Er2O3-doped Glass Research Articles

Structural and spectroscopic properties of γ-ray irradiated Er3+-doped lead phosphate glasses

Structural and spectroscopic properties of varying concentrations of Er3+ ion in P2O5- PbO-K2O-Al2O3-Na2O (PPbKANEr) glasses were studied before and after consecutive γ-ray irradiation. FTIR spectra of all the contemplated glasses confirm the presence of characteristic vibrational bands mainly because of phosphate groups. The optical absorption spectra of Er2O3-doped glasses are more stable and do not exhibit any variations after γ-ray irradiation particularly when Er3+ ions are present in higher concentrations. Judd-Ofelt (JO) analysis was carried out for γ-ray irradiated glasses and the resultant three phenomenological intensity parameters were found to be Ω2 = 1.98, Ω4 = 0.78 and Ω6 = 1.24 (×10–20 cm2). A bright emission corresponding to 4S3/2 → 4I15/2 transition in the green region was observed with the excitation of 379 nm. Broad luminescence peak at 1535 nm (4I13/2 → 4I15/2) are observed in the region of 1400–1700 nm with the excitation of 980 nm. The important spectroscopic properties such as absorption (σabs(λ)) and emission cross-sections (σemi(λ)), gain band width (FWHM × σemi(λ)) for 4I13/2 → 4I15/2 transition at 1.53 µm were assessed for γ-ray irradiated PPbKANEr1.0 glass and the values found to be 6.73 × 10–21 cm2, 7.33 × 10–21 cm2 and 264 × 10–28 (cm3), respectively. The decay curves for the 4I13/2 → 4I15/2 transition of the γ-ray irradiated PPbKANEr glasses exhibit exponential nature and the lifetimes found to be decreased (3.72–0.62 ms) with the increasing Er2O3 concentration (0.05–4.0 mol%). The upconversion luminescence spectra exhibit two emissions at 525 nm (2H11/2 → 4I15/2) and 543 nm (4S3/2 → 4I15/2) in the green region along with a fairly feeble red emission at around 650 nm (4F9/2 → 4I15/2).

Er3+-doped tellurite glasses for enhancing a solar cell photocurrent through photon upconversion upon 1500 nm excitation

Trivalent erbium-doped tellurite glasses have been prepared and investigated with an aim to improve the efficiency of a Silicon (Si) solar cell through photon upconversion processes. The upconversion emissions at 548 nm (4S3/2, 2H11/2 → 4I15/2), 671 nm (4F9/2 → 4I15/2), 800 nm (4I9/2 → 4I15/2) and 975 nm (4I11/2 → 4I15/2) of Er3+ ions have been observed under 1500 nm laser excitation. The 3.0 mol% Er2O3-doped glass exhibits high upconversion emission at 975 nm compared to 0.01 and 0.5 mol% Er2O3–doped glasses. Temporal evolution studies confirm that energy transfer upconversion is responsible for observed upconversion emissions, which is in good agreement with a simple rate-equations model. The upconversion intensity and photocurrent of solar cell are found to increase with the increase of pump power of the laser. A significant enhancement in photocurrent of a solar cell has been observed, when the 3.0 mol% Er2O3-doped glass is placed over a solar cell under 1500 nm laser excitation. All the results indicate that 3.0 mol% Er2O3-doped glass could be suitable for enhancing the solar cell efficiency.

Spectroscopic and pump power dependent upconversion studies of Er3+-doped lead phosphate glasses for photonic applications

Er3+-doped lead phosphate glasses (PKAPbNEr) were prepared by a melt quenching technique and their spectroscopic properties were investigated for 1.54 μm fiber amplifier applications. Judd-Ofelt (JO) analysis was carried out from the absorption spectra of 1.0 mol% Er2O3-doped glass and the derived JO parameters were found to be Ω2 = 4.7, Ω4 = 0.7 and Ω6 = 1.2 (×10−20 cm2). The transition probabilities, branching ratios and radiative lifetimes for several excited states of Er3+ were predicted using JO parameters and refractive index. The stimulated emission-cross section of the green emission (4S3/2 → 4I15/2) has been determined to be 3.31 × 10−21 cm2. Absorption cross-section (σabs(λ)), emission cross-section (σemi(λ)) and gain bandwidth (FWHM × σemi(λ)) of 4I13/2 → 4I15/2 transition at 1.54 μm were deduced from the McCumber theory and found to be 4.97 × 10−21, 6.63 × 10−21 and 267 × 10−28 (cm2), respectively. The decay curves exhibit single exponential nature and the lifetimes were determined to be 4.50, 4.57, 2.61, 2.06, 1.48 and 1.04 ms for 0.05, 0.1, 0.5, 1.0, 2.0 and 4.0 mol %, respectively, for Er2O3-doped lead phosphate glasses. The results confirm that the present Er3+-doped lead phosphate glasses could be considered as promising candidates as gain media for photonic applications.

Influence of germanate anomaly on elastic, structural, and optical properties of xNa2O-(99–x)[80GeO2:20PbO]-1Er2O3 lead–germanate glasses

Abstract A sodium–lead–germanate glass system, with a composition of xNa2O-((100–y)–x)[80GeO2:20PbO]-yEr2O3 (x = 0–25 mol.%, y = 0, 1 mol.%), was prepared by melt quenching and used to investigate the effect of Na2O and Er2O3 on the germanate anomaly. The structural and optical properties of the glass samples were investigated using X-ray diffraction, Fourier transform infrared, and UV–Vis spectroscopy analyses. Elastic properties of Er2O3-doped glasses (y = 1) were studied by measuring longitudinal and shear velocities through the pulse-echo method at 5 MHz. Based on Fourier transform infrared spectroscopy analysis of Er2O3-doped glasses, the conversion of GeO4 into GeO6 indicates that the glass system possesses the germanate anomaly characteristic but has no density anomaly. Longitudinal, shear, bulk, and Young's moduli (C L, μ, K, and E, respectively) increased to their maximum values at x = 10 mol.% but decreased with increasing amount of Na2O added. This finding reveals the elastic nature of the germanate anomaly. Increase in elastic moduli indicates enhanced network rigidity of the glass system in the germanate anomaly region, where the coordination number increased with the transformation of GeO4 to GeO6. Subsequent decrease in elastic moduli (x > 10 mol.%) denotes weakened network rigidity of the glass system because of enhanced formation of non-bridging oxygen. Furthermore, analysis using bulk compression and ring deformation models reveals the nonlinear trends of K bc /K e ratio and average ring size diameter as a result of the germanate anomaly. The anomaly also influenced optical properties of both Er2O3-doped (y = 1) and Er2O3-free (y = 0) glasses, where the optical energy gap (E opt) decreased with the addition of Na2O up to 10 mol.% and slightly increased with more than 10 mol.% Na2O. By contrast, Urbach energy (E U) and refractive index (n) showed opposite trends to that of E opt. The behavior of E U indicates changes in defect concentration, which affects E opt and n.

Optical properties of Er^3+-doped K-Ca-Al fluorophosphate glasses for optical amplification at 153 μm

Er3+-doped K-Ca-Al fluorophosphate glasses were prepared by melt quenching technique and their thermal and optical properties were studied. The thermal stability factor was obtained to be 131 °C. The gain bandwidth, lifetime and quantum efficiency of the 4I13/2→4I15/2 transition were found to be 96.14 × 10−27 cm3, 5.41 ms and 61%, respectively for 1.0 mol% Er2O3-doped glass. The quenching concentration has been evaluated (Q = 2.30 mol%) and found to be higher compared to other reported glasses. These results clearly indicate that present glasses are suitable for laser as well as optical amplifiers in the 1.53 μm region.

1.53 µm luminescence properties of Er3+-doped K–Sr–Al phosphate glasses

Trivalent erbium (Er3+)-doped K–Sr–Al phosphate glasses were prepared and studied their spectroscopic properties as a function of Er2O3 concentration. Judd–Ofelt analysis has been carried out for 1.0mol% Er2O3-doped phosphate glass and in turn radiative properties have been evaluated for the excited levels of Er3+ ion. The radiative lifetime for the 4I13/2 level was found to be higher for the present glass when compared to other Er3+-doped glasses. The Er3+-doped glasses exhibit intense near infrared emission at 1.53µm corresponds to 4I13/2→4I15/2 transition as well as green emission at 546nm corresponding to 4S3/2→4I15/2 under 980nm and 488nm excitations, respectively. The emission cross-section spectrum for 1.0mol% of Er2O3-doped glass has been evaluated using McCumber theory. The gain cross-section has been evaluated as a function of population inversion, which revealed that the lasing action would be achieved at 1.53µm for a population inversion about 40%. Decay curves for the 4I13/2 level were measured and lifetimes have been determined for the studied glasses. The results indicate that the present glasses could be useful for laser as well as optical amplifiers at 1.53µm.

Optical characterization of Er3+-doped zinc fluorophosphate glasses for optical temperature sensors

Trivalent erbium doped zinc fluorophosphate glasses have been synthesized and their luminescence properties in the green visible range have been investigated as a function of temperature. The Judd–Ofelt theory has been used to predict the transition probabilities, branching ratios and lifetimes for the various excited states of Er3+ ions in 0.5mol% of Er2O3-doped glass. The effect of Er3+ concentration on temperature dependent luminescence has been studied for the wide temperature range from room temperature up to 773K. The fluorescence intensity ratio of the green emissions associated to the two transitions from the thermally coupled 2H11/2 and 4S3/2 levels to the 4I15/2 level of Er3+ ion has been studied as a function of temperature, and in turn used to determine the thermal sensitivity and relative thermal sensitivity of the glasses. In the present study, the maximum value for the thermal sensitivity of 79×10−4K−1 at 630K has been obtained for the lowest (0.01mol%) concentration of Er2O3-doped glass, one of the highest sensitivity found in the literature and quite close to the theoretical sensitivity calculated from the Judd–Ofelt theory. The results reveal that the zinc fluorophosphate glass having relatively low concentration of Er3+ ions can be useful as an optical temperature sensor due to their high sensitivity and the absence of radiative energy transfer processes.

Lattice vibration analysis of cryolite A 3B'X 6 and elpasolite A 2BB'X 6 compounds. A force constant calculation of Sr 2ZnTeO 6

Trivalent erbium doped zinc fluorophosphate glasses have been synthesized and their luminescence properties in the green visible range have been investigated as a function of temperature. The Judd–Ofelt theory has been used to predict the transition probabilities, branching ratios and lifetimes for the various excited states of Er3+ ions in 0.5 mol% of Er2O3-doped glass. The effect of Er3+ concentration on temperature dependent luminescence has been studied for the wide temperature range from room temperature up to 773 K. The fluorescence intensity ratio of the green emissions associated to the two transitions from the thermally coupled 2H11/2 and 4S3/2 levels to the 4I15/2 level of Er3+ ion has been studied as a function of temperature, and in turn used to determine the thermal sensitivity and relative thermal sensitivity of the glasses. In the present study, the maximum value for the thermal sensitivity of 79 × 10−4 K−1 at 630 K has been obtained for the lowest (0.01 mol%) concentration of Er2O3-doped glass, one of the highest sensitivity found in the literature and quite close to the theoretical sensitivity calculated from the Judd–Ofelt theory. The results reveal that the zinc fluorophosphate glass having relatively low concentration of Er3+ ions can be useful as an optical temperature sensor due to their high sensitivity and the absence of radiative energy transfer processes.