Multicomponent Phosphate Glasses Research Articles

Tunable, efficient, ultrafast broadband nonlinear optical properties of TiO2–loaded complex phosphate glasses

On account of their excellent optical transparency from ultraviolet to far infrared spectral regions, phosphate glasses have become interesting nonlinear optical (NLO) materials for photonic nonlinear devices. However, small NLO coefficients tend to limit the usage of phosphate–based glasses in nonlinear photonic devices. Herein, we explored the NLO tunability in multicomponent phosphate glasses by increasing the coordination of orthophosphate (PO4)3– structural units with a great number of AlO4 groups through the addition of titanium dioxide (TiO2) in the composition. The NLO absorption and refraction characteristics were ascertained using open and closed–aperture Z–scan configurations respectively in a broadband spectral region ranging from 400 nm to 1200 nm under an ultrafast regime. The Z–scan results illustrate the increase of nonlinear susceptibility of glasses with titanium dioxide content in the composition due to the formation of non–π–conjugated orthophosphate groups which are in connection with AlO4 units. Typically, at 400 nm excitation, the NLO susceptibility improved by 119.91% upon addtion of 5 mol% of TiO2. The outcomes of the study acknowledge a new approach for conceiving highly NLO active phosphate glasses while maintaining deep–ultraviolet transparency through the polymerization of (PO4)3−groups. Consequently, the strategy explored in this work might pave the way for achieving the high NLO features of phosphate–based glasses to excel in their usage in data storage, signal transmission, optical limiting, and harmonic generation functionalities.

Optical Properties of Er3+-Yb3+ Ions Co-activated Multicomponent Phosphate Glasses for Near-Infrared Applications

Optical Properties of Er3+-Yb3+ Ions Co-activated Multicomponent Phosphate Glasses for Near-Infrared Applications

Investigation of structural and optical properties of Pr3+ doped and Pr3+/Dy3+ co-doped multicomponent bismuth phosphate glasses for visible light applications

Pr3+ doped 59.5P2O5+15Bi2O3+10BaF2+10xF+05TeO2+0.5Pr6O11 glasses and Pr3+/Dy3+ co-doped 59P2O5+15Bi2O3+ 10BaF2+ 10xF + 05TeO2+0.5Dy2O3+0.5Pr6O11 glasses (where xF = LiF, NaF, MgF2, KF, CaF2 and SrF2) were synthesized using melt quenching route. Structural properties were researched for different modifier fluorides. With the dopant constant concentration the absorption and luminescence intensity variance influenced by this multicomponent incorporation has been observed. The energy transfer between resonance levels of Pr3+ and Dy3+ through fluorescence studies also examined for Mg and Sr glasses. Long-range nature of prepared glasses, morphological studies with elemental probe, various functional groups pertaining to glass matrices and the non-bridging oxygen bonds with PO4 tetrahedron or depolymarization of oxygen bonds in the presence of the modifier cations with phosphates were thoroughly understood with PXRD, FTIR and 31P NMR characterizations. Judd-Ofelt (J-O) theory has been adopted to estimate important optical parameters. From the fluorescence studies laser characteristic parameters such as optical band gains (σe × τR) and gain bandwidths (σe × Δλeff) were calculated and compared in the present fabricated glasses influenced by various modifiers.

Silicate-clad Dy3+ doped multi-component phosphate glass core glass fiber for yellow laser applications

In this work, strong yellow emission was obtained in Dy3+ doped multi-component phosphate glass due to its high asymmetry and covalency of the local field and high phonon energy. The internal quantum efficiency was measured to be 39.27% and the figure of merit was calculated to be 210.53 pm2 × μs. What is more, silicate-clad Dy3+ doped multi-component phosphate core glass fiber was successfully drawn by using a rod-in-tube method, which has a strong fluorescence emission in yellow spectra band. The Dy3+ doping concentration is 2.6 wt.%, which is much larger than that of Dy3+ doped (0.2 wt.%) ZBLAN fiber. These results suggest that the silicate-clad Dy3+ doped multi-component phosphate glass fibers are potential host matrices for yellow laser.

Nd3+ doped multi-component phosphate glass multi-material fiber for a 1.05 μm laser

Nd3+ doped multi-component phosphate glass was prepared by the conventional melt-quenching method. The absorption spectrum, emission spectrum, and fluorescence lifetime of the prepared glass were measured. Based on the absorption spectrum, Judd-Ofelt (J-O) intensity parameters, spectroscopic quality factor, absorption and emission cross-sections, and figure of merit were calculated and analyzed. What is more, multi-material fibers with Nd3+ doped multi-component phosphate glass core and silicate glass cladding were successfully drawn by using the molten core method. The Nd3+ doping concentration reaches as high as 3.82 × 1020 ions/cm3 (3.86 wt.%). More importantly, 1.05 μm amplified spontaneous emission (ASE) was realized in a 4-cm-long as-drawn multi-material fiber when pumped by an 808 nm laser diode (LD). These results suggest that the Nd3+ doped multi-component phosphate glass multi-material fibers are promising gain material for 1.05 μm fiber laser applications.

Effect of post-heat-treatment on the structural, spectroscopic and dissolution properties of a highly stable Er3+-doped multi-component phosphate glass

In this paper, the impact of the post-heat-treatment on the structural and spectroscopic properties as well as on the chemical durability of a thermally stable Er3+-doped phosphate glass in the system P2O5 - K2O - Al2O3 - B2O3 - BaO - PbO - La2O3 - Gd2O3 is reported. Two crystalline phases, namely La, Gd-monazite and AlKP2O7, were found to precipitate from the surface of the glass after heat-treatment, as confirmed by both X-ray Diffraction (XRD) and Scanning Electron Microscopy/Energy Dispersive X-ray (SEM/EDX) analyses. Moreover, the heat-treatment was responsible for the formation of a more polymerized glass network close to the surface crystalline layer as evidenced using micro-Raman spectroscopy. From the changes in the Er3+ optical properties, some of the Er3+ ions are suspected to enter in the crystals. Both the as-prepared and heat-treated glasses were subjected to a degradation test in hydrochloric acid (HCl) and showed a congruent and incongruent dissolution behavior, respectively.

Single-frequency, pulsed Yb3+-doped multicomponent phosphate power fiber amplifier

High-power, single-frequency, pulsed fiber amplifiers are required in light detection and ranging, coherent laser detection, and remote sensing applications to reach long range within a short acquisition time. However, the power-scaling of these amplifiers is limited by nonlinearities generated in the optical fibers, in particular by stimulated Brillouin scattering (SBS). In this regard, the use of multicomponent phosphate glasses maximizes the energy extraction and minimizes nonlinearities. Here, we present the development of a single-stage, hybrid, pulsed fiber amplifier using a custom-made multicomponent Yb-doped phosphate fiber. The performance of the phosphate fiber was compared to a commercial Yb-doped silica fiber. While the latter showed SBS limitation at nearly 6.5 kW for 40 cm length, the maximum achieved output peak power for the multicomponent Yb-doped phosphate fiber was 11.7 kW for 9 ns pulses using only 20 cm with no sign of SBS.

Optical properties of Nd3+-doped phosphate glasses

Multi-component phosphate glasses with various Nd2O3 content have been prepared using conventional melt-quenching technique. X-ray diffraction was carried out to study the structure of the prepared samples and it was found that all the obtained samples are amorphous. Electrostatic F(2), F(4), F(6), and spin–orbit parameters have been determined from the absorption spectra. Judd-Ofelt theory has been used to analyze and evaluate the radiative transition probability, branching ratio, and radiative lifetime for the metastable level 4F3/2. Luminescence spectra and experimental lifetimes give information regarding the absence of chemical clustering and suggest that the physical clustering is negligible making the glass a suitable candidate for photonic applications.

Phase Formation in Phosphate and Borophosphate Glasses Containing Iron, Chromium, Nickel, and Sulfur

We have prepared multicomponent phosphate and borophosphate glass systems containing considerable concentrations of high-level waste components critical to the vitrification process, such as iron, chromium, nickel, and sulfur, which imitate the composition of the high-level waste in storage tanks. We have studied the glass preparation temperature, viscosity, phase formation, thermal stability, and hydrolytic stability of the materials. The lowest rate of cesium leaching from quenched boron-free aluminophosphate glasses was on the order of 10–5 g/(cm2 day).

Heavily Tb3+ doped multi-component phosphate glass fibers for green fiber lasers

Heavy rare earth (RE) ion doped glass fibers make it possible to obtain high gain and high output power per unit length. It is known that high concentration of RE ions can be incorporated into multi-component phosphate glasses, which are usually used to fabricate high performance gain fibers. However, the increasing doping concentration of RE ions is mainly limited by the concentration quenching effect and crystallization during the fiber drawing process by the conventional rod-in-tube technique. In this work, no fluorescence quenching was observed in the prepared multi-component phosphate glasses even when Tb3+ doping concentration reached 16 mol %. Then, heavily Tb3+ doped multi-component phosphate glass fibers with silicate glass cladding were successfully drawn by a molten core method, which can effectively solve the crystallization problem caused by heavily RE ions doping. To the best of our knowledge, 16 mol % is the record high Tb3+ ion in phosphate glass fibers for green laser. An intense 540 nm green emission with fluorescence lifetime as long as 1.85 ms was obtained from the as-drawn fibers, showing promising applications for green fiber lasers.

Tunable broadband emission from red to blue by gamma radiation in multicomponent phosphate glasses

AbstractWe demonstrate for the first time that the tunable broadband emission from red to blue can be obtained by gamma radiation in multicomponent phosphate glasses. Gamma radiation causes the increased phosphate‐related non‐bridging oxygen hole center and oxygen hole center defects, which lead to the enhanced emission peaking at 452 nm. Meanwhile, the vibration amplitude of O‐P‐O chain's internal decrease, resulting in the decreased emission at 660 nm. Besides, the increased isolated phosphate units (Q0 and Q1), as well as the gradual decrease in P atoms that make up the main phosphate chain contribute to the blue‐shift of the main emission peak at 616 nm, which directly results in the tunable broadband emission from 616 to 460 nm. The gamma radiation process endows this type of multicomponent phosphate glasses with promising applications in solid‐state lighting devices.

Highly Doped Phosphate Glass Fibers for Compact Lasers and Amplifiers: A Review

In recent years, the exploitation of compact laser sources and amplifiers in fiber form has found extensive applications in industrial and scientific fields. The fiber format offers compactness, high beam quality through single-mode regime and excellent heat dissipation, thus leading to high laser reliability and long-term stability. The realization of devices based on this technology requires an active medium with high optical gain over a short length to increase efficiency while mitigating nonlinear optical effects. Multicomponent phosphate glasses meet these requirements thanks to the high solubility of rare-earth ions in their glass matrix, alongside with high emission cross-sections, chemical stability and high optical damage threshold. In this paper, we review recent advances in the field thanks to the combination of highly-doped phosphate glasses and innovative fiber drawing techniques. We also present the main performance achievements and outlook both in continuous wave (CW) and pulsed mode regimes.

Effects of doping SiO_2 on the defect’s change in B_2O_3-containing phosphate based laser glasses used for high energy UV lasers

The introduction of SiO2 affects the glass’s micro-structure and micro-defects as well as the corresponding optical and physical properties of the B2O3-containing multi-component phosphate glasses. The addition of SiO2 increases the transition temperature and causes shifts of the UV cut-off wavelength (λcut-off). The changes of λcut-off are closely related to the PO3-EC and PO4-EC defect centers that are associated with the Q2 tetrahedral in phosphate chains. The corresponding variations of Q2 units can also be found in the Raman, XPS, and 31P MAS-NMR spectra. With increasing the content of SiO2, the ratio of non-bridging oxygen (associated with Q2 units) is gradually decreased down to a critical level when SiO2/B2O3 ratio is 4/1.5, whereas the ratio of non-bridging oxygen increases when SiO2/B2O3 ratio is larger than 4/1.5, which suggests that the doping SiO2 can influence the concentration of PO3-EC and PO4-EC defects. Those results can be better obtained when the sample is exposed to gamma irradiation. As the SiO2 content increased gradually up to 4/1.5, the concentration of the PO3-EC defects declined, while the concentration of PO4-EC and the POHC defects increased when considering the irradiation dose, indicating that the addition of SiO2 can regulate the structure-related defects in phosphate based glasses.

Natural healing behavior of gamma radiation induced defects in multicomponent phosphate glasses used for high energy UV lasers

Obvious healing behavior of gamma radiation induced defects in multicomponent phosphate glass was observed at room temperature. The recovery of the defects depends on the ratio of H3BO3/SiO2 in the investigated glasses, the total gamma radiation dose, and the time of ageing at room temperature. Meanwhile, the synchronous decreases of PO3-EC and POHC defects contribute to the corresponding recovery of the transmittance change at 385 nm and 525 nm, which could be described by the charge transfer. Besides, a general model of the healing mechanism associated with the release and capture of the electrons between PO3-EC and POHC defects in these phosphate glass was proposed.

Effects of doping B_2O_3 on the defects-state in SiO_2-containing phosphate based glasses

The effects of doping B2O3 on the defects and their induced anti-radiation performance change of the multicomponent phosphate glasses were studied in this work. The introduction of B2O3 reduces the connectivity of phosphate chains and thus increases the concentration of PO3-EC and PO4-EC defects in the phosphate glass network that have large absorption in the high-energy region. Meanwhile, B2O3 can improve the oxidizability of those glasses at the same melting temperature under which Fe2+ ions will be more easily oxidized to Fe3+ ions. However, the addition of B2O3 in terms of H3BO3, as it reaches up to 7.5 wt%, could enhance the gamma radiation resistance of the phosphate glasses, in this case B2O3, and enter the phosphate glass network in the form of B5O8 units. The units enhanced the connectivity of the long phosphate chains, and thus reduced the concentration of PO3-EC and PO4-EC defects in phosphate glasses.

Fabrication of crystalline selenium microwire**Project supported by the National Natural Science Foundation for Distinguished Young Scholars of China (Grant No. 61425021) and the Natural Natural Science Foundation of China (Grant Nos. 11374296, 61376054, 61475153, and 61604132).

A method of fabricating selenium (Se) microwire is demonstrated. A multimaterial fiber with amorphous selenium (a-Se) core and multicomponent phosphate glass cladding is drawn by using a conventional optical fiber drawing technique. Then the a-Se core of the fiber is crystallized by a post thermal process at 150 °C. After the multicomponent phosphate glass cladding is stripped from the multimaterial fiber by marinating the fiber in HF acid solution, a crystalline selenium (c-Se) microwire with high uniformity and smooth surface is obtained. Based on microstructure measurements, the c-Se microwire is identified to consist of most hexagonal state particles and very few trigonal state whiskers. The good photoconduction property of c-Se microwire with high quality and longer continuous length makes it possible to apply to functional devices and arrays.

Silver nanoparticles enhanced near-infrared luminescence of Er3+/Yb3+ co-doped multicomponent phosphate glasses

A new way to improve the 1.53 μm emission in Er3+/Yb3+ co-doped multicomponent phosphate glass was demonstrated by introducing silver nanoparticles (NPs) in rare-earth doped glass. The existence of Ag NPs was confirmed by absorption spectra and transmission electron microscopy (TEM) measurements. The homogeneous distribution of silver NPs could be observed by the TEM images. UV-Vis-NIR absorption spectra revealed that the surface plasmon band was centered at about 420 nm. The photoluminescence spectra of glass samples were used to investigate the effect of silver NPs on the fluorescence properties of Er3+. Efficient 1.53 μm emission was obtained in prepared samples when pumped at 980 nm laser diode (LD). The 1.53 μm emission intensity could be enhanced 87% by doping 2 mol.% AgCl due to the increased localized field effect in the vicinity of NPs and the possible energy transfer from silver NPs to Er3+ ions. Our present work may point out one way to enhance the gain coefficient of Er3+/Yb3+ co-doped glass fiber.

Silicate-clad highly Er3 +/Yb3 + co-doped phosphate core multimaterial fibers

Highly rare earth ions (RE-ions) doping phosphate glass fiber makes it possible to obtain high gain and high output power per unit length. However, high concentrations of RE-ions will cause concentration quenching and crystallization during the conventional rod-in-tube fiber drawing process. In this work, highly Er3+/Yb3+ co-doped multi-component phosphate glasses were prepared by the melt-quenching method. Through thorough investigation of 1.53μm luminescent properties of the glasses, optimal RE-ions were ascertained. The Er3+ and Yb3+ doping concentrations reach as high as 13.77×1020 and 2.295×1020ions/cm3, respectively. Then the silicate-clad highly Er3+/Yb3+ co-doped phosphate core multimaterial fibers were successfully fabricated by a molten core method. The multimaterial fibers have a large refractive index difference and good interface between the phosphate glass core and silicate glass cladding. An intense 1.53μm emission was obtained from the multimaterial fiber. The results indicate that the highly Er3+/Yb3+ co-doped multimaterial fibers are promising in applications that require high gain and high power from a short piece of active optical fiber.

Influence of CuO and ZnO addition on the multicomponent phosphate glasses: Spectroscopic studies

The spectra of phosphate-silicate glasses from the P2O5–SiO2–K2O–MgO–CaO system modified with the addition of CuO or ZnO have been studied by means of FTIR, Raman and 31P MAS NMR spectroscopy. All glasses were synthesized by the conventional melt-quenching technique and their homogeneous chemical composition was controlled and confirmed. By using the aforementioned research techniques, the presence of structural units with various degrees of polymerization was shown in the structure of analyzed phosphate-silicate glasses: Q3, Q2, Q1 and Q0. It was found that an increase in the content of CuO or ZnO in the composition of analyzed glasses, which are introduced at the expense of decreasing amounts of CaO and MgO, has a different influence on the phospho-oxygen network. It was shown that copper ions cause its gradual polymerization, while zinc ions cause its depolymerization. At the same time, polymerization of the silico-oxygen subnetwork was found. Additionally, in the case of glasses containing increasing amounts of ZnO, a change of the role of zinc ions in the vitreous matrix was confirmed (from the modifier to a structure-forming component).

Reduced radiation damage in a multicomponent phosphate glass by Nb^5+ or Sb^3+ doping

An experimental investigation on the effects of Niobium and Antimony (Nb and Sb) on the radiation response of the multicomponent phosphate glass used for higher optical gain single mode fiber has been carried out. The samples were irradiated with γ-rays up to 20 kGy. Optical absorption spectra and Electron Paramagnetic Resonance (EPR) were employed to investigate the radiation-induced-defects. We found that the radiation induced attenuation (RIA) decrease with increasing Nb5+ and Sb3+ doping concentration. Only the phosphorus oxygen hole center (POHC) related EPR signals were observed in the Nb5+-doped samples. Both POHC and phosphorus-oxygen electron centers (POEC) related EPR signals decrease obviously with 1 mol % Sb2O3 doping concentration. These experimental results were interpreted by a model that is based on competition between various defects and Nb- or Sb-ions for the holes and electrons generated by the absorption of γ-rays.