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Abstract: An efficient near-infrared (NIR) quantum cutting (QC) involving the emission of two near-infrared photons for each blue photon absorbed is realized in RE3+/Yb3+ (RE=Pr, Tb, and Tm): GeO2–B2O3–ZnO–LaF3 glasses. Upon excitation of Pr3+, Tb3+, and Tm3+ ions with visible photons at 482, 483, and 467nm two near-infrared photons at 950–1100nm (Yb3+:2F5/2 → 2F7/2) through an efficient cooperative energy transfer from Pr3+, Tb3+, and Tm3+ to Yb3+, with an optimal quantum efficiency close to 200% has been demonstrated. The development of the near-infrared quantum cutting oxyfluoride glasses could open a route in achieving high efficiency silicon-based solar cells by means of downconversion in the visible part of the solar spectrum to ∼1000nm photons with a two fold increase in the photon number. [Copyright &y& Elsevier]

Abstract: In this paper, we report the influence of silver nanoparticles (NPs) on the luminescence properties of TeO2–ZnO–Nb2O5–MoO3 glass doped with trivalent praseodymium (Pr3+) ions. From the XRD, Raman and DTA measurements, glasses structural and thermal properties were determined. The experiments were performed with samples containing different concentrations of NPs controlled by heat-treatment of the glass. The enhancement of the Stokes luminescence with an increase of the NPs concentration was observed for these samples excited at 470nm. The influence of the NPs on the frequency upconversion (anti-Stokes) emissions of Pr3+ under excitation at 586nm was also investigated, in resonance with the 3H4→1D2 transition. The excited Pr3+ ions exchange energy in the presence of the nanoparticles, originating efficient conversion from orange to blue. The enhancement in the intensity of the luminescence at ∼493nm, corresponding to the 3P0→3H4 transition, is due to the influence of the large local field on the Pr3+ ions, which are located near the metallic nanoparticles. [Copyright &y& Elsevier]

Abstract: In this paper, we present the photoluminescence properties of Eu3+, Tb3+ and Tm3+-doped oxyfluoride alumino-silicate glasses and glass ceramics. The X-ray diffraction (XRD) and differential thermal analysis (DTA) profiles of these glasses have been carried out, to confirm their structure and thermal stability. Compared to Eu3+, Tb3+ and Tm3+-doped glasses, their respective glass ceramics have shown stronger emissions due to the presence of LiGdF4 crystalline phase. For Eu3+-doped glass and glass ceramics, five emission bands centered at 578nm (5D0 → 7F0), 592nm (5D0 → 7F1), 614nm (5D0 → 7F2), 652nm (5D0 → 7F3) and 698nm (5D0 → 7F4) have been observed with 394nm (5D0 → 7L6) excitation wavelength. Of them, 614nm (5D0 → 7F2) has shown bright reddish-orange emission. With regard to the Tb3+-doped glass and glass ceramic, four emission bands centered at 491nm (5D4 → 7F6), 545nm (5D4 → 7F5), 587nm (5D4 → 7F4) and 622nm (5D4 → 7F3) have been observed with an excitation at 377nm (3F6 → 5G6) wavelength. Of them, 545nm (5D4 → 7F5) has shown bright green emission. Emission bands of 1G4 → 3F4 (650nm) and 3F3 → 3H6 (708nm) transitions for the Tm3+:glass and glass ceramic, with an excitation at 3H6 → 1G4 (469nm) have been observed. The stimulated emission cross-sections of all the emission bands of Eu3+, Tb3+ and Tm3+:glasses and glass ceramics have been computed based on their measured full-width at half maximum (FWHM, Δλ) and lifetimes (τ m). [Copyright &y& Elsevier]

Abstract: In this paper, we present the photoluminescence properties of Pr3+, Sm3+ and Dy3+-doped transparent oxyfluoride alumino-silicate glasses. These glasses have shown strong emission and absorption bands in visible and near-infrared (NIR) region. From the measured absorption spectra, Judd–Ofelt (J–O) intensity parameters (Ω 2, Ω 4 and Ω 6) have been calculated for all the studied ions. For Pr3+-doped glass, emission bands centered at 532nm (3P0 → 3H5), 615nm (3P0 → 3H6) and 647nm (3P0 → 3F2) have been observed with 486nm (3H4 → 3P0) excitation wavelength. Of them, 647nm (3P0 → 3F2) has shown bright red emission. Emission bands of 4G5/2 → 6H5/2 (563nm), 4G5/2 → 6H7/2 (599nm) 4G5/2 → 6H9/2 (645nm) and 707nm (4G5/2 → 6H11/2) for the Sm3+:glass, with excitation at 6H5/2 → 4F7/2 (403nm) have been recorded. Of them, 4G5/2 → 6H7/2 (599nm) has shown a bright orange emission. With regard to the Dy3+:glass, a bright fluorescent yellow emission at 575nm (4F9/2 → 6H13/2) and blue emission at 484nm (4F9/2 → 6H15/2) have been observed, apart from 4F9/2 → 6H11/2 (663nm) emission transition with an excitation at 388nm (6H15/2 → 4I13/2 + 4F7/2) wavelength. The stimulated emission cross-sections of all the emission bands of Pr3+, Sm3+ and Dy3+:glasses have been computed based on their measured full-width at half maximum (FWHM, Δλ) and measured lifetimes (τ m). [Copyright &y& Elsevier]

Abstract: Luminescences from bismuth-doped lime silicate glasses were investigated. Luminescences centered at about 400, 650, and 1300nm were observed, excited at 280, 532 and 808nm, respectively. These three luminescence bands arise from three different kinds of bismuth ions in the glasses. The visible luminescences centered at 400 and 650nm arise from Bi3+, and Bi2+, respectively. The infrared luminescences cover the wavelength range from 1000 to 1600nm when exited by an 808nm laser diode. The full width at half maximum (FWHM) of the infrared luminescences is more than 205nm. The intensity of the infrared luminescence decreases with the increment in CaO content. We suggest that the infrared luminescences might arise from Bi+. Such broadband luminescences indicate that the glasses may be potential candidate material for broadband fiber amplifiers and tunable lasers. [Copyright &y& Elsevier]

Biosensors working in the second near-infrared (NIR-II) spectral region have recently gained great attention owning to their deep tissue bioimaging and high spatiotemporal resolution. However, there is still a challenge to develop efficient nanothermometers based on NIR-II luminescence. Herein, we present a pioneering advancement in the field of nanothermometry by synthesizing a novel nanothermometer, a composite of fluoride nanocrystals and quantum dots. This NaYF 4 :1Nd-Ag 2 S QDs@SiO 2 nanocomposite demonstrates exceptional functionality, being excited by a single light irradiation at 808 nm for NIR-II luminescence imaging. Notably, the composite emits at two distinct wavelengths-1064 nm and 1125 nm, attributable to Nd3+ and Ag 2 S QDs, respectively. This unique emission profile enables deeper tissue penetration, mitigating overheating risks compared to conventional excitation sources at 980 nm. Furthermore, the nanomaterials exhibit remarkable temperature-sensing capabilities, with maximum sensitivities of 0.81%K−1 (S R) at 333 K. These superior sensitivities outperform many existing temperature sensors relying on thermally coupled Stark sublevels. The SiO 2 matrix not only encapsulates and protects the fluoride nanocrystals and quantum dots but also shields them from aqueous environments, ensuring outstanding luminescence stability. Our findings highlight the potential of this nanothermometer as a highly efficient temperature sensor with promising applications in cutting-edge bioapplications. This development introduces a new frontier in temperature sensing and bioimaging, showcasing its potential for transformative contributions to the field. [Display omitted] • Successful synthesis of a novel nanothermometer based on a composite comprising fluoride nanocrystals and quantum dots. • The emission intensity of Nd3+ and Ag 2 S QDs serves as a temperature sensing mechanism (0.81%K−1 (S R) at 333 K). • A versatile platform allows the integration of two different luminescent nanomaterials to meet customized requirements. • The SiO 2 matrix shields NCs and Ag 2 S QDs from water environments, ensuring excellent luminescence stability. [ABSTRACT FROM AUTHOR]

• YAG single crystal fiber with end Sm3+ doped was prepared by LHPG method. • Optimal doping concentration of the Sm3+ ions was investigated. • Optical temperature sensing characteristics of YAG: 0.5 mol%Sm3+ were investigated. • The proposed optical temperature sensor has a wide temperature range from 303 to 1178 K. A series of YAG: x mol%Sm3+ single crystal (SC) materials, in which x is 0.3, 0.5, 1, 2, respectively, have been synthesized through laser heated pedestal growth (LHPG) method. The down-conversion luminescence properties of prepared fluorescent materials were investigated under a 405 nm laser. According to the results, 0.5 mol% was selected as the optimal doping concentration, and the integrated YAG single crystal fiber (SCF) with end Sm3+ doped was further fabricated. Then the optical temperature sensing characteristics were studied by the technique of the fluorescence intensity ratio (FIR) in detail. It shows that 4F 3/2 and 4G 5/2 of Sm3+ ions are thermally coupled energy levels. The FIR of the 4F 3/2 /4G 5/2 → 6H 5/2 increases monotonously as temperature rises, and its temperature measurement range can be extended to 1178 K. The maximum absolute sensitivity and maximum relative sensitivity are 3.046 × 10−4 K−1(1129 K) and 5.033 × 10−3 K−1 (500 K), respectively. Additionally, the FIRs of various emission bands from 4G 5/2 → 6H 5/2, 7/2 and the FIR of the emission sub-bands from 4G 5/2 → 6H 9/2 exhibit temperature dependence in 303–1028 K and 303–878 K, respectively. These results indicate that YAG: Sm3+ SC is a very promising high-temperature sensing material. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we present the near-infrared luminescence from Er–Yb, Bi–Yb, Bi–Nd codoped germanate glasses. Compared with Bi-doped glass, Bi–Yb codoped glass has shown broad infrared luminescence under 800nm excitation wavelength. The near-infrared spectra of Er3+–Yb3+ and Bi and Bi–Yb codoped glasses have shown full width at half maximum (FWHM) around 80nm, 240nm and 300nm, respectively, under 980nm and 800nm LD. The absorption band of the Yb3+ ion was located around 980nm. Though the absorption band of Yb3+ does not interact directly with the incident light at 800nm, near-infrared emission intensity has been highly increased in Bi–Yb codoped glass. We explained the relevant mechanism for the observed enhancement in the near-infrared emission intensity of Bi doped glass with Yb codoping under 800nm excitation. The measured lifetimes of Bi, Bi–Yb codoped glasses were 490μs and 815μs, respectively. The maximum stimulated emission cross sections for 1188nm and 1258nm emission bands of Bi and Bi–Yb codoped glasses were 9.003×10−21 cm2 and 5.445×10−21 cm2. These Er3+–Yb3+, Bi–Yb and Bi–Nd codoped glasses are promising materials for broadly tunable laser sources and broadband optical amplifiers. [Copyright &y& Elsevier]

Abstract: This paper report on the absorption and photoluminescence properties of Pr3+, Nd3+ and Ni2+ ions doped tellurite glasses. The X-ray diffraction (XRD) and differential scanning calorimetry (DSC) profiles of the host glass matrix have been carried out, to confirm its structure and thermal stability. From the measured absorption spectra, Judd–Ofelt (J–O) intensity parameters (Ω 2, Ω 4 and Ω 6) have been calculated for the rare-earth ions doped glasses and B, C, Dq parameters for transition metal ion-doped glass, respectively. The near infrared emission spectrum of Nd3+ ions doped glass has shown full width at half maximum (FWHM) around 50nm (for 4F3/2 → 4I9/2 transition), 50nm (for 4F3/2 → 4I11/2 transition) and 70nm (for 4F3/2 → 4I13/2 transition), respectively. Decay measurements were also carried out for Pr3+, Nd3+ and Ni2+ ions doped glasses. These glasses with better thermal stability and bright visible luminescence should have potential applications in optoelectronic materials and broadband amplifiers. [Copyright &y& Elsevier]

A series of LuAG: 5 mol%Yb3+/0.5 mol%Ho3+/x mol%Ce3+ (x = 0, 0.2, 0.5, 1.0, 2.0) up-conversion (UC) fluorescent materials were prepared using CO 2 laser heating zone melting method. The X-ray diffraction (XRD) patterns confirm that the prepared samples have a pure LuAG crystal phase. Under excitation of a 980 nm laser, the up-conversion luminescence (UCL) spectra of the prepared samples were obtained. Two UCL emission bands of Ho3+ ions were observed, including green emission band of the 5F 4 /5S 2 →5I 8 transition, and red emission band of the 5F 5 →5I 8 transition. Due to the cross-relaxation (CR) processes between Ce3+ ions and Ho3+ ions, the doping of Ce3+ ions can effectively improve the UCL efficiency of Ho3+ ions, and the emission intensity reaches maximum when doped with 1 mol% Ce3+. The temperature sensing characteristics of LuAG: Yb3+/Ho3+ and LuAG: Yb3+/Ho3+/Ce3+ from 303 K to 723 K were studied by fluorescence intensity ratio (FIR) method. By doping 1 mol% Ce3+ ions, the absolute sensitivity of the sample has been significantly improved, with the maximal absolute sensitivity of 0.0951 K−1 (303 K), and the maximal relative sensitivity of 0.0103 K−1 (343 K). The high sensitivity and wide measurement range make LuAG: Yb3+/Ho3+/Ce3+ UCL material ideal for temperature sensing. [Display omitted] • LuAG: Yb3+/Ho3+ doped with Ce3+ ions fluorescent materials were prepared by CO 2 laser zone melting method. • The doping of Ce3+ ions can effectively improve the emission intesnity of LuAG:Yb3+/Ho3+ materials. • The temperature sensing characteristics of LuAG: Ho3+/Yb3+/Ce3+ and LuAG: Yb3+/Ho3+ materials were compared by FIR method. • The LuAG: Yb3+/ Ho3+/Ce3+ has a temperature measurement range from 303 K to 723 K, and absolute sensitivity of 0.0951 K−1. [ABSTRACT FROM AUTHOR]

Te-Bi 2 Te 3 alloy thin film has grown on silicon dioxide substrate by thermal evaporation technique. The Bi 2 Te 3 rhombohedral structure enriched Te in the prepared thin film was identified by high solution transmission electron microscopy (HRTEM), X-Ray diffraction (XRD), Raman spectrum and X-ray photoelectron spectroscopy (XPS). Interestingly, the Te-Bi 2 Te 3 alloy thin film presents a changeover from saturable absorption (SA) to reverse saturable absorption (RSA) as continuously increasing the input intensity, which has been investigated using the open-aperture (OA) z-scan measurement under a femtosecond-pulsed laser at 800 nm. A high modulation depth of 48.3% and large saturation intensity of 24.1GW/cm 2 of the thin film were obtained. Moreover, a large nonlinear absorption coefficient β of ∼10 3 cm/GW is increased with the input intensity elevated. The research results demonstrate that the Te-Bi 2 Te 3 alloy thin film could be an emerging optical material for saturable absorber in Q-switched or mode-locking fiber lasers at low incident intensity while serve as optical limiter at high incident intensity. [ABSTRACT FROM AUTHOR]

PbSe quantum dots (QDs) were used to dope borosilicate glass with a composition of SiO 2 -B 2 O 3 -Al 2 O 3 -ZnO-AlF 3 -Na 2 O-PbO-Se, which was prepared using the conventional melt-quenching technique followed by heat treatment. We observed a broad near infrared (NIR) emission (960–1353 nm) band with a full-width-at-half-maximum (FWHM) value of 168–294 nm and a notable Stokes shift (139–167 nm), which depended on the temperature and duration of the heat treatment. At room temperature, the photoluminescence (PL) lifetime was approximately 1.24–1.92 μs, and it showed a clear dependence on the size and concentration of the QDs. The large FWHM and strong NIR emission of the PbSe QD-doped borosilicate glass may facilitate its application in NIR optical amplifiers and lasers. [ABSTRACT FROM AUTHOR]

We report the space-selective precipitation of Cr 3+ -doped ZnAl 2 O 4 crystals in aluminosilicate glass by femtosecond (fs) laser irradiation. The precipitation of ZnAl 2 O 4 crystal was confirmed by x-ray diffraction (XRD), Raman spectra and transmission electron microscopy (TEM), and the incorporation of octahedron Cr 3+ in ZnAl 2 O 4 crystal was testified by electron paramagnetic resonance (EPR) and luminescence spectra. The laser irradiated area shows greatly enhanced luminescence due to Cr 3+ transitions. This method is promising for waveguide laser and three dimensional (3D) optical storage. [ABSTRACT FROM AUTHOR]

We report a versatile, cost-effective and reproducible solid-state reaction approach to synthesize two-dimensional (2D) WS 2 with strong nonlinear optical performances. The reverse saturable absorption and nonlinear refraction properties of 2D WS 2 incorporated into PMMA were measured by the z-scan configuration under femtosecond pulses at 800 nm. The figure of merit and the nonlinear optical refractive index n 2 were calculated to be ∼ 0.40 × 10 −13 esu cm and ∼ 3.34 × 10 −4 cm 2 /GW, respectively. Furthermore, optical limiting (OL) effects of the WS 2 /PMMA composite were observed with OL threshold F OL ∼ 2.4 mJ/cm 2 , which is lower than those of previously reported OL materials. Such results imply the WS 2 /PMMA composite as a potential candidate for practical OL applications and the solid-state reaction technology provides a feasible approach for the preparation of 2D WS 2 applied in the field of nanophotonics. [ABSTRACT FROM AUTHOR]

Y 2 O 3 :0.5 mol%Tm3+/x mol%Yb3+(x = 3, 5, 7, 10) luminescent materials have been synthesized by the CO 2 laser zone melting method. With 980 nm excitation, the up-conversion luminescence (UCL) emission bands corresponding to 1G 4 →3H 6 , 1G 4 →3F 4 , 3F 2,3 →3H 6 , and 3H 4 →3H 6 transitions of Tm3+ ions were obtained in visible and near-infrared spectral regions, among which the luminescence emitted by 1G 4 →3H 6 , 3H 4 →3H 6 transitions shows obvious Stark splitting. Besides, the optimal doping concentration of Yb3+ is 5 mol%. The up-conversion luminescence spectra of Y 2 O 3 :0.5 mol%Tm3+/5 mol%Yb3+ were recorded from 224 K to 873 K. The temperature sensing properties of 3F 2,3 and 3H 4 , 1G 4(a) and 1G 4(b) energy levels of Tm3+ ions were investigated by the luminescence intensity ratio (LIR) method in a wide temperature range, and the possibility of using 3H 4(a) , 3H 4(b) thermally coupled levels (TCLs) of Tm3+ ions for temperature sensing was developed. The results show that 1G 4(a) and 1G 4(b) , 3F 2,3 and 3H 4 , 3H 4(a) and 3H 4(b) of Tm3+ ions are TCLs, and the Stark sub-levels own relatively high absolute sensitivity at low temperature, whereas the 3F 2,3 and 3H 4 TCLs of Tm3+ ions are more suitable for high temperature measurement. The results show that the Tm3+/Yb3+:Y 2 O 3 luminescent material can be a promising candidate for temperature sensing. • Tm3+/Yb3+:Y 2 O 3 phosphors with various Yb3+ concentrations were prepared by CO 2 laser zone melting method. • The dependence of luminescence emission intensity on Yb3+ ions doping concentration was investigated. • The proposed temperature sensor has a temperature sensing range from 224 K to 798 K. • The absolute and relative sensitivities reach the highest values of 2.13 × 10−3 K−1 at 371.3 K and 10.1 × 10−3 K−1 at 341.79 K, respectively. [ABSTRACT FROM AUTHOR]

We report a simple approach to activate the near-infrared (NIR) long persistent phosphorescence via redox reaction. NIR long persistent phosphorescence is observed in a Cr-doped non-gallate phosphor, i.e. CaTiO 3 : Cr with perovskite structure through heat treatment in reducing atmosphere, while no such phenomenon is observed in the sample with same composition and heat treated in air. The mechanism for activation of Cr-related long persistent phosphorescence is discussed. The designed phosphors successfully break the monopoly of the ordinary Cr 3+ -activated gallate phosphors with the spinel structure and provides a new route for design of long persistent phosphors. [ABSTRACT FROM AUTHOR]

Up-conversion (UC) is a promising route to harvest near-infrared (NIR) sunlight and enhance the power conversion efficiency (PCE) of photovoltaic (PV) cells. However, most of the UC materials have some bottleneck problems associated with them, such as own only narrower excitation band matching with the sun spectrum, lower UC luminescence efficiency, and considerable heat losses. Thus, it is essential to design and find a UC material that can absorb broadband NIR photons through an attractive route named thermal radiation for photon energy UC. In this work, we investigated the UC luminescence properties of single CeVO 4 materials, in which the excitation bands can be augmented at least a range of 808–1064 nm. We also confirmed that this kind of UC emission is triggered by the thermal absorption of VO 4 3− , which might be expanded to other single vanadate materials. The UC luminescence mechanisms were analyzed by power dependence and temperature modeling, and interpreted in terms of blackbody radiation theory. We demonstrated the possibility of photocurrent response in thin-film-hydrogenated amorphous silicon solar cell modified with CeVO 4 powders through blackbody radiation for harvesting NIR photons. Such single vanadate materials can absorb broader NIR photons for UC luminescence through blackbody radiation, will open a new door for the enhancement of the PCE in the next-generation concentrated PV cells. [ABSTRACT FROM AUTHOR]

Recently, long persistent phosphors (LPPs) have been considered to be the most prominent candidates for biomedical applications. However, the LPPs suffer from a dramatic decrease in luminescence intensity after incorporation into the tissue. Therefore, it is very necessary to develop the more competitive LPPs and acquire the reproducible tissue imaging. Here, we propose and experimentally demonstrate an effective bifunctional La 3 Ga 5 GeO 14 : Cr 3+ , Nd 3+ phosphor with the interesting characteristic of near-infrared long persistent phosphorescence and NIR-to-NIR Stokes luminescence. Cr 3+ and Nd 3+ ions are simultaneously selected as the emission centers in order to take advantage of the remarkable phosphorescence properties of Cr 3+ , and the appropriate energy level characteristic of NIR-excitation band (808 nm) and NIR-emission (1064 nm), and the ability as the brilliant auxiliary to create more efficient defects of Nd 3+ . The efficient dual-modal emission is, accordingly utilized to realize the convenient, high-resolution global detection and local imaging. [ABSTRACT FROM AUTHOR]

Highlights: [•] Abnormal elements redistribution behavior was observed in tellurite glass. [•] The refractive index and Raman intensity distribution changed significantly. [•] The relative glass composition remained unchanged while the glass density changed. [•] First time report on the abnormal element redistribution behavior in glass. [•] The glass network structure determines the elemental redistribution behavior. [Copyright &y& Elsevier]

Highlights: [•] Mono-dispersed ZnS: Mn nanocrystals were synthesized by a hydrothermal route. [•] Photoluminescence of nanocrystals were studied by steady and transient state spectra. [•] A novel energy transfer mechanism of ZnS: Mn nanocrystals was proposed. [ABSTRACT FROM AUTHOR]

Abstract: We report on excitation wavelength-dependent near-infrared luminescence from Bi-doped silica glass prepared by chemical vapor deposition technique. The peak position of the emission bands shows a complex change between 1120nm and 1270nm with increasing excitation wavelength from 280nm to 980nm. This behavior can be well explained by existence of two kinds of Bi active centers, Bi0 and Bi+, which contribute to the NIR emissions at 1120nm and 1267nm, respectively. [Copyright &y& Elsevier]

Abstract: Silicate glasses containing PbS quantum dots (QDs) with narrow size distribution were prepared through heat treatment. Transmission electron microscopy (TEM) results show that spherical PbS QDs are densely dispersed in the glassy matrix. Using ZnS–PbO to replace PbS as precursor of PbS QDs, the size distribution of PbS QDs in glasses becomes more uniform. Tunable infrared luminescence from 1100 to 2200nm has been obtained by controlling the glassy matrix and preparation parameters. Obvious optical amplification at communication windows of 1.55μm and 1.33μm is probed, and the PbS QDs doped glasses using ZnS–PbO as precursor exhibit larger optical amplification. The PbS QDs doped glasses with intense optical amplification are considered to be promising candidate as gain medium for broadband fiber amplifier and tunable fiber laser. [Copyright &y& Elsevier]

Abstract: Three individual primary colors were generated from only one piece of Er3+–Eu3+ co-doped oxygen-deficient germanate glass under UV light irradiation. Blue, green, and red emissions were originated from Ge-related oxygen-deficient defect centers (GODCs), Er3+ ions, and Eu3+ ions, respectively. Detailed photoluminescence spectra, decay curve analyses, and electron paramagnetic resonance measurements were carried and the results indicate the existence of energy transfer between Er3+ and Eu3+ ions, GODCs and Eu3+ ions. [Copyright &y& Elsevier]

Abstract: Tm3+–Yb3+ co-doped transparent oxyfluoride glass ceramics were prepared through thermal treatment of the as-prepared glasses. The precipitation of nanocrystals and the incorporation of Tm3+ and Yb3+ into the nanocrystals were confirmed by X-ray diffraction and absorption spectra. Based on the Judd–Ofelt theory, the J–O parameters Ω λ (λ =2, 4, 6), spontaneous radiative transition rates, radiative lifetimes and fluorescence branching ratios of Tm3+ in both as-prepared glasses and glass ceramics were calculated. Intense mid-IR emission and upconversion luminescence in the Tm3+ and Yb3+ co-doped glass ceramics were observed under 980nm excitation. Especially, compared with that of the as-prepared glasses, mid-IR luminescence intensity of Tm3+ in the glass ceramics was greatly enhanced. Desirable spectroscopic characteristics suggest that these oxyfluoride glass ceramics may be promising mid-IR laser active medium. [ABSTRACT FROM AUTHOR]

Abstract: Long lasting phosphorescence has been observed in oxygen-deficient zinc–boron-germanosilicate glass–ceramics after 254nm ultraviolet lights irradiation at room temperature. Electron spin resonance (ESR) spectrum confirms the presence of two paramagnetic centers. And the ESR signal shows a synchronized decay process with afterglow intensity after removing the excitation light, suggesting the afterglow is associated with the paramagnetic centers which are generated during the irradiation. Based on the approximate t −1 decay law of the phosphorescence intensity, the long lasting phosphorescence is attributed to thermal assisted tunneling recombination between pairs of distant electrons and Ge-related oxygen-deficient centers. [Copyright &y& Elsevier]

Abstract: RE3+-Yb3+ (RE=Er, Tm, and Tb) codoped lanthanum aluminum germanate LaAlGe2O7 (LAG) glasses are prepared by melt-quenching method. The blank LAG glass has good transparency in UV/VIS/NIR/MIR range, which makes it suitable for RE ions doping. The doped glasses show strong upconversion (UC) emission under the excitation of a 980nm laser diode assisted by two or three photons. The UC from Er3+/Yb3+ and Tm3+/Yb3+ codoped LAG glasses show high color purity. The mechanism is also discussed to explain the UC processes. [Copyright &y& Elsevier]

Abstract: We report on the luminescence properties of reduced SrO–Al2O3–GeO2 glasses. Metal Al instead of corresponding oxide (Al2O3) is added into SrO–Al2O3–GeO2 glasses in order to control the oxygen-deficient defects. The obtained transparent glass samples, in which Ge2+ defects are stable, emit bright blue, white, and red light when excited by 300, 335 and 370nm ultraviolet light, respectively. Quantities of the defects can be controlled by adjusting the amount of metal Al, resulting in tunable luminescence from blue to white and to red. The origins of different luminescence centers are discussed and the color coordinates of the photoluminescence spectra are also calculated. [Copyright &y& Elsevier]

Abstract: A femtosecond laser with 800nm, 250kHz and 150fs has been used to irradiate Eu3+-doped BaO–TiO2–SiO2 glasses. It is found from micro-Raman spectra and optical microscope that crystalline dots and lines are formed around the focal point of the femtosecond laser beam. Both blue emission at 400nm due to the second harmonic generation and red emission due to the transitions of Eu3+ are observed from the irradiation region with the precipitation of Ba2TiSi2O8 crystal. The mechanism of the observed phenomenon is discussed. [Copyright &y& Elsevier]

Abstract: Transparent Ni2+-doped Li2O–Al2O3–SiO2 glass–ceramics were prepared. β-Eucryptite nanocrystals were precipitated from the glass matrix after heat-treatment. X-ray diffraction analysis revealed that the crystallite sizes were 30–40nm, and the average size increased with increasing temperature. Broadband infrared luminescence centered at around 1300nm with full width at half maximum (FWHM) of more than 300nm was observed from the Ni2+-doped glass–ceramic heat-treated at 650°C for 2h. Optical absorption spectra indicated that Ni2+ ions moved from trigonal bipyramid five-fold sites in the as-made glass to octahedral sites in the glass–ceramics at first, and then to distorted octahedral sites with increasing temperature. The blue-shift of the peak position and the intensity decrease of the infrared luminescence could be attributed to the sites change of Ni2+ ions in the glass–ceramics. [Copyright &y& Elsevier]

Abstract: We report the effect of NiO on the luminescence properties of bismuth-doped barium aluminosilicate glasses. Visible luminescence at about 425nm and broadband infrared luminescence at about 1330nm are observed from the bismuth-doped barium aluminosilicate glasses when excited by ultraviolet light and 808nm laser diode, respectively. The intensity of the two emissions decreases with increasing NiO concentration. The mechanisms of the observed phenomena are discussed. [Copyright &y& Elsevier]

The YAG: Ho3+/xCe3+/Yb3+(x = 0.0, 0.2, 0.5, 1.0 mol%) up-conversion luminescence (UCL) materials were prepared with a melting method utilizing CO 2 lasers. The UCL spectra of the prepared samples were measured under the excitation of a 980 nm laser diode. Since the energy gaps between 5I 6 and 5I 7 levels, 5F 4 /5S 2 and 5F 5 levels, 5F 2,3 /3K 8 and 5F 4 /5S 2 levels of Ho3+ match well with the energy gap between 5F 5/2 and 5F 7/2 levels of Ce3+, the generation of three cross-relaxation (CR) processes between Ho3+ and Ce3+ enables the doping of Ce3+ ions to tune the intensity and intensity ratio of the green emission to the red emission of the YAG: Ho3+/Yb3+ sample. The temperature sensing performances of the samples were analyzed. When both the temperature measurement range and sensitivity are considered, the YAG: Ho3+/0.2 mol%Ce3+/Yb3+ sample may be a more promising candidate for the temperature sensing material, the temperature measurement range of which is 298–1023 K, and the maximum absolute sensitivity and relative sensitivity are 0.0514 K-1 and 0.0094 K-1, respectively. • YAG: Ho3+/Yb3+ luminescence materials co-doped with Ce3+ ions have been prepared by melting method with CO 2 laser. • The intensity ratio of the green emission to the red emission of the YAG: Ho3+/Yb3+ materials can be tuned by doping Ce3+ ions. • The temperature sensing performance of YAG: Ho3+/Yb3+ materials are improved by doping Ce3+ ions. • The temperature measurement range of the sample with the 0.2 mol% Ce3+ doping can be extended from 298 K to 1023 K. [ABSTRACT FROM AUTHOR]

Abstract: We have investigated the space selective precipitation of silver nanoparticles inside Er3+ and Ag+ co-doped silicate glasses by focused femtosecond laser irradiation. Local heating effect of erbium resulted in direct precipitation of silver nanoparticles. We suggest that the local heating effect of Er3+ ions be also helpful to directly fabricate functional nanoparticles other than silver nanoparticles in transparent glasses. [Copyright &y& Elsevier]

Abstract: Water-soluble CdTe quantum dots (QDs) with green and yellow emission are prepared in aqueous solution using thioglycolic acid (TGA) as stabilizing agent. The as-obtained CdTe QDs are characterized by absorption and photoluminescence spectra. Strong emission is observed when the CdTe QDs are excited by an 800nm femtosecond laser. The ln–ln relations between the integral intensity of CdTe QDs and the excitation power are investigated, and the results indicate that the upconversion luminescence is a two-photon assisted process via a virtual energy state. [ABSTRACT FROM AUTHOR]

Abstract: α-Bi2O3 nanoparticles have been produced by femtosecond laser ablation in ethanol at room temperature. Their crystal structure, crystal phase, shape and size distribution, and photophysical property are investigated using X-ray diffraction, Raman, transmission electron microscopy (TEM), high-resolution TEM and UV–vis spectroscopy. The α-Bi2O3 nanoparticles produced by laser ablation with two particle size population distributions having the mean particle size of ∼10 and ∼60nm exhibited a good photocatalytic activity on the photodegradation of indigo carmine under 365nm light emitting diode irradiation. [ABSTRACT FROM AUTHOR]