Co-doped TeO2 Research Articles

Broadband ∼2 μm luminescence properties and energy transfer in Tm3+/Ho3+ co-doped TeO2–Al2O3–BaF2 glass

Tm3+/Ho3+ co-doped tellurite aluminate glasses were prepared using the melt-quenching technique. Under 808 nm laser diode (LD) excitation, these glasses exhibit intense 2 μm band luminescence, with a full width at half-maximum (FWHM) of 144 nm. The energy transfer mechanism between Tm3+ and Ho3+ was explored to investigate the luminescence behavior further. Furthermore, the forward energy transfer coefficient (Tm3+→Ho3+) is greater than the backward energy transfer coefficient (Ho3+→Tm3+), indicating that Tm3+ can effectively sensitize Ho3+. As mentioned above, Tm3+/Ho3+ co-doped tellurite aluminate glass is a competitive material in the laser field.

Improving 2–4 μm mid-infrared fluorescence properties of Ho3+ via Er3+ energy transfer in tellurite glasses

Despite significant advancements in the field of mid-infrared lasers, the fluorescence around the 2–4 μm wavelength range remains a pressing concern. Ho3+/Er3+ co-doped TeO2–ZnO–Nb2O5–PbO (TZNP) glasses were fabricated by conventional melt-quenching technique, and we also characterized their excellent mid-infrared (MIR) fluorescence properties. According to the observed parameter ΔT (144–141 °C) > 120 °C from differential scanning calorimeter (DSC) curves, the manufactured tellurite glass specimens displayed enhanced thermal stability and crystallization resistance. X-ray diffractometer (XRD) images demonstrated the non-crystalline structure of the produced specimens. Ho3+/Er3+ co-doped tellurite glass specimens achieved emission enhancements of 2.0 μm and 4.1 μm through energy absorption of 980 nm LD, which could be assigned to the Ho3+: 5I7 → 5I8 and Ho3+: 5F5 → 5I4 radiation transition processes respectively. Meanwhile, intense 3.1 μm fluorescence was observed, which could be attributed to the transition of Er3+: 4S3/2 → 4F9/2. We investigated the fluorescence properties of the produced glasses in detail, and the processes of energy transferring between Ho3+/Er3+ were discussed on the basis of the quenching and increasing emission intensity at different dopant proportions of Er3+ ions. Additionally, the optimized 1 mol% Ho3+ and 1.5 mol% Er3+ co-doped TZNP glass possessed the strongest emission intensity, and the fluorescence lifetime values of this sample were calculated to be 1.81 ms and 1.38 ms at 2.0 μm and 4.1 μm, respectively. The gain coefficients demonstrated that only small pump energy can achieve the MIR laser gains. These above findings suggest that the prepared samples are potentially competitive and efficient as an innovative glass in the MIR laser design and optical amplifiers applications.

Study on luminescent performance of Dy3+-, Tb3+-doped and Tb3+/Dy3+ co-doped TeO2-(Gd,Lu)2O3-WO3 glass scintillators

Three series of Dy3+-, Tb3+-doped and Tb3+/Dy3+ co-doped 40TeO2-20(Gd,Lu)2O3–40WO3 glasses with density of about 6.75 g/cm3 were successfully prepared by high temperature melt-quenching method. The luminescence properties of these rare earth ions doped 40TeO2-20(Gd,Lu)2O3–40WO3 glass were systematically studied by transmittance, photoluminescence (excitation and emission spectra), time-resolved emission spectra (TRES) and X-ray excited luminescence (XEL) spectra, together with the luminescence decay curves. The optimal doping concentration of Dy3+ and Tb3+ ions in 40TeO2-20(Gd,Lu)2O3–40WO3 glasses was determined under UV and X-ray excitation, respectively. It is found there is an efficient energy transfer from Dy3+ to Tb3+ ions in 40TeO2-20(Gd,Lu)2O3–40WO3 glass in photoluminescence spectra. However, it is not true under X-ray excitation due to the complicated physical process.

Realizing particle population inversion of 2.7 μm emission in heavy Er3+/Pr3+ co-doped low hydroxyl fluorotellurite glass for mid-infrared laser

In this work, the population bottleneck of Er3+: 4I11/2 → 4I13/2 was overcome for the first time in heavy Er3+/Pr3+ co-doped TeO2–BaF2–La2O3–LaF3 (TBLL) low hydroxyl fluorotellurite glasses. Infrared emission spectra and fluorescence lifetime decay curves reveal that Pr3+ ions could deplete the electrons from the Er3+: 4I13/2 level faster than those from the Er3+: 4I11/2 under 980 nm excitation. Specifically, the energy transfer (ET) efficiency of the Er3+: 4I13/2 → Pr3+: 3F3,4 process (ET1) reached 96.27%, while that of the Er3+: 4I11/2 → Pr3+: 1G4 process (ET2) is only 2.17% in the Er3+/Pr3+ co-doped glass. Additionally, the energy transfer mechanism of Er3+ and Pr3+ ions was investigated using the Dexter theory, where the energy transfer microscopic parameters CD-A are 13.21 × 10−40 cm6/s and 0.89 × 10−40 cm6/s for the ET1 and ET2 processes, respectively. Finally, a numerical simulations laser model was developed to discuss the laser properties of the Er3+/Pr3+ co-doped TBLL fibers. The simulation results indicate that a 2.7 μm laser with a maximum output power of 2.26 W and slope efficiency of 13.89% could be achieved when the fiber background loss is reduced to 0.5 dB/m. The above results suggest that the Er3+/Pr3+ co-doped TBLL glass has great potential applications in mid-infrared fiber lasers.

Effect of phonon energy on 2 μm emission in Tm3+/Yb3+ co-doped bismuth-tellurite glasses based on WO3 or B2O3 adjustment

Tm3+/Yb3+ co-doped TeO2–Bi2O3–ZnO glass has been synthesized by using the melt-quenching method in this paper. According to Gaussian fitting and J-O theory, the impact of phonon energy on both structure and fluorescence properties has been investigated by introducing different phonon energy oxides. It was shown that various glass network units were observed in Raman spectra. Moreover, the Te–O–Te can be destroyed via the addition of WO3 and B2O3, resulting in [TeO4] transformed to [TeO3] and [TeO3+δ] groups, while thermal stability and fluorescence properties were enhanced. And the phonon energy (ħω0) increased from 758 to 926 (WO3) and 1097 cm−1 (B2O3). Meanwhile, the intensities of the absorption and fluorescence spectra were improved significantly by the change of glass network units. The effective fluorescent bandwidth (Δλeff) was raised from 223 to 227 and 231 nm, and the gain coefficient was from 1.60 cm−1 to 1.71 cm−1 and 1.72 cm−1. Finally, the micro-parameters for energy transfer processes have been calculated by using a spectral overlap method. Results indicate that the energy transfer process between Tm3+ and Yb3+ was more efficient with the high phonon energy oxide introduction (WO3 and B2O3), which provides practical significance that will be beneficial for obtaining the 2 μm high gain material.

An optical fiber temperature sensor based on fluorescence intensity ratio used for real-time monitoring of chemical reactions

An all-optical temperature sensor based on a fluorescence intensity ratio suitable for real-time monitoring of temperature in chemical reaction processes is proposed and experimentally demonstrated. The sensor can be used for online real-time measurement of the temperature of a chemical reaction system in a small and complex environment. The sensor probe was made of Er3+/Yb3+ co-doped TeO2–WO3–Na2O–ZnF2–Nb2O5 glass and combined with an all-optical sensor system using a discharge melting method. By making different Er3+/Yb3+ concentrations of glass, Er3+/Yb3+ co-doped TeO2–WO3–Na2O–ZnF2–Nb2O5 glass with the best luminescence intensity was explored, and the influence of different excitation powers on the sensing of high-power excitation light material sensing was analyzed. The thermal and optical properties of the material were analyzed, and the possibility of using it as a temperature sensor material was discussed experimentally and theoretically. The maximum temperature sensitivity of the sensor is 0.0067 K-1. Finally, it was applied in the actual chemical reaction.

Er3+/Yb3+ co-doped TeO2–ZnO–ZnF2–La2O3 glass with a high fluorescence intensity ratio for an all-fiber temperature sensor

Er3+/Yb3+ co-doped TeO2–ZnO–ZnF2–La2O3 (TZZL) glasses with different concentrations of Er3+ ions were fabricated. Strong green upconversion emission bands centered at 523 and 545 nm induced by 980 nm excitation were observed. The maximum emission intensity of the TZZL glasses was obtained at the Er3+ ion concentration of 0.2 mol%. High-temperature difference (ΔT = 131.8 °C) between the transition and onset crystallization temperatures was confirmed by differential thermal analysis curve. The relationship between fluorescence intensity ratio value and temperature was examined within 303–560 K. The maximum absolute sensitivity (Sa) and the maximum relative sensitivity (Sr) was 0.006 K−1 at 560 K and 0.012 K−1 at 303 K, respectively. A prototype of an all-fiber temperature sensor was designed, and its temperature-sensing performance within 293–383 K was evaluated. Results showed that the absolute errors were within ±1 K, and the largest value of relative standard deviation was approximately 0.2%, suggesting that Er3+/Yb3+ co-doped TZZL glasses have potential applications in optical-fiber temperature sensors.

Energy transfer and spectroscopic properties of Cr3+/Yb3+ co-doped TeO2–ZnO–La2O3 tellurite glasses under different wavelength excitation lights

In this paper, the upconversion/downconversion (UC/DC), visible (VIS) and near-infrared (NIR) emissions of Cr3+/Yb3+ co-doped TeO2–ZnO–La2O3 (TZL) tellurite glasses under different wavelength excitation lights were investigated. The CIE 1931 chromaticity coordinates for UC emission of Cr3+/Yb3+ co-doped TZL tellurite glasses under different excitation wavelengths were also investigated. Through the energy transfer (ET) and cooperative energy transfer (CET) processes from Cr3+ to Yb3+ and the combination of Cr3+-Yb3+ lead to the intensity of UC-, DC-, VIS-, NIR-emissions of Cr3+/Yb3+ co-doped TZL tellurite glasses significantly increased. Under different wavelength excitation lights, the optimal concentration of Yb3+ for the UC-, DC-, and VIS- emissions of Cr3+/Yb3+ co-doped TZL tellurite glasses is different. In addition, the ET, CET processes between Cr3+ and Yb3+ are also proposed and discussed.

Tailoring the Permittivity in Tellurium Dioxide By Co-Doping

Tellurium oxide (TeO2) due to its glass-forming characteristics, highly non-linear optical properties, good chemical resistivity, low UV- IR absorption, etc. are widely used in a variety of application like acoustic optical devices, radiation detectors, gas sensors. Apart from these applications very little studies emphasize on the dielectric property and its application. Prime aspect for the interest of this material is that the dielectric constant of about 17-25 have been reported for α-TeO2. Such a high dielectric constant may be considered as a potential characteristic sprouting the possibility of TeO2 in the microelectronic industry. In the present study (In0.5Nb0.5) x Te1-xO2 (x=0, 1, 3, 5 %) ceramics were prepared by the solid-state method by co-doping indium oxide and niobium pentoxide with TeO2 and we studied the composition dependence of doping on the dielectric properties (e.g., permittivity, dielectric loss, temperature, and frequency stability) of TeO2 ceramic. The crystal structure and vibrational modes were determined by XRD and Raman spectra respectively. SEM micrographs were used to view the morphology of the sample. XRD and Raman data shows the co-existence of the tetragonal phase of (In0.5 Nb0.5) x Te1-xO2 with space group P41212 along with highly symmetric cubic phase of In0.5 Nb0.5 Te3O8 with space group Ia-3 in the doped samples. From the quantification of XRD data, it is evident that by increasing the doping concentration evolution of the cubic phase is enhanced. Also, decrease in intensity of major Raman vibration modes related to TeO4 unit and the existence of new modes of vibration indicates the new bonding bridges formed which in turn has an effect on the basic structure of TeO2. Dielectric measurement of co-doped samples was carried out over frequency range 500 Hz to 1 MHz and temperature range 90 K to 420 K. Dielectric measurement shows a relevant enhancement of the dielectric constant for co-doped samples with ten times decline in loss (tan δ). As shown in the figure, it can be observed that with 1%, 3%, 5% doping there is an enhancement in ε value are 21.5, 22 and 27.5 respectively (at room temperature) with respect to un-doped TeO2. (ε =21). Also, the temperature and frequency dependence of dielectric constant shows a stable response. The incorporation of the cubic phase does influence the dielectric constant of the co-doped TeO2. By increasing the doping concentration, there is a proportional increase in the cubic phase and from XRD correspondingly the characteristic peak for TeO2 tetragonal phase gradually shifts towards larger diffraction angles indicating the reduction of unit cell volume [1]. This observation is a clear association reciting to the relation between the lattice constant from the XRD peaks and the dielectric constant of the co-doped TeO2. From the Clausius-Mossotti relation, it is can be interpreted that the dielectric constant enhancement through the cubic phase appearance accounts from the molar volume shrinkage [2]. Figure 1. Dielectric constant ε and tan δ of (In0.5 Nb0.5) x Te1-xO2 the samples as a function of indium and niobium co-doping. Reference: [1] Tomida K, Kita K, Toriumi A (2006) Dielectric constant enhancement due to Si incorporation into HfO2. Appl Phys Lett. 89:142902 [2] Shi F et al (2017) Crystal structure characteristics, dielectric properties and vibrational spectra of Nb-rich non-stoichiometric Ba[(Zn1/3Nb2/3)1−xNbx] O3 ceramics J. Mater. Sci., Mater. Electron. 2811455–63 Figure 1

Luminescence and Tm3+-to-Dy3+ energy transfer in TeO2:ZnO glass under NIR/UV excitation

A series of Tm3+/Dy3+ co-doped TeO2:ZnO glass samples were synthetized via fusion method and frequency up- and down-conversion (FUC and FDC) luminescence properties was investigated. A characterization through Raman spectrum and optical absorption of the glass host was first performed, followed by optical absorption and excitation spectra of the Tm3+/Dy3+ doped glass samples. Multi-wavelength light emission was observed in the blue (455 and 480 nm), yellow (580 nm), red (655 nm), and NIR (750, 800, 1400, and 1600 nm) regions, generated via up- or down-conversion, exploiting either NIR (1000–1240 nm) or UV (355 nm) excitation sources, respectively. The excitation routes of both FUC and FDC were proposed. The quasi-resonant overlap of Tm3+ and Dy3+ absorption, excitation, and luminescence spectra in the NIR and UV-VIS spectral regions led to efficient Tm3+-to-Dy3+ energy-transfer processes (Tm3+ [3F4] + Dy3+ [6H15/2] → Tm3+ [3H6] + Dy3+ [6H11/2], Tm3+ [1G4] + Dy3+ [6H15/2] → Tm3+ [3H6] + Dy3+ [4F9/2], and Tm3+ [3H4] + Dy3+ [6H15/2] → Tm3+ [3H6] + Dy3+ [6F5/2]). Time resolve fluorescence confirm Tm3+ ions as donors in the energy-transfer mechanism. The dependence of the luminescence and efficiency of the energy-transfer process upon concentration was evaluated using conventional rate equations.

Enhanced luminescence at 2.88 and 2.04 μm from Ho3+/Yb3+ codoped low phonon energy TeO2–TiO2–La2O3 glass

The high phonon energy and short infrared cut-off wavelength of conventional oxide glass (or crystal) hosts are the limitations to achieve mid-infrared (MIR, λ≥2.5μm) luminescence. In present study, the luminescence performance of low phonon and non-conventional TeO2-TiO2-La2O3-based glass (TTL) host doped with Ho3+ and Ho3+/Yb3+ has been investigated, for visible to MIR range. The MIR emission band with peak at 2.88μm (Ho3+:5I6→5I7) and NIR band at 2.04μm (Ho3+:5I7→5I8) has been realized from Ho3+ singly doped TTL glass due to low phonon energy and extended transmission window of the host. Intensity of MIR and NIR emission bands have enhanced significantly in Ho3+/Yb3+: TTL glass under Yb3+ excitation, signifying an efficient Yb3+→Ho3+ energy transfer. The Judd-Ofelt analysis, on Ho3+ absorption characteristics reveals relatively better radiative transition probability (34.4s−1) and branching ratio (10.5%), which is associated to Ho3+:5I6→5I7 transition. The effective bandwidth of 2.88μm emission band is 180nm, with stimulated emission cross-section is 4.26×10-21cm2 and its gain bandwidth has been evaluated as 7.67×10-26cm3. For 2.04μm (Ho3+:5I7→5I8) emission band, the effective bandwidth of 160.5nm and gain bandwidth of 7.26×10-26cm3 have been accomplished. The non-resonant Förster-Dexter method has been applied to Ho3+/Yb3+: TTL glass on emission (donor, Yb3+) and absorption (acceptor, Ho3+) cross sections. The evaluated donor-donor (CDD) and donor-acceptor (CDA) energy transfer micro-parameters are 1.02×10-38 and 5.88×10-41cm6/s respectively while, maximum energy transfer efficiency has been 80%. In concise, Ho3+/Yb3+ codoped TeO2–TiO2–La2O3 glass host has revealed its potential for MIR to NIR photonic applications.

Preparation and spectral characteristics of Tm3+/Ho3+ co-doped TeO2-B2O3-BaO glass.

TeO–B2O3–BaO glasses with different compositions were prepared by the conventional melt-quenching technique. The spectral properties of Tm3+/Ho3+ co-doped TeO–B2O3–BaO glasses with different doping concentrations were studied. In order to analyze the spectroscopic properties in detail, the Judd–Ofelt intensity parameters, spontaneous radiative probabilities, branching ratios, absorption and emission cross-sections, and gain coefficient spectra were calculated using Judd–Ofelt and McCumber theory based on the absorption and emission spectra. Meanwhile, the optimal doping concentration was determined as Tm2O3: 1.0 mol% and Ho2O3: 1.0 mol%. The results show that Tm3+/Ho3+ co-doped TeO–B2O3–BaO glass is an ideal mid-infrared laser gain medium.

A portable all-fiber thermometer based on the fluorescence intensity ratio (FIR) technique in rare earth doped TeO2–WO3–La2O3–Na2O glass

A portable all-fiber thermometer based on the fluorescence intensity ratio technique in Er3+/Yb3+ co-doped TeO2–WO3–La2O3–Na2O (TWLN) glass fiber was designed and its temperature sensing performance was determined.

Enhanced frequency upconversion and non-colour tunability in Er3+–Yb3+ codoped TeO2–WO3–Pb3O4 glasses

TeO2–WO3–Pb3O4 glasses codoped with Er3+–Yb3+ ions have been prepared by melting and quenching process. Judd–Ofelt analysis has been performed to calculate the various radiative parameters viz., radiative lifetime, branching ratio and stimulated emission crosssections by using the absorption spectra. The nephelauxetic ratio, bonding and covalency parameters have been determined to get the information about the nature of bonding between the rare earth ions and neighbouring oxygen atoms. The near infrared (NIR) to visible frequency upconversion (UC) study upon excitations with 980 nm and 808 nm diode lasers has been performed. The variations observed in the UC emission intensity arising from the Er3+ ions have been explained on the basis of efficient energy transfer Yb3+ → Er3+ ions and back energy transfer Er3+ → Yb3+ processes. On codoping with Yb3+ ions the intensity of the UC emission bands observed in the codoped glass upon excitation at 980 nm has been enhanced by many folds and explained on the basis of the oscillator strengths, UC emission crosssection and temporal evolution analysis. No tuning in the colour emitted from the codoped glass upon excitation at 980 nm is reported. The results suggested that the codoped glass may be suitable in making the NIR to visible upconverter and colour non-tunable optical devices.

Down- and up-conversion emissions in Er3+–Yb3+ codoped TeO2–ZnO–ZnF2 glasses

In this work, we report the near infrared and upconversion emissions of Er3+–Yb3+ codoped fluorotellurite TeO2–ZnO–ZnF2 glasses for different YbF3 concentrations ranging between 0.5 and 2wt%. The study includes absorption and emission spectra and lifetime measurements for the infrared and visible fluorescence. The energy transfer between Yb3+ and Er3+ ions is confirmed by the temporal behavior of the near-infrared luminescence of Yb3+ ions as well as by the enhancement of the 1532nm emission of Er3+ ions in the codoped samples. The Yb3+→Er3+ energy transfer efficiency is calculated from the Yb3+ lifetimes in single and codoped samples. Back transfer from Er3+ to Yb3+ ions is present under near infrared and visible excitation of Er3+ ions at 798 and 488nm respectively. An enhancement of the visible upconversion fluorescence is also observed in the codoped samples due to energy transfer from Yb3+ to Er3+ ions. The standardized value for the efficiency of the green upconversion emission is 1.06×10−4 for the codoped sample with 2wt% of YbF3 which is comparable to that reported in lead–zinc–tellurite glasses. The possible upconversion processes and mechanisms leading to the population of several excited levels are discussed.

Enhanced 2–5 μm emission in Ho3+/Yb3+ codoped halide modified transparent tellurite glasses

Ho3+/Yb3+ codoped TeO2–WO3–ZnO–ZnX2(X=F, Cl) glasses were prepared by melt-quenching method. The absorption spectra, transmittance spectra, X-ray diffraction (XRD) curves, Raman spectra and mid-infrared fluorescence spectra were measured, along with the Judd–Ofelt intensity parameters, stimulated emission and absorption cross-sections were calculated to evaluate the effects of halide amount of the spectroscopic properties. It is shown that the introduction of an appropriate amount of halide can further improve the mid-infrared fluorescence intensity through an enhanced phonon-assisted energy transfer between Ho3+/Yb3+ ions and the energy transfer mechanisms are investigated quantitatively in detail by calculating energy transfer microparameters and phonon contribution ratios. The results indicate that this kind of glasses is a promising material for mid-infrared optical fiber.

Effect of Tm3+ codoping on the near-infrared and upconversion emissions of Er3+ in TeO2–ZnO–ZnF2 glasses

In this work, we report the near-infrared emission and upconversion of Er3+–Tm3+ codoped fluorotellurite TeO2–ZnO–ZnF2 glasses for different Tm3+ concentrations by using steady-state and time-resolved spectroscopy. A broad emission from 1350 to 1700nm corresponding to the 3H4→3F4 (Tm3+) and 4I13/2→4I15/2 (Er3+) emissions which cover the complete telecommunication window of the wavelength-division-multiplexing transmission systems is observed. The full width at half-maximum of this broadband increases with increasing Tm3+/Er3+ concentration ratio up to a value of~150nm. Energy transfer between Er3+ and Tm3+ ions is also observed and analyzed by both the temporal behavior of the near-infrared luminescence and the effect of Tm3+ codoping on the visible upconversion of Er3+ ions. The addition of Tm3+ reduces the upconverted green emission due to Er3+→Tm3+ energy transfer whereas the red emission is enhanced due to the cross-relaxation 3F4→3H6(Tm3+):4I11/2→4F9/2(Er3+) process.

Multicolor visible light upconversion emission in Tm^3+–Er^3+ codoped TeO_2–PbO glass under near-infrared laser radiation

The multicolor intense visible emission from Er3+ and Tm3+ ions codoped in TeO2–PbO glass upon excitation at ∼1064 nm radiation from a nanosecond pulsed Nd:YAG laser has been investigated. The optical parameters of erbium ions codoped in Tm3+–TeO2–PbO glass by using the Judd–Ofelt theory have been determined from the optical absorption spectra. No upconversion (UC) emission was seen in the singly doped Er3+-doped glass upon excitation at 1064 nm. Through the experiments, it has been found that, in the codoped glass, the UC luminescence from Er3+ (2.0 mol. %) in green and red regions corresponding to the H211/2→I415/2, S43/2→I415/2, and F49/2→I415/2 transitions is strengthened about ∼40, ∼60, and ∼130 fold, respectively, at 2.0 mol. % Tm3+ ion concentration in codoped glass. The observed UC emissions and the enhancement observed in their intensity have been explained on the basis of efficient energy transfer and cross-relaxation energy transfer processes.

Er3+–Yb3+ co-doped TeO2–PbF2 oxyhalide tellurite glasses for amorphous silicon solar cells

In this study, we successfully prepared Er3+–Yb3+ co-doped TeO2–PbF2 oxyfluoride tellurite glasses with different Yb3+ concentrations and characterized their upconversion properties. Intense emission bands at 527, 544, and 657nm corresponded to the Er3+ transitions, and the maximum was obtained at an Yb3+-to-Er3+ molar ratio of 3. When this glass was applied at the back of amorphous silicon solar cells in combination with a rear reflector, a 0.45% improvement in efficiency was obtained under co-excitation of AM1.5 and 400mW 980nm laser radiation. Maximum external quantum efficiency and luminescence quantum efficiency of 0.27% and 1.35%, respectively, were achieved at 300mW excitation.

Optical and spectroscopic characterization of Er3+–Yb3+co-doped tellurite glasses and fibers

Optical and spectroscopic properties of Er3+–Yb3+ co-doped TeO2–WO3–Nb2O5–Na2O–Al2O3 glasses and fibers were investigated. Emission spectra and fluorescence lifetimes of 4I13/2 level of Er3+ion as a function of rare earth concentration and fiber length were measured in glasses. Results show that the self-absorption effect broadens the spectral bandwidth of 4I13/2→4I15/2 transition and lengthens the lifetime significantly from 3.5 to 4.6ms. Fibers were fabricated by the rod-in-tube technique using a Heathway drawing tower. The emission power of these Er3+–Yb3+ co-doped Step Index Tellurite Fibers (SITFs; lengths varying from 2 to 60cm) were generated by a 980nm diode laser pump and then the emission power spectra were acquired with an OSA. The maximum emission power spectra, within the 1530–1560nm region, were observed for fiber lengths ranging from 3 to 6cm. The highest bandwidth obtained was 108nm for 8cm fiber length around 1.53µm.