Rare Earth Doped Glasses Research Articles

Physical, optical and structural characterizations of Dy3+-doped lead borate glasses

In the current studies optical, physical and structural properties of rare-earth doped borate glasses have been reported. Bulk samples were prepared by using melt quenching technique with nominal composition 70B2O3-(17-x)ZnO-10PbF2-3Na2O-xDyF3 and 60B2O3-(27-x)ZnO-10PbF2-3Na2O-xDyF3, where (x=0,1). XRD analysis was used to confirm the amorphous nature of prepared samples. Optical and structural properties of as prepared samples were studied using UV-Visible and FTIR absorption spectra. The undoped and doped glasses exhibit characteristic absorption bands due to the presence of rare earth ion. A decrease in the band gap has been observed with the addition of rare earth ion. Variations in density have been observed with the addition of rare earth ion.

Racah Parameter and Nephelauxetic Effect on Er<sup>3+</sup>/Nd<sup>3+</sup> Codoped Lithium Niobate Tellurite Glass

The modification of absorption characteristics in rare-earth doped tellurite glasses is important in photonics application. The Er3+/Nd3+ doped glasses of the form (69-x)TeO2-15Li2CO3-15Nb2O5-1Er2O3-(x)Nd2O3 with x= 0.4, 0.8 and 1.0 mol % are successfully made by using conventional melt-quenching technique. Physical properties such as polaron radius, interionic distance, field strength and average distance between acceptors and donors are determined. The absorption spectra reveal eleven prominent peaks centered at 6535.9 cm-1, 10245.9 cm-1, 11415.5 cm-1, 12437.8 cm-1, 13369.0 cm-1, 15267.2 cm-1, 15949.2 cm-1, 17127.1 cm-1, 19084.0 cm-1, 20449.9 cm-1 and 22271.7 cm-1 which corresponding to the transitions from ground state to various states of Nd3+ ions. The crystal field site increases from 8.120 to 8.169 cm-1 due to increase in contraction of Nd3+-ligand. The nephelauxetic function, increase 0.104 to 0.107. The increasing in value describes, the increasing in ionic bond from-0.0004 to-0.0011. The increment in exhibits the increase in the number of effective positive charge connected to neodymium atom and attracts the electrons from ligands as it increases from 1.0004 to 1.0011. These present glass shows the potential candidate of broadband amplifiers and lasers as it is comparable with other Nd3+ doped another host.

Advanced distributed feedback lasers based on composite fiber heavily doped with erbium ions

Specially designed composite heavily Er3+-doped fiber in combination with unique point-by-point inscription technology by femtosecond pulses at 1,026 nm enables formation of distributed-feedback (DFB) laser with ultra-short cavity length of 5.3 mm whose parameters are comparable and even better than those for conventional Er3+-doped fiber DFB lasers having much longer cavity. The composite fiber was fabricated by melting rare-earth doped phosphate glass in silica tube. The ultra-short DFB laser generates single-polarization single-frequency radiation at 1,550 nm with narrow linewidth (3.5 kHz) and 0.5 mW output power at 600 mW 980-nm pumping. The same fiber with conventional CW UV (244 nm) inscription technology using phase mask enables fabrication of 40-mm long DFB laser with > 18 mW output power at 3.3% pump conversion, which is a record efficiency for Er3+-doped fiber DFB lasers. The developed technologies form an advanced platform for Er3+-doped fiber DFB lasers operating around 1.55 µm with excellent output characteristics and unique practical features, in particular, the ultra-short DFB lasers are attractive for sensing applications.

Structural study of rare earth doped fluoride phosphate glasses by solid-state nuclear magnetic resonance

A series of glasses with the compositions of 10NaF-(90-x) NaPO3-xYF3 (x = 5, 10, 15 and 20 mol%) were prepared via the conventional melt-quenching method. The structures of these glasses were characterized by multiple advanced solid-state nuclear magnetic resonance (SSNMR) techniques. Multiple phosphorus species QmnY were resolved at atomic level. Here, the value m and n denote the number of P–O–P bonds and the number of Y3+ ion bounding to phosphorus oxygen tetrahedron, respectively, which were identified by two dimensional (2D) J-resolved spectroscopy. 19F MAS spectra, 19F↔23Na and 19F↔31P rotational echo double resonance (REDOR) prove that F−ions are involved into the glass networks through Y-F•••Na and P-F•••Na linkages. The 31P {19F} J-coupling based heteronuclear multiple quantum coherence (J-HMQC) spectrum proves that F− ions selectively connect with Q1 species. F− ions show significant preference to connecting with Y3+ over P5+.

Role of Sm<sup>3+</sup> on Mn Nanoparticles Embedded Zinc Tellurite Glasses Absorption and Luminescence Characteristic

Enhancing the optical performance of rare earth doped binary inorganic glasses is an ever-demanding quest. Samarium (Sm3+) doped zinc tellurite glasses containing Manganese (Mn) nanoparticles (NPs) with composition (59-x)TeO2-20ZnCl2-10ZnO-10Li2O-1Sm2O3-(x)Mn3O4, where x = 0 to 0.06 mol% are prepared by melt quenching technique. The role played by Mn NPs in enhancing the optical behaviors are analyzed and discussed. The XRD patterns confirm the amorphous nature of the glass. The UV-Vis-NIR spectra reveal seven prominent absorption bands of Sm3+ ions. The photoluminescence spectra display four peaks corresponding to 4G5/2→6H5/2, 4G5/2 →6H7/2, 4G5/2→6H9/2 and 4G5/2 →6H11/2 transitions. An enhancement in the luminescence intensity is observed up to 0.05 mol% concentration of NPs and the intensity quenches beyond it. The enhancement is attributed to local electric field effect of NPs in the proximity of Sm3+ ion. Our results on improved optical response via precise control of NPs contents may be useful for the development of solid state lasers and amplifiers.

Spectroscopic investigation of different nano metals doped to lead sodium calcium borate glasses

Investigations of different nano metals incorporated in lead sodium calcium borate glass are carried out in detail. Six glasses were prepared by melt and quenching method. The amorphosity and different physical parameters were estimated to know the variation of then due to atomic weight variation. To explore the vibration modes in the prepared glass, the FTIR was used and to evaluate changes in the optical properties, UV–VIS Spectrophotometer has been used. Profound changes in absorption and emission was observed due to the probing of different rare earth doped ternary glass. Colour analysis reveals the LED application for these different nano metals incorporated matrix. The energy band gap, cutoff wavelength and Urbach energy values are evidencing the creation of non bridging oxygen’s (NBO) and the sligth increase of defect in the glass matrix.

An Experimental and Theoretical Investigation of a 2 μm Wavelength Low-Threshold Microsphere Laser

We present our results on an experimental and theoretical investigation into a glass microsphere laser emitting at 2 μm wavelength. First, we fabricated Ho3+-doped tellurite glass fiber and measured the absorption and emission spectra, and the fluorescence lifetime. Using this fiber, a tellurite glass microsphere with a Q-factor of 2 × 106 was also prepared, and a single-mode laser output with a low threshold of 342 μW was observed using a 1150 nm laser as the pump source. The dynamic characteristics of the microsphere laser were studied theoretically by considering rare-earth ion spectroscopy, the rate equation of the rare-earth energy level, and the light-matter interactions in the microsphere. This work can be used to study laser emissions with low thresholds in rare-earth doped compound glass microresonators for a wide range of applications, such as gas sensing, integrated photonics, and medical surgery.

Rare-earth element doping in glass frit for improved performance in silicon solar cells

Glass frit plays an important role in the silver paste for silicon solar cells. In this work, we prepare glass frit doped with different rare-earth elements (Y, La, Sm, Er) and study how the doping element affects the performance of the solar cells. Solar cells with La-doped and Sm-doped glass frits show average conversion efficiencies higher than 17.5%, while solar cells with Y-doped or Er-doped frit show lower efficiencies. By analyzing the Raman spectra of the rare-earth doped glass frits, we find that the average coordination number of Te–O ([Formula: see text]) in the glass can be tuned by the rare-earth dopant. La or Sm doping leads to a moderate value of [Formula: see text], which is believed to achieve a glass formation ability that optimizes the structure of the Ag–Si interface of the cell for the best performance.

Double line waveguide amplifiers written by femtosecond laser irradiation in rare-earth doped germanate glasses

We report the production of active double waveguides in Er/Yb doped GeO2-PbO glasses, by direct femtosecond laser writing. The glasses were produced using the melt-quenching technique and the active waveguides were written using 30 fs laser pulses, at 800 nm, with writing speed of 0.06 mm/s and pulse energy of 32 μJ. The photo-induced negative refractive index change was of −7.4 × 10−3. The Er/Yb doped sample showed a relative gain (signal enhancement of 7.5 dB/cm, for 105 mW of 980 nm pump power. The relative gain compensates both, the propagation losses and the absorption losses, and a positive maximum internal gain of 4.6 dB/cm can be obtained at the signal wavelength of 1550 nm. The results obtained in present work demonstrate that Er/Yb glasses are promising materials for the fabrication of integrated amplifiers, lossless components and lasers based on germanate glasses.

Enhanced photoluminescence and high temperature sensitivity in rare earth doped glass ceramics containing NaGd(WO4)2 nanocrytals

NaGd (WO4)2 nanocrystals were successfully precipitated from silicate glasses for the first time and transparent glass ceramics were prepared. High diffraction peaks and well-resolved lattice fringes confirm the high crystallinity of NaGd (WO4)2 in the glass ceramics. The enhanced photoluminescence emission spectra, long fluorescence lifetime and the increased transition intensity ratio between 5D0→7F2 and 5D0→7F1 transitions of Eu3+ ions suggest that Eu3+ ions were incorporated into the precipitated NaGd(WO4)2 nanocrystals. Gradually enhanced upconversion emission spectra of Er3+ ions in the glass ceramics were observed with the increased thermal treatment time. The dependence of luminescence intensity ratio (LIR) on temperature was determined at the temperature range of 303 K–573 K. The maximum absolute sensitivity Sa is 0.012 K−1 at 542 K and the maximum relative sensitivity Sr is 1.178% at 303 K, which are attributed to the enrichment of Er3+ ions in the precipitated NaGd (WO4)2 nanocrystals and may be used for optical temperature sensors.

Optical properties of peralkaline aluminosilicate glasses doped with Sm3+

Enhancing the fluorescence and thermo-mechanical properties of rare-earth doped aluminosilicate glasses (AS) by modifying the chemical composition with different alkaline earth oxides opens new opportunities for their application as optical devices. This paper provides a study on 1 × 1020 ions/cm3 Sm3+ doped aluminosilicate glasses, with the network modifier oxides BaO, SrO, CaO, MgO (35 mol%), Al2O3 (10 mol%) and SiO2 (55 mol%), denoted as BaAS, SrAS, CaAS and MgAS, prepared by the melt quench technique. Based on the measured UV–visible and NIR absorption spectra, the Judd-Ofelt parameters Ωλ, (λ = 2, 4, 6) were evaluated to predict the radiative properties of Sm3+ ions such as radiative transition probabilities (Arad), radiative lifetimes (τrad) and branching ratios (βR). By using the Füchtbauer-Ladenburg (FL) formula, the gain cross sections were calculated from the stimulated emission cross sections. The glass BaAS has the highest value of Ω2 which corresponds to a high asymmetry at the rare earth sites and the glass MgAS has the highest values of Ω4 and Ω6 which corresponds to a high rigidity and a low optical basicity of the glass. The same glass has the highest quantum efficiency and the highest gain cross section values of the investigated glasses. On the other hand, the glass BaAS has the smallest efficiency and gain cross section, however, it provides the lowest glass transition temperatures which would be beneficial for the production of high-quality glass. Raman spectra of the AS glasses show a broader variation of Qn species and an increasing depolymerization for glasses with network modifier ions of larger ionic radii.

Review on the structural analysis of fluoride-phosphate and fluoro-phosphate glasses

Fluoride phosphate/fluorophosphate (FP) glasses form an intriguing material's basis for diverse applications in optics, photonics and energy storage. The optimization of the materials' properties with regard to the application envisioned demands an understanding of the key concepts describing their local structures on different distance regimes. Because of the inevitable losses of fluoride during melting or annealing, the synthesis and elemental analytical characterization present important and critical challenges. In this contribution we summarize the current state of the literature regarding the structural characterization of these glasses. Foci are the detailed analysis of vibrational spectra with special emphasis on Raman scattering results and multinuclear solid-state NMR spectroscopy. While vibrational spectra give important information about the local environments (short range order) advanced multi-dimensional and multi-resonance methodology can extend the informational content of solid-state NMR into the sub-nanometer distance range, including second and third coordination spheres. Exemplary results will be presented for (a) aluminum fluoride based simple model systems, (b) fluoride phosphate glasses containing heavy transition metals or post-transition metal elements, and (c) rare-earth doped fluoride phosphate glasses for laser applications. The latter application field documents the utility of correlated spectroscopic studies using both methods in understanding the structural foundations of photophysical properties.

Rare-earth doped glasses and light managing in solar cells

Glasses doped with rare earth elements possess unique photoluminescence properties. They find application in several devices, such as lasers, optical amplifiers, and sensors. More recently, rare-earth doped glass thin films have been the subject of investigation for the development of frequency-converting layers able to increase the efficiency of silicon solar cells. Another approach to the improvement of the performance of a solar cell is based on the capture of a larger flux of light by the detector, which can be obtained by surface texture, plasmonics, or waveguide structures. Here, the recent advances in this area will be briefly reviewed.

Simulation of Multilayered Heterojunction-Based Chalcogenide Fiber SPR Sensor With Ultrahigh Figure of Merit in Near Infrared

The dynamic nature of radiation damping in plasmonic structures can have immense potential in relation to significant improvement in plasmonic sensor performance. In this paper, we have explored the careful tuning of dynamic radiation damping in Si-Ag-graphene-Al2O3 heterojunction-based fiber optic plasmonic sensor structure. Low-refractive index rare-earth doped chalcogenide glass is considered as fiber material in near infrared spectral region. The simultaneous tuning of Ag and Al2O3 layer thicknesses with wavelength in appropriate broad ranges is investigated to enhance the sensor’s performance as much as possible. As another interesting step, the presence/absence of graphene layer on sensor’s performance is also examined. The results indicate that significantly large figure of merit (FOM) of magnitude 19212.67 RIU $^{-1}$ at $\lambda = 969$ nm for 5.2-nm-thick Al2O3 layer, and 36.6-nm-thick Ag layer is achievable from the proposed sensor with graphene. The above FOM is substantially larger than the existing (reported) plasmonic sensors claiming large FOM values. The findings of this paper can be crucial for developing surface plasmon reasonance biosensors with highly enhanced performance.

Effect of annealing on the optical and magnetic properties of Mn3O4 nanoparticles embedded into Eu3+ doped borotellurite glasses

Tuning the enhanced optical and magnetic properties of rare earth doped glasses by embedding nanoparticles is a never-ending quest. Influences of heat treatment (annealing) in modifying the spectral features of melt-quench synthesized manganese oxide nanoparticles (Mn3O4 NPs) embedded Eu3+-doped borotellurite glasses are reported. The growth of NPs is tuned by varying the annealing time. TEM micrograph reveals the nucleation of heat treated Mn3O4 NPs and SAED manifest their growth along the (1 1 2) crystallographic planes having average size in the range of 5.2 to 21.4 nm. The SPR bands are evidenced in the range 350 to 700 nm that validates the growth of Mn3O4 NPs in the glass matrix. The luminescence spectra reveal four major emission peaks at 591, 614, 651 and 700 nm originating from 7F1, 7F27F3, and 7F4 transitions levels, respectively. Intensity enhancement displayed by heat treated glass samples is attributed to the local field effect of Mn3O4 NPs while a quenching is due to the energy transfer from Eu3+ to Mn3O4 NPs. The intensity parameters related to the radiative transitions within 4f configuration of Eu3+ ions are determined and analyzed using Judd-Ofelt theory. The magnetization versus field (M-H) at 12 h of Mn3O4 NPs shows the highest saturation magnetization. The ESR spectrum exhibits resonance signals with effective isotropic g values at 1.9, 3.0 and 4.3 where g at 1.9 are attributed to Mn2+ centers in an octahedral asymmetry and g at 3.0 and 4.3 are attributed to the rhombic symmetry of the Mn2+ ions. Present glass compositions are established to be promising for the development of photonic devices.

A comparison on the structural and optical properties of different rare earth doped phosphate glasses

Phosphate glasses with different RE element dopants were prepared by conventional melt quenching method. Dopants like Nd2O3, Sm2O3 and Eu2O3 were added in glass with 0.5% & 1.5% molar ratio. While varying dopant ratio, phosphate glasses exhibits different properties. The XRD characterization reveals the non-crystallinity of the samples. Both FTIR and Raman confine the ionic nature of the samples. The fluorescence emission spectra Nd2O3 shows that the most intense band occurred at 380 nm due to 4D7/2 - 4I3/2 transition but for Sm2O3 and Eu2O3 most intense bands are seen at 375 nm and 379 nm due to the transition 4 D1/2→6H5/2 and of 5G5 - 7F0 respectively.

Physical, structural, optical and thermoluminescence behavior of Dy2O3 doped sodium magnesium borosilicate glasses

Abstract The rare earth doped borosilicate glass materials of composition (60 − x) B2O3 − 20 SiO2 − 10 Na2O − 10 MgO − x Dy2O3 have been prepared by melt quenching method. X-ray diffraction confirms the amorphous nature of the present glasses. FTIR spectra reveal the structure of the present glasses. The density, molar volume, average molecular weight, ion concentration, polaron radius and field strength have been determined. The optical parameters like optical band gap, refractive index, dielectric constant, optical dielectric constant, molar polarizability, reflection loss, molar refractivity, metallization and Urbach energy were also calculated. The glow curve behavior of all the present glass samples irradiated with 50 Gy, 100 Gy, 500 Gy, 1 kGy, 5 kGy and 10 kGy gamma ray doses has been investigated in temperature range 50–400°C. The TL dose response shows that the sample having 0.6 mol% doping of Dy3+ was best suitable for dosimetric applications.

Holmium doped fiber thermal sensing based on an optofluidic Fabry-Perot microresonator

An optical temperature sensor suitable for label free liquid sensing has been designed and characterized. The sensor combines the photochemical stability of rare earth doped glasses and the high sensitivity of interferometric resonators. It is formed by a planar Fabry-Perot (FP) microcavity filled with the liquid to be monitored. A Ho3+ doped tapered optical fiber has been placed inside the microcavity surrounded by the fluid medium. An external laser is focused on the optical fiber inside the cavity to induce the luminescence of the Ho3+ ions, which couples to the FP optical resonances. The spectral position of the FP resonances is highly sensitive to the refractive index of the cavity medium. A second laser is co-aligned with the first one to locally heat the liquid medium around the optical fiber. An average blue shift of the FP resonances around 32 pm/°C is measured. The limit of detection of the laser induced heating of the liquid medium is about 0.3 °C in the biological temperature range. Alternatively, a hot-plate is used to heat the system. Interestingly, a red shift of the FP modes is observed with 75 pm/°C dependence and 0.12 °C limit of detection features.

Structure Prediction of Rare Earth Doped BaO and MgO Containing Aluminosilicate Glasses⁻the Model Case of Gd₂O₃.

The medium-range atomic structure of magnesium and barium aluminosilicate glasses doped with Gd2O3 as a model rare earth oxide is elucidated using molecular dynamics simulations. Our structure models rationalize the strong dependence of the luminescence properties of the glasses on their chemical composition. The simulation procedure used samples’ atomic configurations, the so-called inherent structures, characterizing configurations of the liquid state slightly above the glass transition temperature. This yields medium-range atomic structures of network former and modifier ions in good agreement with structure predictions using standard simulated annealing procedures. However, the generation of a large set of inherent structures allows a statistical sampling of the medium-range order of Gd3+ ions with less computational effort compared to the simulated annealing approach. It is found that the number of Si-bound non-bridging oxygen in the vicinity of Gd3+ considerably increases with growing ionic radius and concentration of network-modifier ions. In addition, structure predictions indicate a low driving force for clustering of Gd3+, yet no precise correlation between the atomic structure and luminescence lifetimes can be conclusively established. However, the structure models provided in this study can serve as a starting point for future quantum mechanical simulations to shed a light on the relation between the atomic structure and optical properties of rare earth doped aluminosilicate glasses.

Controllable optical properties between Ho3+: 5I7 → 5I8 and Tm3+: 3F4 → 3H6 transitions in germanosilicate glasses

Diode-pumped solid-state 2 μm lasers have seen rapid development for their efficient operation, compact size, and stable performance. In this work, doped germanosilicate (SiO2-GeO2-Ga2O3-Lu2O3) glasses with varying Tm3+/Ho3+ concentrations exhibiting excellent physical and optical characteristics were successfully prepared. Thermal and structural properties were analyzed by the measured DSC and Raman spectra. An evident efficient wide absorption band near 770–830 nm demonstrated the feasible energy transfer between Tm3+: 3F4 → 3H6 and Ho3+: 5I7 → 5I8 transitions. Meanwhile, combining with Judd-Ofelt theory, super predicted spontaneous emission probabilities were obtained, which are beneficial to obtain fine laser action for solid-state lasers. This is a first study to demonstrate that a tunable fluorescence peak (1.8–2.05 μm) can be obtained by modulating the combined effects between two luminous activation centers. Therefore, the results indicate a promising rare-earth doped glass host for solid-state 2 μm lasers.