Search

The excitation with a commercial laser diode was measured to gain insight into the optical properties of Bi-doped germanate glasses and the possible mechanism involved for their use in broadband optical fiber amplifiers. The results showed that the optically properties and luminescence intensity of the Bi-doped glasses could be remarkably enhanced by the addition of dopants Ce[O.sub.2], [As.sub.2][O.sub.5], or [Y.sub.2][O.sub.3].

Abstract: Er3+-doped tellurite glasses TeO2–GeO2–Nb2O5–Na2O–K2O–ZnO have been investigated for developing 1.5-μm fiber and planar amplifiers. Effects of GeO2 and Nb2O5 on the thermal stability and optical properties of Er3+-doped tellurite glasses have been discussed. It is noted that the incorporation of GeO2 or Nb2O5 increases the thermal stability of tellurite glasses significantly. Er3+-doped GeO2- and Nb2O5-modified tellurite glasses exhibit the stimulated emission cross-section as great as 10.7×10−21 cm2, which is significantly higher than that of silicate and phosphate glasses. In addition, the intensity of upconversion luminescence of the Er3+-doped GeO2- and Nb2O5-modified tellurite glasses decreased clearly with increasing GeO2 or Nb2O5 content. As a result, Er3+-doped tellurite glasses might be a potential candidate for developing laser or optical amplifier devices. [Copyright &y& Elsevier]

Abstract: This paper investigated on the dehydration of Er3+-doped phosphate glasses using O2 +CCl4 bubble flow method. The influence of parameters of dehydration effect was studied systemically. It was found that the dehydration rate was rather rapidly at the initial stage of bubbling. Increasing gas flow rate and temperature could drive the dehydration process toward lower OH concentration in the melts. The dehydration process was carried out in open system and analyzed by thermodynamic theory of open system, which clarified the process of eliminating of OH groups from the glass melts with bubbling time and gas flow rate. A time-dependent empirical equation about reaction rate constant was derived, and the relationships between rate constant and bubbling flow rate, and temperature were also discussed. This analytical method could be applicable to the dehydration of glass melt using other dehydration agents. [Copyright &y& Elsevier]

Abstract: This paper reports on the optical spectroscopic properties and thermal stability of Er3+-doped antimony-borosilicate glasses for developing 1.5μm optical amplifiers. Upon excitation at 980nm laser diode, an intense 1.5μm infrared fluorescence has been observed with the maximum full width at half maximum (FWHM) of 90nm for Er3+-doped antimony-borosilicate glasses. The emission cross-section and the lifetime of the 4 I 13/2 level of Er3+ ions are 6.3×10−21 cm2 and 0.30ms, respectively. It is noted that the product of the emission cross-section and FWHM of the glass studied is as great as 567×10−21 cm2 nm, which is comparable or higher than that of bismuthate and tellurite glasses. [Copyright &y& Elsevier]

Abstract: This paper reports on frequency upconversion emission properties of Tm3+/Yb3+- and Ho3+/Yb3+-codoped Ga2O3–GeO2–Bi2O3–PbO glass upon excitation of 980nm laser diode. The dependence of the upconversion emission intensity upon the excitation power has been examined and the involved mechanisms have also been discussed. An intense blue emission at 476nm and two weak red emissions at 650 and 689nm have clearly been observed in Tm3+/Yb3+-codoped samples, which are assigned to the 1G4 → 3H6, 1G4 → 3F4 and 3F2,3 → 3H6 transitions of Tm3+ ions. The cube-like dependence of the 476 and 650nm emissions on the incident pump laser power, indicates three-photon contribute to the blue–red upconversion emissions, respectively. Meanwhile intense green and red emissions peaked at 545 and 660nm in Ho3+/Yb3+-codoped samples, which are ascribed to the transitions of (5F4, 5S2)→ 5I8 and 5F5 → 5I8 transitions of Ho3+, have been confirmed that two photons contribute to these upconversion processes. The observed upconversion emission intensity as function of Yb3+ concentration suggests that the presence of the Yb2O3 plays a major role in enhancing the upconversion emission efficiency. [Copyright &y& Elsevier]

Abstract: This paper reports on the spectroscopic properties and energy transfer in Ga2O3–Bi2O3–PbO–GeO2 glasses doped with Tm3+ and/or Ho3+. From the optical absorption spectra of Tm3+, Judd–Ofelt intensity parameters, radiative transitions probabilities, fluorescence branching ratios, and radiative lifetimes have been calculated using Judd–Ofelt theory. The measured differential scanning calorimetry result shows that the glass exhibits excellent stability against devitrification with ΔT =129°C. The measured luminescence spectra show that the 3H4 → 3F4 transition of Tm3+ upon 808nm laser diode excitation possess a broad full width at half-maximum of ∼126nm. The maximum value calculated stimulated emission cross-section and the measured lifetime of 3H4 level from the 1.47-μm transition are ∼4.73×10−21 cm2 and ∼0.239ms, respectively. It is noticed that codoping of Ho3+ could significantly enhanced the ratio of the intensity of 1.47–1.80μm by energy transfer via Tm3+: 3F4 →Ho3+: 5I7. [Copyright &y& Elsevier]

Abstract: We report on the blue-green-red up-conversion spectroscopic properties of Pr3+/Yb3+-codoped oxyhalide tellurite glasses upon excitation of a conventional 980nm laser diode (LD). Significant enhancement of the blue-green-red up-conversion emission intensity has been observed with increasing PbCl2 doping. The up-conversion intensity has a quadratic dependence on incident pump laser power, indicating a two-photon process. The population of the Pr3+ upper 3 P 0 emitting level was accomplished through a combination of a ground state absorption, energy transfer and excitated state absorption. 1.3-μm emission in the second telecom window originated from Pr3+:1G4→3H5 transition has also been investigated upon excitation at 980nm LD. The measured peak wavelength and full width at half-maximum of the fluorescent are 1335nm and ∼100nm, respectively. An enhanced 1.3μm emission with increasing PbCl2 doping has also been observed. Codoping of Yb3+ significantly enhance both the blue-green-red up-conversion emission and 1.3-μm emission intensity by way of a nonradiative Yb3+:2F5→Pr3+:1G4 energy transfer. [Copyright &y& Elsevier]

Abstract: Spectroscopic properties of Er3+-doped Na2O–Sb2O3–B2O3–SiO2 glasses have been investigated for developing 1.5-μm broadband fiber amplifiers. An intense 1.5-μm near infrared emission with a broad full width at half maximum (FWHM) of 88nm has been obtained for Er3+-doped 5Na2O–20Sb2O3–35B2O3–40SiO2 glass upon excitation with a 980nm laser diode. The obtained emission cross-section of the 4I13/2 → 4I15/2 transition and the lifetime of the 4I13/2 level of Er3+ ions are 6.8×10−21 cm2 and 0.36ms, respectively. It is noted that the product of the emission cross-section and the FWHM of the glass, σ e ×FWHM, is as great as 598.4×10−21 cm2 nm, which is comparable or higher than that of Er3+-doped bismuth-based and tellurite-based glasses. These special optical properties encourage in identifying them as important materials for potential applications in high performance optics and optical communication networks. [Copyright &y& Elsevier]