Radiative Lifetimes τR Research Articles

Assessment of luminescent features on Sm3+ ions doped LiF assimilated lead-free borate glasses for visible photonic and optoelectronic applications

The distinctive set containing Sm3+ ions doped LiF incorporated Alkaline borate glasses have been synthesised via the melt quenching practice. 59B2O3+20LiF+(20–X)CaCO3+XBaCO3 +1Sm2O3 (where X = 5, 10, 15, 20 wt%) is the composition used for the glass preparation. The effect of samarium ions concentration dependency on the absorption and emission of barium and calcium oxide has been studied through several spectroscopic studies. The current set of glasses is ionic, determined by the bonding value. The hypersensitive absorption transition is found in the visible region of the absorption spectra, and the transition from 6H5/2 to 6P3/2 shows the highest oscillator strength of 14.87 × 10−6. The intensity parameters are denoted by Ωλ (where λ = 2,4,6) are assessed and discussed. The results indicate that Ω4 is higher when compared to the other two parameters. The lower Ω2 values further ensure the ionic nature of the glass samples. Moreover, the intensity parameters are utilised to predict some radiative properties for the lasing potential evaluation, which includes cross-sections of emission (σPE), probability of radiative transition (A), and experimental and radiative lifetime (τexp and τR). The decay profile was monitored for the 4G5/2 state, and consistently non-exponential behaviour was observed in all the glasses. Through the CIE colour chromaticity analysis, the CCT (colour-correlated temperature), dominant wavelength, colour, and purity of the emitted light have been evaluated. Concerning all aspects, the glass with 20 wt% of BaCO3 is found to be fit for photonic and optoelectronic applications.

Optical and radiation shielding properties of Europium doped Alkaline-Earth Boro Tellurite glasses

This research investigates the influence of Europium (Eu3+) ions concentrations on the optical, radiation shielding characteristics and photoluminescence (PL) properties of Alkaline Earth Boro Tellurite (AEBT) glasses. Absorption measurements of Eu3+ions doped AEBT glasses were used to determine the bonding parameters between the ligands and the ions. Excitation wavelength (394 nm) was used to record the PL spectra of the as prepared glasses , and analyzed for the dependent radiative characteristics and J-O parameters. The experimental lifetime (τexp) and radiative lifetimes (τR) of the as-prepared glass samples were estimated from the PL decay spectral profiles of the 5D0 level recorded at 613 nm emission under 394 nm excitation, and the quantum efficiency was then calculated. Based on its relatively higher values of the stimulated emission cross-sections and quantum efficiency, as well as its intense red luminescence at 613 nm (5D0 →7F2), the 1.0 mol% of Eu3+ ions doped AEBT glass is considered as a good optical material. In addition, the gamma-ray shielding properties have also been investigated at different photon energies ranging from 0.015 to 15 MeV using Phy-X software. From the results it is contemplated that, AEBTEu2.5 glass has the potential with better radiation absorption compared to regular concrete and other glass systems. The as prepared glasses are also suitable for optoelectronic device applications in addition to radiative shielding applications.

Spectroscopic studies of Eu doped CaF2 single crystal

The Eu-doped CaF2 crystal is investigated for potential use in visible-region solid-state lasers. The single-crystal Eu: CaF2 has an FCC crystal structure and belongs to the space group Fm-3 m, as confirmed by single-crystal X-ray diffraction. A Raman shift of 324 cm−1 has been observed in a single crystal of Eu: CaF2. The vibrational mode at low frequency is suitable for minimizing non-radiative emissions and increasing radiative emissions. Eu: CaF2 crystal has two absorption bands, at 399 nm and 415 nm, corresponding to the 7F0→5L6 and 7F0→5D3 transitions, respectively. The strongest absorption peak (399 nm) is associated with the 7F0→5L6 electronic transition. The orange-red emission was observed at 588 nm (5D0→7F1), 612 nm (5D0→7F2), 648 (5D0→7F3), and 685(5D0→7F4) when excited at 399 nm. Measurements of the luminescence intensity ratio (R) between the 5D0→7F2 (electric dipole) transition and the 5D0→7F1 (magnetic dipole) transition predict that Eu3+ ions are situated at the symmetric sites in CaF2. The radiative parameters for the Eu: CaF2 crystal are calculated using the JOES code using the Judd-Ofelt theory. The calculated total radiative transition probability (AR) is 64.54 s−1, and the radiative lifetime (τR) is 15.57 ms. Radiative transition probabilities are 43.41,7.02 and 14.10, and branching ratios are 67.26 %,10.88 % and 21.85 % for 5D0→7F1, 5D0→7F25D0→7F4 transitions respectively.

Spectroscopic and electrical properties of europium doped bismuth antimony fluoroborate glasses

Strong luminescence in the red spectral region is a well-known characteristic of the trivalent europium ion (Eu3+). We investigate a novel europium doped glassy substance for their use in optical devices, optoelectronics and radiation shielding. By using the traditional melt quenching technique, Bismuth antimony fluoroborate glasses are synthesized. XRD investigations support the amorphous nature of the material. Spectral measurements of absorption, photoluminescence (PL) excitation, PL emission, and PL decay curve are made in order to study the lasing properties. Judd-Ofelt (J-O) intensity parameters, from emission spectra, exhibit the trend Ω2> Ω4 furthermore used to find the radiative parameters-transition probability (AR), branching ratio (βR), radiative lifetime (τR), and stimulated emission cross-section (σse) for all the glasses. Decay curves show single exponential behavior and is used to find the quantum efficiency of the prepared glasses. The dielectric properties (dielectric constant (ɛ′), dielectric loss (ɛ″)), impedance and electrical conductivity (σac) of these glasses with variation in frequency have also been studied at the ambient temperature. The radiation shielding properties are evaluated for the photon energy range (1 keV–15 MeV). Based on the trends noticed in the radiative parameters, electrical conductivities and radiation shielding parameters, the present glasses could be found useful as optoelectronic devices, non-linear optical materials, battery anode materials and radiation shielding purposes.

Broadband near infrared emission of Er3+ ions doped fluorophosphate glasses for solid state laser applications

A series of glass compositions (P2O5 + Bi2O3 + Na2CO3 + SrF2 + xEr2O3) with different concentrations of erbium ions (Er3+) was synthesized using the melt quenching method and the samples were subjected to thorough characterization to explore their optical and structural properties. In order to ascertain the amorphous nature of the glass and acquire a deeper understanding of its chemical bonding, conventional methods of characterization, such as X-ray diffraction and Fourier transform infrared spectroscopy, were utilized. The Judd-Ofelt intensity parameters were computed using the absorption spectra of glasses doped with Er3+, providing vital information about the local environment and coordination of Er3+ ions in the glass matrix. Using the Judd-Ofelt intensity parameters and emission spectra to calculate the radiative parameters like total radiative transition probability (AT), radiative lifetime (τR) and radiative branching ratios for 4I13/2 → 4I15/2 transition. The McCumber theory is used to study absorption and emission cross-section for 4I13/2 → 4I15/2 transition. Prepared the PBNSEr05 glass sample suitable candidates for 1.53 μm solid state laser applications.

Application of Judd–Ofelt theory in analyzing Dy: SrCaF4 single crystal

The optical properties of Dy:SrCaF4 crystal in the visible range are investigated. Judd-Ofelt intensity parameters are evaluated following the assignment of Stark levels of absorption bands. The absorption coefficient and absorption cross section are reported, together with the line strengths of several transitions from the ground state to excited state manifold, oscillator strength of the electric and magnetic dipoles moments (fed, fmd). The emission wavelength (λem), calculated fluorescence branching ratios (βR), radiative emission probabilities (AR), total radiative emission probability (Ar) and radiative lifetime (τR) of Dy3+ in CaSrF4 crystal are investigated for the transitions from energy levels 4F9/2 (474 nm), 4I15/2 (452 nm), 6P5/2 (364 nm) and 6P7/2 (348 nm) to related sublevels. Dy:CaSrF4 crystal is a promising gain medium for a continuous wave or tunable solid state visible micro-laser under the pump wavelength of 348 nm, 364 nm and 474 nm.

Spectroscopic properties of Er3+-doped barium phosphate glasses for optical gain media

Barium metaphosphate glasses (PBaLa) doped with erbium (Er3+) ions have been prepared by melt quenching method and studied their optical, structural characteristics by using FT-IR, absorption, radiative de-excitation spectra, decay curves and up-conversion measurements. Judd-Ofelt (Ωλ, λ = 2,4 and 6) parameters have been determined using the absorption transitions of the Er3+(1.0 mol %)-doped glasses which are in turn taken to predict the radiative characteristics that include branching ratio (βR), radiative emission probability (AR) and lifetime (τR) of some important fluorescent levels of Er3+:glasses. Visible emission spectra measured under 378 nm excitation reveals three emission transitions at 663 (4F9/2 → 4I15/2), 547 (4S3/2→ 4I15/2) and 524 nm (2H11/2 → 4I15/2) corresponding to Er3+ ions. Among these, the green emission at 547 nm is relatively intense. Near-Infrared emissions were measured by exciting at 980 nm which exhibits broad emission at 4I13/2→ 4I15/2 (1.53 µm). The stimulated emission cross-section (σemi), FWHM and gain bandwidth (σemi× FWHM) were predicted to be 13.58 × 10-21 cm−2, 59 nm and 801.2 cm3, respectively, for PBaLaEr1.0 glass. The lifetime of 4I13/2 level has been shortened from 2.53 to 0.8 ms with an increase in Er3+ ions concentration from 0.1 to 2 mol %. NIR to visible up-conversion has also been measured for various concentrations of Er3+-doped PBaLaEr glasses with 980 nm excitation. These findings indicate that the Er3+-doped PBaLaEr glasses can be considered for waveguide laser and optical amplifier applications at 1.53 µm.

Enhancing of 4F3/2 → 4I9/2 transition of Nd3+ doped BaO-Ga2O3– Al2O3–B2O3 glasses for near-infrared laser applications

Neodymium, Barium Gallium Aluminium Borate glasses having the composition of [35% B2O3 + 35% BaO + 15% Ga2O3 + (15-x)% Al2O3 + x% Nd2O3, (x = 0, 0.5, 1 and 2%)] were prepared using traditional melt quenching method. Physical properties such as refractive index (n), molar volume (VM), density (ρ), band-gap (Eg), and Urbach energy (ΔE) were measured and calculated. The results revealed that our glass has allowed indirect band-gap transitions and the addition of Nd3+ reduced the Eg energies from 3.24 to 3.01 eV. The Judd-Ofelt parameters were obtained using the least-square technique and they were used to compute the total radiative probability (At), radiative lifetime (τr), fluorescence branching ratio (Br), and quantum efficiency (η) for the meta-stable level 4F3/2. The glass system showed a high Spectroscopic factor (χ) ranging from 1.61 to 1.98. The Br showed that the 4F3/2 → 4I9/2 transition (883 nm) was enhanced at the expense of the 4F3/2 → 4I11/2 transition (1064 nm) and (4F3/2 → 4I13/2) transition (1342 nm). A relatively high quantum efficiency (η = 0.78) was noticed for our glass. Generally the spectroscopic properties and gain factor (γ) showed that the present glass system is a promising candidate for near-infrared laser applications (883 nm).

Spectral studies of Nd3+ doped different fluorophosphate glasses for their aptness in laser applications at 1060 nm

Neodymium doped fluorophosphate (FP:Nd3+) glasses with different chemical compositions (59NH4H2PO4+15ZnO +15BaF2+10X+1·0NdF3 (X=LiF, NaF, CaF2, SrF2, AlF3)) were prepared by melt quenching. Their structures and spectroscopic properties were studied using x-ray diffraction, FTIR, FT-Raman and 31P, 27Al MAS NMR techniques. Various structural groups were identified using FTIR and FT-Raman spectra. The depolymerisation of metaphosphate chains are described by the decrease of Q2 tetrahedral sites allowing the formation of pyrophosphate groups revealed by 31P MAS NMR spectroscopic studies. Optical properties were studied using absorption and photoluminescence spectroscopy. Judd–Ofelt intensity parameters Ωλ (λ=2, 4 and 6) were estimated from absorption spectra. Radiative parameters such as transition probabilities (A), radiative lifetimes (τR), integrated absorption cross-sections (Σ) and branching ratios (βR) were calculated. Two emission lines at 1060 and 1330 nm were observed for Nd3+ in all the fluorophosphate glasses. From the emission spectra, emission characteristics were studied via optical band gains (σe×τR) and gain bandwidths (σe×Δλeff). Fairly large numerical values for peak emission cross-sections (σe) and branching ratios (β) for 4F3/2Æ4I11/2 transition of Nd3+ ion doped calcium fluorophosphate glass were observed. These results are rosy for NIR laser application at 1060 nm.

Down-conversion and up-conversion photoluminescence studies of Er3+ doped calcium zinc borosilicate glass for optical fiber amplifiers

A series of Er3+ ion doped calcium zinc borosilicate (CZBS) glass with composition 15ZnO-(10-x)CaO-10SiO2-65B2O3-xEr2O3 (x = 0.1, 0.5, 1.0, 1.5, 2.0 mol%) has been synthesized using conventional melt quenching technique. The non-crystalline nature of the as-synthesized glass is established through X-Ray diffraction (XRD). Fourier Transform Infrared (FT-IR) spectral studies present a full picture of the functional groups present in the glass system. The absorption, up-conversion (UC) and down-conversion (DC) photoluminescence (PL) and corresponding PL decay dynamics, and laser power dependent PL are investigated to better understand the optical properties and energy transfer mechanism in the glass matrices. The radiative properties such as transition probability (AR), branching ratios (βR), radiative lifetimes (τR) and near infrared (NIR) emission quantum efficiency (η) are estimated. The absorption, emission cross-sections and optical gain coefficients reveal the potential applications as laser amplifiers. The results favorably suggest the potential utility of these Er3+ doped CZBS glasses in solid-state lighting and optical communication devices.

Structural and optical studies of Sm3+-doped silica glass along with TiO2 nanoparticles for photonic applications

Sm3+ doped in SiO2:TiO2 nanocomposite glass-ceramic were prepared by sol-gel technique and the physical, structural, and optical properties were investigated. Parameters like refractive index, density, polarizability, etc. are measured and listed for prepared glass material. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (ATR-FTIR), and transmission electron microscopy (TEM) are utilized to study the structure of the prepared material. The XRD and TEM measurements confirmed the presence of TiO2 nanocrystals. Judd-Ofelt (J-O) intensity parameters (Ωλ) were determined from the absorption spectrum and photoluminescence (PL) spectra were recorded by using 450 nm laser excitation. Using the J-O parameters, different radiative parameters like radiative transition probabilities (AT), radiative lifetimes (τr), measured and calculated branching ratios (βr), effective bandwidths (Δλeff), and cross-sections of stimulated emission (σP) were estimated. The CIE 1931 chromaticity diagram is evidence of the color purity of the synthesized materials, which is slightly amplified by the appropriate Sm3+ ion addition.

Physical and Stimulated Emission Cross Section (SEC) Properties of Nd<sup>3+</sup> Doped Lithium Fluorophosphate (LFP) Glasses

This work describes a study that utilizes the Nd3+ ions (1.0 mol%) doped in glass material with the chemical formula 59P2O5 - 20Li2O - 10AlF3 - 10NaF. To obtain a glass medium with good homogeneity, all samples in the form of powder were mixed thoroughly and melted at 1100 °C for 3 hours. This sample preparation method is widely known as the melt-quenching method. The cutt and polish process is carried out to obtain a proportional and highly transparent of glass sample. Several parameters of physical properties were measured and then calculated to obtain the values of other parameters. The optical properties and stimulated emission cross sections (ECS) of a glass medium were obtained by observing the absorption and emission spectra. Based on the analysis of ECS, it was found that the radiative lifetime (τR) for Nd3+ ions experimentally and calculated were 132μs and 248μs respectively. Meanwhile, the quantum efficiency is achieved up to 53%

Optical, emission, and excitation dynamics of Eu3+ -doped bismuth-based phosphate glass for visible display laser applications.

Eu3+ -doped-bismuth-based phosphate glasses with chemical equation (60 - x)P2 O5 -20Bi2 O3 -10Na2 CO3 -10SrF2 -xEu2 O3 (PBNSEu), (where x= 0, 0.1, 0.5, 1.0, 1.5 and 2mol%) were fabricated using the melt-quenching method. Obtain X-ray diffraction (XRD), energy-dispersive X-ray (EDAX), and Fourier transform infrared (FTIR) spectra were used to characterize the structure of the prepared PBNSEu glass. The J-O (Judd-Ofelt) intensity parameters (Ω2 , Ω4 ) were estimated using photoluminescence emission spectra. When excited with a xenon lamp at λexc = 394 nm, the most intense red-emission transition occurred at ~612 nm (5 D0 →7 F2 ). J-O intensity parameters were used to calculate radiative properties, whereas the radiative branching ratio (βR ), radiative transition probability (AR ), radiative lifetime (τR ), and total radiative transition rate (Aτ ) were calculated for the transitions 5 D0 →7 FJ (where J = 0-4) and were obtained in the emission spectra for europium ion-doped in the current glass. Using the CIE1931 chromaticity coordinates axes, the colours of various concentrations of Eu3+ ion-doped PBNS glass were evaluated using the emission spectra. Temperature-dependent luminescence spectra were recorded for the optimized PBNSEu20 glass to calculate the activation energy. These results strongly suggested red components in w-LEDs and visible display laser applications.

Er3+ and Sm3+ co-doped ZnS quantum dots: Judd-Ofelt, luminescent properties and energy transfer

ZnS semiconductor quantum dots (QDs) co-doped with Er3+ and Sm3+ ions were successfully fabricated using a wet chemical method. The presence of Er3+ and Sm3+ in the ZnS host was confirmed using X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). XRD and transmission electron microscopy (TEM) analyses showed that the QDs had a zinc blende (ZB) structure with spherical shape and a particle size of approximately 4 nm. The optical properties of ZnS QDs were investigated by changing the Er3+ ion concentration and fixing the Sm3+ ion concentration. Judd-Ofelt (J-O) intensity parameters were determined from optical absorption spectra. The obtained J-O parameters illustrate the covalency related to the ligands and rare-earth ions. The radiative transition probabilities (Ar), branching ratios (βr), and radiative lifetimes (τr) of various excited states of the Er3+ ions were calculated. For the first time, the energy transfer (ET) processes from the ZnS host to Er3+ ions and from Er3+ to Sm3+ ions were confirmed and explained in detail. Er3+ and Sm3+ co-doped ZnS QDs showed a very long lifetime (up to milliseconds) compared to undoped ZnS. This exciting property has potential applications in photocatalysis, biosensing, and photovoltaics.

White luminescence and energy transfer studies in Tb3+-Eu3+ co-doped phosphate glasses

Europium and Terbium co-doped phosphate glasses with a chemical composition of 80NaH2PO4–18Na2CO3–2Al2O3, which have been named PNA, were well produced with melt-quenching technique. We studied the structural and optical properties of the material. According to the XRD pattern, all the samples have an amorphous structure. After adding Tb3+, it was revealed that the photoluminescence (PL) intensity of the 5D0 →7F2 transition increased. It was observed that the Tb3+ ion functions as a sensitizer for the Eu3+ ion, and significantly enhances the spectroscopic features of Eu-doped PNA. We demonstrated the possibility of excitation transfer from Tb3+ to Eu3+. The radiative lifetime (τR) calculated from Judd-Ofelt (J-O) theory, and the, empirically discovered, measured lifetimes (τmes) were compared for Eu-doped PNA and (Eu; Tb) co-doped PNA. The results reveal that the quantum efficiency (η) was found to increase after adding Tb3+ from 87 to 94% for the 5D0 →7F2 transition. The energy transfer was identified and explained both experimentally using the excitation and emission spectra and theoretically using the J-O theory. The results of the CIE chromaticity coordinates of (Eu, Tb) co-doped PNA were found in the white region, which suggests a significant promise in field emission displays.

Dependence of the radiative lifetime on the type-II band offset in GaAsxSb1−x/GaAs quantum dots including effects of photoexcited carriers

In quantum dot (QD) heterostructures that have a type-II band alignment, either the electron or the hole is confined inside the QD. Due to smaller electron–hole overlap in such structures, relatively long radiative lifetimes can be realized, which is beneficial for devices such as intermediate-band solar cells. The use of GaAsxSb1−x/GaAs QDs allows us to control the energy level of the confined state by changing the type-II conduction-band offset (CBO) without the need of changing the QD size. However, the dependence of the radiative lifetime τr on the CBO needs to be considered to achieve optimum device performance. In this work, GaAsxSb1−x/GaAs QDs were grown by molecular beam epitaxy. The amount of deposition was controlled to obtain QDs with approximately the same size even for different values of As composition x, and the carrier lifetime was determined by time-resolved photoluminescence measurements. Since the CBO becomes smaller for larger values of x, a simple model would predict a larger electron–hole overlap for larger x values, and thus, the lifetime should decrease monotonically. However, the experimentally obtained lifetime does not decrease monotonically, which has interesting implications for applications. We explain the observed trend by the effect of photoexcited carriers; a triangular potential well is formed around the QDs in the case of high excitation densities, and thus, electrons are localized near the QDs. We also calculated τr considering the effect of photoexcited carriers to confirm our model, and a similar tendency was obtained.

Study of structural and spectroscopic characteristics of novel color tunable yellowish-white Dy3+ doped Gd4Al2O9 nanophosphors for NUV-based WLEDs

Urea-assisted solution combustion (SC) synthetic method is employed to prepare a series of yellowish-white light emitting Dy3+doped Gd4Al2O9 (x = 1–6 mol%) phosphors. Phase identification and refinement parameters of designated nanomaterials are analyzed by means of Rietveld refinement technique. All doped samples are structured into monoclinic crystal system with P21c space group. Scherrer's formula and Williamson-Hall (W-H) linearly fitted method are employed to enumerate the crystallite size that are observed in the domain of nano-scale. The transmission spectrum of diffused reflectance is utilized to calculate the optical energy band gap of optimized sample Gd3.97Dy0.03Al2O9 that come out to be 5.11 eV. TEM micrograph discloses the existence of non-uniform agglomerated particles. The photophysical characteristics of doped phosphors are analyzed by exploiting their photoluminescence excitation (PLE) and emission profiles. The most intense excitation peak is found to be at 351 nm, which is meticulously harmonized with the distinctive wavelength of commercialized near ultra-violet (NUV) based LED chips. The emission profile of all doped samples possesses sharp emission lines centered at 481, 573, and 667 nm, which are ascribed to 4F9/2→6H15/2, 4F9/2→6H13/2, and 4F9/2→6H11/2 intraconfigurational transitions of Dy3+ ion, correspondingly. The emission decay curves are well fitted with bi-exponential function and in good agreement with findings of the refinement analysis viz. existence of two non-centrosymmetric sites attained by the Dy3+ ions. Auzel's model is used to estimate the radiative lifetime (τR= 5.14356 ± 0.65104 ms). The chromaticity coordinates and correlated color temperature (CCT) values for all doped samples are found close to standard white coordinates, thus proved them a potential candidate in single-phase phosphor converted WLEDs.

Optical and spectroscopic studies of Dy3+ ions doped Alumino tungsten borate glasses for w-LEDs applications

Alumino tungsten borate (AlWB) glasses doped with dysprosium ions are prepared by melt-quenching method and characterized using spectroscopic techniques such as optical absorption, photoluminescence (PL), and decay spectral studies to comprehend the importance in photonic devices, visible solid state lasers, and other applications. The amorphous nature of the as-prepared glasses were confirmed by XRD studies. The oscillator strengths are measured by using absorption spectra are intern used to evaluate the Judd-Ofelt (Ω2, Ω4, and Ω6) parameters. The PL spectra of the as-prepared glasses manifested three significant emission bands at 483 nm (blue), 575 nm (yellow) and 664 nm (red), and their corresponding electronic transitions are identified from 4F9/2 to 6H15/2,6H13/2 and 6H11/2 respectively. Various radiative parameters such as branch ratio (βR), transition probability (AR), radiative lifetime (τR), effective bandwidth (Δλp), and stimulated emission cross-section (σse) have been calculated. The CIE Chromaticity coordinates evaluated from the emission spectra of Dy-doped AlWB glasses reveal white light emission. Quantum efficiency values are evaluated by correlating the radiative lifetime with the experimental lifetime values measured from the PL decay spectral features. The data acquired from the as-prepared glasses allows us to contemplate that, the titled glasses are suitable to fabricate photonic devices. such as white LED’s and lasers.

Near-infrared photoluminescence studies of neodymium ions doped SrO-Al2O3-BaCl2-B2O3-TeO2 glasses for laser and fiber amplifier applications

This paper reports, preparation and characterization of Neodymium (Nd3+) ions doped Oxy Chloro Boro Tellurite (OCBT) glasses. The influence of Nd3+ ions concentration on physical, absorption, emission, and decay properties of OCBT glasses were studied in detailed using spectroscopic techniques. The experimental oscillator strengths measured from the absorption spectral data were subjected for Judd-Oflet (JO) analysis to estimate the best fit JO parametes and the dependent radiative properties of the as prepared glasses. The photoluminescence (PL) spectra recorded under 824 nm laser diode excitation reveal three emission peaks positioned at 887, 1064 and 1340 nm pertaining to 4F3/2→4I9/2, 4F3/2→4I11/2 and 4F3/2→4I13/2 transitions respectively. Correlation of radiative parameters information with PL spectral data allows to estimate various lasing parameters like emission cross section (σsec), gain bandwidth (σsec×ΔλP) and optical gain (σsec×τR). The PL decay spectra recorded for the as prepared glasses for 4F3/2→4I11/2 intense emission transition (observed at 1064 nm) reveal single exponential nature. The experimental lifetimes (τexp) measured from the PL decay profiles are correlated with the radiative lifetimes (τR) measured from the JO analysis to estimate quantum efficiency (η%) of the titled glasses. Among all the as prepared OCBTNd samples, 1 mol% of Nd3+ ions doped OCBTglass sample flourishes highest quantum efficiency. From the productive results obtained, it can be suggested that OCBTNd1.0 glass grabs plenty of applications in solid state lasers technology, fabrication of optical fiber amplifiers and NIR laser applications.

Enhancement of spectroscopic properties of Er3+ doped TeO2-Nb2O5-ZnO glassy systems for optical amplifiers at 1.53 µm

Tellurite-based glasses doped with varying amounts of Er3+ ions were elaborated by the melt quenching process. Based on Judd-Ofelt model, the local structures around erbium ions were studied and various optical parameters such as quantum efficiency (η), radiative lifetime (τR) and quality factor (χ) were determined. Following the addition of Er2O3, the results showed an enhancement in luminescence intensity at 1530 nm as well as a significant improvement of the effective bandwidth (108.8 nm), the emission cross section (9.1 ×10−21 cm2)and the quantum efficiency (91.8%) ascribed to the emission band at 1530 nm. The impact of adding a large amount of Er2O3 on the experimental lifetime of the 4I13/2 level was analysed using the Inokuti-Hirayama model. The obtained results were correlated with the concentrations of hydroxyl groups to investigate the luminescence quenching process in the tellurite glasses and to explain the decrease in some spectroscopic parameters. Accordingly, the results indicate that TeO2-based glass which contains optimum erbium concentrations may be a suitable material in the design of wide-band optical fiber amplifiers (EDFAs).