ZBLAN Glass Research Articles

UV-violet emission properties of 2F(2)5/2 energy level of Nd3+ ions in ZBLAN glass

In this work the short-wavelength emission properties are investigated for the highest observed 4f metastable energy level 2F(2)5/2 of Nd3+ ions in fluorozirconate ZBLAN glass. Various dopant concentrations, ambient temperatures and excitation conditions have been considered throughout the study. Distinct spectral features were observed under pulsed and cw excitation at 514 nm. In particular, pulsed pumping enabled recording of 2F(2)5/2 emission spectra, not observable under CW excitation, as well as the level’s fluorescence decay dynamics and its evolution with temperature and dopant concentration. According to the best of the authors’ knowledge, neither the fluorescence lifetime of 2F(2)5/2 of Nd3+ in ZBLAN, nor its concentration dependent evolution were reported before.

Spectroscopic Properties of Er<sup>3+</sup>-Doped Ga<sub>2</sub>O<sub>3</sub>-GeO<sub>2</sub>-Bi<sub>2</sub>O<sub>3</sub>-PbO Glass

Spectroscopic properties in Er3+-doped Ga2O3-GeO2-Bi2O3-PbO（BP）glass have been investigated and their promising application as Er3+-doped fiber amplifiers (EDFA) has also been evaluated under the excitation of 980 nm. The important roles of Bi2O3 substitution for PbO on spectroscopic properties, such as Judd-Ofelt intensity parameters (t=2, 4, 6) and emission spectra of Er3+, have been studied. The calculated peak emission cross-section of the 4I13/2→4I15/2 transition of Er3+ ions are 16.03×10-21 cm2 when the substituted PbO content by Bi2O3 is about 25 mol. The product of the peak emission cross-section ( ) and the full width at half-maximum (FWHM) of the sample is~689.29×10-28 cm3, which is higher than that of Er3+-doped silicate, phosphate and ZBLAN glasses. It was found that the substitution of Bi2O3 for PbO provides two potentials: broadening the full width at half-maximum of 1.53 μm fluorescence and improving the values of FWHM× of Er3+. The results strongly support that the Er3+-doped BP2 glass could be identified as a promising material for achieving 1.53 μm fiber amplifier.

Spectroscopic investigation of Nd^3+-doped ZBLAN glass for solar-pumped lasers

We evaluated the optical properties required for the design of a solar-pumped laser for Nd3+-doped ZrF4-BaF2-LaF3-AlF3-NaF (ZBLAN) glass. The quantum efficiency (QE) of near-infrared emission from the 4 F3/2 state of Nd3+ using sunlight as an excitation source was 70%. The product of the stimulated emission cross section and the radiative lifetime (σseτr) of the 4F3/2→4I11/2 was 1.5×10−23 cm2·s. The integrated absorption strength in the 450–900 nm region was the largest among Nd3+-doped fluoride glasses. The high QE, large σseτr product, and large integrated absorption strength indicate that Nd3+-doped ZBLAN is one of the most promising materials for solar-pumped lasers.

Fifty percent internal slope efficiency femtosecond direct-written Tm^3+:ZBLAN waveguide laser

We report a 790 nm pumped, Tm³⁺ doped ZBLAN glass buried waveguide laser that produces 47 mW at 1880 nm, with a 50% internal slope efficiency and an M² of 1.7. The waveguide cladding is defined by two overlapping rings created by femtosecond direct-writing of the glass, which results in the formation of a tubular depressed-index-cladding structure, and the laser resonator is defined by external dielectric mirrors. This is, to the best of our knowledge, the most efficient laser created in a glass host via femtosecond waveguide writing.

Spectroscopic properties of Er doped and Er, Nd codoped fluoride glasses under simulated sunlight illumination

We investigated the fluorescence characteristics of Er codoped Nd doped ZBLAN glasses proposed for solar pumped fiber laser (SPFL) under simulated sunlight. Er is used as a sensitizer because it absorbs a part of the ultraviolet and visible light where is no absorption of Nd. Under simulated sunlight illumination, Er singly doped fluoride glass displayed four emission bands with peaks at 550, 848, 977 and 1533 nm attributed to the 4S 3/2- 4I 15/2, 4S 3/2- 4I 13/2, 4I 11/2- 4I 15/2 and 4I 13/2- 4I 15/2 electronic transitions of Er, respectively. The quantum efficiency measurement was carried out using an integrating sphere and under the simulated sunlight excitation showed a maximum of 73% for 0.5 mol.% of ErF 3 in ZBLAN glass. In Nd, Er codoped fluoride glass, the 1.05 μm emission of Nd was observed under 380 nm excitation what supposes the energy transfer from Er to Nd in ZBLAN glasses as Nd has no absorption at the wavelength. Er, Nd codoped fluoride glasses are promising as a sensitized laser media for solar pumped fiber lasers.

Thermal stability and crystallization behavior of TiO2 doped ZBLAN glasses

ZBLAN glasses with the composition (in mol%) of (100−x)(53 ZrF4+19 BaF2+5LaF3+3AlF3+20NaF)+xTiO2 (x=0, 1.0 and 2.0mol%) were prepared using a conventional melting technique in dry nitrogen atmosphere. The thermal stability, glass-forming ability, and crystallization kinetics of the ZBLAN system as a function of the TiO2 concentrations were investigated by Differential Scanning Calorimetry (DSC). Also, the crystalline phases were determined by X-ray Diffraction (XRD). Our study indicates that adding TiO2 in a fluoride system improves the thermal parameters of the glass, which is interesting for applications as optical fiber.

Spectroscopic properties of Tm 3+ doped TeO 2-R 2O-La 2O 3 glasses for 1.47 μm optical amplifiers

Upon excitation at 808 nm laser diode, an intense 1.47 μm infrared fluorescence has been observed with a broad full width at half maximum (FWHM) of about 124 nm for the Tm 3+-doped TeO 2-K 2O-La 2O 3 glass. The Judd–Ofelt parameters found for this glass are: Ω 2 = 5.26 × 10 −20 cm 2, Ω 4 = 1.57 × 10 −20 cm 2 and Ω 6 = 1.44 × 10 −20 cm 2. The calculated emission cross-sections of the 1.47 μm transition are 3.57 × 10 −21 cm 2, respectively. It is noted that the gain bandwidth, σ e × FWHM, of the glass is about 440 × 10 −28 cm 3, which is significantly higher than that in ZBLAN and Gallate glasses, a high gain of 35.5 dB at 1470 nm can be obtained in a TKL glass fiber. TeO 2-R 2O (R = Li, Na, K)-La 2O 3 glasses has been considered to be more useful as a host for broadband optical fiber amplifier.

Up-conversion sensitization luminescence in Pr3+and Yb3+ co-doped fluoride glasses

In experiment, Pr3+,Yb3+:ZBLAN glass is chosen as a frequency up-conversion fluorescence material, and detailed reasons for choosing ZBLAN glass as a material are given. In this paper we also analyze the relations between up-conversion fluorescence intensity and pump light intensity and between up-conversion fluorescence intensity and ions doped concentration. Therefore we obtain experimental conditions to realize a clear two-frequency up-conversion 3-D display.

Tm3+/Yb3+共掺杂ZBLAN玻璃的多光子紫外上转换发光

The ultraviolet upconversion luminescence properties of the Tm3+ ion sensitized by the Yb3+ ion were studied,in fluoride glass as excited by a 980 nm continuous wave diode laser.Red,blue,and even ultraviolet emissions were observed with ZrF4-BaF2-LaF3-A1F3-NaF glass,and it was also found that the peaks at 291,347,363,454,475,643,687 and 804 nm correspond to the transitions of 1I6→3H6,1I6→3F4,1D2→3H6,1D2→3F4,1G4→3H16,G4→3F4,3F3→3H6,and 3H4→3H6,respectively.According to the relationship between the pump power and the upconversion peaks intensity,347 nm and 363 nm ultraviolet emissions are five photon and four photon processes respectively.The research results show that the ZrF4-BaF2-LaF3-A1F3-NaF glass of the Tm3+ ion sensitized by the Yb3+ ion can effectively transform the near-infrared waveband laser to the ultraviolet.

Improving Er3+ 1.53 μm luminescence by CeF3 nanocrystallization in aluminosilicate glass

In order to develop promising materials for the Er3+-doped fiber amplifier, transparent glass ceramics containing hexagonal CeF3 nanocrystals were prepared by melt-quenching and subsequent heating. The obvious Stark splitting in the absorption and emission spectra, the intensification of the 1.53 μm emission, and the prolongation of the Er3+:I413/2 decay lifetime demonstrated the partition of Er3+ ions into the CeF3 nanocrystals. Evidently, the efficient cross-relaxation between Ce3+ and Er3+, i.e., Er3+:I411/2+Ce3+:F25/2→Er3+:I413/2Ce3+:F27/2 led to the quenching of the upconversion and the enhancing of the desired Er3+ 1.53 μm emission. Based on the emission and absorption spectra, it was further calculated that the glass ceramic possesses broad bandwidth as that of the ZBLAN glass, and large emission cross-section close to the silicate glass, for the 1.53 μm emission.

Samarium-Doped Fluorochlorozirconate Glass-Ceramics as Red-Emitting X-Ray Phosphors

We have examined the photoluminescence (PL) and X-ray luminescence (XL) of fluorochlorozirconate (FCZ) glass–ceramics (FCZ-GC) doped with Sm3+ and Sm2+ ions. Sm-doped FCZ-GCs have been prepared by annealing a ZBLAN glass of nominal composition 53% ZrF4, 20% NaF, 3% AlF3, 3% LaF3, 1% SmF3, 1% BaF2, 19% BaCl2 (mol%) above the glass transition of the host glass matrix. SmF3 was added to the initial glass mix for trivalent samarium doping. Sm2+ doping was achieved by reducing Sm3+ to Sm2+ during the melting of the initial mix by the addition of NaBH4. FCZ-GC contains BaCl2 nanocrystals formed during the annealing with embedded Sm2+ ions, which dominate PL and XL. The PL of Sm2+ ions embedded in BaCl2 nanocrystals strongly depends on their crystal structure (hexagonal or orthorhombic) and may be used to identify that structure. The correlation of the PL spectra with X-ray diffraction data is used to estimate the size of nanocrystals. The nanocrystals with average dimensions <∼30 nm are mainly hexagonal while larger crystals are mostly orthorhombic. XL is more efficient in glass–ceramics containing relatively large BaCl2 nanocrystals with hexagonal crystal structure.

Characteristic of the 1S 0 level in Pr 3+:ZBLAN glass by two-step excitation

We experimentally report on the energy position, branching ratios, lifetimes and emission cross sections of the 1S 0 level in Pr 3+:ZBLAN glasses by two-step excitation process: 3H 4 → 1D 2 → 4f5d. The calculated branching ratios and lifetimes of 1S 0 by the standard as well as the modified Judd-Ofelt theories are compared with the measured ones. The results by the modified Judd-Ofelt theory, which more reasonably takes into account the effects of the configuration energies on the 5d perturbations to the 4f levels, have better agreements with the experimental results. The 1S 0 luminescence by another two-step excitation process 3H 4 → 3P 0 → 4f5d is also discussed.

Evaluating upconversion materials developed to improve the efficiency of solar cells: reply to comment

The current search for efficient upconversion (UC) materials is driven by numerous potential applications; one of them is solar cell efficiency improvement. The data on the absolute UC efficiency of materials are of extreme importance for estimation of real feasibility of approaches suggested for applications; however, these data have been reported only for a few materials. In 1, an indirect method of evaluation of the significance of upconversion materials for solar cells is proposed. We discuss this method and support our considerations by the results of experimental measurements of the absolute UC efficiency of Er-doped modified ZBLAN glass.

Yellow laser oscillation in Dy 3+ -doped waterproof fluoro-aluminate glass fibre pumped by 398.8 nm GaN laser diodes

In this reported work, the authors successfully drew a low-loss Dy-doped optical fibre (0.3 dB/m at 532 nm) of a waterproof fluoro-aluminate glass system and demonstrated yellow laser oscillation in the Dy 3+ -doped fluoride fibre pumped by a 398.8 nm GaN laser diode. Maximum output power was 10.3 mW and the slope efficiency was 17.1% at 575 nm. Since the fluoro-aluminate-glass system has a remarkable water resistance advantage compared to ZBLAN glass, Dy-doped fluoro-aluminate glass fibre is expected to contribute to making a solid-state yellow fibre laser with high chemical durability without a frequency doubling technique.

Energy level decay and excited state absorption processes in dysprosium-doped fluoride glass

The primary excited state decay processes relating to the H613/2→H615/2∼3 μm laser transition in singly Dy3+-doped fluoride (ZBLAN) glass have been investigated in detail using time-resolved fluorescence spectroscopy. Selective laser excitation of the F69/2, H67/2 energy levels at 1125 nm and F611/2, H69/2 energy levels at 1358 nm established that the energy levels above the H611/2 level, excluding the F49/2 level, are entirely quenched by multiphonon emission in ZBLAN glass. The H611/2 and H613/2 energy levels emit luminescence with peaks at ∼1700 and ∼2880 nm, respectively, but at low quantum (luminescence) efficiencies. The quantum efficiency of the H611/2 level and H613/2 level is ∼9×10−5 and ∼1.3×10−2, respectively, for [Dy3+]=0.5 mol % based on calculations of the radiative lifetimes using the Judd–Ofelt theory. Excited state absorption (ESA) was detected by monitoring the rise time of the 1700 nm luminescence after tuning the probe wavelength across the spectral range from 1100 to 1400 nm. As a result of nonradiative decay of the higher excited states, ESA contributes to the heating of ∼3 μm fiber lasers based on Dy3+-doped fluoride glass. For [Dy3+] up to 4 mol %, we found no evidence of energy transfer processes between Dy3+ ions that influence the decay characteristics of the H611/2 and H613/2 energy levels.

On competition between two types of anti-Stokes emission in Ho 3+ and Nd 3+ ions in glasses

An interesting competition between two anti-Stokes emissions has been observed and interpreted in ZBLAN and fluoroaluminate (ALF) glasses activated by Ho 3+ and Nd 3+ ions, respectively. The intensity of an emission line situated spectrally close to the excitation wavelength, was seen to increase with temperature, whereas the intensity of another, upconverted emission line, in the same conditions, was seen to decrease. Both effects are believed to be caused by the same mechanism, which we have identified as the anti-Stokes multiphonon excitation of the state responsible for the first emission, followed by upconversion of the ESA (excited state absorption) or an energy transfer type process. Analysis of the kinetics of the observed effects enabled us to fit a theoretical model to the experimental data. It appears likely that the described competition may be a universal feature not restricted to the materials described in this work.

Stark splitting of the ground state of Er 3+ in fluorozirconate glass at low temperature

Optical properties of Er 3+-doped ZBLAN glass matrix have been studied by luminescence spectroscopy under 488 nm excitation. The spectrum of the 4S 3/2 4I 15/2 transition, carried out at temperature T = 2 K, shows a new line in the lowest energy region. This new line, centered at 17 996 cm −1, was attributed to the lower transition between the Stark components of the 4S 3/2 4I 15/2 transition. Measurements from T = 2 K to room temperature show the disappearance of this new line. From the results we estimate the splitting of 415 cm −1 for the ground state and 100 cm −1 for the 4S 3/2 excited multiplet. The experimental result allows us to assign the positions of the eight Stark components of the ground state multiplet of the Er 3+ in the ZBLAN glass matrix.

Multi-colour laser oscillation in Pr 3+ -doped fluoro-aluminate glass fibre pumped by 442.6 nm GaN-semiconductor laser

The successful drawing of a Pr-doped optical fibre of a waterproof fluoro-aluminate glass in an AlF3-YF3- PbF2 system with low loss (0.1 dB/m) is reported and multi-colour laser oscillation in a Pr3+-doped fluoro-aluminate glass fibre pumped by a 442.6 nm GaN-semiconductor laser is demonstrated. Since the fluoro-aluminate glass in an AlF3-YF3-PbF2 system has a remarkable water resistance advantage compared to ZBLAN glass, Pr-doped fluoro-aluminate glass fibre is expected to contribute to making a visible fibre laser with high chemical durability without a frequency doubling technique.

Strong 153 μm to NIR-VIS-UV upconversion in Er-doped fluoride glass for high-efficiency solar cells

Optical spectra of Er-doped modified ZBLAN glasses are studied at room temperature. Radiative quantum yields of the 4I11/2 and 4I13/2 levels are estimated from the experimentally measured lifetimes and from the spontaneous emission probabilities calculated from the Judd-Ofelt theory. The spectra of upconversion (UC) luminescence excited with 1.53 μm cw Er fiber laser are investigated in a wide spectral domain [from the near-infrared (NIR) to UV]. Absolute UC efficiency (i.e., the ratio of UC luminescence power to the absorbed pump power) is experimentally measured; efficiency of up to 12.7% is obtained. A conclusion is made about perspectives of use of the studied glasses as upconverter material for solar cells of enhanced efficiency.

Multiphoton upconversion process in Tm 3+ doped ZBLAN glass by CW laser irradiation

Blue, even ultraviolet emissions and very strong red emissions have been observed in ZBLAN glass doped with Tm 3+ under 800 nm CW laser excitation. The red emissions were demonstrated to be of sequential two-photon process, while the ultraviolet emissions be of three-photon process, according to the intensity dependence.