Barium Gallo-germanate Glasses Research Articles

Broadband near-infrared emission in barium gallo-germanate glasses co-doped with bismuth, chromium and erbium ions

This work presents barium gallo-germanate glasses co-doped with Bi+/Er3+ and Cr3+/Er3+ ions for NIR luminescence. The addition of Al2O3 content in the glass matrix made it possible to obtain luminescence corresponding to the 3P1→3P0 transition of Bi+ ions. Co-doping with the Bi+/Er3+ system resulted in a broad luminescence spectrum of 1.0-1.6 µm and Cr3+/Er3+ co-doping in selected glass matrix resulted in luminescence in 0.9-1.6 µm band. However, the luminescence of the Cr3+ ions is much lower than that of Er3+ ions. Full Text: PDF References T. Suzuki, G.S. Murugan, and Y. Ohishi, 'Optical properties of transparent Li2O-Ga2O3-SiO2 glass-ceramics embedding Ni-doped nanocrystals', Appl. Phys. Lett., 86(13), 131903 (2005). CrossRef N.V. Golubev et al., 'Pre-crystallization heat treatment and infrared luminescence enhancement in Ni2+-doped transparent glass-ceramics', J. Non-Cryst. Solids, 515, 42 (2019) CrossRef Z. Xu, W. Feng, T. Chen, X. Liu, and J. Qiu, 'Tuning optical properties in PbSe quantum dot-doped borosilicate glass fiber by modulation of network topology', Opt. Laser Technol., 158, 108910 (2023). CrossRef M.A. Hughes, T. Suzuki, and Y. Ohishi, 'Spectroscopy of bismuth-doped lead-aluminum-germanate glass and yttrium-aluminum-silicate glass', J. Non-Cryst. Solids, 356(44), 2302 (2010). CrossRef J. Song, Z. Zhou, B. Zhong, M. Zhang, J. Huang, and L. Han, 'Ultra-broadband near-infrared Cr3+-doped multi-phase glass-ceramics realized by the selective enrichment strategy for near-infrared spectroscopy applications', J. Alloys Compd., 968, 172126 (2023). CrossRef M.A.U. Martines, M.R. Davolos, M.J. Júnior, D.F. de Souza, and L.A.O. Nunes, 'Cr3+ and Cr4+ luminescence in glass ceramic silica', J. Lumin., 128(11), 1787 (2008). CrossRef S. Zhou, H. Dong, H. Zeng, J. Hao, J. Chen, and J. Qiu, 'Infrared luminescence and amplification properties of Bi-doped GeO2−Ga2O3−Al2O3 glasses', J. Appl. Phys., 103(10), 103532 (2008). CrossRef T. Suzuki and Y. Ohishi, 'Ultrabroadband near-infrared emission from Bi-doped Li2O-Al2O3-SiO2 glass', Appl. Phys. Lett., 88(19), 191912 (2006). CrossRef T. Minh Hau et al., 'Super broadband near-infrared emission and energy transfer in Bi-Er co-doped lanthanum aluminosilicate glasses', Opt. Mater., 35(3), 487 (2013). CrossRef H.K. Dan et al., 'Effects of Y3+on the enhancement NIR emission of Bi+-Er3+ co-doped in transparent silicate glass-ceramics for Erbium-doped fiber amplifier (EDFA)', J. Lumin., 219, 116942 (2020). CrossRef E.M. Dianov, 'Bismuth-doped optical fibers: a challenging active medium for near-IR lasers and optical amplifiers', Light Sci. Appl., 1(5) (2012). CrossRef L. Wang, L. Tan, Y. Yue, M. Peng, and J. Qiu, 'Efficient Enhancement of Bismuth NIR Luminescence by Aluminum and Its Mechanism in Bismuth‐Doped Germanate Laser Glass', J. Am. Ceram. Soc., 99(6), 2071 (2016). CrossRef Z. Jiang et al., 'Effects of Al2O3 composition on the near-infrared emission in Bi-doped and Yb-Bi-codoped silicate glasses for broadband optical amplification', J. Non-Cryst. Solids, 383, 196 (2014). CrossRef

The key role of yttrium oxide on devitrification resilience of barium gallo-germanate glasses: Physicochemical properties and crystallization study

Two barium gallo-germanate glass series were elaborated to investigate the effect of the yttrium introduction on the glass physicochemical properties and crystallization behavior. One to twenty mol% of YO3/2 were either added into the glass matrix or substituted for gallium oxide. The glass structure was studied by Raman spectroscopy and the thermal, optical, thermo-mechanical and physical properties are examined. The introduction of yttrium ions in both glass series increases the glass transition temperature, crystallization temperature, softening temperature, coefficient of linear thermal expansion and density. Through differential scanning calorimetry and X-ray diffraction analyses, it was found that competition occurs between the gallo-germanate zeolite-type phase and the yttrium-containing phase. From 13 mol% of YO3/2, the yttrium introduction impedes the formation of surface crystallization in these glasses.

Optical and structural characterization of femtosecond laser written micro-structures in germanate glass

We report on direct femtosecond laser writing in zinc barium gallo-germanate glasses. A combination of spectroscopic techniques allows to progress in the understanding of the mechanisms taking place depending on the energy. In the first regime (type I, isotropic local index change) up to 0.5 µJ, the main occurrence is the generation of charge traps inspected by luminescence, together with separation of charges detected by polarized second harmonic generation measurements. At higher pulse energies notably at the threshold corresponding to 0.8 µJ or in the second regime (type II modifications corresponding to nanograting formation energy domain), the main occurrence is a chemical change and re-organization of the network evidenced by the appearance of molecular O2 seen in the Raman spectra. In addition, the polarization dependence of the second harmonic generation in type II indicates that the organization of nanogratings may be perturbed by the laser-imprinted electric field.

Structure and luminescence properties of Tm3+ doped barium gallo-germanate glass tailored by Lu2O3

Structure and luminescence properties of Tm3+ doped barium gallo-germanate glass tailored by Lu2O3

Raman and Infrared Spectroscopy of Barium-Gallo Germanate Glasses Containing B2O3/TiO2

Modified barium gallo-germanate glass hosts are still worthy of attention in studying structure-property relationships. In this work, two different series of glass systems based on (60-x)GeO2-xTiO2-30BaO-10Ga2O3 and (60-x)GeO2-xB2O3-30BaO-10Ga2O3 (x = 10, 30, 50 mol%) were synthesized, and their properties were studied using spectroscopic techniques. X-ray diffraction (XRD) patterns revealed that all fabricated glasses were fully amorphous material. The absorption edge shifted toward the longer wavelengths with a gradual substitution of GeO2. The spectroscopic assignments of titanium ions were performed with excitation and emission spectra compared to the additional sample containing an extremely low content of TiO2 (0.005 mol%). On the basis of Raman and FT-IR investigations, it was found that increasing the TiO2 content caused a destructive effect on the GeO4 and GeO6 structural units. The Raman spectra of a sample containing a predominantly TiO2 (50 mol%) proved that the band was located near 650 cm-1, which corresponded to the stretching vibration of Ti-O in TiO6 unit. The deconvoluted IR results showed that the germanate glass network consisted of the coexistence of two BO3 and BO4 structural groups. Based on the experimental investigations, we concluded that the developed materials are a promising candidate for use as novel glass host matrices for doping rare-earth and/or transition metal ions.

Influence of TiO2 concentration on near-infrared luminescence of Er3+ ions in barium gallo-germanate glasses

Erbium (Er)-doped barium gallo-germanate (BGG) glasses modified by TiO2 have been investigated for near-infrared luminescence applications. Luminescence at 1.5 μm associated to 4I13/2 → 4I15/2 transition of Er3+ ions has been examined in function of TiO2 concentration. Several spectroscopic and near-infrared (NIR) laser parameters for Er3+ such as stimulated emission cross-section, luminescence bandwidth and lifetime, quantum efficiency, gain bandwidth and figure of merit were determined based on experiments and theoretical calculations using the Judd-Ofelt framework. Our systematic investigations indicate that Er-doped glass with molar ratio GeO2:TiO2 = 1:2 shows excellent luminescence properties and could be successfully applied to near-infrared broadband optical amplifiers.

Thermal and structural modification in transparent and magnetic gallogermanate glasses induced by Gd2O3

A series of new transparent and magnetic barium gallogermanate glasses in the system ( x ) Gd 2 O 3 – (100- x ) [20BaO−15Ga 2 O 3 −65GeO 2 ] with x = 0, 8, 14, 18, 22 and 25 mol% were synthesized. Their thermal, structural and magnetic properties were characterized. Based on the differential scanning calorimetry results, one determined the composition domain exhibiting the highest thermal stability toward crystallization and provided a detailed experimental fabrication method for the production of optical fibers. The local glass structure investigated using combined Raman and Infrared vibrational spectroscopies shows a progressive depolymerization of the 3D glass germanate network accompanied with an increase of non-bridging oxygens when increasing the Gd 2 O 3 content. The incorporation of gadolinium ions tends to extend the IR transmission window. Thanks to the magnetic susceptibility measurements, the paramagnetic behavior was evidenced, and increases with the Gd 3+ content. The combination of the optical, thermal and magnetic properties of Gd 2 O 3 gallogermanate glasses as well as their ability to be shaped into optical fibers make them promising materials for their integration in MIR functional optical components. • Novel transparent and magnetic glasses in the system Gd 2 O 3 – BaO − Ga 2 O 3 − GeO 2 were synthesized by melt-quenching method. • Investigation of thermal, structural and magnetic properties. • Fabrication of paramagnetic fibers was demonstrated using preform-to-fiber approach. • The paramagnetic behavior was evidenced using the magnetic susceptibility measurements.

Formation of nanogratings driven by ultrafast laser irradiation in mid-IR heavy oxide glasses

This work demonstrates for the first time the formation of nanogratings inside Barium Gallo-Germanate (BGG) glasses using femtosecond laser direct writing. These heavy oxide glasses, with a characterized transparency window up to 6 μm, along with the polarization sensitive birefringent nanostructures induced by femtosecond laser, offer an excellent platform for the development of mid-Infrared photonic applications. The fabricated glasses, containing both rare earth elements (Gd, Y) and transition metals (Zn, Ta), are directly compared to amorphous GeO2 and commercial alumino-germanate (Corning-9754) glasses commonly used in this field. The nanogratings processing window in each glass was investigated by varying laser parameters (pulse duration, energy, repetition rate), and electron microscopy imaging directly evidenced the porous nanostructures. Among the results, a strong form birefringence in 8% ZnO containing BGG glass, e.g., up to −0.029 ± 0.001, was reported. Finally, birefringent embedded Fresnel GRIN plates were directly written in a BGG glass, to demonstrate the functionalization potential of these materials.

Ultrafast Laser-Induced Nanogratings in Derived Barium Gallo-Germanate Glasses for Mid-Ir Applications

Ultrafast Laser-Induced Nanogratings in Derived Barium Gallo-Germanate Glasses for Mid-Ir Applications

Radiation resistance property of barium gallo-germanate glass doped by Nb2O5

Effects of Nb2O5 dopant on the radiation response of barium gallo-germanate (BGG) glass are studied mainly by electron paramagnetic resonance and absorption spectroscopy. Owing to the Nb5+↔Nb3+ interconversion in doped samples, formations of Ge-related non-bridging oxygen hole center and Ge-related electron center defects after γ-ray irradiation are inhibited. Thereby, Nb2O5 dopant can enhance radiation resistance of BGG glass, and 1.0% Nb2O5 concentration is the best.

Holmium doped barium gallo-germanate glasses for near-infrared luminescence at 2000 nm

Holmium singly doped barium gallo-germanate glasses have been studied for near-infrared luminescence at 2000 nm. Near-infrared luminescence spectra corresponding to 5I7 → 5I8 transition of trivalent holmium and their decays have been examined as a function of BaF2 and activator (Ho3+) concentration. The integrated intensities of luminescence bands increase up to 0.5 mol% Ho3+ and then reduce with further increasing activator (Ho3+) concentration. Luminescence linewidths increase with increasing Ho3+ concentration, but remain nearly unchanged with BaF2 content. The glass samples exhibit the shortened decay curves with increasing activator concentration, which is due to the presence of energy transfer between Ho3+ ions. The luminescence lifetime 5I7 (Ho3+) is found to be maximum at 5 mol% of BaF2.

Influence of transition metal ion concentration on near-infrared emission of Ho3+ in barium gallo-germanate glasses

The influence of Cr3+ concentration on near-infrared emission of Ho3+ in barium gallo-germanate glass has been studied. Near-infrared emission bands, due to 4T2 → 4A2 (Cr3+) as well as 5I6 → 5I8 and 5I7 → 5I8 (Ho3+) transitions, were observed under excitation of Cr3+. The enhanced and broadband near-infrared emission was obtained for glasses in the presence of transition metal (Cr3+) and rare earth (Ho3+) ions. This prosperity was optimized as a function of donor (Cr3+) and acceptor (Ho3+) concentration. The integrated intensities of emission bands were determined and their values are found to be maximal at 0.25 mol% Cr3+ and 0.5 mol% Ho3+. The energy transfer from Cr3+ to Ho3+ occurs through a nonradiative process with an efficiency up to 23%.

Influence of the rare earth ions concentration on luminescence properties of barium gallo-germanate glasses for white lighting

Barium gallo-germanate glasses co-doped with Ce3+ and Dy3+ were synthesized and their luminescence properties were studied using optical spectroscopy. The characteristic luminescence bands originating to electronic transitions of Ce3+ and Dy3+ ions were observed under direct excitation of Ce3+. Furthermore, the influence of rare earth ions concentration on luminescence properties of glass systems was examined. Luminescence lifetimes for the upper 4F9/2 excited state of Dy3+ ions were also evaluated and discussed in detail. The obtained experimental results indicate that energy transfer between these rare earth ions is possible. From the emission spectra, the Commission Internationale de I'Eclairage (CIE) chromaticity coordinates (x, y) are calculated in relation to potential application of germanate glass systems for white light emitting devices. It has been proved that our glass systems exhibit neutral/cool white emission originating from the simultaneous generation of several bands of Ce3+ and Dy3+ under the UV–visible light excitation.

Properties, structure and crystallization study of germano-gallate glasses in the Ga2O3-GeO2-BaO-K2O system

Mid-infrared transparent germano-gallate glasses (with gallium oxide as main component) have been studied following the composition law (100-x)[48.3GaO3/2-32.2GeO2-19.5BaO]-xKO1/2 (with x = 0, 5, 10, 13, 17 mol%). All prepared glasses are transparent from approximately 280 nm up to 5.5 μm, with a measured linear refractive index and density decreasing respectively from 1.72 to 1.67 (at 1538 nm) and 4.79 to 4.34 g/cm3 with increasing potassium oxide content. As expected, the increase of potassium oxide content also results in a decrease of the glass transition temperature (698 to 671 °C) and the viscosity in the softening regime whereas the thermal expansion coefficient increases (4.8 to 10.3 × 10−6 K−1). These results are related to the depolymerization of the 3D interconnected glass network which has been studied by Raman spectroscopy. Large thermal stability criteria (difference between onset of crystallization and glass transition temperatures) ranging from 182 to 199 °C have been measured by DSC for the compositions containing potassium oxide, suggesting strong potential for fiber drawing from glass preforms. The 40.1GaO3/2-26.7GeO2-16.2BaO-17KO1/2 glass composition (in cation mol.%, which corresponds to 28Ga2O3-37GeO2-23BaO-12K2O in mol.%) was then selected for further investigation. Its mechanical properties (Young and shear moduli, Poisson's ratio, hardness) were measured, showing values close to those reported for well-known barium gallo-germanate (BGG) glasses. A thorough crystallization study was then carried out using DSC (Marotta's method), X-Ray diffraction and electron microscopies (TEM and SEM) to better understand the unexpected surface crystallization issues observed during the glass preform fiber drawing process. The potential of using such germano-gallate glasses to produce mid-infrared optical fiber of high mechanical strength is discussed.

Temperature dependent energy transfer in Bi/Er codoped barium gallogermanate glasses for tunable and broadband NIR emission

A tunable and further broadened NIR emission can be realized in Bi/Er codoped barium gallogermanate glasses by tuning the Er3+content, the temperature and the pumping schemes.

White light emission through energy transfer processes in barium gallo-germanate glasses co-doped with Dy3+-Ln3+ (Ln =Ce, Tm)

Fully amorphous rare earth co-doped barium gallo-germanate glasses were synthesized using the traditional melt quenching-technique. The glass systems were doped with selected pairs of rare earths Dy3+/Ce3+ and Dy3+/Tm3+ ions. To study the spectroscopic properties of gallo-germanate glasses co-doped with Dy3+ and Ln3+ (Ln = Ce, Tm) ions, the luminescence spectra and luminescence decay curves were recorded. It was observed that luminescence bands corresponding to characteristic transitions of Ln3+ (Ln = Ce, Tm) and dysprosium ions are present in the emission spectra measured under direct excitation of Ln3+. The experimental results indicate that energy transfer between dysprosium and cerium/thulium ions is effective. From the emission spectra, the Commission Internationale de I'Eclairage (CIE) chromaticity coordinates (x, y) were calculated in relation to the potential application of gallo-germanate glasses for white LEDs. It has been proved that our glass systems exhibit white emission originating from the simultaneous generation of several bands of Dy3+, Ce3+/Tm3+ under the UV-visible light excitation.

Rare earth-doped barium gallo-germanate glasses and their near-infrared luminescence properties

Near-infrared luminescence properties of Nd3+ and Ho3+ ions in barium gallo-germanate glasses have been reported. Several spectroscopic parameters for Nd3+ and Ho3+ ions have been determined from the Judd-Ofelt analysis and absorption/luminescence measurements. Quite large luminescence lifetime, quantum efficiency and stimulated emission cross-section have been obtained for the main 4F3/2 → 4I11/2 (Nd3+) and 5I7 → 5I8 (Ho3+) laser transitions of rare earths in barium gallo-germanate glasses. It suggests that barium gallo-germanate glass is promising for near-infrared laser application at emission wavelengths 1064 nm (Nd3+) and 2020 nm (Ho3+).

Passively Mode-Locked Tm3+-Doped Fiber Laser With Gigahertz Fundamental Repetition Rate

We propose and demonstrate a compact passively mode-locked $\text{Tm}^{\text{3+}}\hbox{--}\text{doped}$ fiber laser with a fundamental repetition rate up to 1.6 GHz. A 5.9 cm home-made, heavily $\text{Tm}^{\text{3+}}\hbox{--}\text{doped}$ barium gallo-germanate glass fiber with a gain coefficient of 2.3 dB/cm at 1950 nm is employed as gain medium. The compact Fabry-Perot (FP) laser cavity contains a fiber mirror by directly coating the SiO2/Ta2O5 dielectric films on a fiber ferrule. The miniature FP laser pumped by a 793-nm laser diode is passively mode-locked by a semiconductor saturable absorber mirror. Stable self-started mode-locking is successfully achieved at a low pump threshold of 107 mW. The mode-locked operation at the central wavelength of 1959.7 nm has a spectral bandwidth of 12.2 nm, and the pulse duration of 7.2 ps. In particular, the pulse repetition frequency of the fundamental mode-locking can be as high as 1.6 GHz. Moreover, numerical simulation for the 2-μm mode-locked Tm-doped fiber lasers is performed using the lumped model, and the numerical results are in good agreement with the experimental ones. This is, to the best of our knowledge, the highest fundamental repetition frequency for the 2-μm mode-locked fiber lasers.

Tm3+-doped barium gallo-germanate glass single-mode fiber with high gain per unit length for ultracompact 1.95 µm laser

Heavily Tm3+-doped barium gallo-germanate glass single-mode (SM) fibers were successfully drawn. A gain per unit length of 3.6 dB/cm at 1.95 µm was obtained. To the best of our knowledge, this is the highest gain per unit length reported for Tm3+-doped germanate glass SM fibers. A single-frequency fiber laser operating at 1.95 µm has been built using a 1.5-cm-long active fiber pumped by a 1568 nm fiber laser. The direct output power from the ultracompact laser cavity is 227 mW. The results show that the fibers are highly promising for high-power and ultracompact single-frequency laser applications.

Crystallization of lead-based and lead-free oxyfluoride germanate glasses doped with erbium during heat treatment process

Oxyfluoride lead-based and lead-free germanate glasses were heat-treated in order to fabricate transparent glass-ceramics. Cubic β-PbF2 nanocrystals are well formed during crystallization of lead germanate glass. The up-conversion luminescence spectra of Er3+ ions in lead germanate glass-ceramic system are enhanced significantly due to partial incorporation of the optically active ions into fluoride crystalline phase. These effects are not significant in oxyfluoride lead-free germanate glass after heat treatment process. The crystallization of barium gallo-germanate glass with BaF2 is more complex and the presence of four crystalline phases BaF2, BaO, Ba3Ga2Ge4O14 and GeO2 was verified by X-ray diffraction measurements.