanoluminescence of fluoride glass ceramics from rigid to flexible media toward multi-scene mechanical sensors

First time dual-mode mechanoluminescence in fluoride glass ceramics, transitioning from rigid to flexible media for versatile mechanical sensing.

Exploiting the uniqueness of fluoride glass fibers for efficient lasing from visible to mid-infrared

Exploiting the uniqueness of fluoride glass fibers for efficient lasing from visible to mid-infrared