Doped Fluoride Glass Research Articles

Evolutionary behavior of thermal and optical properties of fluoride fiberglass with Er3+ doping

AbstractEr3+‐doped fluoride glass and fiber have been widely used in multiple fields such as mid‐infrared laser, visible laser, and amplifier. However, there is no unified conclusion on the thermal and optical properties with respect to varying concentrations of Er3+ doping. Furthermore, this is a paucity of systematic guidance on the preparation of Er3+‐doped fluoride glass and fiber. In this study, fluorozirconate fiberglass with Er3+ doping is systematically examined. Additionally, a preliminary explanation of the evolutionary behavior of glass devitrification, thermal properties, and fluorescence properties is provided. Energy transition models were built for 1.5 and 2.7 µm emissions in Er3+‐doped fluorozirconate at room temperature. Moreover, a suitable doping concentration is proposed based on the evolutionary behavior of thermal and optical properties. In this study, guidance on appropriate Er3+ doping concentration levels in fluorozirconate glass is provided and potential applications are explored.

Influence of the 4f5d-1S0 energy gap on the decay times of Pr3+-doped fluoride scintillating glasses

A comparative analysis of praseodymium (Pr3+)-doped fluoride glasses, APLF [20Al(PO3)3–80LiF–PrF3], BCAYF (19BaF2–33.25CaF2–42.75AlF3–5YF3–PrF3), and BCAPLF (19BaF2–33.25CaF2–42.75AlF3–15P2O5–20LiF–PrF3), reveals the effect of the host matrix on the optical properties, particularly the luminescence behavior of Pr3+ ions. X-ray absorption near edge structure (XANES) spectroscopy verifies the presence of Pr ions in the glasses with a +3 oxidation state. Absorption spectra results suggest that the lowest energy level of the Pr3+ 4f5d configuration is influenced by the oxide/fluoride ratio of the glasses. As both interconfigurational 4f5d and intraconfigurational 4f2 transitions are observed, the energy gap between the lowest level of the 4f5d configuration and the overlapping 1S0 level of the 4f2 configuration is found to influence the predominance of UV emissions from the 4f5d and 1S0 levels as well as their decay times. Consequently, a larger 4f5d-1S0 energy gap of ∼5000 cm−1 leads to a more intense UV emission from the 4f5d level with a faster decay time. These results underscore the significance of minimizing the energy of the 4f5d level and increasing the gap between 4f5d-1S0 levels to be able to obtain fast UV emissions from Pr3+-doped fluoride glasses.

ErF3 microcrystals controllably deposited in perfluoride glass for upconversion red emission

To the best of our knowledge, this paper first reports ErF3 microcrystals controllably deposited in perfluoride glass using phase-separation engineering techniques. The sample exhibited strong upconversion red-light emission owing to the small distance between Er3+ ions and low phonon energy (585 cm−1). The sample has a high red/green ratio of up to 18.6, which, to our knowledge, is the highest reported value in Er3+-doped fluoride glass ceramics. Furthermore, the sample has a long fluorescence lifetime (3.18 ms @660 nm), good color saturation (0.6255,0.3707), and good thermal stability (ΔE=0.31eV). Therefore, this sample has the potential for application across multiple fields, such as color display, visible laser, and lighting.

Effective 3.9 μm emission in fluorotellurate glass with Ho3+: Highly doping

The ∼3.9 μm mid-infrared (MIR) laser based on high concentration Ho3+ doped fluoride glass possesses unique advantages, but its low thermal stability does not meet the requirements of the MIR laser technology for optoelectronic device materials. In this paper, fluorotellurate glass with TeO2 and high doping concentration of Ho3+ was prepared. The excellent thermodynamic properties (ΔT = 108 °C) and low phonon energy (799 cm−1) render the matrix a promising candidate for the development of laser gain medium doped with Ho3+: ∼3.9 μm. The calculated theoretical parameters and the measured spectral information confirm that the scheme of ∼3.9 μm luminescence by high doping of Ho3+ in the fluorotellurate glass matrix is reasonable and effective.

Intense broadband 3.1 μm emission in Er3+-doped fluoroaluminate-tellurite glass for mid-infrared laser application

Er3+ single doped fluoroaluminate-tellurite glasses were made by employing a conventional melt-quenching technique. A strong fluorescence around 3.1 μm was achieved from Er3+-doped fluoride glasses, under a 980 nm laser diode pump, which was assigned to the Er3+: 4S3/2 → 4F9/2 radiation transition process. The up-conversion and mid-infrared spectra of emission for fluoroaluminate-tellurite glasses with various concentrations of Er3+ ions dopant was researched. In addition, the calculated fluorescence lifetime value about 3.1 μm reaches 0.48 ms. The findings indicate that fluoroaluminate-tellurite glasses doped with Er3+ have prospects of being developed into 3.1 μm mid-infrared fiber and laser materials.

Spectroscopic properties and Stark splitting of Nd3+ ions in different host glasses to obtain pure blue laser

In this study, we investigated the spectroscopic properties and Stark splitting of Nd3+ in several typical host glasses by focusing on the 0.9 μm fluorescence (4F3/2 → 4I9/2). Absorption, emission spectra and decay curves of Nd3+ doped borate, phosphate, fluoride, tellurite, silicate, germanate and fluorophosphate glasses were measured. Judd−Ofelt parameters, Stark splitting and crystal field strength in these glasses were calculated and analyzed. Results demonstrated that broad absorption and emission bands, large Judd−Ofelt parameters (5.14 × 10−20 cm2), strong local field strength (7089.2 cm−1) and high values of fluorescence branching ratio (43.7%) and fluorescence lifetime (542.95 μs) of Nd3+ ions were found in silicate glass. Results indicate that silicate and germanate host glasses show promising potential for pure blue lasers by frequency doubling of 0.9 μm fluorescence.

Boosting visible luminescence of Tb3+-activated ZBLAN fluoride glasses by Dy3+ co-doping

Tb3+ ions doped optical materials have emerged as gain media for green fiber lasers. Dy3+ ions were proposed as a sensitizer of Tb3+ ions in glasses to increase the excitation efficiency, yet a systematic understanding of the impact of Dy3+ doping on spectroscopic and physiochemical properties of glasses remains lacking. Here, using Tb3+/Dy3+ doped fluoride glass as a model system, we reveal that Dy3+ doping not only enhances Tb3+ emission intensity, but also increases the thermal stability of fluoride glasses. Detailed spectroscopic characterizations indicate that co-doping Dy3+ ions boosts visible luminescence intensity of Tb3+ ions in fluoride glasses due to sensitization of Tb3+ by Dy3+ ions. Importantly, we deeply research the energy transfer process, ascertain several important factors affecting energy transfer efficiency and propose optimal doping concentrations of Tb3+ and Dy3+ ions for visible emission. We envisage that our finding provides a new perspective for the synthesis of Tb3+-doped fluoride glasses with enhanced thermal stability, and may be extended for the fabrication of Tb3+-activated optical fibers.

White-light emission and chromaticity characterization of Dy3+ doped fluoride glass for standard white light source

In this paper, we reported the white light emission properties of Dy3+ doped ZrF4-BaF2-AlF3-NaF (ZBAN) glass. Physical properties of the host glass were examined. The intensity parameters were determined from Judd–Ofelt theory based on the absorption spectrum. The chromaticity coordinates calculated using emission spectrum are located in the white area of the CIE chromaticity diagram. Judd–Ofelt theory was used to analyze the relationship between the Dy3+ doping concentration and the yellow/blue ratio of the fluorescence. Furthermore, the change of chromaticity coordinates in the CIE chromaticity diagram was predicted. Anomalous change caused by fluorescence quenching at high concentrations was also discussed. In order to find the fluorescence closest to the equal energy light, the chroma difference between the fluorescence and the equal energy point was calculated. These results demonstrate that Dy3+ doped fluoride glass is a suitable material for use as a standard white light source.

Long period fiber gratings for the mitigation of parasitic laser effects in mid-infrared fiber amplifiers.

A concept to mitigate parasitic lasing in mid-IR fiber amplifiers using a single long period fiber grating is shown. Using tightly confined ultrashort laser pulses at 800 nm, a grating was directly inscribed into the core of an erbium doped fluoride glass fiber showing a strong attenuation down to -27 dB at desired wavelength. The concept reveals great potential to improve the average output power and attainable spectral range of low repetition rate in-amplifier supercontinuum generation.

Sensitization effect between Ln3+ ions in zinc fluoride glasses for MIR applications

A system of zinc fluoride glasses were synthesized to analyse the sensitization mechanism between doped Ln3+ ions under 808 or 980 nm excitation. Differential scanning calorimetry (DSC) curve and Raman spectra indicate the favourable thermal stability and a low maximum phonon energy of the host. Judd-Ofelt (J-O) theory together with the absorption spectra were utilized to compute the Ωt for predicting radiative features of each sample which coincide with the later measured emission spectra. Broadband emission ranging from 2400 to 3300 nm with a half-width of 361 nm in Er3+/Dy3+ codoped zinc fluoride glasses under 980 nm pumping has been investigated, which may be applicated in mid-infrared fiber amplifier and broadband tunable lasers field. On the other hand, the efficient sensitization effect mechanism between Er3+ and Dy3+ around 3 μm band with an extremely high energy transfer efficiency Ƞ (96.1%) of Er3+:4I13/2→Dy:6H11/2 has been researched under 808 nm excitation. Hence, Er3+ and Dy3+ doped zinc fluoride glasses may be potential optical candidates of great development foreground in the fields of mid-infrared applications.

Numerical Analysis of Q-Switched Erbium Ion Doped Fluoride Glass Fiber Laser Operation Including Spontaneous Emission

Partial differential equations are solved to perform a spatiotemporal analysis of Q-switched operation of a fluoride fiber laser doped with erbium ions. A method of lines is applied in order to reduce the partial differential equations to a set of ordinary differential equations. The latter set is then solved using an algorithm designed for a solution of stiff equation problems. A spontaneous emission term is added to equations that model the dynamics of the photon population within the laser cavity for the infrared signal wave. The results show that, without an inclusion of the spontaneous emission term, the correct behavior of the photon population and energy level populations cannot be reproduced.

Er3+-doped fluorozirconate glass modified by PbF2 with high stimulated emission cross-section

Er3+-doped fluoride glass modified by PbF2 is developed. Upon 980 nm laser-diode excitation, intense luminescence emission around 2.71 μm from the Er3+4I11/2 → 4I13/2 transition is observed. On the basis of the Judd–Ofelt theory, the intensity parameters and radiative properties are determined from the absorption and emission spectra. Compared with conventional Er3+-doped fluoride glass (Er:ZBLAN), the proposed glass possesses a large spontaneous emission probability (Arad, 29.76 s−1) and a high stimulated emission cross-section (σem) at 2.71 μm (1.25 × 10−20 cm2). In addition, fibers with high strength might be drawn from the glass preform owing to its good chemical stability; therefore, it may be useful for increasing the output power of mid-infrared lasers. The results indicate that the present glass can be a good candidate for mid-infrared fiber lasers.

Preparation and MIR Luminescence Properties of Er<sup>3+</sup> Doped Fluorochloride Glass

The Er3+ doped fluorochloride glass sample was prepared by incorporating Cl- into the fluoride glass (ZBLAN) using a conventional melt quenching method. The chemical stability, thermal stability and fluorescent properties of the Er3+ doped fluorochloride glass were reasearched by increasing the Cl- concentration. The effect of different Cl- concentrations on the luminescent properties of the fluorochloride glass was compared. The results show that the luminescent intensity of infrared increases with the increase of Cl- concentration. When the Cl- concentration reaches 15 mol%, the luminescent intensity is the strongest. At the same time, the effects of different Er3+ concentrations on the luminescence properties of fluorochloride glass were compared. The optimum doping concentration of Er3+ was 1 mol%. Hence, it is represented here as ZBLAN:15Cl, 1Er. The X-ray diffraction (XRD), absorption spectrum, near-infrared spectrum (NIR) and mid-infrared spectrum (MIR) of Er3+ doped fluorochloride glass were analyzed by experiments. The energy level diagram of Er3+ and the infrared luminescence of the sample were analyzed. The infrared luminescence of Er3+ at the excitation of 980 nm was mainly studied. The Judd-Ofelt parameters were calculated. It was found that the value of Ω2 increased first and then decreased to the Cl- contents increasing in the glass matrix, while Ω4 and Ω6 did not change obviously in different glass composition. This is because the environment of the crystal field around the rare earth ions has changed. In the Er3+-doped fluoride glass, the introduction to Cl- significantly enhances the mid-infrared luminescent intensity of the fluorochloride glass. The calculation of J-O theoretical parameters shows that the introduction to Cl- enhances the covalentity of the coordination bond with Er3+, reduces the local symmetry, and significantly enhances the luminescent intensity of fluoride glass. Rare earth ion doped fluorochloride glass provides a theoretical basis of improving luminescent properties. At the same time, it has important guiding significance of the research, development and application of similar MIR luminescent materials.

Emission properties of 1.8 and 2.3 μm in Tm3+-doped fluoride glass

In this work a Tm3+-doped fluoride glass with good thermal stability is prepared. Intensive 1.8 and 2.3 μm emissions are obtained when pumped by an 800 nm laser diode. And the 1.48 μm emission is limited because of the much strong radiation around 1.8 μm. On the basis of absorption spectrum, radiative properties are investigated and discussed according to Judd–Ofelt parameters (Ω2, Ω4, Ω6) calculated by Judd–Ofelt theory. Besides, absorption and emission cross-sections of 3 F 4 → 3 H 6 transition are figured out and analyzed by using McCumber and Beer–Lambert theories. The high gain around 1.8 μm was predicted by the large σemiτrad product (29.8 × 10–21 cm2 ms). The results obtained indicate that the Tm3+-doped fluoride glass can be a promising 2.0 μm laser glass material.

Intense 2.7 μm emission in Er3 + doped zinc fluoride glass

A novel erbium ion doped zinc fluoride glass was prepared. 2.7μm emission and transmittance properties together with thermal ability were investigated. An enhanced 2.7μm emission was observed by introducing ZnF2 in the ZrF4-based fluoride glass. Meanwhile, the J-O parameters and branching ratios (β) of Er3+-doped zinc fluoride glass were calculated and analyzed. The present Er3+-doped zinc fluoride glass with large emission cross-section (0.92×10−20cm2) and long decay lifetime (2.05ms) at 2.7μm indicates that it have very promising applications for solid state lasers around 3μm.

Visible to near-infrared down-shifting in Tm3+ doped fluoride glasses for solar cells efficiency enhancement

In this paper, down-conversion of Tm3+ doped fluoride ZLAG glasses with composition of 70.2ZrF4–(23.4−x)LaF3–0.6AlF3–5.8GaF3–xTmF3 (x = 0.25, 0.5, 0.75, 1, 2, 3 and 5 mol%) were tested as encapsulation materials for solar cells. The current density – voltage (J-V) characterizations were performed under solar simulator irradiation. The influence of Tm3+ concentration on the mono crystalline silicon solar cells performances was investigated. A slight increase of the solar cell efficiency was observed in the case of fluoride ZLAG for Tm3+ doping concentrations up to 1 mol% Tm3+. Further increase of the Tm3+ concentration leads to a decrease of solar cell conversion efficiency as a result of concentration quenching.

Study with Analytical Equations of Absorption Spectra Containing Interference Dips in Fluoride Glasses Doped with Cr(3.).

The optical absorption of Cr(3+)-doped fluoride glasses has been investigated. The lowest energy absorption band (4)A2 → (4)T2 shows distinct interference dips due to spin-orbit coupling between (4)T2, (2)E and (2)T1 excited states. The dips were analyzed using an analytical method proposed by Bussière et al. ( J. Phys. Chem. A 2003 , 107 , 1258 ) based on coupled potential energy surfaces. Then a theoretical crystal-field analysis based on the Racah tensor algebraic method was carried on Cr(3+) ions occupying octahedral site symmetry in the fluoride glasses. Satisfactory correlations were obtained between the experimental and calculated energy levels. The fitting of the interference dips also provided a measure of the spin-orbit coupling constant for Cr(3+) in fluoride glasses, intermediate between the theoretical value calculated for a fluoride crystal and the value deduced from Racah parameters.

Electronic Structure and Fano’s Antiresonance Study of Cr3+ Doped BIGaZYTZr Fluoride Glass

Electronic Structure and Fano’s Antiresonance Study of Cr3+ Doped BIGaZYTZr Fluoride Glass

Enhanced solar photons harvesting of a-SiC:H solar cells with ZBLA fluoride glasses containing rare earth ions

As encapsulation glasses for a-SiC:H cells, Yb3+/Ce3+-Er3+ tri-doped ZBLA fluoride glasses were prepared using the high temperature melt-quenching method and the optical characteristic of the glass were measured. Depending on the nature of rare earth doped ZBLA fluoride glasses, both near infrared (low-energy) and ultraviolet (high-energy) solar photons can be transformed into visible photons. By downshifting the ultraviolet (280–350 nm) light combined with upconverting the near infrared (900–1100 nm) light, the glass can emit strong visible (500–700 nm) light, which matches well with the spectral responsivity of a-SiC:H cells. The conversion of non-absorption photons energies by upconversion and downshifting leads to promote the improvement of a-SiC:H cells performances, and measurement shows relatively increase of 7.6%–0.8% in cell efficiencies.

Enhanced 2.7- and 2.9-μm emissions in Er3+/Ho3+ doped fluoride glasses sensitized by Pr3+ ions

In this report, Er3+/Ho3+/Pr3+ tri-doped fluoride glass was prepared. The enhancement of 2.7 and 2.9μm emissions from Er3+/Ho3+doped system were achieved successfully after the addition of Pr3+. The combination of low OH− concentration, low maximum phonon energy and high mid-infrared transmittance is beneficial to the realization of mid-infrared emissions. The energy transfer mechanism among Er3+, Ho3+ and Pr3+ was investigated. The decay profiles of several levels were measured to further examine the enhanced mid-infrared emissions. Moreover, high stimulated emission cross sections at 2.7- and 2.9μm (1.08×10−20cm2 and 2.0×10−20cm2, respectively) were determined. Er3+/Ho3+/Pr3+ tri-doped fluoride glass might provide a new choice for mid-infrared laser.