High Branching Ratio Research Articles

Energy growth in VLVL→ VLVL, VLVLh scattering to probe Higgs cubic and HEFT interactions

We compute the energy scales of perturbative unitarity violation in VLVL → VLVLh processes and compare them to VLVL → hhh process, where VL refers to a longitudinal mode of Z or W boson, and h the Higgs boson. Using these energy scales, we determine which process is more sensitive to potential modifications in the Higgs sector at high-energy colliders. Within the Higgs Effective Field Theory (HEFT), we consider the Higgs cubic coupling and other interactions with and without derivatives. Any HEFT interactions predict the perturbative unitarity violation at a finite scale, and in a generic case, the minimalistic process is 2 → 3 scattering. Our analysis reveals that the energy scales for unitarity violation in VLVL → VLVLh and VLVL → hhh processes are similar across all scenarios considered. If the backgrounds are similar, VLVLh final states are more feasible because VLVLh has higher branching ratios in cleaner decay modes than hhh. We also investigate HEFT derivative interactions derived from various UV models. In these cases, both VLVL → VLVL and VLVL → hh processes exhibit unitarity violating behavior. We demonstrate that the energy scales for unitarity violation in VLVL final states are comparable to or even lower than those in the hh final state.

Probing the effect of Y3+/Gd3+ on the optical properties of Gd2-xYxTiO5:Eu3+: Insight into local site-luminescence correlation

Phosphor converted light emitting diodes (pcLEDs) are considered as the most efficient materials to resolve the issue of energy scarcity. In this regard, the design of an efficient red phosphor could be a game changer due to the lack of the same in the current existing phosphor library. Here in this work, we have investigated high color purity, moderate photoluminescence quantum yield (PLQY) and long excited state lifetime red emitting Gd2-xYxTiO5:1.0 %Eu3+ phosphor with varying Y3+/Gd3+ ratio. It was found that higher Y3+ containingGd0.5Y1.50TiO5:1% Eu3+ emerged victorious in terms of luminescence intensity, asymmetry ratio and PLQY ∼ 10 %. Higher PLQY of this particular composition has been attributed to lowest non-radiative channels in them. The same has been further supported by PALS as it suggested lowest defect density in Gd0.5Y1.50TiO5:1% Eu3+ as most of the vacancies have moved out of the lattice to the surface and is responsible for improved optical properties as defect triggered non-radiative pathways reduced significantly. The O2–→ Eu3+ charge transfer energy on the other hand eases in higher gadolinium counterparts owing to more structural distortion of distorted pentagonal bipyramid (DPB) and distorted hexagonal bipyramid (DHB) in them. Based on the number of Stark components of 5D0→7F0 there are two types of Eu3+ with distinct chemical environments. It was inferred that longer lived trivalent europium ions are the one located at a less distorted DPB whereas short lived Eu3+is ascribed to the one occupying a highly distorted DHB. The trend in Judd-Ofelt parameter Ω4 < Ω2 revealed that Eu3+ ions are localized in high asymmetric locations in all the samples under the doping level used in this work. The high branching ratio of 5D0→7F2 transitions for all the samples reflected in very high color purity of more than 99 %. These results suggest that Eu3+doped A2TiO5 luminescent crystals with moderate PLQY, high red color purity and long excited state lifetime could serve as efficient red phosphor and with further improvement can be potential candidate for various applications.

A Hawkes process analysis of high-frequency price endogeneity and market efficiency

ABSTRACT We use the Hawkes process to model the high-frequency price process of 108 stocks in the Chinese stock market, in order to understand the endogeneity of price changes and the mechanism of information processing. Using a piece-wise constant exogenous intensity, we employ non-parametric estimation, residual analysis, and Bayesian Information Criterion (BIC) to determine that a power-law kernel is the most appropriate for our data. We propose the internal branching ratio to represent endogeneity within a finite interval. The branching ratio tends to be higher after the market opens and before the market closes, with a mean value of around 0.81, suggesting significant endogeneity in price changes. In addition, we explore the relationship between branching ratios and stock characteristics using panel regression. Higher branching ratios are associated with lower levels of price efficiency at high, but not low, frequencies. Finally, the branching ratio increases over time without significant impact from COVID-19.

Synthesis and optical behavior of neodymium ion doped borophosphate glass for laser applications

Nd3+ ion doped lithium aluminum gadolinium borophosphate glasses were synthesized by melt quenching technique. The hypersensitive transitions were identified in the absorption spectra for ultraviolet (UV), visible (Vis) and near infrared (NIR) region, which the highest intensity is recorded at the transitions 4I9/2→4D5/2, 4I9/2→4G5/2 and 4I9/2→4F5/2 with wavelengths of 352, 582 and 804 nm, respectively. The spectroscopic properties of emission spectra in Nd3+ doped present glasses were investigated under 808 nm laser excitation and shows the strongest intensity at 1063 nm, which corresponding the transition 4F3/2→4I11/2. Furthermore, JO parameters (Ω2, Ω4 and Ω6) are produced, which are then utilized to examine the radiative characteristics of Nd3+ doped glasses for example radiative transition probability (AR), radiative lifetimes (τrad), branching ratios (β), gain bandwidth (Δλeff×σe), optical gain (σe×τrad) and emission cross-section (σe). The results demonstrated that the LBPNd0.5 glass might be used in laser applications around 1.058 µm region, which represent highest stimulated emission cross-section (53.49 ×10–21 cm2), higher branching ratio (>0.5), highest quantum efficiency (84.58%), lower non-radiative decay rates (720 s−1) compared with other glasses.

Study on Sm3+ ion concentration in physical, structural and optical properties of magnesium-sodium fluoroborate glasses for reddish-orange visible laser applications

The influence of Sm3+ ion concentration on physical, structural and optical properties of magnesium-sodium fluoroborate glasses were studied and analyzed. The XRD, FTIR, SEM with EDS spectra validated the non-crystalline nature, presence of functional groups, morphology and elementary analysis of the prepared glasses. The bonding parameters, oscillator strength, JO intensity parameters and radiative properties were evaluated using absorption and emission analysis. In JO intensity parameters, the lower Ω2 value implied higher symmetry and less covalency at higher Sm3+ concentration. The 4G5/2 → 6H7/2 emission transition possesses higher stimulated emission cross section (15.75 ✗ 10−22) and higher branching ratio 0.533 (βcal), 0.51 (βexp) for BMNNFS1.5 glass. The higher values of radiative parameters witnessed the suitability of prepared glasses for laser applications. Decay measurements were carried out and BMNNFS0.1 glass has higher quantum efficiency as 72%. The color coordinates (x.y) of prepared glasses lie in the reddish-orange region of the CIE diagram this confirmed the reddish-orange visible laser applications.

Judd-Ofelt analysis, optical and structural features of borate glass doped with erbium oxide

This article presents a description of the structural-optical relationship in amorphous borate glass, with a decent investigation of Judd-Ofelt parameters to understand the effect of structural changes on optical properties due to the erbium oxide addition. Using density measurements, the effect of heavy molecular weight and larger ionic radius of erbium oxide was demonstrated. FT-IR analysis revealed the BO3 to BO4 conversion, confirming the network polymerization and connectivity. Astonishingly, the effect of erbium oxide on the increased band gap energy and the mitigated Urbach energy was demonstrated. Interestingly, Judd-Ofelt analysis was utilized to demonstrate the impact of the composition changes on the relation between the structural changes and optical properties. The influence of excited configurations of Er3+ ions was measured from the line strengths. The hypersensitive transitions from I15/24toH11/24 and G9/24 were observed at 375 nm and 519 nm, which have relatively higher intensities compared to other ones. Thus, they are attractive transitions for light emitting devices, LEDs, and solid lasers. The decreased values of Ω2 parameter is related to the increase in symmetry and high polarization around Er3+ ions. Consequently, the decrement in Ω2 suggests that the bond nature between Er3+ and O2− ions tends to be more ionic. Calculations of radiative parameters such as spontaneous radiative transition probability, radiative lifetime, and branching ratio were presented. The hypersensitive transitions have the highest values of the spontaneous radiative transition probability, predicting their high luminescence efficiency in glass host, besides the effectiveness of their usability in designing photonic devices. The obtained high branching ratio confirmed the lasing action of Er3+ ions in the glass host, especially the hypersensitive transitions of Er3+ ions.

Eu3+ as a spectroscopic probe to understand local site-luminescence correlation in novel Y2TiO5:Eu3+ phosphor

Red emitting phosphor materials play a very important role in improving the color rendering index and lighting efficiency of phosphor-converted white light-emitting diodes (pc-WLEDs). However, the research pertaining to design and development of the same has somehow saturated with real lack of novel compositions and functionalities. In this work, a sincere effort has been vested in designing relatively new compositions Y2TiO5:x%Eu3+(x = 1–10) using simple solid-state reactions for efficient, narrow and pure red emission. Europium is distributed at both Y(1) and Y(2) site with higher excited state lifetime. Under the optimal mid and near ultraviolet light excitation, Y2TiO5:5%Eu3+shows a strong red emission at 608 nm with a high color purity of 99.96% and a moderate internal quantum efficiency of 13%. Impressively, this red-emitting phosphor exhibits a concentration quenching at 5.0 mol%, internal QY of ∼34%, lower non-radiative channels and higher branching ratio. Trend in Judd-Ofelt parameter suggested that there is monotonic increase in degree of distortion and as the concentration increases Eu-O bond becomes highly polarizable. This work and the obtained results suggested that Y2TiO5:Eu3+ phosphor has great potential to serve as red emitting phosphor for pc-WLEDs, opening a new perspective for developing new titanate-based luminescent materials.

Computational and optoelectronic quantification of semi-conducting, warm ruby red color emanating Eu3+ complexes with hetro-cyclic ligands.

Six Eu3+ complexes were synthesised with β-keto acid as main ligand and secondary ligands through liquid assisted grinding method. These complexes were characterised by various techniques such as spectroscopic technique, XRD, EDAX, SEM analysis, thermal technique, Urbach energy and optical band gap investigation. The luminous photophysical properties were studied by PL spectroscopy in solid as well as solution phase and some theoretical calculation was done to investigate the radiative (Arad) & non-radiative (Anrad) transition rate, quantum efficiency (ɸ), Judd Ofelt parameters for 5D0 → 7F2,4 transitions in both states. Judd Ofelt parameters were also calculated by the JOES software and the outcomes are well harmonised with theoretical values. The complexes have CIE color coordinate value in ruby red region and above 88.65% color purity in both phases, which made them attractive candidates for red light-emitting displays. 5D0 → 7F2 transition was proposed as a laser emission transition owing to their high branching ratio (67.18-74.24%) in solid and (60.09-74.40%) in solution phase. Computational methods were employed to determine the structure and energy of various molecular orbitals. Antimicrobial assay of complexes was also rationalised and found that the complexes are pertinent as good bactericidal and fungicidal agents in pharmaceutical industry.

Measurement of nonprompt and prompt D0 azimuthal anisotropy in Pb-Pb collisions at √SNN = 5.02 TeV

Heavy quarks are primarily produced via initial hard scatterings, and thus carry information about the early stages of the Quark-Gluon Plasma (QGP). Measurements of the azimuthal anisotropy of the final-state heavy flavor hadrons provide information about the initial collision geometry, its fluctuation, and more importantly, the mass dependence of energy loss in QGP. Due to the larger bottom quark mass as compared to the charm quark mass, separate measurements of charm and bottom hadron azimuthal anisotropy can shed new light on understanding the dependence of the heavy quark and medium interaction. Because of the high branching ratio and large D0 mass, measurements of D0 meson coming from bottom hadron decay (nonprompt D0) can cover a broad kinematic range and be a good proxy of the parent bottom hadrons results. In this talk, we report on the prompt D0 and the first nonprompt D0 measurements of the azimuthal anisotropy elliptic (v2) and triangular (v3) coefficients of nonprompt D0 in PbPb collisions at √SNN = 5.02 TeV. The measurements are performed as functions of transverse momentum pT, in three centrality classes, from central to midcentral collisions. Compared to the prompt D0 results, the nonprompt D0 v2 flow coefficients are systematically lower but have a similar dependence on pT and centrality. A non-zero v3 coefficient of the nonprompt D0 is observed. The obtained results are compared with theoretical predictions. The comparison could provide new constraints on the theoretical description of the interaction between heavy quarks and the medium.

Heteroleptic Eu(III) emissive complexes: Luminescent, optoelectronic and theoretical investigation

The synthesis of four red emissive complexes of europium with formula [Eu(Hfodo)3L] based on 6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedione (Hfodo) and 1,10-phenanthroline derivatives (L) is described. The coordination sphere of europium ion is formed by the oxygen and nitrogen atoms of three bidentate fluorinated diketones and one bidentate auxiliary moiety, respectively. The outcome of the luminescence analysis has confirmed the intense monochromatic red emission of the synthesized complexes in the powder and solution form. From the emission spectral data, colorimetric parameters were calculated which also affirm the luminescent behavior of prepared complexes. The range of band gap, high color purity and branching ratio (∼70%) analogous to 5D0 → 7F2 confirm the usefulness of bright emissive materials in displays and laser diodes.

Photoluminescence and optical transition properties of Sm3+ activated lead-borate glasses

The Sm2O3-doped B2O3- K2O-PbF2 host glasses were synthesized by melt-quenching process. to comprehend visible luminescence and lasing potentiality, optical absorption, excitation, emission and decay measurement of developed glasses were studied. The experimental oscillator strength were calculated from absorption spectra of BKPFSm0.5 (optimized) glass sample. The decline in decay time as the proportion of samarium ions in the host glass increase indicates energy transfer between samarium ions. To establish potentiality of these glasses as visible lasers, the radiative properties of fluorescent transition acquired from photoluminescence emission spectra were determined. The quantum efficiency acquired from experimental and theoretical lifetimes was found to be 74% for the BKPFSm0.5 glass. The high quantum efficiency (η), large stimulated emission cross-section (σe = 6.49 × 10−22 cm2) and high branching ratios (βR = 59%) for 4G5/2 → 6H7/2 transition of the BKPFSm0.5 glass specify acceptability of this glass for improvement of lasing (orange) and the photonic devices emitting the in visible region.

Influence of ZnF2 and ZnCl2 on luminescence investigations and crystal field calculation of Eu3+ doped zinc oxide-phosphate glasses

A series of Eu3+-doped 70NaPO3–20ZnO-10(ZnF2/ZnCl2) glasses were prepared by conventional melting quenching method. The samples were characterized by differential scanning calorimetry (DSC), X-ray diffraction (XRD), electron probe microanalysis (EDS/WDS) and optical spectroscopy. Using the emission spectra a set of Judd-Ofelt (JO) intensity parameters (Ω2, Ω4, Ω6) was refined, which in turn permitted to calculate transition probabilities (AED, AMD), branching ratios (β), radiative lifetimes (τrad) and stimulated emission cross-sections for the 5D0-7FJ transitions. The relative luminescence intensity ratio of 5D0-7F2-5D0-7F1 transitions has been evaluated to estimate the local site symmetry around the Eu3+ ions. Second and fourth rank crystal-field (CF) parameters together with the CF strength parameter have been reported for the first time for such study by assuming the C2v symmetry for the Eu3+ ions in both the phosphate glasses. Large stimulated emission cross-section, high branching ratios and quantum efficiencies (∼80%), also, intense red luminescence at 616 nm confirm that these present glasses suggesting for visible red lasers materials and optical devices.

Judd-Ofelt and luminescence properties of Pr3+ doped ZnO-Gd2O3/GdF3-BaO-P2O3 glasses for visible and NIR applications

Two optimized glasses were prepared with composition 10ZnO-10Gd2O3–10BaO–69P2O3-1Pr2O3 (1ZGPr) and 10ZnO-10GdF3-10BaO–69P2O3-1Pr2O3 (2ZGPr) by melt-quenching technique and study their structural, optical, physical and emission properties. In the absorption spectra seven absorption bands were observed corresponding to transition from 3H4 state at 443 nm (3P2), 467 nm (3P1), 481 nm (3P0), 589 nm (1D2) in visible region and 1438 nm (3F4), 1527 nm (3F3) and 1940 nm (3F2) in NIR-region. The trend observed for JO-parameters for both 1ZGPr and 2ZGPr is Ω4>Ω6>Ω2. The 2ZGPr has higher value of Ω2 parameter value than 1ZGPr, showing more covalency and asymmetric environment around Pr3+-ions. Emission in NIR region exhibits three f-f transition located at 870 nm (3P1 → 1G4), 1040 nm (1D2 → 3F3, 3F4), and 1470 nm (1D2 → 1G4). The 3P0 → 3F2 (in visible) and 1D2 → 1G4 (in NIR region) transitions has higher branching ratio and stimulated emission cross section for 2ZGPr glass than 1ZGPr glass. The Full-width-half-maxima (FWHM) is analyzed for transition at 870 nm is 61 nm for 1ZGPr and 58 nm for 2ZGPr glass. The possibility of efficient signal-amplification in E-band, S-band due to affirmative emission of Pr3+-ions within broadband wavelength region in 1ZGPr and 2ZGPr glasses with transition at 1470 nm covering E−, S– C- and L-band. The assessed values of color-coordinates (x, y) are (0.57, 0.36) and (0.54, 0.36) for 1ZGPr and 2ZGPr respectively. Hence 2ZGPr glass has enough potential enough capability to emit bright red-laser at 640 nm.

Optical and spectroscopic behavior of Eu3+ doped heavy metal phosphate glasses

Europium (Eu3+)-doped heavy metal phosphate glass systems have been synthesized by melt-quench technique. Optical as well as spectroscopic characteristics are analyzed in detail. X-ray diffraction (XRD) pattern of synthesized samples confirms their glassy nature. Optical band-gap (Eg) for the synthesized samples has been calculated using different methods. Refractive index and other parameters such as dielectric constant, molar refraction, reflection losses, and polarizability have also been determined for prepared glass samples. Photoluminescence properties are examined from the excitation as well as emission spectra and results revealed prominent emissions in red region. The optical band gap for the prepared samples has been evaluated using three different methods viz. Tauc's method, absorption spectrum fitting (ASF) method and differential absorption spectrum fitting (DASF) method. Similar results have been obtained by all the three methods. Judd-Ofelt (J-O) theory has been employed to emission bands of Eu3+ ions for determination of phenomenological intensity parameters i.e. Ω2,Ω4 and Ω6, radiative rate, branching ratio and radiative lifetime. J-O analysis revealed that the large value of Ω2 parameter indicated high covalency between metal-ligand bonds along with the distortion among symmetric sites of Eu3+. Branching ratio (βR) is greater than 0.5 for 5D0→7F2 (transition) indicating their prospective for usefulness in laser-based applications. High branching ratio values and color purity suggests the potential use of glass samples for red laser applications.

Structural and spectroscopic analyses on the multi former glasses developed with Eu3+ ions in favor of red laser gain medium applications

Certainly, multi glass formers are reckoned to be prospective efficient laser hosts due to their collective influence. Lead by this idea, a batch of Eu3+ ions activated modifier incorporated multi former glasses were fabricated via conventional melt quenching technique in favor of red laser applications. The produced glasses were collectively coded as BTPEM (M = Zn, Ba, Li, Sr & Ca) and their structural, spectroscopic traits were analyzed through XRD, SEM-EDX, FTIR, Raman, absorption and luminescence studies. The calculated positive bonding parameter (+δ) from the absorption study revealed the covalent nature of the titled glasses. The radiative parameters were derived from the JO intensity parameters (Ωλ) utilizing the emission spectra. Moreover, the luminescence spectra of the samples exposed a striking red peak at 614 nm (5D0→7F2 transition) with an elevated stimulated emission cross-section (σsec) and high luminescence branching ratio (βR) for the zinc containing glass (BTPEZn). Additionally, the acquired color coordinates (x, y) that lie close to the standard red color (x = 0.67, y = 0.33) accompanied with the high quantum efficiency (73%) affirmed the adequacy of the BTPEZn glass as a solid potential red laser host.

Judd-Ofelt analysis and luminescence studies of Er3+ doped halogeno-antimonate glasses

This research paper emphasized on application of Judd-Ofelt's (JO) theory for low doped erbium (0.2 mol%) halogeno-antimonate based glasses with molar composition (90 –x) Sb 2 O 3 - x ZnBr 2 - 10 NaCl (where x = 10, 20, 30 and 40 mol%). 80 Sb 2 O 3 – 9.8 ZnBr 2 - 10 NaCl - 0.2 Er 2 O 3 glass sample has low phonon energy and high refractive index is a potential candidate for luminescence applications. Differential scanning calorimetry (DSC) measurements show good the thermal stability of the prepared glass samples and on the other hand density, expansion coefficient and elastic moduli were reported. Judd-Ofelt's (JO) parameter intensities Ω 2 = 3.27 × 10 −20 cm 2 , Ω 4 = 1.24 × 10 −20 cm 2 and Ω 6 = 1.88 × 10 −20 cm 2 were found and these were compared with the literature. Radiative parameters such as spontaneous emission rate, branching ratio and lifetime were calculated. We focused on a high branching ratio radiative transitions 2 H 11/2 → 4 I 15/2 (β = 0.94) and 4 F 9/2 → 4 I 15/2 (β = 0.901). The overlap between absorption and emission bands is partial and stokes type shifts were presented. The gain curves were determined after calculation of absorption and stimulated emission cross sections. The infrared transmission curve of the glass matrix was marked extrinsic absorption bands SiO and hydroxyl OH possessed high vibration energy played quenching effect for photoluminescence. • SZNE02 novel glass system was developed by the conventional melt quenching method. • Judd-Ofelt's (JO) parameter intensities were compared with the literature. • High branching ratio radiative transitions. • Optical gap energy (E p = 2.95 eV) and refractive index n = 2.25 • Stimulated emission gains as a function of wavelength for different states of population inversion.

Structural and spectroscopic investigations of neodymium-doped strontium borophosphate glass.

Neodymium-doped glass finds application in lasers with high energy and low pulse width. In the present study, a series of Nd3+ ions (0-2 mol%)-doped strontium borophosphate (SBP) glass samples was prepared through the conventional melt quench method. A broad peak in the X-ray diffraction spectrum confirmed the formation of a single-phase amorphous borophosphate glass. Fourier transform infrared spectra of the doped and undoped glass samples indicated the presence of borate and phosphate groups that form the anionic network. The thermal properties of the glass samples were determined from thermogravimetry/differential thermal analysis. Photoluminescence and ultraviolet-visible light techniques were used to investigate the optical properties of the as-prepared SBP:Nd glass. The Judd-Ofelt (JO) intensity parameters Ωλ (2, 4, 6), stimulated emission cross-section, branching ratios, and transition probabilities of the Nd3+ -doped glass were obtained through the JO analysis. Characteristic Nd3+ emission peaks were observed at 1330, 1060, and 876 nm, corresponding to the 4 F3/2 →4 IS/2 (S = 13, 11, and 9) transitions, respectively. The suitability of SBP:Nd (0.5 mol%) glass for use in solid-state lasers was demonstrated by its intense luminescence, high transition probability, high emission cross-section, optical gain, and luminescence branching ratio.

Red-emission analysis, Judd–Ofelt intensity parameters and laser properties of CdMgZnO:xEu3+ nanocrystals: the effects of Eu3+ concentration

In this paper, we discuss a strong red Eu3+-concentration-dependent emission line associated with an electric dipole transition (5D0 → 7F2) at 616 nm in CdMgZnO:xEu3+ nanocrystals made via a sol–gel synthesis route. Oxygen interstitial defects created by the presence of a mixed-valence state of Eu 3+ and Eu2+ ions as rare-earth cations lead to a structural distortion which is confirmed by x-ray photon electron spectroscopy. The Judd–Ofelt intensity parameters, Ω2 and Ω4, obtained from the emission spectra, show a trend for Ω2 > Ω4 that translates to stronger covalence and a stable local structure surrounding the Eu3+ ions in CdMgZnO nanocrystals. The asymmetry ratio (R o), radiative lifetime (), branching ratio , stimulated emission cross-section, and the gain bandwidth (δ e× Δλ eff) for 5D0 are computed and analysed. A radiative lifetime ranging from 789 to 984 µs points to a suitable material for orange-red fluorescent phosphors for lighting and display technologies. The gain bandwidth (δ e× Δλ eff), which is dependent on the Eu3+ concentration, suggests the use of the CdMgZnO:xEu3+ nanocrystal material in fibre amplifiers, while the sample with x = 1.5%, which yields the largest emission cross-section (15.79 × 10−22 cm2), the highest gain bandwidth (28.8 × 10−28 cm3), and a high branching ratio (71%), is the best candidate for red laser applications.

Structural, dielectric, optical and photoluminescence studies of Tm3+ doped B2O3-BaO-MgO-Li2O-Na2O-LiF glasses featuring strong blue emission

A series of Tm3+ doped lithium sodium barium borate glasses with following matrix compositions (50-x) B2O3-10BaO-10MgO-10Li2O-10Na2O-10LiF-xTm2O3 (x=0.25, 0.5, 1.0 and 1.5 mol %) were prepared by melt-quenching technique. The structural, dielectric, optical and luminescence properties of the glasses were studied. FTIR study shows the presence of various vibrational bands and the number of bridging (N4) and non-bridging (N3) oxygens were calculated from the deconvoluted FTIR spectra. The frequency and temperature dependent dielectric properties were analyzed in the frequency range 1Hz-1MHz and the temperature ranges 50 - 400 °C. The UV-Visible-NIR spectrum of the glasses showed the presence of five transition peaks emerging from the ground state (3H6) of Tm3+ ions. Bonding parameter showed the ionic nature exists between Tm3+ ions and its neighbouring ligands. Judd-Ofelt parameters were calculated following the same trend as Ω2 >Ω6> Ω4 for all the prepared glasses. The emission spectra of the glasses were recorded in the visible region and exhibited a strong blue emission at 454 nm from the level 1D2 → 3F4. Also, the prepared glasses have high experimental branching ratio value (~0.9) which suggests that the prepared glasses can be used for blue laser application. Commission Internationale de I'Eclairage (CIE) coordinates and color correlated temperature (CCT) values (~1500K) supported the application of the glasses for cool blue solid-state lighting.

Concentration dependent neodymium doped oxy fluoroborate glasses for 1.08 μm laser applications

Different concentrations of neodymium-doped (Nd3+ ions) Oxy Fluoroborate (OFB) glasses were fabricated and systematically analyzed by employing spectroscopic techniques such as optical absorption, photoluminescence (PL) and PL decay spectral measurements to understand the NIR lasing potentialities. The information pertaining to absorption spectral features were subjected to Judd-Ofelt (J-O) analysis to understand the radiative properties such as transition probability (AR), radiative lifetime (τR) and branching ratios (βR) possessed by the as prepared Nd3+ ions doped OFB glasses. By correlating the radiative properties with the emission and PL decay spectral profiles, the emission cross-sections (σse) and quantum efficiency values are evaluated for the prominent fluorescent levels of Nd3+ ions in the as prepared glasses. Under 808 nm diode laser excitation, all the OFB glasses under investigation showcased two prominent NIR emissions at 1085 nm (4F3/2 → 4I11/2) and 1328 nm (4F3/2 → 4I13/2). The intensities of both the emission peaks escalates with increases in Nd3+ ions concentration up to 1 mol% and beyond decreases showcasing concentration quenching. The experimental lifetime values estimated from the single exponential PL decay profiles of 4F3/2 level are decreasing monotonously with increase in Nd3+ ions concentration in the as prepared OFB glasses. Relatively higher branching ratios, emission cross-sections and quantum efficiency values estimated for Nd3+ ions doped OFB glasses indicates the potential usage of the as prepared glasses for 1.08 μm laser applications.