Spectral Properties of Erbium—Doped Oxyfluoride Silicate Glasses for Broadband Optical Amplifiers

The new oxyfluoride silicate glasses of Er^3 -doped 50SiO2-(50-x) PbO-xPbF2 were prepared. With increasing PbF2 content in the glass composition, the fluorescence full width at half maximum and lifetimes of the ^4I13/2 level of Er^3 increase, while the refractive indices and densities decrease. Er^3 -doped 50SiO2-50PbF2 glass showed broad fluorescence spectra of 1.55μm with a large stimulated emission cross-section and long lifetimes of ^4I13/2 level of Er^3 . Compared with other glass hosts, the gain bandwidth properties of Er^3 -doped 50SiO2-50PbF2 glass are close to those of tellurite and bismuth glasses, and have advantages over those of silicate, phosphate and germante glasses. The broad and flat ^4I13/2→^4I15/2 emission of Er^3 around 1.55μm can be used as host material for potential broadband optical amplifier in wavelength-division-multiplexing network system.     

Mechanisms and Concentration Dependence of Upconversion Fluorescence in Er^3＋ and Tm^3＋ Codoped Tellurite Glasses

We investigate the upconversion luminescence of Er3^ and Tm^3 codoped tellurite glasses under both the 975 and 80Ohm excitations. By Tm^3 codoping, the Er^3 green emission corresponding to the (^4S3/2, 2H11/2) → 4I15/2 transitions was quenched, while the red emission corresponding to the ^4F9/2 → ^4I15/2 transition was selectively sensitized. The red emission has a maximum in the range where the ratio of Er^3 - to Tm^3 -content is about two and its fluorescence intensity becomes 1.5 and 5 times larger at the maximum than those in the absence of Tm^3 for 975 and 800 nm excitations, respectively. The results were explained considering the influence of energy transfers between these two active ions.     

Composition Dependence of Spectroscopic Properties of Er^3＋ Doped TeO2-WO3-ZnO Glasses

Er^3 -doped TeO2-WO3-ZnO glasses were prepared and the absorption spectra, emission spectra and fluorescence lifetimes were measured. With more Te02 content in the glasses, the emission full width at half maximum (FWHM) increases while the lifetime of the ^4I13/2 level of Er^3 decreases. The stimulated emission cross-sectionof Er^3 calculated by the McCumber theory is as large as 0.86pm^2. The product of the FWHM and the emissioncross-section σe of Er^3 in TeO2-WO3-ZnO glass is larger than those in other glasses, which indicates that the glasses are promising candidates for Er^3 -doped broadband amplifiers. The Judd-Otfelt parameter Ω6 shows close composition dependence of the 1.5μm emission bandwidth. The more the TeO2 content is, the larger thevalues of Ω6 and FWHM.     

Structural and Upconversion Fluorescence Properties of Er^3＋／Yb^3＋-Codoped Lead-Free Germanium-Bismuth Glass

We study the structural and infrared-to-visible upconversion fluorescence properties of Er^3 /yb^3 -codoped leadfree germanium-bismuth glass. The structure of lead-free germanium-bismuth-lanthanum glass is investigated by peak-deconvolution of F~aman spectroscopy. Intense green and red emissions centred at 525, 546, and 657nm,corresponding to the transitions ^2H11/2 → 4I15/2, ^4S3/2 → 4I15/2, and 4F9/2 → 4I15/2, respectively, are observed at room temperature. The quadratic dependence of the 525, 546, and 657nm emissions on excitation power indicates that a two-photon absorption process occurs under 975nm excitation.     

Enhanced NIR emission in Ce^3＋/Er^3＋-doped YAG induced by Bi^3＋ doping

Ce^3＋/Er^3＋/Bi^3＋ triply-doped yttrium aluminum garnet （YAG） is synthesized using co-precipitation method. The Bi^3＋ concentration-dependent near-infrared （NIR） emission behavior is systemically in- vestigated. The NIR emission of Er^3＋ ions at 1531 nm is enhanced threefold by the addition of 7 mol% Bi^3＋. Bi^3＋doping results in the formation of exciton in YAG and the variation in the local environment of the doped rare-earth ions. The enhancement in NIR luminescence is ascribed to the combined effects of the sensitization of exciton→Ce^3＋ →Er^3＋ and the Bi^3＋ doping-induced adjustment of the local environment for Ce^3＋ and Er^3＋ ions.     

Characterization of Amplified Spontaneous Emission from Er^3＋-Doped Tellurite Fibre

We present the characterization of amplified spontaneous emission (ASE) from newly fabricated Er^3 -doped tellurite fibres.When pumped at 98Ohm,a very broad erbium ASE in the range 1450-1650nm is observed.The changes of ASE with regard to fibre lengths and pumping power were measured.The output of 2mW from an Er^3 -doped tellurite fibre ASE source is obtained with the pump power of 540mW.     

Frequency Upconversion Fluorescence Emission of Er^3＋-Doped Oxychloride Germanate Glass

Frequency upconversion fluorescence property of Er^3 -doped oxychloride germanate glass is investigated. Intense green and red emissions centred at 525, 546, and 657nm, corresponding to the transitions ^2H11/2→4I15/2,^4S3/2→^4I15/2, and ^4F9/2→^4I15/2, respectively, were simultaneously observed at room temperature. The quadratic dependence of the 525, 546, and 657nm emissions on excitation power indicates that a two-photon absorption process occurs under 975 nm laser diode (LD) excitation. The Raman spectrum investigation indicates that oxychloride germanate glass has the maximum phonon energy at-805cm^-1. The thermal stability of this oxychloride germanate glass is evaluated by differential scanning calorimetry, and thermal stability factor AT(△T = Tx -Tg) is 187℃. Intense upconversion luminescence and good thermal stability indicate that Er^3 -doped oxychloride germanate glass is a promising upconversion laser material.     

Tm^3＋-doped Ga2O3-GeO2-Bi2O3-PbO（PbF2） Glasses for 1.47-μm Optical Amplifications

We report the spectroscopic properties and thermal stability of Tm^3＋-doped Ga2O3-GeO2-Bi2O3-PbO（PbF2） glasses for 1.47-μm optical amplifications. Effects of PbF2 doping on the optical properties and thermal stability of Tm^3＋ -doped gallate-germanium-bismuth-lead glass are inestigated. The measured peak wavelength and full width at half-maximum of the fluorescence are 1465nm and - 120 nm, respectively： Siguificant enhancement of the 1.47-μm emission and the lifetime of a a^3H4 level with increasing PbF2 doping have been observed. The presence of GeO2 provides two potentials of increasing the thermal stability and shortening the ultraviolet cutoff band of host glasses.     

不同Tm3＋浓度掺杂碲酸盐玻璃光谱性质研究

制备了70TeO₂-20WO₂-10ZnO-xTm₂O₃系统玻璃，根据所测玻璃的吸收光谱，应用Judd-Ofelt(J-O)理论计算出Tm^3＋离子在碲酸盐玻璃的J-O强度参数、Tm^3＋在玻璃中的自发辐射概率A、荧光分支比β及荧光辐射寿命 τ_R 等各项光谱参数.测定了玻璃的荧光光谱，并计算了Tm^3＋在碲酸盐玻璃中的荧光有效线宽、峰值受激发射截 面.比较了Tm^3＋在不同掺杂浓度下的光谱特性，认为当Tm₂O₃掺杂浓度达到 0.8wt％—1wt%时，所获得的荧光强度与荧光线宽达到最佳值，掺Tm^3＋ 碲酸盐玻璃是一种理想的S波段宽带光纤放大器用基质材料. 关键词： 碲酸盐玻璃 宽带光纤放大器 荧光线宽 荧光峰值发射截面     

Spectroscopic properties in Er3＋/yb3＋ Co-doped fluorophosphate glass

Using the technique of high-temperature melting, a new Er3＋/Yb3＋ co-doped fluorophosphate glass was prepared. The absorption and fluorescence spectra were investigated in depth. The effect of Er3＋ and Yb3＋ concentration on the spectroscopic properties of the glass sample was also discussed. According to the Judd Ofelt theory, the oscillator strength was computed. The lifetime of 4113/2 level （t-m） of Er3＋ ions was 8.23 ms, and the full width at half maximum of the dominating emission peak was 68 nm at 1.53 μm. The large stimulated emission cross section of the Er3＋ was calculated by the McCumher theory. The spectroscopic properties of Er3＋ ion were compared with those in different glasses. The full width at half maximum and σe are larger than those of other glass hosts, indicating this studied glass may be a potentially useful candidate for high-gain erbium-doped fiber amplifier.