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Dy3+-doped oxide glass with 30 mol.% Gd2O3 content in the glass host was prepared by melt quenching under CO reducing atmosphere. The luminescence properties were investigated under UV and X-ray excitation. The 4F9/2→6H J ( J = 15/2, 13/2, 11/2, and 9/2) luminescence was observed with intense blue (484 nm; 4F9/2→6H15/2) and yellow (576 nm; 4F9/2→6H13/2) emissions. Energy transfer from Gd3+ to Dy3+ ions was confirmed by photoluminescence excitation and emission spectra as well as photoluminescence decay measurements. The integral scintillation efficiency of 11% of Bi4Ge3O12 scintillator was obtained. [ABSTRACT FROM AUTHOR]

Highly transparent samarium (Sm3+) doped borophosphate glasses were prepared using the melt-quenching technique. The tunable light emission and wideband near-infrared luminescence properties of Sm3+-doped glasses were investigated systemically. Tuning the Sm3+ concentration and excitation wavelength can generate hues that vary from blue to white. Two wide luminescence bands in the 850 nm to 1070 nm range and in the 1100 nm to 1250 nm range, respectively, were also achieved. The results suggest that Sm3+-doped borophosphate glasses can be used as conversion materials for blue light-emitting diode chips to generate white light-emitting diodes and for optical amplification. [ABSTRACT FROM AUTHOR]

An Yb-Er co-doped phosphate glass double-clad fiber with hexagonal inner cladding was fabricated by stack-and-draw method. Output power of 4.9 W was extracted with slope efficiency of 30 % from the fiber with 55 cm in length. [ABSTRACT FROM AUTHOR]

We have demonstrated a 45 μm core diameter Neodymium-doped all-solid silicate glass photonic crystal fiber laser with a single mode laser output. The structure parameters and modes information of the fiber are both demonstrated by theoretical calculations using Finite Difference Time Domain (FDTD) method and experimental measurements. Maximum 0.8 W output power limited by launched pump power has been generated in 1064 nm with laser beam quality factor M2 1.18. [ABSTRACT FROM AUTHOR]

Abstract: Yb/Bi co-doped borophosphate glasses and fibers were prepared. The effect of Yb3+ on the near-infrared (NIR) luminescent properties and the mechanism of luminescence of Bi-ions were investigated. Under 976nm laser diode (LD) excitation, the NIR emission intensity of the glass with 8mol% Yb2O3 co-doped glass is ~37 times stronger than that of Bi singly-doped glass. The fluorescence lifetime increases by ~7 times with 5mol% Yb2O3 co-doped glass. The energy transfer efficiency is ~59.1%. It is also suggested that the broadband NIR luminescence pumped by 808nm and 976nm LDs derives from Bi+ and Bi2+, respectively. [Copyright &y& Elsevier]

We design and fabricate a silica optical fiber doped with yttrium aluminosilicate (YAS, Y 2 O 3 –Al 2 O 3 –SiO 2 ) nanoparticles in the core. The optical fiber is drawn directly from a silica tube with YAG (Y 3 Al 5 O 12 ) ceramics and silica powders (the molar ratio 1:18) in the core at the temperature of ∼1950 °C. The YAS nanoparticles are formed during the optical fiber drawing process. Supercontinuum (SC) generation in the optical fiber is investigated at different pump wavelength. At the pump wavelength of ∼1750 nm which is in the deep anomalous dispersion region, SC spectrum evolution is mainly due to multiple solitons and dispersive waves (DWs), and three pairs of multiple optical solitons and DWs are observed. When the pump wavelength shifts to ∼1500 nm which is close to the zero-dispersion wavelength (ZDW), flattened SC spectrum with ±7 dB uniformity is obtained at the wavelength region of ∼990–1980 nm, and only one obvious soliton and DW are observed. At the pump wavelength of ∼1100 nm, a narrow SC spectrum from ∼1020 to 1180 nm is obtained in the normal dispersion region due to self-phase modulation (SPM) effect. [ABSTRACT FROM AUTHOR]

A series of Ho 3+ -doped silica glasses containing different Al 2 O 3 /Ho 2 O 3 mole ratios were prepared successfully using a sol–gel method combined with high temperature sintering. The X-ray diffraction (XRD), nuclear magnetic resonance (NMR) spectra of 27 Al, and X-ray photoelectron spectra (XPS) of O1s, as well as the absorption and fluorescence spectra of the Ho 3+ ions in these silica glasses, were recorded and analyzed systematically. The 27 Al-NMR spectral studies indicated that Al 3+ ions entered the glass structure mainly in sixfold and fivefold co-ordination for the series of sol–gel HAS glasses with constant 0.2 mol% Ho 2 O 3 content. The NMR and XPS results obtained indicated a relationship between the amounts of Al 2 O 3 and Ho 2 O 3 and the Al coordination. Based on the structure and spectroscopic properties of the Ho 3+ -doped silica glasses, it was concluded that the optimum Al 2 O 3 /Ho 2 O 3 mole ratio for the Ho 3+ /Al 3+ co-doped silica glass for a 2-μm laser was 15. [ABSTRACT FROM AUTHOR]

Glasses with compositions of (95.8-x) SiO 2 –4Al 2 O 3 –xP 2 O 5 –0.2Nd 2 O 3 (in mol%, x = 0–10) were prepared. Structural variation caused by P 5 + was investigated by Judd–Ofelt parameters and Raman spectra. Results reveal that Nd 3 + preferentially coordinates to P O sites at molar ratio of P 5 + /Al 3 + > 1 and thus it leads to a sudden change in fluorescence effective linewidth, stimulated emission cross section, fluorescence lifetime and non-radiative transition rate of Nd 3 + ions. The fluorescence lifetime changes in the range of 315–379 μs. The emission cross section changes in the range of 1.39–1.79 × 10 − 20 cm 2 . With the increase of P 5 + /Al 3 + ratio, the fluorescence effective linewidth varies from 45.77 to 37.03 nm. The shortest fluorescence lifetime was observed at molar ratio of P 5 + /Al 3 + = 1. The maximum non-radiative transition rate of 1694/s occurred at molar ratio of P 5 + /Al 3 + = 1.25. The highest emission cross section of 1.79 × 10 − 20 cm 2 was obtained at the highest P 5 + /Al 3 + molar ratio. Furthermore, structure–property relationship in these glasses was discussed through Judd–Ofelt parameters and luminescent behaviors. [ABSTRACT FROM AUTHOR]

Lead silicate glass samples with varying lead oxide content were prepared in this study, and their luminescent properties were examined and analyzed. It was found that with increasing lead oxide content, the maximum phonon energies of the glass samples decreased, while their spontaneous transition probabilities first increased and then decreased. The influence of the spontaneous transition rate, A 10 , and the multi-phonon relaxation rate, W 10 , on the sample luminescent properties was analyzed using rate equations. As a result, it was found that with increasing lead oxide content, W 10 / A 10 decreased, while the quantum efficiency increased. Thus, the luminescent intensity at ∼2 μm increased in the glass samples with increased lead oxide content. The high luminescent intensity and long lifetime indicate that silicate glasses containing high levels of lead oxide could potentially be used in ∼2 μm lasers. [ABSTRACT FROM AUTHOR]

Two series of silica glasses [(95.9− x )SiO 2 –4Al 2 O 3 – x P 2 O 5 –0.1Yb 2 O 3 (in mol%, x =0–10) and (92− y ) SiO 2 –4Al 2 O 3 –4P 2 O 5 – y Yb 2 O 3 (in mol%, y =0–0.2)] were prepared by sol–gel method combined with high-temperature sintering. The relationship between the glass structure and spectroscopic properties is investigated. Significant alterations in density, refractive index, absorption and emission cross sections, fluorescence lifetime, and scalar crystal field N J are observed at a molar ratio of P 5+ /Al 3+ =1 due to the transformation of P 5+ structure type from AlPO 4 -like to PO 4 units. This structural change is clearly observed in Raman spectra. In addition, NMR experimental results suggest that Yb 3+ is mainly located in AlPO 4 -like but not SiO 4 units at a molar ratio of P 5+ /Al 3+ =1, and also Raman spectra reveals the presence of P=O linkage in samples with molar ratio of P 5+ /Al 3+ >1. This further demonstrates that it is due to the formation of P=O site but not the simple addition of P 2 O 5 in Yb 3+ /Al 3+ /P 5+ co-doped silica glass to significantly decrease the absorption and emission cross sections of Yb 3+ . It reflects in the change of Yb 3+ Stark splitting, and is revealed by the decline of Yb 3+ asymmetry degree. [ABSTRACT FROM AUTHOR]

Two series of Ho 3+ and Al 3+ co-doped silica glasses containing different Al 2 O 3 /Ho 2 O 3 mole ratios and concentrations of Ho 3+ ions were successfully prepared by the sol–gel method combined with high temperature sintering. Using the fluorescence spectra and fluorescence lifetimes, it was found that the optimum Al 2 O 3 /Ho 2 O 3 mole ratio of Ho 3+ and Al 3+ co-doped silica glass for realizing a 2-μm laser is 15. Ho 3+ and Al 3+ co-doped silica glasses with compositions of x Ho 2 O 3 –15 x Al 2 O 3 –(100−16 x ) SiO 2 (in mol%, x =0.14, 0.2, 0.3, 0.4, and 0.5) were designed to investigate the concentration dependence of the 2.0-μm emission and concentration quenching of the 5 I 7 emission. The Judd–Ofelt intensity parameters and the stimulated emission and absorption cross-sections of 0.3Ho 2 O 3 –4.5Al 2 O 3 –95.2SiO 2 were systematically studied. The analysis on the relationship between the 5 I 7 lifetime and the Ho 3+ doping concentration reveals that self-quenching for a rather large Ho 3+ doping range is well described by a limited diffusion process, and that the critical concentration for self-quenching is 4.84×10 20 ions/cm 3 . The results show that Ho 3+ and Al 3+ co-doped silica glass is an ideal candidate for realizing ~2-μm laser. [ABSTRACT FROM AUTHOR]

Tm 3+ /Al 3+ co-doped silica glass was prepared by sol–gel method combined with high temperature sintering. Glasses with compositions of x Tm 2 O 3 –15 x Al 2 O 3 –(100 − 16 x ) SiO 2 (in mol%, x = 0.1, 0.3, 0.5, 0.8 and 1.0) were prepared. The high thulium doped silica glass was realized. Their spectroscopic parameters were calculated and analyzed by Judd–Ofelt theory. Large absorption cross section (4.65 × 10 −21 cm 2 at 1668 nm) and stimulated emission cross section (6.00 × 10 −21 cm 2 at 1812 nm), as well as low hydroxyl content (0.180 cm −1 ), long fluorescence lifetime (834 μs at 1800 nm), large σ em × τ rad (30.05 × 10 −21 cm 2 ms) and large relative intensity ratio of the 1.8 μm ( 3 F 4 → 3 H 6 ) to 1.46 ( 3 H 4 → 3 F 4 ) emissions (90.33) are achieved in this Tm 3+ /Al 3+ co-doped silica glasses. According to emission characteristics, the optimum thulium doping concentration is around 0.8 mol%. The cross relaxation (CR) between ground and excited states of Tm 3+ ions was used to explain the optimum thulium doping concentration. These results suggest that the sol–gel method is an effective way to prepare Tm 3+ doped silica glass with high Tm 3+ doping and prospective spectroscopic properties. [ABSTRACT FROM AUTHOR]

New fluoroaluminate–tellurite glasses with high thermal stability were fabricated through introducing TeO 2 into the fluoroaluminate glass (AlF 3 –YF 3 –CaF 2 –BaF 2 –SrF 2 –MgF 2 ). 2.7 μm emission properties were investigated through the measured absorption and emission spectra. For the first time it was found that the OH − absorption coefficient at 2.84 μm was reduced to 1/15 for the fluoride system by introducing TeO 2 . X-ray diffraction showed that the sample without TeO 2 composition showed some crystallization phases when the glass was reheated. However, the addition of TeO 2 changed the crystallization mechanism and improved the glass forming ability of the fluoroaluminate glass. Enhanced 2.7 μm emission was observed in the fluoroaluminate–tellurite glass under 980 nm excitation and the calculated spontaneous transition probability ( А ), branching ratio ( β ) and emission cross section ( σ em ) were larger than some reported values. These results indicate that this kind of fluoroaluminate–tellurite glass has potential applications as host material for 2.7 μm lasers. [ABSTRACT FROM AUTHOR]

Spectroscopic property and energy transfer processes of singly doped and codoped Er 3+ and Nd 3+ fluoroaluminate glasses with low phosphate content are systematically analyzed. The absorption spectra of these glasses are tested, and the Judd–Ofelt (J–O) and radiative parameters are discussed based on J–O theory and the parameters changes substantially because of the other codoping ions. As for Nd 3+ : the main emission bands at 0.9 and 1.05 μm decrease in the codoped sample under the excitation of an 800 nm laser diode from the emission spectra because the Er 3+ : 4 I 11/2 level reduces the Nd 3+ : 4 F 3/2 level effectively through the energy transfer process Nd 3+ : 4 F 3/2 → Er 3+ : 4 I 11/2 . For Er 3+ , the emission at 1.5 μm is restrained by codoping with Nd 3+ ions from the energy transfer process Er 3+ : 4 I 13/2 → Nd 3+ : 4 I 15/2 . The emission at 2.7 μm is enhanced because the Nd 3+ ions deplete the lower level and exert a positive effect on the upper laser level. The microparameters of the energy transfer between the Er 3+ and Nd 3+ ions are calculated and discussed using Forster–Dexter theory. The energy transfer efficiencies of the Nd 3+ : 4 F 3/2 to the Er 3+ : 4 I 11/2 and the Er 3+ : 4 I 13/2 to the Nd 3+ : 4 I 15/2 are 28.8% and 74.5%, respectively. These results indicate that Nd 3+ can be an efficient sensitizer for Er 3+ to obtain Mid-infrared (Mid-IR) emission and the codoped Er 3+ /Nd 3+ fluoroaluminate glass with low phosphate content is suitable to be used as the fiber optical gain media for 2.7 μm laser generation. [ABSTRACT FROM AUTHOR]

Two novel Tm3+-doped silicate glasses (one with fluoride addition) with good thermal stability were prepared in this work. Luminescence properties of these two samples were compared. After the addition of fluoride, the luminescence intensity of 1.8µm was much improved whereas that of 1.47µm was reduced. The rates of nonradiative processes populating and depopulating 3F4 were calculated quantitatively and a new method of calculating the quenching rate of hydroxyls was proposed. It was found that multiphonon relaxation rate of 3F4→3H6 was really low and could be neglected in both samples. The addition of fluoride in glass could reduce the quenching rate of hydroxyls but raised the cross-relaxation (3H6+3H4→3F4+3F4) rate. Thus the quantum efficiency of 1.8µm luminescence was improved after the introduction of fluoride. [ABSTRACT FROM AUTHOR]

Abstract: Tm2O3-doped multi-component silicate glasses without alkali ions are prepared using a conventional melt quenching method. The Judd–Ofelt theory is applied to calculate the intensity parameters of the resultant glass. The intensity parameters of silicate glasses without alkali ions are larger than those of silicate glasses with alkali ions. The spontaneous radiation probability of the transition from 3F4 to 3H6 of glasses without alkali ions is 191.89s−1, which is larger than that of glasses with alkali ions. Moreover, the measured lifetime of the 3F4 energy level of glasses is larger too. Emission cross section results show a maximum value 3.89×10−21 cm2 at 1882nm. These findings indicate that the glass in this study can be used to realize ~2μm lasers. The effect of variations in Tm2O2 concentration on the emission properties is also studied. Cross-relaxation and emission intensity enhance with increasing Tm2O3 content. However, the lifetime of the 3F4 level decreases because of concentration quenching. The influence of OH groups on the emission properties is also investigated. [Copyright &y& Elsevier]

A broad Stark splitting of Yb 3+ -doped fluorophosphate (FP) core glass and phosphate cladding glass with outstanding thermal and mechanical performance were prepared in this work. Yb 3+ -doped FP core and phosphate cladding heterogeneous fiber with hexagonal-shape inner cladding was fabricated by the stack-and-draw method. A maximum output power of 2 W was obtained with slope efficiency of 25.6% from a 35 cm fiber. The laser spectrum had a full width at half maximum (FWHM) of 1.5 nm with the central wavelength at 1013 nm. Therefore, FP glass fiber might be a good alternative for gain medium in short-linear-cavity single-frequency fiber laser. [ABSTRACT FROM AUTHOR]

A Ho 3+ -doped silica glass, 0.08Ho 2 O 3 –1.6Al 2 O 3 –98.32SiO 2 (mol%), was prepared by the sol–gel method combined with high temperature sintering. The 2 μm luminescence properties of the Al 3+ /Ho 3+ co-doped silica core glass were investigated. A single-mode double cladding Al 3+ /Ho 3+ co-doped silica fiber with a 15 μm core diameter and 0.08 core numerical apertures was prepared. Pumped with a 1.95 μm Tm 3+ fiber laser, 320 mw laser output centered at 2040 nm with M 2 factor of 1.14 was obtained from a 150-cm-long double-cladding fiber. The laser has a threshold of 850 mw launched power with a slope efficiency of 48.46%. For the first time a robust single-mode 2 μm fiber laser was realized in a fiber with Al 3+ /Ho 3+ co-doped silica core glass prepared by the sol–gel method. [ABSTRACT FROM AUTHOR]

Yb 2+ -doped silica glass was prepared through vacuum sintering of solution-doped nanoporous silica glass powder. Spectroscopic properties of Yb 2+ ions were characterized with absorption, photoluminescence and radioluminescence spectroscopies. Photoluminescence band centering at 506 nm was observed and the lifetime is 51 μs. Under excitation of an X-ray tube, radioluminescence at 525 nm was obtained. This suggests that Yb 2+ -doped silica glass could be used to convert high-energy sources into visible photons. [ABSTRACT FROM AUTHOR]

Abstract: A novel Tm3+-doped lead silicate glass with good thermal stability was prepared in this work. Through thorough investigation of 2µm luminescent properties of the glasses, optimal Tm2O3 doping concentration was checked to be 3wt%. Double cladding fiber was prepared by stacking method. As a result, 2µm laser output was realized in a 40cm fiber and the maximum output power reached 70mw. [Copyright &y& Elsevier]