Thermal Stability Of Glass Host Research Articles

Broadband near-infrared luminescence property in Nd3+/Tm3+ co-doped tellurite glass

The near-infrared (NIR) band luminescent characteristics of tellurite glasses doped with Nd3+ and Tm3+ ions synthesized by melt-quenching conventional technology were explored. Differential scanning calorimetry (DSC) curves, Raman spectra, X-ray diffraction (XRD) patterns, absorption spectra, fluorescence spectra and fluorescence decay curves were measured. The XRD patterns demonstrated the amorphous state structural nature of the prepared glasses, the various structural units such as TeO4, TeO3+1, TeO3, BiO6, ZnO4, WO6 and WO4 were determined by Raman spectra, and DSC curves revealed the excellent thermal stability of glass host with ΔT of 150 °C. Based on the Judd-Ofelt theory, the transition probabilities and fluorescence branching ratios of the Nd3+:4F3/2→4I13/2 and Tm3+:3H4→3F4 transitions corresponding to 1.33 µm and 1.47 µm band emissions were (570.56 s−1, 10.94 %) and (320.75 s−1, 8.17 %), respectively. Under excitation at 808 nm laser diode (LD), the spectral overlap of these two bands produced a relatively flat and broadband fluorescence spectra located primarily at S + E band region with the full width at half maximum (FWHM) of 201 nm, which could provide an effective supplement to the present C + L-band of Er3+. The broadband luminescence mechanism of Nd3+ and Tm3+ ions and the interactions between them were discussed.

Broadband NIR radiative transitions in Er3+/Tm3+ co-doping tellurite glass material

The radiative property of Er3+/Tm3+ co-doping tellurite glass containing metallic silver nanoparticles (Ag NPs) in near-infrared (NIR) band region was studied under the 808 nm pumping. The tellurite glass was prepared by applying melt-quenching and heat-treated technique, and characterized by measuring differential scanning calorimeter (DSC) curve, transmission electron microscopy (TEM) image, absorption spectrum and fluorescence spectrum. Under the optimized combination of Er3+ and Tm3+ ions, a flat and wide NIR band fluorescence in spectral range of 1350 to 1650 nm with full width at half maximum (FWHM) of 161 nm, originating from Er3+:4I13/2→4I15/2 radiative transition (1.53 µm) and Tm3+:3H4→3F4 radiative transition (1.47 µm), was observed in the studied tellurite glass. The fluorescence intensity was increased by about 91% when the Ag NPs with size of ∼17.4 nm was embedded into the doping glass. A similar wide optical amplification spectrum was also observed through the theoretical simulation of stimulated radiative transition of tellurite glass fiber co-doped with Er3+/Tm3+ ions, indicating the potential of Er3+/Tm3+ co-doping tellurite glass applied for broadband fiber amplifiers and tunable lasers. Additionally, the DSC curve revealed the excellent thermal stability of glass host with transition temperature of 381°C and the difference between crystallization onset temperature and transition temperature of 141°C. Some important spectral parameters like radiative transition probability and fluorescence branching ratio among different levels were determined according to Judd-Ofelt theory to better understand the observed broadband and flat NIR luminescence phenomenon.

Concentration dependent structural, thermal and luminescence properties in Er3+/Tm3+ doped tellurite glasses

Tellurite glasses with compositions (70-x)TeO2-20ZnO-5Na2O-4.8Bi2O3–0.2Er2O3- xTm2O3 (x = 0, 0.2, 0.4, 0.6 and 0.8 mol%) in fixed Er3+ and variable Tm3+ doped concentrations were synthesized by using conventional melt-quenching technique, and the concentration dependent structural nature, thermal stability and near-infrared band luminescent property were investigated. Under the excitation of 808 nm laser diode (LD), the Er3+/Tm3+ codoped tellurite glasses produced a broad near-infrared band fluorescence emission ranging from 1350 to 1650 nm, which completely covers the telecommunication window of WDM transmission system. The full width at half-maximum (FWHM) of this broadband emission contributed by the Er3+:4I13/2 → 4I15/2 and Tm3+:3H4 → 3F4 radiative transitions increased with the decrease of Er3+/Tm3+ doped concentration ratio, and reached to a value of about 148 nm in the 0.2 mol% Er2O3 and 0.8 mol% Tm2O3 codoped tellurite glass sample. The quantitative analyses of energy transfers between the Er3+/Tm3+ ions as well as the fluorescence decaying behavior of Er3+ were carried out to elucidate the observed broadband luminescent phenomena. Judd-Ofelt analysis was presented and some important spectroscopic parameters such as the spontaneous radiative transition probability, fluorescence branching ratio and radiative lifetime were estimated to reveal the potential luminescent properties. Meanwhile, the amorphous structural nature of the synthesized tellurite glasses with different doped concentrations was confirmed by the X-ray diffraction (XRD) patterns, the presence of functional vibrations assigned to the tellurite network was clarified by the Raman spectra and the good thermal stability of glass host was revealed by the differential scanning calorimeter (DSC) analyses. Also, the optical band gap energy corresponding to the direct and indirect allowed transitions was derived. The obtained results indicate that Er3+/Tm3+ codoped tellurite glass might be a promising candidate material for the development of near-infrared broadband fiber amplifiers.

Pr3+/Er3+ co-doped tellurite glass with ultra-broadband near-infrared fluorescence emission

Pr3+/Er3+ co-doped tellurite glass with composition 80TeO2-10Na2O-5WO3-5Nb2O5 was synthesized by the conventional melt-quenching technique, and the obtained glass was characterized by the UV/Vis/NIR absorption spectrum, near-infrared fluorescence spectrum, differential scanning calorimeter (DSC) curve, X-Ray diffraction (XRD) pattern and Raman spectrum. Under the 488nm excitation, it was found that Pr3+/Er3+ co-doped tellurite glass could emit an ultra-broadband near-infrared fluorescence which extended from 1200 to 1650nm with full-width at half-maximum (FWHM) of about 236nm, and this ultra-broadband fluorescence was contributed by the multichannel emissions of Pr3+ and 1.53µm band emission of Er3+. The luminescent mechanism and energy transfer processes between Pr3+ and Er3+ ions which are responsible for the observed ultra-broadband fluorescence were analyzed. Meanwhile, optical absorption bands that are assigned with corresponding electronic transitions with respect to Pr3+ and Er3+ ions were identified from the measured absorption spectrum, and based on the optical absorption data, the gain coefficient and important spectroscopic parameters like Judd-Ofelt intensity parameter, spontaneous radiative transition probability, radiative lifetime and branching ratio were calculated to elucidate the radiative properties of doped rare-earth ions. In addition, the DSC curve exhibited the good thermal stability of glass host with ΔT >150°C, Raman spectral study displayed the presence of different vibrational groups and XRD pattern confirmed the amorphous structural nature of the prepared glass. The present results indicate that Pr3+/Er3+ co-doped tellurite glass is promising for the ultra-broadband near-infrared band fiber amplifiers covering the expanded low-loss communication window.

Enhancement of spectroscopic and luminescence properties of Er3+ doped tellurite glasses by adding P2O5 for lasing materials

Er3+-doped phosphor-tellurite glasses has been synthesized by conventional melting method. Results of differential scanning calorimetry (DSC) measurements indicate a good thermal stability of tellurite glasses. The DSC measurements show an improvement of thermal stability of glass hosts after adding P2O5. The structures of glasses were investigated by X-ray diffraction (XRD) and Raman spectroscopy to understand their dependence of structure on composition. Absorption spectrum from near infrared to visible was obtained and the Judd–Ofelt (J-O) intensity parameters (Ω2, Ω4, and Ω6) were determined. Spontaneous emission probabilities of some relevant transitions, branching ratio, and radiative lifetimes of several excited states of Er3+ have been predicted using intensity J-O parameters. Up-conversion luminescence characteristics, under 977 nm excitation wavelength, have been investigated at room and low temperature in these glasses. Intense green and red emissions from Er3+ centered at 534 nm, 548 nm and 660 nm, corresponding to the transitions 2H11/2→4I15/2, 4S3/2→4I15/2 and 4F9/2→4I15/2, respectively, were simultaneously observed. The quadratic dependence of the up-conversion emission on the excitation power indicates that two-photon steps are involved for the three visible emission bands. The PL lifetimes is found to decrease in the temperature range 77–300K. Using the Mc-Cumber method, emission cross-section (σe), Absorption cross-section (σa), and gain cross-section (G(λ)) for the 4I13/2→4I15/2 transition, were calculated. By analyzing obtained data based to all advantages after adding P2O5, the tellurite glasses can be used as potential host material for developing optical amplifiers applied for 1.53 µm band broad and high-gain erbium-doped fiber amplifiers (EDFA).

Improvement of thermal and spectroscopic behavior of Er3+/Ce3+ co-doped tellurite glass for lasing materials

Tellurite glasses (TeO2–ZnO–Nb2O5) mono-doped Er3+ and co-doped Er3+/Ce3+ have been prepared using the melt-quenching technique. To evaluate the effect of Ce3+ on the structural, thermal stability of glass hosts and fluorescence properties of Er3+, X-ray diffraction patterns, Ftir spectra, differential scanning calorimeter curves, absorption spectra, fluorescence emission spectra, fluorescence lifetimes, up-conversion emission spectra of glass samples were measured and investigated. Using Judd–Ofelt theory, we calculated intensity parameters (Ω2, Ω4 and Ω6), spontaneous emission probabilities, the radiative lifetime, luminescence branching factors and the quantum yield of luminescence for 4I13/2 → 4I15/2 transition. The co-doping with Ce3+ was effective on the suppression of up-conversion emission of Er3+ owing to the phonon-assisted energy transfer: Er3+:4I11/2 + Ce3+:2F5/2 → Er3+:4I13/2 + Ce3+:2F7/2 which contributed the effective enhancement of 1.53 µm fluorescence emission. The change in optical properties with the addition of Ce3+ ions have been discussed and compared with other glasses. Using the Mc Cumber method for the 4I13/2 → 4I15/2 transition, absorption cross-section, calculated emission cross-section, and gain cross-section values support that TZNEr1Ce1 glass is a potential material for developing broad-band and high-gain erbium-doped fiber amplifiers applied for 1.53 µm.

The 1.85 μm spectroscopic properties of Er3+/Tm3+ co-doped tellurite glasses containing silver nanoparticles

The Er3+/Tm3+ co-doped tellurite glasses with and without silver nanoparticles (Ag NPs) have been synthesized by the conventional melt-quenching technique and characterized by the UV/Vis/NIR absorption spectra, 1.85 μm band fluorescence emission spectra, differential scanning calorimeter (DSC) curves, X-ray diffraction (XRD) curves and transmission electron microscopy (TEM) images to investigate the effects of Ag NPs on the 1.85 μm band spectroscopic properties of Tm3+ ions, thermal stability and structural nature of glass hosts. The TEM image reveals the presence of Ag NPs with average diameter of ∼14 nm in the prepared Er3+/Tm3+ co-doped tellurite glasses, and the presence of Ag NPs significantly enhance the 1.85 μm band fluorescence emission of Tm3+ ions under the excitation of 808 nm LD, which is mainly attributed to the intensified local electric field induced by Ag NPs scattered around the doped rare-earth ions, together with the energy transfer between Er3+ and Tm3+ ions. The energy transfer mechanisms between Er3+ and Tm3+ ions were further investigated by calculating energy transfer micro-parameters and phonon contribution ratios. Meanwhile, the Judd-Ofelt intensity parameters Ωt(t = 2,4,6), spontaneous radiative transition probabilities, fluorescence branching ratios and radiative lifetimes of relevant excited levels of Tm3+ ions were calculated based on the Judd-Ofelt theory to reveal the improved effects of Ag NPs on the 1.85 μm band spectroscopic properties. An improvement by about 75% of fluorescence intensity is found in the studied Er3+/Tm3+ co-doped tellurite glass containing 1.0 mol% amount of Ag NPs, and the thermal stability of glass host increases slightly with the Ag NPs while the glass structure maintains the amorphous nature. The above results indicate that the prepared Er3+/Tm3+ co-doped tellurite glass with an appropriate amount of Ag NPs is a promising host material applied for 1.85 μm band solid-state lasers and amplifiers.

The 1.53 μm spectroscopic properties of Er3+/Ce3+/Yb3+ tri-doped tellurite glasses containing silver nanoparticles

The metallic silver nanoparticles (NPs) was introduced into the Er3+/Ce3+/Yb3+ tri-doped tellurite glasses with composition TeO2–ZnO–La2O3 to improve the 1.53μm band fluorescence. The UV/Vis/NIR absorption spectra, 1.53μm band fluorescence spectra, fluorescence lifetimes, X-ray diffraction (XRD) curves, differential scanning calorimeter (DSC) curves and transmission electron microscopy (TEM) image of tri-doped tellurite glasses were measured, together with the Judd–Ofelt intensity parameters, emission cross-sections, absorption cross-sections and radiative quantum efficiencies were calculated to investigate the effects of silver NPs on the 1.53μm band spectroscopic properties of Er3+ ions, structural nature and thermal stability of glass hosts. It is shown that Er3+/Ce3+/Yb3+ tri-doped tellurite glasses can emit intense 1.53μm band fluorescence through the combined energy transfer (ET) processes from Yb3+ to Er3+ ions and Er3+ to Ce3+ ions under the 980nm excitation. At the same time, the introduction of an appropriate amount of silver NPs can further improve the 1.53μm band fluorescence owing to the enhanced local electric field effect induced by localized surface Plasmon resonance (LSPR) of silver NPs and the possible energy transfer from silver NPs to Er3+ ions, and an improvement by about 120% of fluorescence intensity is found in the studied Er3+/Ce3+/Yb3+ tri-doped tellurite glass containing 0.5mol% amount of silver NPs with average diameter of ∼15nm. The energy transfer mechanisms from Yb3+ to Er3+ ions and Er3+ to Ce3+ ions were also quantitatively investigated by calculating energy transfer microparameters and phonon contribution ratios. Furthermore, the thermal stability of glass host increases slightly with the introduction of silver NPs while the glass structure maintains the amorphous nature. The results indicate that the prepared Er3+/Ce3+/Yb3+ tri-doped tellurite glass with an appropriate amount of silver NPs is an excellent gain medium applied for 1.53μm band EDFA pumped with a 980nm laser diode (LD).

Enhanced 1.53 μm radiative transition in Er3+/Ce3+ co-doped tellurite glass modified by B2O3 oxide

Er3+/Ce3+ co-doped and B2O3 modified tellurite glasses with initial composition of TeO2–GeO2–Li2O–Nb2O5 were prepared using melt-quenching technique for potential applications in Er3+-doped fiber amplifiers (EDFAs) and lasers. The absorption spectra, fluorescence spectra, up-conversion spectra, Raman spectra and differential scanning calorimeter (DSC) curves of glass samples were measured to evaluate the effect of B2O3 modification on the 1.53μm band spectroscopic properties of Er3+, structural nature and thermal stability of glass hosts. It was shown that the introduction of an appropriate amount of B2O3 oxide can further improve the 1.53μm band fluorescence emission through an enhanced phonon-assisted energy transfer (ET) from Er3+ to Ce3+ ions under the excitation of 980nm, and the quantitative studies were carried out to elucidate the ET mechanism via calculating the microscopic parameters and phonon contribution ratios. Meanwhile, the thermal stability of glass hosts increases slightly with the introduction of B2O3 oxide. Furthermore, the 1.53μm band optical signal amplification was simulated based on the rare-earth ion rate and light power propagation equations. An increment in signal gain by about 1.4dB at 1532nm was observed in the Er3+/Ce3+ co-doped tellurite glass fiber containing 6mol% amount of B2O3 oxide, and the maximum signal gain reaches to 31dB on a 50cm fiber pumped at 980nm with power 200mW. The present results indicate that the prepared Er3+/Ce3+ co-doped tellurite glass modified by an appropriate amount of B2O3 oxide has good prospect as a gain medium applied for 1.53μm band EDFAs and lasers.

Enhanced 1.53 µm fluorescence and energy transfer mechanism in tellurite glasses doped with Er3+/Ce3+/Yb3+

Tellurite glasses (TeO2–ZnO–La2O3) doped with Er3+, Er3+/Ce3+ and Er3+/Ce3+/Yb3+ have been prepared using the melt-quenching technique, and the absorption spectra, fluorescence and up-conversion emission spectra together with the differential scanning calorimeter (DSC) curves and X-ray diffraction (XRD) patterns were measured to evaluate the effects of Ce3+ and Yb3+ introduction on the 1.53µm band spectroscopic properties of Er3+, thermal stability and structural nature of glass hosts. The Judd–Ofelt intensity parameters Ωt (t=2,4,6), spontaneous emission probabilities, radiative lifetimes and branching ratios of several Er3+ transitions were calculated from the measured absorption spectra based on the Judd–Ofelt theory. The co-doping with Ce3+ was effective on the suppression of up-conversion emission of Er3+ owing to the phonon-assisted energy transfer: Er3+:4I11/2+Ce3+:2F5/2→Er3+:4I13/2+Ce3+:2F7/2, while the co-doping with Yb3+ had the effect of obviously increasing the Er3+ population at 4I11/2 level via the resonant energy transfer: Yb3+:2F5/2+Er3+:4I15/2→Yb3+:2F7/2+Er3+:4I11/2, both of which contributed the effective enhancement of 1.53µm fluorescence emission. The quantitative studies were carried out to elucidate the energy transfer mechanism by calculating the microscopic parameters and phonon contribution ratios. The glass transition temperature (Tg), crystallization onset temperature (Tx) and the difference ΔT(=Tx−Tg), which characterize the thermal stability of glass host, increased with the Ce3+ and Yb3+ co-doping and for all glass samples the value of ΔT is larger than 145°C. The glass structural nature was demonstrated from the measured XRD patterns with no sharp diffraction peaks. The results of the present work indicated that the prepared Er3+/Ce3+/Yb3+ co-doped tellurite glass is a potential material for developing broad-band and high-gain optical amplifiers and other optical devices.

Enhanced 1.53 μm band fluorescence in Er3+/Ce3+ codoped tellurite glasses containing Ag NPs

The silver nanoparticles (Ag NPs) was introduced into Er3+/Ce3+ codoped tellurite glasses with composition of TeO2–ZnO–La2O3 and the effects of Ag NPs on the 1.53μm band spectroscopic properties of Er3+ ions, structural nature and thermal stability of glass hosts were investigated. The absorption spectra, upconversion emission spectra, 1.53μm band fluorescence spectra together with the X-ray diffraction (XRD) patterns, differential scanning calorimeter (DSC) curves and transmission electron microscopy (TEM) image were measured. It was found that the near-spherical shape Ag NPs with average diameter of about 19nm dispersed uniformly in the glass matrix, and the Er3+/Ce3+ codoped tellurite glasses containing Ag NPs exhibited an obvious enhancement in the 1.53μm band fluorescence, which is attributed to the intensified local electric field induced by Ag NPs and the possible energy transfer from Ag NPs to Er3+ ions. The enhanced effect of Ag NPs on the 1.53μm band fluorescence was elucidated by the obtained large Judd–Ofelt intensity parameter Ω6 and the calculated quantum efficiency of Er3+:4I13/2 level. In addition, the thermal stability of prepared glass samples increased with the introduction of Ag NPs and the amorphous structural nature was demonstrated by the measured XRD patterns with no sharp diffraction peak. The present results indicate that the prepared Er3+/Ce3+ codoped tellurite glass with Ag NPs has good prospect as a gain medium applied for 1.53μm band Er3+-doped fiber amplifiers (EDFAs).

Intense visible upconversion and energy transfer in Ho3+/Yb3+ codoped tellurite glasses for potential fiber laser

New Ho3+/Yb3+ codoped tellurite glasses (TeO2–Bi2O3–ZnO–Na2O) prepared by melt-quenching technique were investigated to realize visible-band upconversion emissions applied for compact fiber lasers. The absorption spectra, upconversion emission spectra, differential scanning calorimetry (DSC) curves, X-ray diffraction (XRD) and Raman spectra were measured to characterize the spectroscopic properties of Ho3+, thermal stability and structural nature of glass hosts. Under the excitation of 980nm laser diode (LD), the intense green (∼543nm) and red (∼657nm) upconversion emissions corresponding to 5F4(5S2)→5I8 and 5F5→5I8 transitions of Ho3+ respectively are simultaneously observed. The power dependence study of upconversion intensities on excited pump power revealed that the Ho3+ population at 5F4(5S2) and 5F5 levels was originated from two-photon absorption process based on the energy transfer from Yb3+ to Ho3+. The energy transfer mechanism from Yb3+ to Ho3+ was investigated and relevant micro-parameters (energy transfer coefficient and critical radius) and phonon contribution ratio were presented. With the increase of Yb3+ doped concentration, both the green and red upconversion intensities enhanced greatly, meanwhile the thermal stability of glass hosts, characterized by the three characteristic temperatures, also got a slight improvement. Furthermore, the glass structure was briefly analyzed with the calculated Judd–Ofelt intensity parameters, the measured Raman spectra and XRD curves. The present results indicate that the new synthesized Ho3+/Yb3+ codoped tellurite glass with intense green and red upconversion emissions is a promising medium applied for the visible-band fiber lasers.

Enhanced 2 µm fluorescence and thermal stability in Ho3+/Tm3+ codoped WO3 modified tellurite glasses

A certain amount of WO3 oxide was introduced into the Ho3+/Tm3+ codoped tellurite glass, and the absorption spectra, fluorescence spectra, Raman spectra, X-ray diffraction patterns and differential scanning calorimeter curves were measured to illustrate the enhanced effects of WO3 on the 2µm fluorescence of Ho3+ and thermal stability of glass host. Under the excitation of 808nm LD, the 2µm fluorescence of Ho3+ increases obviously with the partial substitution of TeO2 by WO3 oxide, which is attributed to the enhanced energy transfer process from Tm3+:3F4 to Ho3+:5I7 level by providing a relatively large phonon energy. Meanwhile, the thermal stability of glass host increases accordingly, which is mainly attributed to the formation of thermal stability W=O bond. The intense 2µm fluorescence together with good thermal stability indicates that Ho3+/Tm3+ codoped WO3 modified tellurite glass is a potential laser glass for efficient 2µm emission.

Enhanced upconversion emissions in Ho3 +/Yb3 + codoped tellurite glasses containing silver NPs

Ho3+/Yb3+ codoped zinc-tellurite glasses containing silver nanoparticles (NPs) were prepared using the conventional melt-quenching technique. The detailed effect of silver NPs on the upconversion emission of Ho3+, thermal stability and structure behavior of glass hosts was investigated from the measured absorption spectra, upconversion emission spectra, differential scanning calorimeter (DSC) curves, X-ray diffraction (XRD) patterns and transmission electron microscopy (TEM) images. Two frequency upconversion emission bands centered at 546nm (green) and 657nm (red) corresponding to Ho3+ transitions of 5F4(5S2)→5I8 and 5F5→5I8, respectively, are simultaneously observed under the 980nm excitation at room temperature. It is shown that the introduction of silver NPs can further improve the upconversion emissions of Ho3+and thermal stability of glass host, while the glass structure maintains the amorphous nature. The enhanced upconversion emission is mainly attributed to the increased local electric field around Ho3+induced by localized surface plasmon resonance (LSPR) effect of silver NPs. Furthermore, the energy transfer (ET) mechanism from Yb3+:2F5/2 level to Ho3+:5I6 level is quantitatively analyzed by calculating relevant micro- parameters and phonon contribution ratio.

Effect of SiO2 on the thermal stability and spectroscopic properties of Er3+-doped tellurite glasses

Er3+-doped tellurite glass (TeO2-ZnO-Na2O) prepared using the conventional melt-quenching method is modified by introducing the SiO2, and its effects on the thermal stability of glass host and the 1.53 μm band spectroscopic properties of Er3+ are investigated by measuring the absorption spectra, 1.53 μm band fluorescence spectra, Raman spectra and differential scanning calorimeter (DSC) curves. It is found that for Er3+-doped tellurite glass, besides improving its thermal stability, introducing SiO2 is helpful for the further improvement of the fluorescence full width at half maximum (FWHM) and bandwidth quality factor. The results indicate that the prepared Er3+-doped tellurite glass containing an appropriate amount of SiO2 has good prospect as a candidate of gain medium applied for 1.53 μm broadband amplifier.

Silver nanoparticles enhanced 1.53 µm band fluorescence of Er3+/Yb3+ codoped tellurite glasses

The silver nanoparticles (NPs) was introduced into the Er3+/Yb3+ codoped tellurite glasses with composition of TeO2–ZnO to improve the 1.53µm band fluorescence of Er3+ and the thermal stability of glass host. The UV–Vis–NIR absorption spectra, 1.53µm band fluorescence spectra and fluorescence decaying curves, the differential scanning calorimeter (DSC) curves, X-ray diffraction (XRD) patterns and transmission electron microscopy (TEM) images of glass samples were characterized to investigate the effect of silver NPs on the fluorescence properties of Er3+, thermal stability and structure behavior of glass host. It is shown that the Er3+/Yb3+ codoped tellurite glass emits intense 1.53µm band fluorescence with peak wavelength located at about 1532nm under the 980nm excitation. The introduction of silver NPs further improves the fluorescence intensity of Er3+ which is attributed to the enhanced local electric field effect induced by localized surface Plasmon resonance (LSPR) of silver NPs and the possible energy transfer from silver NPs to Er3+. An improvement by about 62% of 1.53µm band fluorescence intensity was found in the studied Er3+/Yb3+ codoped tellurite glass containing 0.5mol% amount of AgNO3. In addition, the thermal stability of glass host increases with the introduction of silver NPs while the glass structure maintains the amorphous nature. The present results indicate that the prepared Er3+/Yb3+ codoped tellurite glass with an appropriate amount of silver NPs has good prospect as a gain medium applied for 1.53µm band broad and high-gain erbium-doped fiber amplifiers (EDFAs).

Annealing time dependent 1.53 µm fluorescence enhancement in Er3+-doped tellurite glasses containing silver NPs

Silver nanoparticles (NPs) were introduced into the Er3+-doped tellurite glasses (TeO2–Bi2O3–TiO2) and their effects on the 1.53µm band fluorescence of Er3+ and thermal stability of glass host were investigated. It was found that the presence of silver NPs nucleated and grown during the heat annealing process, could improve the thermal stability and the 1.53µm band fluorescence. Maximum enhancement in the 1.53µm band fluorescence was obtained in sample heat-treated for 48h. However, further increase in the heat annealing time (~72h) reduces the fluorescence intensity. Enhancement in the 1.53µm band fluorescence is attributed to the increased local electric field induced by silver NPs whereas the quenching is ascribed to the energy transfer from Er3+ ions to silver NPs.

Er3+/Tm3+ codoped tellurite glass for blue upconversion—Structure, thermal stability and spectroscopic properties

The Er3+/Tm3+ codoped WO3 modified tellurite glasses with molar composition of (75−x)TeO2–20ZnO–5Na2O–xWO3–0.2wt%Er2O3–0.8wt%Tm2O3 (x=0,4,8,12mol%) were prepared to realize the blue upconversion emission. The absorption spectra, visible upconversion spectra and 1.53µm band fluorescence spectra of glass samples were measured, together with the quantitative calculations of relevant spectroscopic parameters of Tm3+ and energy transfer micro-parameters between Er3+ and Tm3+ ions, to evaluate the effects of WO3 oxide on the spectroscopic properties of Er3+–Tm3+ ions. It was found that the introduction of WO3 oxide can further improve the blue upconversion emission of Tm3+ through an enhanced phonon-assisted energy transfer process. Meanwhile, with the increase of WO3 amount, the thermal stability of glass hosts, characterized by the difference between the glass crystallization onset temperature and the transition temperature which obtained from the measured differential scanning calorimeter (DSC) curves, increased and no obvious crystallization peak was detected when the WO3 amount increased to 12mol%. Furthermore, the glass structure was briefly analyzed with the obtained Judd–Ofelt intensity parameters, the measured Raman spectra and X-ray diffraction (XRD) curves. The present results demonstrate the feasibility of realizing strong blue upconversion emission by introducing WO3 oxide with high phonon energy into the Er3+/Tm3+ codoped tellurite glass and also indicate its potential application as a glass host applied for the blue upconversion lasers.

Improvement of the 1.53 μm fluorescence and thermal stability in Er3+-doped WO3/B2O3 modified tellurite glass

WO3 and B2O3 oxides were introduced into the Er3+-doped tellurite glass (TeO2–ZnO–Na2O), and their effects on the 1.53μm band fluorescence of Er3+ and thermal stability of glass host were investigated. It was found that introducing a certain amount of WO3 or B2O3 could improve the thermal stability and the 1.53μm band fluorescence. Better thermal stability and stronger fluorescence intensity were realized in the B2O3 modified tellurite glasses while broader fluorescence emission spectrum was found in the WO3 modified ones. The tellurite glass containing 6mol% amount of B2O3 exhibited an increment of about 37°C in ΔT and 15% in fluorescence intensity, whereas that containing 3mol% amount of WO3 showed a broadening of 18nm in FWHM and meanwhile maintained a relatively larger ΔT compared with the conventional tellurite glass.

Influence of WO3 on the spectroscopic properties and thermal stability of Er3+/Ce3+ codoped tellurite glasses

The WO3 oxide was introduced into the Er3+/Ce3+ codoped tellurite glasses with the composition of TeO2ZnONa2O, and the absorption spectra, fluorescence emission spectra, fluorescence lifetimes, Raman spectra, XRD and DSC curves of glass samples were measured and investigated, respectively, to evaluate the effect of WO3 component on the 1.53μm band spectroscopic properties of Er3+ and thermal stability of glass hosts. It is shown that the introduction of WO3 component can significantly improve the 1.53μm band fluorescence intensity through an enhanced phonon-assisted energy transfer between Er3+ and Ce3+ ions and the total quantum efficiency corresponding to the 4I13/2→4I15/2 transition reveals a similar increasing trend. The introduction of WO3 component is also beneficial to obtain a large fluorescence FWHM, peak stimulated emission cross-section σep and amplification quality factors of σep×FWHM and σep×τm. Furthermore, the thermal stability of glass hosts increases with the content of WO3 component. The results indicate that the prepared Er3+/Ce3+ codoped tellurite glass containing WO3 oxide is a potential gain medium applied for 1.53μm band broad and high-gain EDFA.