Nd-doped Glass Research Articles

A Nd-doped silica glass with high doping concentration, low hydroxyl content, and 900 nm fluorescence emission fabricated by laser additive manufacturing

The 900 nm wavelength laser is effective for atmospheric detection and various other applications.The frequency-doubled 450 nm deep blue laser can be used in maritime military, quantum optics, biomedicine, laser storage, laser display, and deep ultraviolet laser fields, among others. Although Nd3+ is considered the optimal medium for generating 900 nm lasers, competition with the 1060 nm emission wavelength must be addressed. In Nd-doped silica glass, without the introduction of aluminum, the emission intensity of the three-level transition is higher than that of the four-level transition. However, it can cause a concentration quenching between Nd3+, but co-doping with Al can effectively suppress it. As the Al/Nd ratio increases, the emission intensity at 1060 nm increases relative to that at 900 nm. By precisely adjusting the Al/Nd ratio, it is possible to suppress the 1060 nm emission while also inhibiting concentration quenching caused by Nd3+.

Gd2O3-modulated borate glass for the enhancement of near-infrared emission via energy transfer from Gd3+ to Nd3.

(Li2O)0.20(SrO)0.30(Nd2O3)0.01(B2O3)0.49-x(Gd2O3)x, where x = 0, 3, 5, 7, and 10 mol%, glass was melt-quenched to test it as a laser source in the near-infrared (NIR) region. The structural modification, absorption spectra, Judd-Ofelt (J-O) parameters, luminescence spectra, radiative laser parameters, lifetimes, XRD, and FTIR spectra were studied. Luminescence spectra excited at λexc = 584 nm revealed the highest intensity peak at 1073 nm due to the transition of 4F3/2 → 4I11/2. An important phenomenon of concentration quenching was observed and optimized luminescence was achieved with the sample having the concentration x = 07 mol%. The lifetimes of the donor and acceptor and energy transfer from gadolinium to neodymium were obtained from the luminescence decay kinetics. The findings show that Nd-doped Gd2O3-modified glass materials have potential as NIR laser sources.

Effect of mixed alkali ions on the structural and spectroscopic properties of Nd3+ doped silicate glasses

In the present work the effect of alkali ions (Li, Na, K) and the combination of them on structural and spectroscopic properties of Nd3+ doped silicate glasses were systematically investigated. Results from infrared and Raman spectroscopy, as well as density and refractive index, were used to investigate the effect on the structural properties of the silicate glasses. Absorption and emission spectra of the glass samples were measured in the UV-VIS and NIR ranges. Relatively large, stimulated emission cross-section at 1.06 μm was obtained for samples containing a combination of alkali ions, especially with potassium. Moreover, the splitting induced by the Stark effect on the hypersensitive transition of Nd3+,4I9/2 → 4G5/2, 2G7/2 was larger for the samples containing potassium, probably due to its larger ionic size. Judd-Ofelt theory was applied to evaluate the phenomenological intensity parameters Ω2, Ω4, Ω6, transition probabilities, radiative lifetimes and branching ratios related to Nd3+ ions, calculated from optical absorption and luminescence spectra and the results were compared to the values obtained for different Nd-doped glasses reported in the literature.

Nd-doped CsPbBr3 borosilicate glass ceramics: Crystallization behavior and photoluminescence kinetics

Rare-earth (RE) doping is one of the valid approaches to optimize the optical performance of the CsPbBr3 perovskite quantum dot glass. Thus, the research on the crystallization behavior of RE ions doped CsPbBr3 borosilicate glass and the energy transformation mechanism between the RE ions and CsPbBr3 is significant for the development of advanced Ln-doped perovskite glass materials. In this work, CsPbBr3 borosilicate glass ceramics doped with different concentrations of Nd2O3 were successfully synthesized. It was found that Nd2O3 makes the glass network structure more compact and then inhibits the precipitation of CsPbBr3 nanocrystals. Additionally, there is energy transfer between Nd3+ and CsPbBr3, which quenches the photoluminescence of CsPbBr3 borosilicate glass. This work deepens the understanding of the structural and photophysical properties of Ln-doped CsPbBr3 borosilicate glass ceramics and provides a reference value for the related work of RE ions doped perovskite borosilicate glass.

Optical and photophysical portrayal of Sm3+ complexes possessing two band gaps for relevance in solar cells and photovoltaic devices

Octa-coordinated samarium (III) complexes were synthesised using a fluorinated β-keto carboxylic acid (L) as prime ligand and N-donor systems as auxillary ligands, by ecologically desirable grinding method. The photoluminescent properties were investigated in powder and solution form. The characteristic emission at ∼605 nm (solid state) and ∼599 (solution phase) relative to 4G5/2 → 6H7/2 transition is accountable for the bright vermillion color of complexes. Quantum yield and colorimetric parameters were obtained for solid and solution state. CCT and color purity value characterise these complexes as warm orange light source. Reflectance spectra of solid complexes were fitted nonlinearly to procure optical band gap and Urbach band tail width. Two band gaps were reported in each complex, hence can have materiality in solar cell and photovoltaic devices. The FWHM obtained for most emissive transition (4G5/2 → 6H7/2) is found to be comparable with Nd-doped fluorophosphates glass. Energy transfer pathway studied for all the synthesised complexes, affirmed the effective energy transfer from ligands to Sm3+ ion. Investigation of antimicrobial behaviour of complexes revealed either higher or similar activity with respect to the ligand.

Monolithic edge-cladding process for the elliptical disk of N31-type Nd-doped high-power laser glass

Abstract This paper investigates the monolithic edge-cladding process for the elliptical disk of N31-type Nd-doped phosphate laser glass, which will be utilized under liquid cooling conditions for high-power laser systems. The thermal stress, interface bubbles and residual reflectivity, which are due to high-temperature casting and bonding during the monolithic edge-cladding process, are simulated and determined. The applied mould is optimized to a rectangular cavity mould, and the casting temperature is optimized to 1000°C. The resulting lower bubble density makes the mean residual reflectivity as low as 6.75 × 10−5, which is enough to suppress the amplified spontaneous emission generated in the Nd-glass disk, and the resulting maximum optical retardation is converged to 10.2–13.3 nm/cm, which is a favourable base for fine annealing to achieve the stress specification of less than or equal to 5 nm/cm. After fine annealing at the optimized 520°C, the maximum optical retardation is as low as 4.8 nm/cm, and the minimum transmitted wavefront peak-to-valley value is 0.222 wavelength (632.8 nm). An N31 elliptical disk with the size of 194 mm × 102 mm × 40 mm can be successfully cladded by the optimized monolithic edge-cladding process, whose edge-cladded disk with the size of 200 mm × 108 mm × 40 mm can achieve laser gain one-third higher than that of an N21-type disk of the same size.

High pressure effect in the near-infrared emission of Nd3+-doped alkali silicate glasses

ABSTRACT The effect of high pressure (7.7 GPa) densification on the absorption and near-infrared emission of Nd-doped lithium, sodium and potassium disilicate glasses was investigated. Judd-Ofelt parameters Ωλ (λ = 2, 4 and 6) were calculated from the absorption spectra, before and after densification of glasses, indicating that the irreversible structural changes induced by pressure increased the symmetry of the Nd-O bonding. Density and refractive index of the glasses also increased, probably related to the close packing of SiO4 tetrahedra during densification. The magnitude of the splitting due to the Stark effect was larger for potassium silicate, before and after densification. The radiative transition probabilities of the hypersensitive transition for sodium and potassium silicate increased after densification while the radiative lifetime decreased. For lithium silicate, the opposite behavior was observed. The experimental results corroborate the influence of alkali ion and densification on the luminescence properties of Nd-doped alkali silicate glasses.

Influence of Nd3+ modifying on 80TeO2–xZnO–(20−x)Na2O ternary glass system

In this study, the ternary system of TeO2–ZnO–Na2O (TZN) with a fixed TeO2 content of 80 mol. % and with a varied ZnO and Na2O content of totally 20 mol. % was examined for thermal/mechanical properties, Raman and x-ray absorption fine structure (XAFS) spectra, and the evolution of medium distance (correlation length) of order, called blob size here, given from low-frequency Raman spectra and longitudinal/transverse sound velocities as a function of ZnO concentration. The TZN glasses were doped with Nd2O3, and the effects of Nd doping on the above-mentioned properties were reported. High-temperature in situ x-ray diffraction experiments were also conducted to know possible oxygen coordination numbers of these main-constructive cations from crystalline phases precipitated at elevated temperatures. According to the information, the evolution of blob size of Nd-doped and non-doped TZN glasses was attempted to be predicted with a term of theoretical volume of their molar unit constructed with cation–oxygen polyhedra of TeO3, TeO4, ZnO4, ZnO5, NaO4, and NaO5. A transition region due to the structural change owing to the coordination numbers of Te–O and Zn–O was elucidated concerning density, molar volume, and Poisson ratio. XAFS spectroscopy revealed that the ZnO component had different polyhedra of ZnO4 and ZnO5, whose ratio was dependent not only on ZnO concentration but also on whether Nd3+ ions were doped or not. Based on the information taken from a variety of observations, our preliminary analysis suggested that the different mechanical properties between the doped and non-doped glasses were explained by five-coordinated zinc in the glasses. Possible molecular models shall be given for lower and higher ZnO concentrations in TZN glasses.

Synthesis and Properties of Nd-Doped Chlorofluorosilicate Lead Glasses

Synthesis and Properties of Nd-Doped Chlorofluorosilicate Lead Glasses

Sensitivity enhancement in photothermal interferometry by balanced detection of the complex response to moving excitation.

The sensitivity of photothermal detection relies on both the magnitude of the response of a sample to excitation and the way the response is sensed. We propose a highly sensitive photothermal interferometry by addressing the above two issues. One is the use of moving excitation to enable a different manner in sample heating and cooling, which results in a strong thermoelastic response of the sample. The other is the use of a balanced Mach-Zehnder interferometer with a defocused probe beam to sense the complex response induced by the phase delays taking place at the sample surface and in the surrounding air. The method was verified experimentally with a Nd-doped glass to have 68-fold sensitivity enhancement over the classical photothermal common-path interferometry.

Optimized monolithic edge-cladding glass for N31-type Nd-doped high power laser glass

In this paper, six edge-cladding glasses are prepared and analyzed, which are designed to clad the elliptical disk of N31-type Nd-doped phosphate laser glass by monolithic edge-cladding technique. The transition temperatures, soften temperatures, thermal expansion coefficients, high temperature viscosities and refractive indices of the prepared edge-cladding glasses are determined, which must be consistent with these parameters of N31 glass as possible. The residual stresses and residual reflectivities are determined for the cladded N31 elliptical disks and slab samples, which are the most important parameters for the monolithic edge-cladding technique and must be as low as possible to meet the index requirements for high power laser applications. The interface bubbles, edge-cladding interface and the controllability of divalent Cu2+ ions are also discussed. By the optimized edge-cladding glass, it is verified that the elliptical disk of N31-type Nd-doped phosphate laser glass can be successfully cladded by the optimized monolithic edge-cladding glass, which can be utilized securely in a strong liquid cooling to pursue a better high-power laser performance with a higher laser shot rate.

Investigation on Residual Stress in Monolithic Edge-Cladding of Elliptical Nd-Doped Phosphate Laser Glass for High-Peak Power Solid-State Laser

Investigation on Residual Stress in Monolithic Edge-Cladding of Elliptical Nd-Doped Phosphate Laser Glass for High-Peak Power Solid-State Laser

Phosphor in glass using β-SiAlON:Eu2+, CaAlSiN3:Eu2+ and Nd-doped silicate glass for enhanced color gamut of white LED

A phosphor-in-glass (PiG) was fabricated to realize a robust white light emitting diode (wLED) with wide color gamut. β-SiAlON:Eu2+ and CaAlSiN3:Eu2+ were employed for the green and red phosphors, respectively. Nd2O3 doped silicate glass was used to reduce the emission bandwidths of the phosphors, utilizing the hypersensitive transition of Nd3+: 4I9/2 → 4G5/2, 2G7/2. The content of green and red phosphors was varied to produce a white emission. The emission spectra, color coordinates and color gamuts of the wLEDs with the PiGs were examined by varying phosphors and Nd2O3 content. A wLED with 5 mol% Nd2O3 doped glass had an enhanced color gamut up to 88%. The thermal stability of the PiGs was also monitored to demonstrate its practical feasibility as a white light source in display applications.

Thermal behaviour and photoluminescence properties of Er- and Nd-doped yttrium aluminate glasses

Yttrium aluminate glasses (76.8 mol% of Al2O3, 23.2 mol% of Y2O3) doped with Er3+ and Nd3+ ions at different concentration levels (0.25 mol%, 0.5 mol% and 0.75 mol% Er2O3/Nd2O3) were prepared by flame synthesis in the form of glass microspheres. The prepared samples were XRD amorphous, without presence of any crystalline phases in measured patterns. The two exothermic effects (~ 940, ~ 1010 °C), which can be assigned to the two steps of YAG crystallization, were observed in the DSC records of all prepared samples. The high temperature XRD measurements showed YAG (900–1200 °C) and α-Al2O3 (1300–1450 °C) phase crystallization. The emission spectra were measured in the VIS and NIR regions for Er-doped samples and in the NIR region for Nd-doped samples. All measured emission spectra contain of characteristic bands due to the typical 4f–4f transitions within the Er3+ and Nd3+ ions. Comparison of the measured intensities of Er-doped samples made it evident that the highest intensities were obtained for the 0.5 mol% Er2O3-doped sample (in both the NIR and VIS spectral regions). The maximum intensity for Nd-doped samples was found when the sample was doped with 0.75 mol% of Nd2O3. The slowly increasing of emission intensities in samples after 20 min annealing at 1000 °C and Stark splitting of emission bands in samples after 40 and 60 min annealing at 1000 °C and after 20, 40 and 60 min annealing at 1500 °C was observed.

阴离子改性抛光剂对磷酸盐激光钕玻璃抛光的影响

阴离子改性抛光剂对磷酸盐激光钕玻璃抛光的影响

Chemical and structural heterogeneities in Nd-doped oxynitride phosphate laser glasses

The application of oxynitride glasses in optics has been limited due the issues inherent in their preparation that result in bubbles, metallic inclusions or opacity. Although the synthesis of oxynitride phosphates is easier than in silicates, due to their lower melt viscosity, the remaining water in the form of OH causes, for instance, the neodymium luminescence to be negatively affected. We report on the preparation of oxynitride Nd phosphate glasses that are submitted first to a dehydroxylation, so that their structure and properties can be studied as a function of the nitrogen content taking a completely homogeneous OH-free glass as the starting point of each synthesis. Raman and Brillouin Spectroscopy confirmed the segregation in oxide and N-enriched regions, and NMR of the glasses has been used to calculate the O/P ratio from the distribution of P(O,N)4 groups. The difference between this and the experimental one obtained from the elemental analyses confirms the segregation in oxide and oxynitride regions that is produced during the ammonolysis of the phosphate glass. The oxynitride glass network could thus be considered a non-homogeneous mixture of the oxide and the nitrided phases that are segregated due to the non-randomness of the nitridation reaction.

(INVITED) Impurities in large scale produced Nd-doped phosphate laser glasses. I. Cu ions

Impurity ions such as transition metals and rare earth metals in Nd-doped phosphate laser glasses will degrade Nd-laser performance, among which Cu is the most harmful. Divalent Cu2+ not only results in an optical loss at Nd-laser wavelength, but also reduces the energy storage for laser amplification. A large-scale production of Nd-doped phosphate laser glasses is required to meet quality demand and to realize economy of scale. To balance between the controlled impurity level in the glasses and the cost of raw materials for thousands of slabs of meter-scale Nd-doped phosphate laser glasses, it is important to determine an upper limit for Nd-laser degradation due to divalent Cu2+ ions. The absorption edge of Cu singly-doped phosphate glass prepared in an oxidizing atmosphere shows the evidence of monovalent Cu+. X-ray photoelectron spectroscopy is utilized to further verify the existence of monovalent Cu+ ions in Cu, Nd codoped phosphate glass. The results show that both Cu+ and Cu2+ ions most probably coexist in Nd-doped phosphate laser glasses produced in the oxidizing atmosphere to eliminate Pt inclusions in the glasses. Accordingly, this paper discusses the extinction coefficient and the fluorescence quench factor caused by divalent Cu2+ ions, as well as their influence.

Optical, spectroscopic properties and Judd–Ofelt analysis of Nd3+-doped photo-thermo-refractive glass

A comparative study of spectral-luminescent and Judd–Ofelt analysis of photo-thermo-refractive (PTR) glasses doped with a variable content of neodymium (0.5–2.11 mol%) has been carried out for the first time. The change of Judd-Ofelt parameters (Ω2, Ω4, Ω6), radiation lifetime, experimental lifetime, branching ratio and emission cross sections were demonstrated as a function of Nd2O3 concentration and compared to the equivalent parameters in other works. It was found that the 4F3/2 → 4I11/2 transition is enhanced in Nd-doped PTR glass. The quantum efficiency of 0.5 mol% Nd-PTR for the same transition is 90.3% and the induced emission cross section is 1.743 × 10−20 cm2. The saturation intensity for 4F3/2 → 4I11/2 laser transition in the same sample is 20.62 kW/cm2, it is lower than that in some commercially produced glasses of same Nd3+-concentration. Laser action of a 0.5 mol% Nd-PTR was demonstrated, it was found that the round-trip loss of this gain medium is 0.34%, this value is quite low, and it is comparable to that in some commercially fabricated Nd-YAG crystals.

(INVITED) Impurities in large scale produced Nd-doped phosphate laser glasses. II. Pt ion and Pt inclusion

Platinum is a special kind of impurity in Nd-doped phosphate laser glasses. Firstly, its presence in the glass depends on the production processes, rather than the purity of the raw materials used. Secondly, there coexist Pt ion and Pt inclusion in the glass, which one is the oxidized and the other is the reduced. The detection for these two kinds of Pt impurities in the large-scale produced Nd-doped phosphate laser glasses can reflect the control level and stability of the processes. To determine more accurately the content of Pt ion in the glass, a hemi-cyanine dye, instead of SnCl2 previously used, is utilized to color Pt ion solution by dissolving the glass. On the basis of such a new hemi-cyanine spectrophotometric analysis, the factor of proportionality between Pt ion content and its absorption coefficient at 400 nm is determined and discussed. To avoid the interference from other cations in the multi-cation solution by dissolving the glass, when doing ICP-MS analysis for Pt, a magnetic poly-ionic liquid is synthesized successfully by bonding an ionic liquid to nano-Fe3O4 particles covered by C. Such a new magnetic poly-ionic liquid can adsorb Pt ions with a better selection. The element distribution of Pt, O and P for differently sized Pt inclusions in the glass is analyzed by EPMA.

Athermal behavior of a phosphate glass matrix at low temperatures investigated by interferometry

The thermal expansion (α) and the thermo-optic (dn/dT) coefficients of a phosphate glass dubbed as PANK were simultaneously measured using a single arm double interferometer from 100 to 400 K of the temperature range. An athermal behavior of the optical path difference in a two-beam interferometer was found around 200 K. This result is in agreement with a similar observation carried out applying the Thermal Lens spectrometry (TLS) of Nd-doped PANK glass at ∼180 K. The main difference between these temperature values is ascribed to the sample surface curvature induced by the laser beam in thermal lens measurements. The athermal behavior shows that this glass has the potential for laser applications as an ion host at low temperature, and small changes in the glass composition should be explored to bring this property to room temperature.