Single-doped Glasses Research Articles

Divalent tin activator for Nd3+/Yb3+ emission in lanthanum borate glass and its impact on inter-ionic phenomena and thermometry

The co-existence of divalent tin activator and Nd3+/Yb3+ rare earths in the borate glasses were utilized and examined to achieve the effective enhancement of the useful near-infrared emission in the wide spectral region. The UV Sn2+ excitation is extremely relevant for the effectiveness of both (Nd,Yb) near-infrared emission, however, Sn-Nd energy transfer efficiency is particularly prominent. The different advantageous inter-ionic phenomena made it possible to explore the diverse energy transfer routes leading to the population of the relevant ytterbium and neodymium excited states. Consequently, adequate multi-model temperature sensing can be proposed and verified considering single-doped and co-doped borate glass systems. The dissimilar effect of temperature on the complementary Sn2+, Nd3+ and Yb3+ optical transitions was investigated in detail. Employing the temperature-dependent spectra of optically active ions, high values of temperature relative sensitivity (1.3 % K−1) were estimated especially in the physiological range (30 – 75 ⁰C).

Blue and white light emissions and energy transfer in Tm3+ and Dy3+/Tm3+ doped lithium-aluminum-zinc phosphate glasses

Lithium-aluminum-zinc phosphate glasses doped with thulium and dysprosium ions are characterized by using spectroscopy techniques. The Judd-Ofelt parameters were evaluated to calculate the radiative parameters of thulium 1D23F4 and 1G43H6 visible transitions and 3H43F4 near infrared transition, which shows the highest optical amplification parameters. Upon 356 nm excitation, the Tm3+ doped phosphate glass emits blue light with CIE1931 chromaticity coordinates x = 0.1540 and y = 0.0283 and color purity around 96.8%. With excitations at 347 and 350 nm, the Dy3+/Tm3+ doped phosphate glass emits neutral and cold white light with correlated color temperature values of 4716 and 6628 K, respectively. The dysprosium emission decay time in the codoped glass is shorter than that in the Dy3+ single-doped glass, indicating a non-radiative energy transfer from Dy3+ to Tm3+. The dominant electrical interaction involved in the energy transfer, following the model Inokuti-Hirayama, is of dipole-dipole type. The energy transfer probability and efficiency are 769.0 s-1 and 0.53, respectively. Tm3+ doped and Dy3+/Tm3+co-doped lithium-aluminum-zinc phosphate glasses could be appropriate for blue and neutral/cold white light-emitting device applications.

Sn2+/Mn2+ co-doped germanate glass with quasi-sunlight spectrum visible-emission and its high-quality w-LED application

Light sources with the spectrum distribution approaching the sunlight, even in the visible range, are preferred. Up to now, sunlight simulator is still a great challenge to the scientists. In this work, the Sn2+/Mn2+ doped germanate glasses with the emission near to the sunlight spectral distribution in the visible wavelength region were developed, and the corresponding applications in w-LEDs were demonstrated. The spectral properties including excitation and emission characteristics, concentration quenching, fluorescence dynamics for Sn2+ and Mn2+ single-doped germanate glasses were studied. It is found that both Sn2+ and Mn2+ single-doped glasses can be effectively excited by broadband ultraviolet and subsequently generate broadband visible emissions. However, the emission from each of single-doped glasses does not cover full visible wavelength range. Fortunately, it is found that the lack of the red spectral component in the broadband visible emission of Sn2+ single-doped glass can be compensated by the broadband red emission of Mn2+. On that base, the Sn2+/Mn2+ co-doped germanate glasses were fabricated and studied. Broadband emission covering full visible range, good luminescence thermal stability and excellent chromatic performance were realized in the co-doped glasses by optimizing concentration and engineering energy transfer. Finally, a prototype w-LED was assembled by the Sn2+/Mn2+ co-doped germanate glass and a 310 nm LED chip. The prototype w-LED reveals the sunlight-like visible spectrum, good color coordinates (0.380, 0.371), low correlated color temperature (CCT) of 3811 K and high color rendering index of 95.3, indicating that the Sn2+/Mn2+ co-doped germanate glasses are promising candidate to develop high performance w-LED.

Broadband near-infrared luminescence in erbium ion single-doped tellurite glass for optical amplification.

This Letter proposes a simple approach for the realization of a broadband near-infrared (NIR) luminescence source in erbium ion single-doped tellurite glass, which is bent on tailoring the network structure. Under the collective action of multiple broadening mechanisms and fluorescence capture, broadband fluorescence with a full width at half maximum (FWHM) of 132 nm (1500-1632 nm) was achieved. To the best of our knowledge, this is the largest FWHM reported for erbium single-doping of tellurite glass materials. Meanwhile, this fiberglass exhibits excellent thermal stability and high visible to NIR transmittance. Furthermore, a novel equivalent five-level Stark splitting model is proposed that can effectively explain the spectrum broadening. This study is beneficial for the further development of broadband optical amplification.

Opto-Dielectric Properties of TeO2-Li2O-LiCl-Eu2O3 Glasses

Europium oxide (Eu2O3) doped lithium tellurite glasses were prepared via melt quenching method. The effects of Eu2O3 doping at varying concentrations on the physical, electrical and optical properties of tellurite glasses were determined. The physical properties utilizing density and molar volume are determined. Electrical and dielectric constant in the 0.01–10 MHz frequency range was monitored as a function of temperature (298–398 K). At room temperature, the conductivity and activation energy increase with an increase in Eu2O3 concentration. Small polaron hopping (SPH) is used to explain the conduction mechanism. The density of the localized state is found to decrease with increasing Eu2O3 concentration in the range of 21.3 to 17.3 eV−1 cm−3. Dielectric parameters which are dielectric constant and loss tangent are found to increase with the increase in the concentration of Eu2O3. To study the spectroscopic properties of fabricated glasses, absorption and emission spectroscopy have been performed. UV–vis-NIR absorption spectra of glass samples divulged two significant peaks. Under the excitation of a 393 nm laser diode, six emission bands were observed in the Eu3+ single-doped glasses of which the peak at 613 nm corresponding to the transition 5D0 → 7F2 is highly intense for such glasses. Increasing intensity ratio ranging from 1.13 to 2.13 with increased Eu2O3 concentration is attributed to the low symmetry environment around Eu3+ ions. The findings of the current study can be used in advanced functional optoelectronic applications.

Effects of coordination field environment on the fluorescence properties of transparent ZnGa2O4 glass-ceramics doped with Mn2+ and Cr3+ ions

The transparent ZnGa2O4 glass-ceramics doped with Mn2+/Cr3+ ions were prepared by a one-step crystallization method. The visible light fluorescence properties of Mn2+ ions in 6-coordination and 4-coordination environments and the visible light fluorescence properties of Mn2+/Cr3+ ions co-doped in transparent ZnGa2O4 glass-ceramics were studied. The results manifest that in the parent glass, Mn2+ ions mainly occupy the network former in the form of Hexa-coordination, and the luminescence center can emit orange-yellow light at ~600 nm. In transparent ZnGa2O4 glass-ceramics, Mn2+ ions and Cr3+ ions appear at the four-coordination site (Zn site) and six-coordination site (Ga site) in ZnGa2O4 spinel, respectively, and they can radiate green (510 nm) and red light (688 nm), respectively. An energy transfer mechanism of Mn2+→Cr3+ exists in ZnGa2O4: Mn2+/Cr3+ and different colors of luminescence can be produced by changing the molar ratios of components and test conditions. CIE results show that Mn2+-single-doped parent glass and glass-ceramics can be used in orange-yellow and green light displays, while Mn2+/Cr3+ co-doped transparent ZnGa2O4 glass-ceramics can be used as ideal materials for the green and red light displays.

Silver-Neodymium Codoped Lithium Aluminum Metaphosphate Glasses for Radio-Photoluminescence Dosimeter.

Commercial radio-photoluminescence (RPL) glass dosimeters generally use Ag single-doped phosphate glass as a single-wavelength sensor. Now, a novel type of Ag–Nd-codoped phosphate glass has been developed, which can be applied to dual-wavelength or multi-wavelength RPL sensors, and can thus improve the accuracy and stability of RPL dosimeters. An anhydrous 99.5 (0.7LiPO3–0.3Al (PO3)3) −0.25Ag2O–0.25Nd2O3 glass was prepared and irradiated at different doses, and then the absorption, fluorescence, infrared transmission spectra, as well as fluorescence lifetimes were tested and analyzed. The results show that there is an energy transfer between the Ag defect center and Nd3+ ions, and the transfer efficiency using 380 nm excitation is greater than that using 310 nm excitation. Aside from the 650 nm fluorescence of the Ag defect center, strong 882 nm and 1054 nm fluorescences of Nd ions are exhibited. It is possible that these fluorescences would allow the developed Ag–Nd-codoped phosphate glass to be applied to new RPL glass sensors and dosimeters.

Net Optical Gain Coefficients of Cu+ and Tm3+ Single-Doped and Co-Doped Germanate Glasses.

Broadband tunable solid-state lasers continue to present challenges to scientists today. The gain medium is significant for realizing broadband tunable solid-state lasers. In this investigation, the optical gain performance for Tm3+ and Cu+ single-doped and co-doped germanate glasses with broadband emissions was studied via an amplified spontaneous emission (ASE) technique. It was found that the net optical gain coefficients (NOGCs) of Tm3+ single-doped glass were larger than those for Cu+ single-doped glass. When Tm3+ was introduced, the emission broadband width of Cu+-doped glass was effectively extended. Moreover, it was found that for the co-doped glass the NOGCs at the wavelengths for Tm3+ and Cu+ emissions were larger than those of Tm3+ and Cu+ single-doped glasses at the same wavelengths. In addition, the NOGC values of Tm3+ and Cu+ co-doped germanate glasses were of the same order of magnitude, and were maintained in a stable range at different wavelengths. These results indicate that the Tm3+ and Cu+ co-doped glasses studied may be a good candidate medium for broadband tunable solid-state lasers.

Scintillation properties of Ce3+/Tb3+ co-doped oxyfluoride aluminosilicate glass for exploration of X-ray imaging

Ce3+ or Tb3+ single-doped and Ce3+/Tb3+ co-doped oxyfluoride scintillation glass samples were prepared by high temperature melting method. The structures were analyzed by X-ray diffraction (XRD), the optical and luminescent properties were studied by transmittance, photoluminescence excitation, photoluminescence, X-ray excited luminescence (XEL) and fluorescence decay. The luminescence intensity in the Ce3+/5 mol% Tb3+ co-doped (CT5) glass sample under 304 nm light and X‐ray excitation is significantly enhanced compared to 5 mol% Tb3+ single-doped (T5) glass sample. The maximum integrated XEL intensity of CT5 glass sample is about 67% of the standard Bi4Ge3O12 (BGO) crystal. Through the study of energy transfer mechanism, the results indicate that there is an energy transfer from Gd3+ ions or Ce3+ ions to Tb3+ ions. The lifetime of CT5 glass sample is 2.13 ms. The obtained results confirm that CT5 glass sample could be a promising scintillating material used in X-ray imaging. So we have demonstrated X-ray imaging using Ce3+/1–15 mol% Tb3+ co-doped (CT1-15) glass samples and confirmed they can reach a spatial resolution of 10.0 lp/mm. Further, the X-ray imaging effect of CT5 glass sample is the best, and the capability of CT5 glass sample for X-ray imaging application is confirmed.

Dy3+/Er3+/Tm3+ tri-doped tellurite glass with enhanced broadband mid-infrared emission

Dy3+/Er3+/Tm3+ tri-doped tellurite glass was synthesized using melt-quenching technology, and the enhanced broadband mid-infrared band luminescence around 3.0 µm was reported for the first time under the excitation of 808 nm laser diode. The broadband mid-infrared luminescence observed in the range of 2600–3200 nm comes from the spectral overlapping of Er3+:2.7 µm and Dy3+:2.84 µm emissions, while the significant enhancement is mainly contributed by the energy transfers from Er3+:4I13/2 to Dy3+:6H11/2, Er3+:4I13/2 to Tm3+:3F4 and Tm3+:3F4 to Dy3+:6H11/2 levels. Compared with Dy3+ single-doped tellurite glass, the peak intensity of this mid-infrared band luminescence in tellurite glass tri-doped with 0.5 mol% Dy2O3, 0.5 mol% Er2O3 and 1.0 mol% Tm2O3 increases by about 214%. Additionally, the spectroscopic properties of Dy3+ ions were investigated by applying Judd-Ofelt theory and the energy transfer mechanism was analyzed to understand the enhanced broadband luminescence phenomena. The obtained results reveal that Dy3+/Er3+/Tm3+ tri-doped tellurite glass is a promising lasing medium for 3.0 µm band mid-infrared broadband photonic devices.

Tunable luminescence in Pr3+ single-doped oxyfluoride glass ceramic and fibers

Tunable luminescence from red to white in Pr3+ single-doped oxyfluoride glass and glass ceramic.

Enhanced IR luminescence properties of Ho3+ ions in oxide glasses modified by the introduction of chloride

Ho3+-doped multifunctional multicomponent glass fibers with effective 2.8 μm emission have attracted significant attention owing to their wide range of applications in various fields over the past decades. However, certain challenges in satisfying the demands of high-efficiency lasers remain to be overcome. In this study, Ho3+ ion single-doped oxide glasses modified by chloride were successfully fabricated and analyzed. The results of the X-ray diffraction (XRD) and differential scanning calorimetry (DSC) indicated the multicomponent glass exhibited better thermal stability and crystallization resistance. The effect of varying chloride content on the structural units of the glass network was carefully analyzed based on the Raman results, indicated that the introduction of chloride can promote the transition of structural units in the glass network environment and lead to a positive impact on the luminescence of Ho3+ ions. Furthermore, the mid-infrared luminescence of Ho3+ was systematically investigated with enhanced luminescence performance under 650 and 1177 nm pumping sources. Hence, these experimental results suggested that Ho3+ doped multicomponent glass can be considered as an attractive candidate medium for high-efficiency laser applications in the infrared region.

193 nm excimer laser-induced color centers in Yb3+/Al3+/P5+-doped silica glasses

Yb3+, Yb3+/Al3+, and Yb3+/P5+ co-doped silica glasses, as well as pure silica, Al3+, and P5+ single-doped silica glasses, were prepared using a sol–gel method combined with high-temperature sintering. The glasses were irradiated with a 193 nm ArF excimer laser for different durations. The species of the 193 nm laser-induced color centers were identified by radiation-induced absorption (RIA), in-situ photoluminescence (PL), and continuous-wave electron paramagnetic resonance (CW-EPR) spectroscopic techniques. To obtain the RIA and CW-EPR characteristics of each color center, the Gaussian decomposition of RIA and the line-shape simulation of the CW-EPR spectra were performed. The formation mechanism of the color centers was correlated with the glass microscopic structure, which was obtained by nuclear magnetic resonance (NMR) spectroscopy. The results show that the oxygen hole center and the Yb2+ ion pairs are primarily responsible for the radiation-induced darkening, and their formation is highly dependent on the charge balance between the Yb3+ ion and its ligand. This work provides insights into the underlying mechanism of pump light and/or external radiation-induced optical losses in Yb3+-doped silica fibers.

Spectroscopic investigations of near-infrared emission from Nd3+-doped zinc-phosphate glasses: Judd-Ofelt evaluation

Zinc-phosphate glasses doped with different concentrations of Nd3+ ions have been prepared by the melt quenching technique and characterized the spectroscopic properties. The physical properties by means of density and molar volume are determined. The amorphous nature of the glasses has been confirmed by X–ray diffraction analysis. FTIR spectra exhibited the fundamental stretching vibrations modes of glass network. In order to study the spectroscopic properties of fabricated glasses, absorption and emission spectroscopy has been performed. Additionally, the spectroscopic properties of Nd3+ ions were analyzed using J–O theory. UV–Vis–NIR absorption spectra of glass samples divulged twelve significant peaks. Considerable enhancement of Ω2 values with increasing neodymium content indicated an improvement in the covalency and asymmetry of Nd3+ ions environment. Under the excitation of 808 nm laser diode, two near-infrared emission bands at around 890 and 1060 nm from 4F3/2 → 4I9/2 and 4I11/2 radiative transitions respectively were observed in the Nd3+ single doped glasses. The major intensity is observed for 1060 nm for such glass samples. Nd3+ ions dopant is found to augment the luminescence intensity by a factor as much as 2.23 times as the concentration of Nd3+ ions increase up to 1.5 mol%. The lifetimes of this level has been experimentally determined through decay profile studies. The developed glass possesses high fluorescence quantum efficiency (η = 96%). The results indicate that the prepared glass system could be a suitable candidate for using it as laser gain media around 1060 nm, solid-state lasers and fiber amplifiers.

Near-infrared and upconversion luminescence of Tm3+ and Tm3+/Yb3+-doped oxyfluorosilicate glasses

Oxyfluorosilicate glasses-doped with different concentrations of Tm3+ and Tm3+/Yb3+ ions have been synthesized and characterized their absorption, photoluminescence, luminescence decay and upconversion properties. The Judd-Ofelt intensity parameters have been obtained from the absorption spectrum of Tm3+ single-doped glass and are in turn used to calculate radiative properties such as transition probabilities, branching ratios and lifetimes for the fluorescent levels of Tm3+ ions. Visible and near-infrared emission spectra of Tm3+ and Tm3+/Yb3+-doped glasses have been measured under 473 nm laser excitation. The quenching of emission intensities at higher concentrations of Tm3+ ions has been found to be due to cross-relaxation mechanisms. The Tm3+/Yb3+ co-doped glasses show upconverted emissions under 975 nm laser excitation. The mechanism of upconversion has been explained based on the pump power dependence of upconversion luminescence. The results reveal that the co-doped glasses are promising for optical fiber amplifiers operating at the relatively low-loss wavelength regions.

Tunable reddish to magenta upconversion luminescence in Tm3+-doped glass

Generation of the color-tunable reddish to magenta upconversion luminescence in Tm3 + -single-doped glasses under near-infrared (1.1 to 1.3 μm) excitation is reported. Upconversion emission in the ultraviolet, blue- and red-spectral regions due to D21-H63, D21-F43, G41-H63, G41-F43, and F2,33-H63 transitions, respectively, was observed. The dependence of upconversion emission upon excitation power and Tm3 + content was also investigated. Adjusting the excitation power and Tm3 + concentration, the overall fluorescence emission can be tuned across the reddish to magenta color in the international commission on illumination color chromaticity diagram. The CIE-1931 color coordinates move from red toward the bluish region occupying the magenta region with an increase in the excitation power.

Luminescence enhancement and white light generation of Eu3+ and Dy3+ single-doped and co-doped tellurite glasses by Ag nanoparticles based on Ag+-Na+ ion-exchange

The Dy3+ and Eu3+ single-doped and co-doped tellurite glasses containing silver nanoparticles (NPs) were prepared by the Ag+-Na+ ion-exchange method. The influence of local surface plasmon absorption (LSPR) at the 455 nm of Ag NPs on the photoluminescence (PL) of Dy3+ and Eu3+ single-doped and co-doped tellurite glasses was investigated. The results indicated that the different PL enhancement factors of tellurite glasses single-doped with Eu3+ and Dy3+ were obtained by adjusting the overlapping relationship between excitation or emission wavelength and the LSPR of Ag NPs. When the excitation wavelength is overlapped with the LSPR of Ag NPs, the larger enhancement factor was obtained in the Eu3+ doped tellurite glasses due to the excitation field enhancement. When the emission wavelength is overlapped with the LSPR of Ag NPs, the selective enhancement of 485 nm emission of Dy3+ is obtained due to the radiative decays rate increasing besides the excitation field enhancement. The energy transfer enhancement from Dy3+ to Eu3+ caused by the LSPR of Ag NPs was observed in the Dy3+ and Eu3+ co-doped glasses. The Dy3+ and Eu3+ co-doped tellurite glasses exhibited the white light emission upon the blue chip excitation, which indicated that they have a potential application for the blue converted WLEDs.

The enhanced and broadband near-infrared emission in Pr3+/Nd3+ co-doped tellurite glass

This paper reports an enhanced and broadband near-infrared fluorescence emission in the Pr3+/Nd3+ co-doped tellurite glass, which was prepared using melt-quenching technique. Under the excitation of 488 nm laser diode (LD), three near-infrared emission bands at around 0.9, 1.04 and 1.30 μm from 3P1,0 → 1G4, 1G4→3H4 and 1G4→3H5 radiative transitions respectively were observed in the Pr3+ single-doped glass, and the fluorescence intensities increased further with the introduction of Nd3+ ions, which is mainly attributed to the energy transfers from Nd3+ to Pr3+ emissions. Meanwhile, the spectral overlapping of Pr3+:1G4→3H4 and Nd3+:4F3/2 → 4I11/2 radiative transitions resulted in a broadband emission ranging from 1000 to 1100 nm, whose full-width at half-maximum (FWHM) reached about 66 nm. Additionally, the spectroscopic properties of Nd3+ and Pr3+ ions were analyzed using Judd-Ofelt theory and the thermal stability property of prepared glass was characterized by the differential scanning calorimeter (DSC) measurement, and larger than 134 °C for the difference ΔT(=Tx−Tg) was observed, which indicates its feasibility for later fiber drawing. The enhanced fluorescence and broadband emission indicate that Pr3+/Nd3+ co-doped tellurite glass can be applied in the near-infrared band tunable lasers and broadband optical amplifiers.

Compositional dependence of broadband near-infrared downconversion and upconversion of Yb3+-doped multi-component glasses

Yb3+ single-doped glasses show a strong excitation band in the 300–400 nm region, and efficiently emit photons with wavelengths of 920–1150 nm, and have potential applications in solar cells operating in an extraterrestrial situation. In this work, we systematically study the broadband near-infrared downconversion and upconversion of Yb3+-doped silicate, germanate, phosphate, tellurite and tungsten tellurite glasses. All samples show a broad excitation band in the 300–400 nm range, which is attributed to the charge transfer of the Yb3+–O2− couple. The position of the charge transfer band (CTB) shifts from 300 nm to longer wavelengths around 350 nm when the length of the R–O(Si, P, Ge, Te) increases. The longer R–O gives rise to a smaller central void for Yb3+, thus resulting in a small proportion of Yb3+ ions, thus leading to the blue-shift of the CTB. A smaller proportion of Yb3+ in silicate glasses causes in the strongest upconversion emission at 500 nm.

Tm/Tb/Eu triple-doped lithium aluminoborate glass for white light generation

The aim was to design a multi-chromatic phosphor based on the colour mixing principle, whereby white light can be produced from an appropriate mixture of blue, green, and red emissions by a single phosphor. In this perspective, Tm2O3, Tb4O7, and Eu2O3 were simultaneously doped in single host glass matrix. A series of Tm2O3 single- as well as Tm/Tb/Eu triple-doped glasses were synthesised. The photoluminescence behaviour and luminescence quenching were investigated for Tm2O3 single-doped glasses. Keeping Tm2O3 constant at the saturation concentration in the Tm/Tb/Eu triple-doped glasses and varying the doping ratio of the two other lanthanides (Tb4O7 and Eu2O3) in the host glass allow to some extent the control of the spectral composition and consequently the generation of tunable colour impressions. The latter can also be adjusted by keeping the concentration ratio of the three lanthanides constant and varying the excitation wavelength. Upon 358-nm excitation of the Tm/Tb/Eu triple-doped glasses, white light emission is achieved and the corresponding correlated colour temperatures are also determined. The different energy transfers occurring in between the three lanthanides are investigated and possible energy transfer routes are proposed.