Spectroscopic study of thulium doped transparent glass ceramics

A systematic investigation on fluorescence spectroscopy of trivalent thulium doped in oxyfluoride glass ceramics containing LaF3 nanocrystals has been carried out in a spectral range from 400 to 900 nm under the direct excitation of 1D2 level at a low temperature. Specific optical transitions related to the fluorescence emissions are studied based on experimental measurements in frequency and time domain. Fluorescence emissions from the ions in crystal phase are distinguished from what in glass phase and their spectroscopic properties are explored. The dynamical process shows that the temporal decay of fluorescence emission consists of two parts： a rapid decay from the ions in glass phase and a slower decay from the ions in crystal phase.     

掺铒重金属氧氟硅铋酸盐玻璃的光谱性质

研究了重金属氧氟硅铋酸盐玻璃 (50-x)SiO2 xBi2O3 50PbF2(x=0, 3, 5, 8, 10, 13, 15 mol%)中Er3+离子的吸收光谱、荧光光谱、荧光半高宽、荧光 寿命和热稳定性能.应用Judd Ofelt理论计算了玻璃的强度参数Ωt(t=2,4,6)，应用 McCumber计算了能级4I13/2→4I15/2跃迁的受激发射截面. 结果发现荧光半高宽与Ω6有较大联系，Ω6越大，荧光半高宽越宽.对Er3+ 关键词： 重金属氧氟硅铋酸盐玻璃 光谱性质 Er3+离子 Judd Ofelt参数     

Spectroscopic properties of Tm ions in chalcogenide Ge-As-S glass containing minute amount of Ga and CsBr

We have experimentally confirmed that the absorption and emission properties for intra-4f-configurational transitions of Tm³⁺ ions doped in Ge-As-S glass, one of representative chalcogenide glasses, are modified dramatically upon the introduction of minute amount of Ga and CsBr, tantamount to a low doping level. This compositional adjustment makes local chemical environments of Tm³⁺ being rearranged spontaneously without any further thermal treatment applied. The hypersensitive ³H₆ ↔ ³F₄ transition, in particular, turns out to reflect the modified chemical environments more significantly than other transitions. Redistribution of the stark levels of ³F₄ manifold is mainly responsible for the significant changes in emission spectra for ³H₄ → ³F₄ and ³F₄ → ³H₆ transitions. Since the addition of small amount of the group III elements and alkali halides alters only the optical properties of rare-earth ions, while keeping thermal stability of the chalcogenide glass hosts unchanged, our compositional adjustment method would be quite useful for practical applications of rare-earth activated chalcogenide glasses.     

Spectroscopic properties of neodymium-doped tellurite glass fiber

Nd3+-doped tellurite glass and a single mode tellurite glass fiber with a core diameter of 8 μm were prepared in this work. The 1.33-μm emission from the 4F3/2→4I13/2 transition of Nd3+ with a spectral bandwidth of 55 nm in tellurite glass fiber is observed.The lifetime of 164μs of 4F3/2 level and quantum efficiency of about 100 ％ are obtained.     

一种新型掺铒碲酸盐玻璃的光谱性质研究

研究了一种新型掺Er³⁺碲酸盐玻璃的光谱性质；应用Judd-Ofelt理论计算了碲 酸盐玻璃中Er³⁺离子的强度参数Ω(Ω₂=479×10^-20 cm²,Ω₄= 152×10^-20cm²,Ω₆=066×10^-20cm2)，计算了离子的自发跃迁概 率，荧光分支比；应用McCumber理论计算了Er³⁺的受激发射截面(σ_{e=1040×1 0^-21cm²)，Er³⁺离子⁴I13/ 2→⁴I15/2发射谱的 荧光半高宽(FWHM=655nm)及各能级的荧光寿命(⁴I13/2 能级为τrad =399ms)；比较了不同基质玻璃以及不同类型碲酸盐玻璃中Er³⁺离子的光谱 特性， 结果表明该掺铒碲酸盐玻璃具有更好的光谱性能，更适合于掺Er³⁺光纤放大 器实现宽带和高增益放大. 关键词： 碲酸盐玻璃 光谱性质 Judd-Ofelt理论}     

Thin sol-gel bismuth silicate films

The sol-gel method is used to obtain thin films with the composition Bi₁₂SiO₂₀. The characteristic features of the technology for obtaining the films are presented. Diffractometry confirmed that the films possess γ-Bi₂O₃-type structure. The transmission spectra of the films were investigated. The spectral dependence of the absorption coefficient of the films matches well with the spectra determined using bulk Bi₁₂SiO₂₀ crystals. Fiz. Tverd. Tela (St. Petersburg) 41, 1003–1005 (June 1999)     

Spectroscopic properties of Ni and rare-earth codoped Ge-Ga-Sb-S glass

The infrared emission properties of rare-earth (i.e., Dy³⁺, Pr³⁺ or Sm³⁺) and nickel-codoped Ge-Ga-Sb-S glasses were investigated by photoluminescence measurements. It was found that the emission intensities of the rare-earth doped glasses were significantly weakened even with very few amount of nickel (i.e., 500 at. ppm). On the other hand, the nickel-doped glasses show larger indices of refraction, which property will be desirable in nonlinear optics. Our results, however, suggest that to obtain rare-earth doped chalcogenide glasses of better infrared emission property it is necessary to keep the nickel dopant as low as possible.     

Spectroscopic properties of Sm3+ ions in lead fluorophosphate glasses

The Sm³⁺-doped lead fluorophosphate glasses of composition 44P₂O₅–17K₂O–9Al₂O₃–(24?x)PbF₂–6Na₂O–xSm₂O₃, where x=0.01, 0.05, 0.1, 0.5, 1.0 and 2.0 mol%, have been prepared by conventional melt quenching technique and are characterized through differential thermal analysis, Raman, absorption and emission spectra and decay rate measurements. Free-ion Hamiltonian model for energy level analysis and Judd–Ofelt theory for spectral intensities have been used to analyze the spectroscopic properties of Sm³⁺ ions in lead fluorophosphate glasses. The decay rates for the ⁴G_5/2 level of Sm³⁺ ions have been measured and are found to be single exponential at lower concentration (≤0.1 mol% Sm₂O₃) and turn into non-exponential at higher concentrations (≥0.5 mol% Sm₂O₃) due to energy transfer through cross-relaxation. The experimental lifetimes for ⁴G_5/2 level of Sm³⁺ ions are found to decrease from 2.54 to 0.92 ms when the concentration increased from 0.01 to 2.0 mol% Sm₂O₃ due to energy transfer. In order to know the nature of the energy transfer mechanism, the non-exponential decay rates are well fitted to Inokuti–Hirayama model for S=6, which indicates that the energy transfer process is of dipole–dipole type.     

Nonlinear optical properties of Cu nanoclusters by ion implantation in silicate glass

Metal nanocluster composite glass prepared by 180 keV Cu ions into silica with dose of 1 × 10¹⁷ ions/cm² has been studied. The microstructural properties of the nanoclusters were analysed by optical absorption spectra and transmission electron microscopy (TEM). Third-order nonlinear optical properties of the nanoclusters were measured at 1064 nm and 532 nm excitations using Z-scan technique. The nonlinear refraction index, nonlinear absorption coefficient, and the real and imaginary parts of the third-order nonlinear susceptibility were deduced. The mechanisms responsible for the nonlinear response were discussed. Absolute third-order nonlinear susceptibility χ⁽³⁾ of this kind of sample was determined to be 2.1 × 10⁻⁷ esu at 532 nm and 1.2 × 10⁻⁷ esu at 1064 nm, respectively.     

Spectroscopic properties of Mn2+ in new bismuth and lead contained fluorophosphate glasses

Luminescence, absorption and electron spin resonance (ESR) spectroscopic measurements are performed for two new Mn²⁺ doped fluorophosphate glass systems containing bismuth and lead, respectively, i.e., 45Ba(PO₃)₂-55BiF₃ and 45Ba(PO₃)₂-55PbF₂, to elucidate the nature of dopant–ligand bonding in terms of the covalence degree of dopant–ligand bond and ligand field strength. It is found from luminescence measurements that an octahedral coordination of dopant is formed, which is the same as that in fluoroberyllate and phosphate glasses. The optical absorption measurements indicate that the position of the absorption band, ⁴T_1g(G), is red shifted, and the Racah coefficient B is 625 and 627 cm^-1, respectively, as ligand field strength increases in the order of fluoroberyllate, fluorophosphate, phosphate and silicate glasses. The hfs constant A determined from the ESR measurements is 94.33 and 92.12 Oe for two glass systems, respectively. The hfs constant A is also found to be 89.98 Oe and 94.33 Oe in the respective crystalline and glasses 45P₂O₅-55BiF₃. In addition, the resonance observed at g2 in both glass systems is mainly attributed to Mn²⁺ ions in an environment close to octahedral symmetry distorted by agglomeration of resonant centers. It, thus, can be concluded from the ESR measurements that the degree of covalency of dopant–ligand bond in both fluoroberyllate and phosphate glasses is similar, and the crystallization of the glass leads to an increase in the degree of covalency of the ligand–Mn²⁺ bond. PACS 42.70.Ce; 61.43.Fs; 78.55.Qr     

Polarization effects associated with two-wave interaction in bismuth titanate and bismuth silicate crystals

Polarization effects associated with two-wave interaction in Bi₁₂TiO₂₀ and Bi₁₂SiO₂₀ crystals are investigated. The experimental data are subjected to the required theoretical analysis. A new procedure is proposed for determining the density of acceptor centers (N _A) in photorefractive crystals. The values of N _A obtained by this procedure are in good agreement with published data. Fiz. Tverd. Tela (St. Petersburg) 39, 1990–1994 (November 1997)     

Formation and optical properties of CdSSe semiconductor nanocrystals in the silicate glass matrix

Technological conditions providing the formation of CdS _x Se_1−x semiconductor crystal grains with sizes ranging from 2 to 8 nm in a silicate glass matrix have been determined. As the temperature of forming annealing increases, the size of crystal grains increases without changes in their crystal structure and composition. The observed short-wavelength shift of the optical absorption edge indicates that the quantum confinement affects the energy band structure of the nanocrystals. Intense luminescence of the samples is due to radiative transitions involving defects at the semiconductor nanocrystal-silicate matrix interface or intrinsic defects of nanocrystals.     

Photosensitive bismuth ions in lead tungstate

Electron paramagnetic resonance (EPR) signals of Bi²⁺ ions have been detected in the EPR spectrum of manganese-, bismuth-, and tin-doped PbWO₄ single-crystals irradiated by xenon and mercury lamps at 100 K. The parameters of the Zeeman, hyperfine, and superhyperfine interactions and the localization of Bi²⁺ ions have been determined.     

Optical properties of Ag nanoparticle embedded silicate glass prepared by field-assisted diffusion

Ag nanoparticle embedded silicate glass was prepared by field-assisted diffusion, combined with post-annealing process. Surface plasmon resonance (SPR) bands were observed in the optical absorption measurement. The properties of optical absorption were strongly affected by the process parameters. With increasing electric field intensity and diffusion time, the SPR peak position and the full width at half maximum (FWHM) of the plasmon band were almost invariable. With increasing post-annealing time, the SPR peak was blue-shifted and the FWHM of SPR band decreased. The experimental results could be well simulated using modified Mie scattering theory considering the spill-out effects and the limitation of the mean free path.     

掺铒铋酸盐玻璃的光谱性质和热稳定性研究

测试了铋酸盐玻璃(85-x)Bi2O3-(10+x)B2O３-5Na2O(x=0，5，10，15，20，25 mol%)中Er3+离子的吸收光谱、荧光光谱、荧光寿命及热稳定性.应用Judd-Ofelt理论计算了铋酸盐玻璃中Er3+离子的强度参数(Ω2=(352—386)×10-20cm2,Ω4=(138—152)×10-20cm2,Ω6=(093—117)×10-20cm2),应用McCumber理论计算了Er3+离子的受激发射截面(σe=(70—95)×10-21cm2)及Er3+离子4I13/2→4I15/2发射谱的荧光半高宽(FWHM=57—79nm)，测得了Er3+离子４I13/2能级荧光寿命(τm=265—159ms)，分析了玻璃的热稳定性能.研究了Er3+离子各种光谱参数对成分的依赖性，发现随着玻璃中B2O3含量的增加，强度参数Ωt(t=2,4,6)、荧光半高宽(FWHM)、热稳定性均相应增加，而测得的荧光寿命却减小.比较了不同基质玻璃中Er3+离子的光谱特性，结果表明掺铒铋酸盐玻璃更适合于掺Er3+光纤放大器实现宽带和高增益放大. 关键词： 铋酸盐玻璃 光谱性质 成分依赖性 Er3+离子     

Spectroscopic properties of magnesium aluminosilicate glass-ceramics doped with divalent cobalt ions

Electronic absorption and luminescence spectra and nonlinear optical properties of magnesium aluminosilicate glass-ceramics doped with divalent cobalt ions are studied in relation to their synthesis conditions. The lifetimes of the ⁴ T ₁(⁴ P) and ⁴ T ₁(⁴ F) excited levels of tetracoordinate Co²⁺ ions in these glass-ceramics are found to depend on the cobalt concentration and lie within the ranges from 25 to 40 and from 120 to 450 ns, respectively. Using the absorption saturation curves, the ground state absorption cross section for the wave-length of 1.54 μm is estimated to be σ_GSA=3.3×10^?19cm². The induced emission of the tetrahedrally coordinated Co²⁺ ion, which dominates over the absorption from the excited state in the spectral range from 640 to 690 nm (⁴ T ₁(⁴ P)→⁴ A ₂ transition), is found.