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A group of highly Er3+-doped TeO 2 –BaF 2 –LaF 3 –La 2 O 3 fluorotellurite glasses was prepared by high-temperature melting and rapid cooling. The Judd-Ofelt (J-O) theory intensity parameters, radiative transition rate, and radiative lifetime of Er3+ ions were calculated based on the absorption spectra. The luminecence spectra at 2.7 μm and luminescence lifetime curves of Er3+ ions in fluorotellurite glasses, excited at 980 nm, were studied. The fluorotellurite glass exhibits high infrared transmittance (88 %), excellent thermal stability (ΔT > 105 °C), and low phonon energy (781 cm-1). According to Fuchbauer-Ladenburg theory, the absorption and emission cross sections of Er3+-doped fluorotellurite glass at 2.7 μm are 5.50×10−21 and 6.28×10−21cm2, respectively. These findings suggest that the glass holds significant potential for applications in mid-infrared (MIR) fiber lasers. • The fluorotellurite glass possesses high infrared transmittance (88 %). • The prepared glass exhibits excellent thermal stability (ΔT > 105 °C). • The prepared glass has low phonon energy (781 cm-1). • The fluorotellurite glass exhibits strong luminescence at 2.7 μm. [ABSTRACT FROM AUTHOR]

A study of the optical, spectral-luminescent and holographic properties of the chlorine-containing photo-thermo-refractive (PTR) glass doped with neodymium ions was carried out. The chlorine-containing PTR glass has been recently produced by replacing the bromine in the standard PTR glass with chlorine. The glass was doped with different concentrations of neodymium ions. The spectroscopic analysis of neodymium in the glass has been performed using the Judd-Ofelt theory based on experimental absorption and emission measurements. Spectroscopic parameters, such as the Judd-Ofelt intensity parameters, radiative and non-radiative transition probabilities, fluorescence lifetimes, stimulated emission cross-sections, and branching ratios, were obtained and found to be comparable with the parameters of the standard PTR glass doped with neodymium. The mechanism of non-radiative energy transfer was analyzed based on the lifetime kinetics measurements. It was found that cross-relaxation among neodymium ions is the dominant non-radiative energy transfer mechanism. Holographic characteristics of the chlorine-containing PTR glasses doped with neodymium have been also studied. The volume Bragg grating was recorded in the doped and undoped glasses. It was found that the UV exposure and heat treatment do not change the spectroscopic characteristics of neodymium ions in the glasses, while the neodymium ions reduce the sensitivity of the glass. The energy transfer from cerium to neodymium when irradiating using the 325-nm laser makes the hologram recording possible on the samples of low neodymium concentrations only. Studying the spectroscopic and holographic properties of the chlorine-containing PTR glass doped with neodymium ions demonstrates the potential of using such a material in the applications of photonics integration and monolithic optical devices like distributed-feedback lasers. • Spectroscopic properties of Nd ions in Cl-PTR glass are comparable to those of Nd in the standard (Br-PTR) glass. • VBG was recorded in the undoped Cl-PTR glass, as well as in the glass doped with Nd. • UV exposure and heat treatment do not affect the spectral-luminescent properties of Nd in the Cl-PTR glass. • Nd reduces the photosensitivity of Cl-PTR due to energy transfer from Ce to Nd during the hologram recording at 325 nm. [ABSTRACT FROM AUTHOR]

The photoluminescence and scintillation properties of Sn2+-doped gadolinium aluminum-silicate Gd 2 O 3 –Al 2 O 3 –SiO 2 (GAS) glasses with Si 3 N 4 as reducing agent were investigated. The glasses showed a wide emission band in the range of 360–730 nm due to the relaxation of S 1 –S 0 and T 1 -S 0 of Sn2+ luminescent centers. The luminescent intensity of Sn2+-doped GAS glasses reaches maximum at 0.3 mol% Sn2+. The lifetimes of the glasses vary between 6 and 12 μs, which related to the full width at half maximum (FWHM) of the emission spectra. Different oxides were added to explore the relationship between optical basicity and the luminescent properties of glasses. The addition of B 2 O 3 increases the photoluminescence quantum yield (PL QY) of the glasses, which is due to reduction of the Stokes shift and increment of radiative transition probability in energy level transition. The X-ray induced scintillation luminescence of the glasses were observed and studied. • The relationship between Stokes shift and optical basicity of the aluminum-silicate glasses. • High photoluminescence quantum yield (PL QY) in the Sn-doped glasses. • Quantitative analysis of the effect of phonon-electron interaction during Sn2+ luminescence. • The luminescence of Sn2+ centers excited by X-ray was observed for the first time in aluminum-silicate glasses. [ABSTRACT FROM AUTHOR]

Abstract: The spectroscopic properties of tellurite glasses of composition (in mol%) TNKNd: (70− x)TeO2–15Nb2O5–15K2O–xNd2O3 (x =0.1, 1.0, 1.5, 2.0 and 2.5) and TNLNd10: 69TeO2–15Nb2O5–15Li2O–1.0Nd2O3 and lithium metaborate glass of composition LBNNd10: 89LiBO2–10Nb2O5–1.0Nd2O3 have been investigated using absorption and emission spectra and decay curve analysis. An energy level analysis has been carried out considering the experimental energy positions of the absorption and emission bands, using the free-ion Hamiltonian model. The spectral intensities have been calculated by using the Judd–Ofelt theory and in turn the radiative properties such as radiative transition probabilities, emission cross-sections, branching ratios and radiative lifetimes have been estimated. The decay curves at the lower concentrations are exponential while they show a non-exponential behavior at higher concentrations (⩾1.0mol%) due to energy transfer processes. The effective lifetimes for the 4F3/2 level are found to decrease with increase in Nd2O3 concentration for all the glasses under investigation. The non-exponential decay curves have been well-fitted to the Yokota–Tanimoto model with S =6, indicating that the nature of energy transfer is of dipole–dipole type and energy migration also plays an important role. The results obtained have been compared with Nd3+-doped phosphate, fluorophosphate, lead borate, tellurite, germanate and silicate glasses and Nd3+-doped YAG ceramic and Ca2Nb2O7 crystals. [Copyright &y& Elsevier]

Abstract: This article reports the effect of mixed alkalis on the optical absorption and emission spectra of Sm3+ and Dy3+ doped chloroborate glass matrices of the compositions 69.5B2O3 xLiCl(30− x)NaCl0.5R2O3 and 69.5B2O3 xLiCl(30− x)KCl0.5R2O3 (where R=Sm and Dy and x =5, 10, 15, 20 and 25). Using Judd–Ofelt theory, the spectral intensities and Judd–Ofelt intensity parameters (Ω 2, Ω 4 and Ω 6) were obtained from the measured absorption bands of the spectra. Using these intensity parameters, total radiative transition probabilities (A T), radiative lifetimes (τ R), branching ratios (β) and peak emission cross-sections (σ P) were obtained for the two rare earth ions in these two glass matrices. Variation of these parameters with x in the glass matrix has been discussed. It is found that for Sm3+ ion, the transition, 4G5/2 → 6H9/2 shows highest emission cross-section and is maximum at x =10mol% in lithium–sodium and at x =20mol% in lithium–potassium glass matrices. For Dy3+ ion, the transition, 4F9/2 → 6H13/2 shows highest emission cross-section and is maximum at x =20mol% in lithium–sodium and at x =10mol% in lithium–potassium glass matrix. [Copyright &y& Elsevier]

Abstract: Spectroscopic characterization for optical amplification and laser application of the Er3+-doped Bi4Si3O12 glass is performed through its absorption and luminescence spectra. The spontaneous radiative transition probabilities from the first seven excited states to the ending states are calculated to obtain the luminescence branching ratios and radiative lifetimes. Intense infrared to visible luminescence of the Er3+ ion is observed with 4I9/2 state excitation (800nm) under a 200mW laser excitation power. The value obtained for the ratio of the 4I11/2 → 4F7/2 excited-state absorption oscillator strength to the 4I15/2 → 4I11/2 ground state absorption oscillator strength is in accordance with those reported for Er3+-doped materials pumped efficiently at 4I11/2 level excitation wavelengths. Gain cross-section spectra as a function of the inverted population rate and the stimulated emission cross-section spectrum were determined for the 4I13/2 → 4I15/2 infrared (IR) laser transition. The large gain bandwidth of the 4I13/2 → 4I15/2 IR emission has resulted in being close to those reported for Er3+-doped oxide glasses suitable for broadband amplifiers. [Copyright &y& Elsevier]

Abstract: Fluorophosphates glasses YF3–BaF2–Ba(PO3)2 doped with Er3+ and Er3+–Yb3+ were prepared and the structures of the samples were briefly investigated. The experimental intensity parameters were calculated according to the Judd–Ofelt theory, from which the radiative transition probabilities, fluorescence branching ratios, and radiative lifetimes of Er3+ were obtained. Bright green and red upconversion emissions was observed in Er3+–Yb3+ co-doped samples excited by 980nm laser diode, and two-photons absorption processes were determined for the emissions by examining the dependence of the emission intensity on the excitation power. The concentration effects on the intensity and decay time of the upconversion emission revealed that growing Er3+ concentration declined the probability of sequential energy transfer from Yb3+ to Er3+, and thus increasing the intensity ratio of the red emission to the green ones. The temperature effects on the intensity ratios of different emission bands showed that the maximum transducer sensitivity based on the fluorescence intensity ratio (FIR) was calculated to be 0.0015/°C at 6°C. [Copyright &y& Elsevier]

Abstract: 53.3BiO1.5–33.3GeO2–13.4NaO0.5 (cation%) glasses with various Tm3+ concentration were prepared by melt-quenching method. These glasses show high density, high refractive index, low phonon energy and good stability against crystallization. Absorption spectra of Tm3+-doped bismuthate glass were measured to obtain the radiative lifetimes by Judd-Ofelt theory. The absorption (4.5×10−21 cm2) and emission (6.7×10−21 cm2) cross-sections were calculated by Beer–Lambert and McCumber theory. The results show that the Tm3+ (3F4 → 3H6) in these glasses have high spontaneous radiative transition probabilities and large stimulated emission cross-section. Then the fluorescence emission spectra were measured under 808nm excitation and the maximum emission intensity at 1.8μm is obtained at 0.9mol% Tm2O3 in the glasses. [Copyright &y& Elsevier]