ZBLAN Glass Research Articles

Theoretical evaluation on the possibility of laser cooling and simultaneous temperature sensing in Er3+ doped LiYF4 single crystal

In our previous work, a novel laser cooling method was developed using anti-Stokes fluorescence from thermal equilibrium levels of Er3+, with its efficacy proven in Er3+ doped ZBLAN glass. This study has extended the method to Er3+ doped LiYF4 single crystal, where anti-Stokes fluorescence from 2H11/2 is utilized by excitation at the 4S3/2 level of Er3+ for optical in situ temperature control. The non-radiative and radiative transition probabilities among 4f levels of Er3+ were assessed, and the populations of all levels relevant to laser cooling and temperature sensing were calculated. Results demonstrate that the Er3+ doped LiYF4 crystal achieves effective cooling within a specific temperature range, exhibiting high temperature sensitivity.

Influence of erbium doping on the femtosecond laser damage characteristics of fluorozirconate glasses

In this study, we systematically investigated femtosecond laser-induced damage characteristics of ZHBLAN (27ZrF4–25HfF4–10BaF2–5SrF2–5CaF2–4LaF3–14AlF3–10NaF), and the impact of Er3+ doping on the optical characteristics and damage characteristics of the matrix material. The glasses were subjected to a comparative analysis with respect to typical ZBLAN glasses. The sizes and morphology of damaged craters changed with the power of the 800 nm femtosecond laser. The samples were analyzed using digital and scanning electron microscopes, and their femtosecond laser-induced damage thresholds (LIDTs) were calculated by linear regression. The LIDTs decreased obviously from 612 mJ/cm2 to 532 mJ/cm2 after Er3+ was doped into the ZHBLAN glass. This is related to the absorption of Er3+ near the wavelength of the femtosecond laser and the change in the bandgap structure of the glass due to Er3+ doping. In addition, we have analyzed the electron convergence rate within the material during laser irradiation. The combination of physical models and simulation results reveals the association between the ionization rate of optical materials and the laser damage threshold.

Tailoring of the femtosecond-laser-induced damage properties and hydrolysis resistance of fluoroaluminate glass

In this study, we investigated and compared the hydrolysis resistance properties of three different types of fluoride glasses and their damage characteristics induced by an 800 nm fs (fs) laser. The results show that the hydrolysis resistance of the fluoroaluminate (AYF) glass is significantly higher than that of the fluorozirconate (ZBLAN) and the fluoroindate (IZBS) glass. After soaking in distilled water for 7 days, the average transmittance of the fluoroaluminate glass (AYF) remains around 80% in the range of 2–6 μm, while that of the other two glasses decrease to zero at the hydroxyl group absorption wavelength of ∼2.96 μm. After 24 h of immersion, the mass loss rate of AYF glass is less than one-eleventh of ZBLAN glass and one-eighth of IZBS glass, respectively. Under the irradiation of fs laser (800 nm, 91 fs, 1 kHz), the “1-on-1″ mode laser-induced damage threshold of the AYF glass is as high as 5164.9 mJ/cm2, which is 80.3% higher than that of the IZBS glass (2863.3 mJ/cm2) and 16.8% higher than that of the ZBLAN glass (4420.1 mJ/cm2). The higher laser damage threshold is attributed to the relative larger optical bandgap and higher Al–F energies of the AYF glass. Using this mechanism, we further tailored the fluoroaluminate glass's optical bandgap increased and the accumulation rate of electrons decreased by introducing up to 20 mol % TeO2 into the AYF glass, finally the fs laser-induced damage threshold of the corresponding sample with 20 mol % TeO2 increased by about 79.5% to the maximum 9272.2 mJ/cm2, compared with the TeO2-free AYF sample.

Energy conversion efficiency from a high-order soliton to fundamental solitons in the presence of Raman scattering

We formulate the energy conversion efficiency from a high-order soliton to fundamental solitons by including the influence of interpulse Raman scattering in the fission process. The proposed analytical formula agrees closely with numerical results of the generalized nonlinear Schrödinger equation as well as to experimental results, while the resulting formulation significantly alters the energy conversion efficiency predicted by the Raman-independent inverse scattering method. We also calculate the energy conversion efficiency in materials of different Raman gain profiles such as silica, ZBLAN, and chalcogenide glasses ( A s 2 S 3 and A s 2 S e 3 ). It is predicted that ZBLAN glass leads to the largest energy conversion efficiency of all four materials. Energy conversion efficiency is a notion of utmost practical interest for the design of wavelength converters and supercontinuum generation systems based on the dynamics of a soliton self-frequency shift.

The Experimental Investigation of Kinetics of Glass Transition of ZBLAN Glass by using Differential Scanning Calorimetry

A ZBLAN glass is a heavy metal fluoride (HMF) glass that possesses high thermal stability and excellent property as atransmitting material. The current study examines the thermal properties of ZBLAN glass utilizing Differential scanningcalorimetry (DSC) at various heating rates. The temperature of glass transition, Tg, is observed to vary with heating rate,indicating its kinetic nature. Through the use of Kissinger's and Augis- Bennett's methodologies and the heating ratedependency of Tg, the activation energy (E) has been determined. These methodologies have also been used to obtain thefragility index (m), which can be used to evaluate the glass forming ability (GFA) of the system. The fragility index found isgreater than 16, indicating that the ZBLAN glass is "fragile."

Ultrahigh-Q WGM microspheres from ZBLAN for the mid-IR band.

The advantages of high-quality-factor (high-Q) whispering gallery mode (WGM) microresonators can be applied to develop novel photonic devices for the mid-infrared (mid-IR) range. ZBLAN (glass based on heavy metal fluorides) is one of the most promising materials to be used for this purpose due to low optical losses in the mid-IR. We developed an original, to the best of our knowledge, fabrication method based on melting of commercially available ZBLAN-based optical fiber to produce high-Q ZBLAN microspheres with the diameters of 250 to 350 μm. We effectively excited whispering gallery modes in these microspheres and demonstrated high quality factor both at 1.55 μm and 2.64 μm. Intrinsic quality factor at telecom wavelength was shown to be (5.4 ± 0.4) × 108 which is defined by the material losses in ZBLAN. In the mid-IR at 2.64 μm we demonstrated record quality factor in ZBLAN exceeding 108 which is comparable to the highest values of the Q-factor among all materials in the mid-IR.

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.

Excited-state absorption in thulium-doped materials in the near-infrared.

Excited-state absorption (ESA) is a key process for upconversion pumping schemes of thulium (Tm3+) doped laser materials. We have systematically studied two ESA transitions in the near-infrared spectral range, namely 3F4 → 3F2,3 (at ∼1 µm) and 3F4 → 3H4 (at ∼1.5 µm), in various Tm3+-doped fluoride (ZBLAN glass, cubic KY3F10 and CaF2, tetragonal LiYF4 and LiLuF4, monoclinic BaY2F8 crystals) and oxide (cubic Y3Al5O12, orthorhombic YAlO3 crystals) laser materials, using a pump-probe method with a polarized light. An approach to calculate the constants of energy-transfer upconversion (ETU) is also presented.

Effect of Ga2O3-doping on Properties and Structure of ZBLAN Glass

Effect of Ga2O3-doping on Properties and Structure of ZBLAN Glass

Femtosecond laser–induced damage characteristics of the novel fluorozirconate glasses

In this study, we systematically investigated the femtosecond laser–induced damage and the physical characteristics of a series of multicomponent fluorozirconate (MFZ) glasses: xZrF4–(52–x) HfF4–10BaF2–5SrF2–5CaF2–4LaF3–14AlF3–10NaF (x = 27, 29, 31, 33 mol%, named MFZ27, MFZ29, MFZ31, and MFZ33), and these MFZ glasses were compared with typical ZBLAN glasses. The sizes of damaged craters and the morphology changed under different powers of 800 nm fs laser. They were measured and analyzed with a digital microscope and scanning electron microscopes. The femtosecond laser-induced damage thresholds (LIDTs) of all the samples were calculated using the linear regression method. The highest LIDT of 616.9 mJ/cm2 was obtained in MFZ27. We compared the hydrolytic resistance of ZBLAN glass with that of MFZ27 glass. The laser-induced damage characteristics and the LIDT of the samples after hydrolysis were also studied. To the best of our knowledge, this study is the first to investigate in detail the femtosecond laser–induced damage characteristics using the fluorozirconate glass.

Efficient coupling between single mode fibers and glass chip waveguides via graded refractive index fiber tips.

Coupling characteristics between a single mode fiber (SMF) and a waveguide embedded in a glass chip via a graded index fiber (GIF) tip are investigated at a wavelength of 976 nm. The GIF tips comprise a coreless fiber section and a GIF section. A depressed cladding waveguide in a ZBLAN glass chip with a core diameter of 35 μm is coupled with GIF tips that have a range of coreless fiber and GIF lengths. An experimental coupling efficiency as high as 88% is obtained while a numerical simulation predicts 92.9% for the same GIF tip configuration. Since it is measured in the presence of Fresnel reflection, it can be further improved by anti-reflection coating. Additionally, it is demonstrated that a gap can be introduced between the chip waveguide and the GIF tip while maintaining the high coupling efficiency, thus allowing a thin planar optical component to be inserted. The results presented here will enable miniaturization and simplification of photonic chips with integrated waveguides by replacing bulk coupling lenses with integrated optical fibers.

Recent advances in luminescence and lasing research in ZBYA glass

In the last few decades, fluoride glasses have attracted a growing interest due to their unique advantages compared to multi-component oxide glasses. Among them, the most studied and widely used were fluorozirconate glasses, represented by ZrF4–BaF2–LaF3–AlF3–NaF (ZBLAN) glasses. However, compared with ZBLAN glasses, a kind of fluorozirconate glass with the components ZrF4–BaF2–YF3–AlF3 (ZBYA) has higher thermal and chemical stability. In this paper, we first introduce the advantages of ZBYA glasses compared to ZBLAN glasses. Then we review and discuss recent advances in research on luminescence and lasing in ZBYA glass and fiber. These studies suggest that ZBYA glass has strong potential for use as a gain medium material in high power mid-infrared fiber lasers.

Low thermal expansion ZBLAN‐based glass ceramics containing CaZrF6 crystals

AbstractFluoride glass is considered as an excellent optical material owing to its ultralow phonon energy (578 cm−1). However, its high thermal expansion coefficient (15.87 × 10−6/K) and deformability severely limit applications under service environments with high temperature, high humidity, and high‐power irradiation. To overcome these limitations, we developed a ZBLAN‐based fluoride glass ceramics (CZBLAN GCs) contained the negative thermal expansion material‐CaZrF6 crystals by phase‐separation engineering. The ability to control the precipitation of the desired crystal phase was achieved by adequate compositional design for phase separation, yielding improved or new properties in the development of fluoride GCs. With the successful precipitation of very uniformly dispersed single CaZrF6 crystals in the glass phase (up to ∼40% crystallinity), a significantly lower thermal expansion coefficient (3.66 × 10−6/K) in the fluoride system was achieved. Moreover, enhanced fluorescence properties of Eu‐doped CZBLAN GCs were observed compared with those of Eu‐doped ZBLAN glass owing to the lower phonon energy in GCs.

A Study on Material Dispersion around Zero Material Dispersion Wavelength of Different Material Composition based Optical Fiber

The Optical Fiber-based communication system has established its proficiency and inevitability towards regular progress and advancement worldwide. The most attractive wavelength for optical fiber communication is 1.55 μm, as it represents the lowest loss. The other challenging parameter ‘Material Dispersion’ gets reduced to ‘Zero’ at 1.27 μm wavelengths for conventional pure silica-based Optical Fiber. To improve the system towards a better unification between the loss and dispersion, the Dispersion Shifted Fiber (DSF) has been introduced. The Dispersion Flattened Fiber has introduced the concept of flat dispersion over a wide range of wavelengths. But the effective combination of the mechanisms to compensate for all the challenges is yet to be established properly. The said mechanisms are complex to design and implement. So, there is an immense scope to search for an alternative to get control over the loss and dispersion. At present, a fair number of material compositions of optical fiber are reported with different specifications. Our study on some of these fiber compositions has produced some interesting data towards the broader flatness and the minimum dispersion effect over a considerable range of wavelengths around the Zero Material Dispersion Wavelength (ZMDW). It helps to have more effective wavelength division Multiplexing (WDM). In this paper, we have studied different prospective options of optical fiber doping profiles to explore and propose an effective and optimized alternative among the available fiber profiles. We have studied the samples of pure SiO2 fibers along with B2O3 and GeO2 doped fibers and samples of Fluoride-based ABCY and ZBLAN glass Fibers to propose an effective combination of materials among the available options to get the optimized conjugation of loss and dispersion. Our report on the comparative study of different fiber materials has produced some effective results to have minimum material dispersion at the lowest loss wavelength to invite worldwide attention from system designers.

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.

Spectroscopic properties of Er3+-doped fluoroindate glasses

The optical and thermal properties of a new class of fluoroindate glass with different erbium contents were investigated via Raman, transmission, and fluorescence spectroscopies, fluorescence decay curve analysis, and differential scanning calorimetry. The strength parameters of the samples were calculated using the Judd–Ofelt theory. The mid-infrared luminescence properties of erbium-doped fluoroindate glasses were studied, and a strong emission at 2.7 μm was obtained. Compared with the traditional ZBLAN glass, this glass has excellent emission properties, especially a longer fluorescence lifetime (7.09 ms) and larger emission cross-section (6.95 × 10−21 cm2) at 2.7 μm. The results indicate that fluoroindate glass is an attractive host for mid-infrared lasers and as a gain medium for optical amplifier applications.

Experimental and theoretical analysis of Dy3+-doped fiber lasers for efficient yellow emission.

We report a detailed experimental and theoretical analysis of the $^4{{\rm F}_{9/2}}$ to $^6{{\rm H}_{13/2}}$ lasing transition of a dysprosium (${{\rm Dy}^{3 +}}$)-doped ZBLAN fiber, a strong candidate for future compact and highly efficient yellow laser emission. Experimentally, we used a gallium nitride laser diode emitting at 447 nm as a pump source and measured yellow laser output generated with a maximum slope efficiency of 33%, which is less than half of the Stokes limit (of ${\sim}78\%$). This result is commensurate with two other reports of yellow emission from ${{\rm Dy}^{3 +}}$. As a result, we developed a numerical model to understand and analyze the improvement potential of this fiber laser system. For reliable spectroscopic data input to the numerical model, we measured the absorption and emission cross sections from ${{\rm Dy}^{3 +}}$-doped ZBLAN glass. We investigated the potential causes of the low experimental slope efficiency and found contributions from the background loss of the fiber and excited-state absorption (ESA) of the intracavity yellow light. We estimated the signal re-absorption cross section using the emission cross section and the McCumber relation, which was subsequently used in our numerical model to compare successfully with our experimental results. We show that the ESA can be reduced for future ${{\rm Dy}^{3 +}}$-doped yellow laser systems by cascade lasing or co-doping with a suitable rare earth ion desensitizer.

High content Er3+ doped ZBLAN glass: The spectral characteristics and high slope efficiency MIR laser investigation

The ZBLAN glass with high content of Er3+ was prepared and studied. The glass has a wide infrared transmittance range of 2.5–8.0 µm, which means a lower maximum phonon energy. By testing and analyzing the fluorescence spectrum and lifetime curves under different penetration depths, the intrinsic emission spectrum and lifetime of the sample are obtained without the influence of sub-absorption. Under 980 nm excitation, the maximum emission cross section and the lifetime of 2.7 µm are 6.10 × 10−21 cm2 and 6.49 ms, indicating that high-concentration doping has a larger laser quality factor. According to the rate equation and transmission equation, cascaded and non-cascaded fiber laser models are established to conduct research on 2.7 µm fiber lasers. The slope efficiency can reach 40.38% at a pump wavelength of 980 nm and a fiber background loss of 0.1 dB/m. The high emission cross section, long fluorescence lifetime and high slope efficiency output make ZBLAN glass heavily doped with Er3+ an ideal host material for mid-infrared lasers.

Experimental measurements of the spectral absorption coefficient of infrared optical fibers

Infrared optical fibers are used in numerous applications in various industries. Knowledge of the radiative properties of optical fiber materials is important for the design and analysis of the processes in which the fibers are used. An experimental method for measuring the spectral absorption coefficient of infrared optical fibers using FTIR spectroscopy is presented. Blackbody radiation from a calibration source at different temperatures is transmitted through an optical fiber into an FTIR spectrometer. A mathematical model of the radiative heat transfer in the fiber is used to develop a linear spectral instrument response function relating the radiative energy from the calibration source to the output signal of the detection system. The spectral absorption coefficient of an infrared optical fiber is estimated from the ratio of the slopes of the instrument response functions for fibers of differing length. The method is used to estimate the room-temperature spectral absorption coefficient of infrared optical fibers made of arsenic trisulfide chalcogenide glass, ZBLAN glass, and indium fluoride glass.

Energy transfer process of Nd3+/Ho3+ co-doped fluoride halide glasses with anion substituted multi-wavelength tunable mid-infrared luminescence

Ho3+ doped ZBLAN glass with 2.0 and 2.9 μm emission was prepared. In order to further improve the luminescence of Ho3+, halogen ions (Cl, Br, I) were introduced to reduce the maximum phonon energy and phonon state density of the sample. At the same time, Nd3+ was introduced to transfer the energy to Ho3+ pumped with a 793 nm laser (Nd3+:4F5/2,4F3/2→Ho3+:5I6). The effect of different halogen ion on the luminescent properties of the fluoride halide glass was compared. The results show that the luminescent intensity of infrared increases with the introduction of different halogen ions. By comparison, it is found that the sample with I– has the strongest luminescence of 1064 nm, 2.0 μm and 2.9 μm. This is consistent with the calculated J-O intensity parameters. In addition, the 2.0 and 2.9 μm emission of Ho3+ pumped with a 450 nm laser will not disappear. A mid-infrared sample with multi-wavelength excitation and multi-wavelength emission can be obtained. Nd3+/Ho3+ co-doped fluoride halide glasses with 1064 nm, 2.0 μm and 2.9 μm luminescence were prepared by melt quenching method. The luminescent mechanism and the energy transfer process between the two ions of Nd3+/Ho3+ co-doped fluoride halide glass were studied. The J-O parameters, luminescence lifetime and absorption emission cross-sectional area of Ho3+ and Nd3+ were calculated, respectively. It is found that the value of Ω2 in the glass matrix increases with the introduction of different halogen ions, while Ω4 and Ω6 do not change obviously in different glass compositions. This is because the environment of the crystal field around the rare earth ions changes. The crystal phase and phonon energy of the sample were analyzed by X-ray diffraction pattern and a Fourier transform infrared spectrometer, respectively. Based on the above spectra and data (phonon energy is 634.71 cm−1), it can be predicted that Nd3+/Ho3+ co-doped fluoride halide glass is a potential mid-infrared luminescent material.