ZBLAN Fluoride Glass Research Articles

Double Gain of Efficient UV‐C Phosphor and Fast Scintillator Based on Pr3+‐doped KY3F10 Nano‐Glass Composites

AbstractGlassy phosphors offer a promising opportunity to overcome the limits of polycrystalline counterparts, thanks to their merits including excellent optical transparency, abandonment of organic binders, and capability of drawing fibers, etc. However, research and development of glassy UV‐C phosphors and fast scintillators have seriously lagged behind crystals. Here, a new type of efficient UV‐C phosphors and fast scintillators (double gain) is developed from Pr3+‐doped transparent nano‐glass composites (nano‐GCs) containing KY3F10 nanocrystals. Such a material combines favorably the advantages of both crystal and glass, exhibiting intense interconfigurational 5d‐4f emissions of Pr3+ upon deep‐UV, high energy electron‐beam and X‐ray excitations. The emission profile ideally overlaps with the germicidal effectiveness curve. The Pr3+‐doped nano‐GCs are endowed with a radiative decay time shorter than that of extensively studied Ce3+‐doped glasses and nano‐GCs. They exhibit intense X‐ray excited radioluminescence that is comparable to the standard Bi4Ge3O12 (BGO) crystal and significantly stronger than Pr3+‐doped ZBLAN fluoride glass known for the high luminescence efficiency. An X‐ray imaging system with a good spatial resolution using the Pr3+‐doped nano‐GCs is also demonstrated.

Mid-infrared ZBLAN glass optical components made by hot embossing technique

We demonstrate the successful development of refractive lenses made of ZBLAN fluoride glass using the hot embossing technique. Synthesized in-house ZrF4-BaF2-LaF3-AlF3-NaF glass is thermally stable and has high transmission in the range of 0.4–8.0 µm. A lens was formed with a brass stamp inside a resistant furnace under standard atmosphere conditions. No mechanical or chemical postprocessing is used to obtain the optical quality of the lens surface. As a proof-of-concept, we have developed plano-convex lenses with a diameter of 10 mm and f#=3. The tested lenses have good imaging properties with a resolution of 23 pl/mm and 8 pl/mm for 1.5 µm laser and broadband thermal source emitting in the mid-infrared range, respectively.

Mid-Infrared Luminescence of the High Stability Perovskite CsPb1-xErxBr3-ZrF4-BaF2-LaF3-AlF3-NaF Fluoride Glass.

Perovskites have been studied because of their adjustable wavelength range, high color purity, and wide color gamut. However, they still face some problems such as poor stability and insufficient infrared luminescence. The perovskite glass can improve the stability and luminescence properties of the perovskite. In this paper, a highly stable CsPb1-xErxBr3-ZBLAN fluoride glass with mid-infrared and visible light emission was prepared. The ZBLAN fluoride glass has good inertness, which can improve the stability of the CsPb1-xErxBr3 perovskite. The CsPb1-xErxBr3-ZBLAN fluoride glass can prevent the perovskite from being destroyed by water, oxygen, and laser. The Er3+ replaces Pb2+ to bond with Br- to become the luminescent center of the CsPb1-xErxBr3-ZBLAN perovskite glass, which extends the luminescence to the mid-infrared region. In addition, its luminescent intensity is significantly higher than those of the ZBLAN-Er glass and CsPb1-xErxBr3 perovskite. After irradiation with a 365 nm UV lamp for 13 h, the luminescence intensity of the CsPb1-xErxBr3-ZBLAN perovskite glass decreases only by 10%. The EDS spectrum shows that the elements of the CsPb1-xErxBr3 perovskite are uniformly distributed in the glass matrix. The X-ray diffraction spectrum shows that the sample has both the CsPb1-xErxBr3 perovskite phase and the glass phase. This indicates that CsPb1-xErxBr3 is well crystallized in the ZBLAN glass matrix. The three parameters calculated by the Judd-Ofelt theory show that the CsPb1-xErxBr3 perovskite can increase the covalency and asymmetry around the rare earth ion Er3+. The transmission electron microscope can clearly see the morphological structure of the CsPb1-xErxBr3 perovskite in the ZBLAN glass matrix. The infrared Fourier transform spectroscopy shows that the sample has lower phonon energy. This proves that the sample has good infrared luminescence characteristics. Finally, the visible and infrared light sources were prepared. Under the irradiation of the 365 nm ultraviolet lamp and 980 nm laser, the perovskite glass produces green light and infrared emission.

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.

Fluoride fiber optic SPR sensor with enhanced performance: Simulation and analysis within the framework of Kubo formulation for graphene

Abstract The performance of a fiber optic SPR sensor with ZBLAN fluoride glass core, NaF clad, Ag layer, and graphene monolayer is simulated and analyzed under the synchronized tuning of temperature, near infrared (NIR) wavelength, and graphene’s chemical potential. The simulation is carried out by considering the graphene’s conductivity variations as per Kubo formulation. For other constituent media, the thermo-optic effect is considered. The simulation results suggest a general outcome that a combination of shorter NIR wavelength, higher temperature, and larger chemical potential can provide considerably enhanced performance. A finer analysis predicts that 1310 nm wavelength, 0.61 eV chemical potential, and 332.4 K temperature can be used as a pragmatic combination in order to achieve significantly enhanced sensing performance. The proposed sensor provides higher figure-of-merit than most recent works reported on SPR-based sensors.

Role of Yb(3+) ions on enhanced ~2.9 μm emission from Ho(3+) ions in low phonon oxide glass system.

The foremost limitation of an oxide based crystal or glass host to demonstrate mid- infrared emissions is its high phonon energy. It is very difficult to obtain radiative mid-infrared emissions from these hosts which normally relax non-radiatively between closely spaced energy levels of dopant rare earth ions. In this study, an intense mid-infrared emission around 2.9 μm has been perceived from Ho3+ ions in Yb3+/Ho3+ co-doped oxide based tellurite glass system. This emission intensity has increased many folds upon Yb3+: 985 nm excitation compared to direct Ho3+ excitations due to efficient excited state resonant energy transfer through Yb3+: 2F5/2 → Ho3+: 5I5 levels. The effective bandwidth (FWHM) and cross-section (σem) of measured emission at 2.9 μm are assessed to be 180 nm and 9.1 × 10−21 cm2 respectively which are comparable to other crystal/glass hosts and even better than ZBLAN fluoride glass host. Hence, this Ho3+/Yb3+ co-doped oxide glass system has immense potential for the development of solid state mid-infrared laser sources operating at 2.9 μm region.

Experimental study on a nonlinear photonics process of Er(05)Yb(3):FOV oxyfluoride nanophase vitroceramics

We study the nonlinear photonics of rare-earth-doped oxyfluoride nanophase vitroceramics (FOV), oxyfluoride glass (FOG), and ZBLAN fluoride glass. We found that an interesting fluorescence intensity inversion phenomenon between red and green fluorescence occurs from Er(0.5)Yb(3):FOV. The dynamic range summation operator of the intensity inversion between red and green fluorescence of Er(0.5)Yb(3):FOV is about 5.753 x 10(2), which is 100 to 1000 times larger than those of other materials. One of the applications of this phenomenon is double-wavelength fluorescence falsification-preventing technology, which is proved to possess the novel antifriction loss and antiscribble properties.

Near-infrared emission character of Tm3+-doped heavy metal tellurite glasses for optical amplifiers and 1.8 µm infrared laser

Intense 1.8 µm and efficient 1.47 µm infrared emissions have been recorded in Tm3+-doped alkali–barium–bismuth–tellurite (LKBBT) glasses with lower phonon energies under the excitation of a 792 nm diode laser. The maximum emission cross-sections for the 1.8 and 1.47 µm emission bands are derived to be 6.643 × 10−21 and 3.551 × 10−21 cm2 and the peak values are obviously higher than those in Tm3+-doped ZBLAN fluoride and TBSN tellurite glasses, respectively. In low concentration doping, the full-widths at half-maximum (FWHMs) of the two emission bands are 206 nm and 109 nm, respectively, and peak intensity ratio between them is about 2. When the doping concentration increases to 1 wt%, the peak intensity ratio exceeds 7 and the quantum efficiency of 3H4 level is only 64.6% due to the cross-relaxation process [3H4, 3H6] → [3F4, 3F4], which benefits to achieve powerful 1.8 µm emission. The efficient and broad 1.8 and 1.47 µm infrared emission bands indicate that Tm3+-doped LKBBT glasses are suitable materials in developing S- and U-band amplifiers and 1.8 µm infrared laser.

Study of up-conversion luminescence of Er(2):ZBLAN excited by 1520 nm laser

Plentiful up-conversion luminescence experimental phenomena of the ZBLAN fluoride glass Er(2):ZBLAN, excited by 1520 nm semiconductor laser, are studied in this article. The common-fluorescence spectra are measured also in this article in order to study up-conversion comprehensively. It is clear that the strong up-conversion luminescence lines (407.0m, 410.4 nm), (523.2, 528.3m nm), (543.0, 549.5m nm), (655.2, 666.1m nm), 801.6m nm, 817.8 nm, and (839.6m, 844.6 nm) are the fluorescence-transitions of (2G4F2H)9/2→4I15/2, 2H11/2→4I15/2, 4S3/2→4I15/2, 4F9/2→4I15/2, 4I9/2→4I15/2, (2G4F2H)9/2→4I9/2, and 4S3/2→4I13/2, respectively. The weak up-conversion fluorescence lines 382.6 nm, (449.3, 453.6m nm) and (487.1, 491.5m nm) are the transitions of 4G11/2→4I15/2, 4F5/2→4I15/2 and 4F7/2→4I15/2, respectively. It is interesting that the slopes of logF–logP curves, the double logarithmic variation of up-conversion luminescence intensity F with the laser power P, are different from each other for these observed up-conversion luminescences. It is clear that the {382.6 nm 4G11/2→4I15/2}, and {(407.0m, 410.4 nm) (2G4F2H)9/2→4I15/2}, {(523.2, 528.3m nm) 2H11/2→4I15/2, (543.0, 549.5m nm) 4S3/2→4I15/2, and (655.2, 666.1m nm) 4F9/2→4I15/2}, and {801.6 nm 4I9/2→4I15/2} up-conversion luminescences are five-photon, four photon, three-photon, and two photon up-conversion luminescence, respectively, because their slopes of the logF–logP curves are near to 5, 4, 3, and 2, respectively. It is found that the absorption from ground-state 4I15/2 level to 4I13/2 level is very large because its oscillation strength f is very large and its energy matching with 1520 nm laser is very good, resulting in the sequential energy transfer up-conversion easy to achieve.

Dynamics of permanent structural transformations in ZBLAN induced by self-channeled plasma filament

Abstract The time-resolved dynamics of permanent structural transformations in the ZBLAN (fluoride glass) induced by self-channeled plasma filament were first observed in situ using a high-intensity femtosecond (110 fs) Ti: sapphire laser (λp=800 nm). Self-channeled plasma filament would be induced in ZBLAN glass at the irradiation higher than input intensity of 1.0 × 1012 W/cm2 and photoinduce either the refractive index modification or optical crack modification. At the domain of refractive index modification, the lifetime of induced self-channeled plasma filament was 30 ps and structural transition time for forming the refractive index change was 40 ps. At the domain of optical cracks, however, the lifetime of induced self-channeled plasma filament was 70 ps and structural transition time for forming the optical cracks was 70 ps. A maximum value of refractive index change (Δn) was measured to be 1.3 × 10−2. The intensity profile of the output beam transmitted through the refractive index modification showed that the bulk modification produced a permanent structure of optical waveguide.

Up-conversion luminescence research of Er(0.5):ZBLAN material for volumetric display application when excited by 1520 nm laser

The up-conversion luminescence of the ZBLAN fluoride glass Er(0.5):ZBLAN, when excited by a 1520 nm semiconductor laser, is studied in this paper. The absorption and common-fluorescence spectra are also measured in order to understand the up-conversion clearly. It is found that there are seven strong up-conversion luminescence lines (406.97m, 410.42 nm), (521.97m, 527.56 nm), (542.38m, 549.27 nm), (654.27m, 665.70 nm), 801.57m nm, 819.46 nm and 840.00 nm, which can be recognized as the fluorescence transitions of (2G4F2H)9/2?4I15/2, 2H11/2?4I15/2, 4S3/2?4I15/2, 4F9/2?4I15/2, 4I9/2?4I15/2, (2G4F2H)9/2?4I9/2 and 4S3/2?4I13/2 respectively. Meanwhile, the small up-conversion fluorescence lines 379.20 nm, 453.10 nm and 490.60 nm are the transitions of 4G11/2?4I15/2, 4F5/2?4I15/2 and 4F7/2?4I15/2 respectively. It is interesting that the slopes of log F?logP curves, the double-logarithmic variation of up-conversion luminescence intensity F with laser power P, are different from each other for these observed up-conversion luminescence, this being valuable for the volumetric display. Comprehensive discussions find that the 4G11/2?4I15/2, (2G4F2H)9/2?4I15/2, (2H11/2?4I15/2, 4S3/2?4I15/2, 4F9/2?4I15/2) and 4I9/2?4I15/2 up-conversion luminescences are five-photon, four-photon, three-photon and two-photon up-conversion luminescences respectively. It is found also that the absorption from ground-state 4I15/2 level to 4I13/2 level is very large, which is beneficial to the sequential energy transfer up-conversion to occur.

Field-swept pulsed electron paramagnetic resonance ofCr3+-doped ZBLAN fluoride glass

Field-swept pulsed electron paramagnetic resonance (EPR) spectraof a ZBLAN fluoride glass doped with a low concentration of Cr3+ areobtained using echo-detected EPR and hole-burning free induction decaydetection. We review the utility of the pulsed EPR technique in generatingfield-swept EPR spectra, as well as some of the distorting effects thatare peculiar to the pulsed detection method. The application of thistechnique to Cr3+-doped ZBLAN reveals that much of the broadresonance extending from geff = 5.1 to geff = 1.97,characteristic of X-band continuous wave EPR of Cr3+ in glasses, isabsent. We attribute this largely to the variation in nutation frequenciesacross the spectrum that result from sites possessing large fine structureinteractions. The description of the spin dynamics of such sites iscomplicated and we discuss some possible approaches to the simulation ofthe pulsed EPR spectra.

Effects of chloride introduction on the optical properties and the upconversion emission with 980-nm excitation of Er3+ in ZBLAN fluoride glasses

Effects of chloride introduction on the optical properties and the upconversion emission with 980-nm excitation of Er3+ in ZBLAN fluoride glasses

Effects of chloride introduction on the optical properties and the upconversion emission with 980-nm excitation of Er 3+ in ZBLAN fluoride glasses

Er-doped ZBLAN fluoride glasses and those containing chloride were prepared. The parameters of optical transitions were determined experimentally. By the introduction of chlorine as replacing NaF with NaCl up to 20 mol% NaCl, the Judd-Ofelt parameters, Ω 2 and Ω 4 , were increased and the multiphonon-relaxation rate decreased. With these parameters inserted into the rate equations, they were numerically solved. The upconversion mechanisms of Er 3+ with 980-nm excitation and the effects of chlorine in the samples on the upconversion processes were observed. The upconversion processes for both 550-nm and 660-nm emissions were found to be dominated by the resonant and the phonon-assisted energy transfers. The intensity ratio of the 660-nm emission to the 550-nm emission decreased with increasing NaCl content. This change of intensity ratio was due to the suppression of the phonon-assisted energy transfer by chlorine.

Strong red-light scattering from colloidal copper in ZBLAN fluoride glass

Following extended thermal processing under reducing conditions, fluoride glasses with a composition close to the standard 53% ZrF 4-20% BaF 2-4% LaF 3-3% AlF 3-20% NaF (ZBLAN) formulation scatter red light in a band centred at around 600 nm, together with an associated extinction band centred at around 570 nm. Some samples show a dichroic effect of appearing red in back-scattered light but blue in transmitted light. The spectra are attributed to a dilute colloidal precipitate of copper, present as a residual impurity in the starting material with a concentration of around 1 ppm by volume. Calculations of the extinction and scattering spectra for copper colloidal particles show that the light scattering efficiency peaks at around 600 nm, but is insignificant compared with absorption for particle radii less than about 30 nm. For particle radii between about 30 and 50 nm, the scattering dominates the beam-particle interaction and is still peaked in the red region. For larger radii, the peak in the scattering efficiency becomes invariant and broadens. Fittings based on the calculations suggest that the copper particles responsible for the observed spectra in ZBLAN glass have radii in the range of 16 to 45 nm.

Photosensitivity of rare-earth-doped ZBLAN fluoride glasses

We have performed experiments to elucidate the mechanism of photosensitivity in rare-earth-doped fluorozirconate (ZBLAN) glasses. Glasses doped with Ce, Tb, Tm, and Pr were studied. Permanent holographic gratings were written in bulk samples using 248 nm light, with the strongest gratings observed in Ce:ZBLAN. Ultraviolet (UV) induced changes in both absorption and electron spin resonance (ESR) spectra were observed. In the Ce-doped glasses, the grating formation dynamics were recorded as a function of write beam intensity and Ce concentration. The results indicate that the mechanism of photosensitivity involves color center(s) creation through a stepwise two photon excitation of a Ce ion. The color center(s) can be subsequently bleached by a single photon at 248 nm.

Nonlinear luminescence of and ions in ZBLAN fluoride glasses

An avalanche luminescence of ions and cooperative fluorescence of ions in fluoride glasses have been observed. The mechanism of avalanche luminescence of is discussed, and a preliminary analysis of the effects of on has been made.

IR-to-visible up-conversion mechanisms in Pr 3+-doped ZBLAN fluoride glasses and fibers

The infrared-to visible up-conversion in Pr 3+-doped ZBLAN fluoride glasses has been investigated for different activator concentrations and for different type-materials, either bulk or fiber. Single beam experiments using continuous wave (CW) laser excitation and pulsed laser excitation allow to point out different up-conversion mechanisms, namely excited state absorption (ESA) and energy transfer up-conversion (ETU). The 2.8th power dependence of the blue fluorescence from the 3P 0 state under CW resonant pumping of the 1G 4 state indicates a dominant three-photon mechanism involving the 1D 2 state. Pulsed laser excitation shows that an ETU process is occurring. When the excitation wavelength is resonant with an ESA transition from the 1G 4 state, a two-photon process is pointed out. Concerning the red fluorescence issued from 1D 2 state, under CW excitation of the 1G 4 state, it is attributed to an ETU process which is greatly enhanced by ESA of the 1.3 μm signal, in the amplification regime in fibers. The influence of the Stark splitting and subsequent transition probabilities on the optical spectra is discussed, enlightening a behavior particular to Pr 3+ ion as compared to other rare earth ions.

Investigation of multiphonon assisted side band absorptions in rare-earth-doped halide glasses and crystals

Absorption outside the commonly considered electronic transition absorption regions in rare-earth-ion-doped ZBLAN fluoride glass have been investigated in detail and compared with those in halide crystals. Exponential decays with respect to energy have been found both in Stokes and anti-Stokes excitations, and the exponential parameters have been measured. By comparing with exponential parameters for multiphonon non-radiative decay, it is found that the phonons coupled to multiphonon side band absorption are generally smaller than the highest phonon cut off frequency which is known to be operative in non-radiative decay.

Effect of Yb3+‐Codoping on the Upconversion Emission Intensity in Er3+‐Doped ZBLAN Fluoride Glasses under 800‐nm Excitation

The effect of Yb3+‐codoping on the upconversion emission intensity in Er3+‐doped ZBLAN fluoride glasses is investigated. The codoping of Yb enhanced the emission intensity for the samples excited by an 800‐nm laser diode beam. The enhancement in a constant YbF3 content (2 mol%) increased with increasing ErF3 content was about 70% of the initial value at 550 nm for the glasses containing 8 mol% of ErF3. The emission intensity at 550 nm in a constant ErF3 content (5 mol%) increased remarkably with the addition of YbF3 and was maximized around 7 mol% of YbF3 content, giving an increased ratio of about 200% of the initial value. The reason for the enhancement is discussed and it is derived mainly from two‐step excitation of Er3+ assisted by Yb3+ excited through the energy transfer from Er3+.