Diode laser pumped Gd2O3:Er3+/Yb3+ phosphor as optical nano-heater

An intense green upconversion (UC) emission (λ _exc=976 nm) followed by the heating effect in Yb³⁺/Er³⁺ co-doped Gd₂O₃ nanoparticles has been detected. A temperature rise up to 504 K has been observed (on a noteworthy low laser excitation of 290 mW) using fluorescence intensity ratio (FIR) method of the thermalized UC luminescence bands ²H_11/2→⁴I_15/2 and ⁴S_3/2→⁴I_15/2 of Er³⁺ ion. The reported controlled optical heating of nanoparticles and its nano-volume has potential applications in biomedicines and in the creation of holes in soft materials.     

Efficient UV–visible up-conversion emission in Er3+/Yb3+ co-doped La2O3 nano-crystalline phosphor

A nano-crystalline La₂O₃: Er³⁺/Yb³⁺ phosphor sample has been synthesized through the solution combustion route using urea as a reducing agent. Thermal, structural and optical characterizations have been carried out to explore several of its properties. By thermal analysis one concludes to the presence of moisture and hydroxide phases [La(OH)₃ and LaOOH] of lanthanum in the as-synthesized sample, which further changes to La₂O₃ phase above 600°C temperature. Up-conversion (UC) study shows the intense emission bands in the UV, blue, green and red regions. This paper also reports the first observation of UC emission bands extending up to the UV (240 nm) region on excitation with 976 nm wavelength. Heat treatment of the samples shows a change in the crystallite phase along with crystallite growth and relative UC luminescence intensities. The input pump power dependence shows the involvement of up to four photons.     

Up conversion luminescence of Yb3+–Er3+ codoped CeO2 nanocrystals with imaging applications

The effects of Yb³⁺ doping on up conversion in Yb³⁺–Er³⁺ co-doped cerium oxide nanocrystals are reported. Green emission around 545 and 560 nm attributed to the ²H_11/2, ⁴S_3/2→⁴I_15/2 transitions and red emission around 660 and 680 nm due to ⁴F_9/2→ ⁴I_15/2 transitions under 975 nm excitation were studied at room temperature. Both green and red emission intensities increase as the Yb³⁺ concentration increases from 0%. Emission strength starts to decrease after the Yb³⁺ concentration exceeds a critical amount. The green emission strength peaks around 1% Yb³⁺ concentration while the red emission strength peaks around 4%. An explanation of competition between different decay mechanisms is presented to account for the luminescence dependence on Yb³⁺ concentration. Also, the application of up converting nanoparticles in biomedical imaging is demonstrated.     

Color tunable emission from (GdxY1−x)2O3: Er3+, Yb3+ phosphor prepared by combustion method

The (Gd_xY_1?x)₂O₃: Er³⁺, Yb³⁺ [x=0.0, 0.1, 0.5, 0.9, 1.0] phosphor samples with 0.5 mol% concentration of Er³⁺ and 3.0 mol% of Yb³⁺, have been prepared using combustion route. The effect of variation of composition on the morphology, crystallinity and photoluminescence characteristics of the material has been investigated. The samples were post-heated at a temperature 1200 °C, for 5 h. We find systematic color tunability from red to green with an increase of Gd₂O₃ content in Y₂O₃ lattice. Further, the post-heated samples show an enhancement of fluorescence intensity for more than fifteen times. The samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), photoluminescence measurement and Fourier transform infrared (FTIR) techniques in order to find out the structural changes in host lattice. An increase in crystallite size has been marked with increasing Gd content while FTIR analysis explains the reason of variation in the fluorescence of rare earth ions in different host matrices.     

Colour emission tunability in Ho3+–Tm3+–Yb3+ co-doped Y2O3 upconverted phosphor

The frequency upconversion (UC) emission throughout the visible region from the Y₂O₃:Ho³⁺?CTm³⁺?CYb³⁺ co-doped phosphors synthesized by using low temperature combustion process upon excitation with a diode laser operating at 980?nm have been presented. The colour emission tunability in co-doped phosphor has been observed on increasing the pump power and seen by the naked eyes. The tunability in colour emission has also been visualized by CIE chromaticity diagram. The variation in UC emission intensity of the ¹G₄????³H₆ (Tm³⁺) and ⁵F₃????⁵I₈ (Ho³⁺) transitions lying in the blue region has been monitored with increase in the pump power and marked that their ratio can be used to determine the temperature. The developed phosphor has been used to record fingerprints. The observed most intense visible colour emission from the developed material may be used for photodynamic therapy and as an alternative of traditional fluorescent biolabels.     

Spectroscopic Properties of Er3+/Yb3+-codoped PbO–Bi2O3–Ga2O3–GeO2 Glasses

We investigate the spectroscopic properties of the 1.5-μm emission from the ⁴I_13/2 → ⁴I_15/2 transition of Er³⁺ ions in PbO–Bi₂O₃–Ga₂O₃–GeO₂ glasses for applications in broadband fiber amplifiers. The measured emission peak locates at 1,532 nm with a full width at half-maximum of ∼45 nm. The glasses exhibit a large stimulated emission cross-section of 0.89 × 10⁻²⁰ cm² and a large product of 40.0. Infrared-to-green upconversion occurs simultaneously upon excitation of the 1.5-μm emission with a commercially available 980 nm laser diode. The green-upconversion intensity has a quadratic dependence on incident pump laser power, indicating a two-photon process. Energy transfer processes and nonradiative phonon-assisted decays could account for the population of the ²H_11/2 of Er³⁺. The results indicate the possibility towards the development of lead–bismuth–gallate–germanate based glasses as photonics devices.     

Upconversion Properties of Er3+/Yb3+ Co-doped TeO2–TiO2–K2O Glasses

The Er³⁺/Yb³⁺ co-doped TeO₂–TiO₂–K₂O glasses were prepared by conventional melting procedures, and their upconversion spectra were performed. The dependence of luminescence intensity on the ratio of Yb³⁺/Er³⁺ was studied, and the relationship between green upconversion luminescence intensity and Er³⁺ concentration is discussed in detail. The 546 nm green upconversion luminescence intensity is optimised in the studied glasses either when the Yb³⁺/Er³⁺ ratio is 25/1 and Er³⁺ concentration is 0.1 mol%, or when the Yb³⁺/Er³⁺ ratio is 10/1 and Er³⁺ concentration is 0.15 mol%. These glasses could be one of the potential candidates for LD pumping microchip solid-state lasers.     

Quasi-one dimensional Er3+–Yb3+ codoped single-crystal MoO3 ribbons: Synthesis,characterization and up-conversion luminescence

The quasi-one dimensional (Q1D) Er³⁺–Yb³⁺ codoped single-crystal MoO₃ ribbons with width range from 1 to 5 μm, and maximum length about 30 μm have been synthesized by the vapor transport method. The samples were characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscope, and luminescence spectra. By a 975 nm laser diode (LD) as excitation source, the blue, green and red emission bands centered at about 408, 532, 553 and 657 nm were detected, which attributed to the ²H_9/2 → ⁴I_15/2, ²H_11/2, ⁴S_3/2 → ⁴I_15/2 and ⁴F_9/2 → ⁴I_15/2 transitions of Er³⁺, respectively. The three-, and two-photon process was responsible for the blue, green and red up-conversion emissions mechanism for the Q1D Er³⁺–Yb³⁺ codoped single-crystal MoO₃ ribbons, respectively. The results suggested that the Q1D Er³⁺–Yb³⁺ codoped single-crystal MoO₃ ribbons will have potential applications in remote bio-imaging and surface enhanced Raman scattering.     

Er3+/Yb3+共掺Gd3Sc2Ga3O12晶体的上转换发光

研究了提拉法生长的Er3+/Yb3+:Gd3Sc2Ga3O12和Er3+:Gd3Sc2Ga3O12晶体在室温下320-1700 nm范围的吸收光谱和500-750 nm范围内的上转换荧光谱,同时对其上转换荧光的可能发生机制、途径以及上转换过程可能对Er3+的2.8 μm波段激光振荡产生的影响进行了分析和讨论.结果表明:Yb3+的敏化显著地增强了晶体在966 nm附近的吸收能力,大幅度加宽了晶体在该处的吸收带宽.在940 nm激光的激发下,Er3+/Yb3+:Gd3Sc2Ga3O12中的上转换荧光强度明显强于Er3+:Gd3Sc2Ga3O12中的上转换荧光强度,表明Yb3+与Er3+之间存在高效率的能量传递,其主要上转换机制可能为Yb3+-Er3+,Er3+-Er3+能量传递.     

Visible luminescence properties of Er3+–Dy3+ codoped tellurite glasses

Er³⁺ and Dy³⁺ codoped tellurite glasses have been synthesized. Five emission bands in the PL spectrum under 325 nm pumping were observed. Three of them correspond to Er³⁺ and the other two correspond to Dy³⁺, respectively. The PL spectrum revealed that the intensity of Dy³⁺ characteristic emission was enhanced as Er³⁺ concentration increased while keeping Dy³⁺ concentration constant. Due to small mismatch between the energy level of Er³⁺:⁴F_7/2 and Dy³⁺:⁴F_9/2 resonant energy was possibly transferred between them. This process can give rise to an enhancement of the PL intensity of 484 and 574 nm from Dy³⁺. The PL spectra of these glasses cover the blue, green and red wavelength range and the intensities of those emission bands could be controlled by adjusting the concentration of relevant rare-earth ions. These glasses with the controllable CIE coordinates might be a potential candidate for the widely realistic application such as solid-state white lighting and multicolor display.     

Self-mixing gas leakage detection of tank based on Er3+–Yb3+ codoped Distributed Bragg Reflector fiber laser

In this paper we present a novel method of gas leakage detection based on self-mixing interference with an extremely compact Er³⁺–Yb³⁺ codoped Distributed Bragg Reflector (EYDBR) fiber laser. According to the simulation and theoretical analysis of gas leakage of tank, we infer that the vibration frequency peak of tank caused by gas leakage increases with the internal pressure. In the experiment, the results agree with the theoretical prediction and the relevance of polynomial fitting about the spectrum peak of tank vibration and internal pressure is 0.99725. Thus, we can get the internal pressure of tank by measuring the vibration frequency peak of tank. Moreover, it has important significance in the prevention of the accident of flammable or explosive gas leakage.     

Ultraviolet to near-infrared downconversion in Yb3+–Na+ codoped Sr2CaWO6

This study investigated photoluminescent properties of Sr₂CaWO₆:Yb³⁺, Na⁺ phosphor. The samples were successfully synthesized via a solid-state reaction method with various doping concentrations. The phosphor can efficiently absorb ultraviolet photons of 250–350 nm and transfer its absorbed photon energy to Yb³⁺ ions. Then subsequent quantum cutting between WO₆ groups and Yb³⁺ ions takes place, down-converting an absorbed ultraviolet photon into two photons of 1007 nm radiations. Analyses of decay curves of different samples reveal an efficient energy transfer from WO₆ groups to Yb³⁺ ions. Cooperative energy transfer from host to Yb³⁺ ions is responsible for downconversion via lifetime analysis. Quantum efficiencies were calculated, and estimated maximum efficiency reached 190%. These phosphors combine wide wavelength absorption in the ultraviolet range with high quantum efficiency, enabling potential application of efficiency enhancement of Si solar cell.     

Yb3+掺杂浓度对Er3+/Yb3+共掺SiO2-Al2O3-La2O3玻璃光谱性质的影响

测量了不同Yb3+ 离子掺杂浓度下 ,Er3+ /Yb3+ 共掺SiO2 Al2 O3 La2O3玻璃的吸收光谱、荧光光谱和Yb3+离子2 F5/ 2 的能级寿命 ,应用迈克康伯 (McCumber)理论计算了Er3+ 的受激发射截面σemi,讨论了Yb3+ 离子浓度对其自身吸收性质、Er3+ 离子发光性质 ,以及Yb3+ →Er3+ 能量传递效率 (η)的影响 ,初步探明该基质玻璃中Yb3+ 离子掺杂数浓度的最佳范围为 3 .94× 1 0 2 0 cm- 3至 5 .92× 1 0 2 0 cm- 3,在此掺杂范围内 ,Yb3+ 离子的最大吸收系数为9.8cm- 1 ,Er3+ 的峰值发射截面和Yb3+ →Er3+ 能量传递效率 (η)分别为 0 64× 1 0 - 2 4 m2 和 92 %。     

Yb3+/Er3+/Gd3+掺杂Lu2O3、Y2O3荧光粉的上转换发光及温度特性

通过溶胶-凝胶法制备了Er~(3+)、Yb~(3+)和Gd~(3+)共掺杂的Y_2O_3、Lu_2O_3荧光粉,并研究了其上转换发光和温度敏感特性。在980 nm激光激发下,样品辐射出明亮的绿光、红光和弱的紫外光。并讨论了紫外区Er~(3+)→Gd~(3+)的能量传递。利用荧光强度比方法研究了基于Er~(3+)的~2H_(11/2)和~4S_(3/2)两个热耦合能级在313～573 K范围内的光学温度传感特性,当Gd~(3+)离子掺杂浓度为10%时,样品的灵敏度最大为0.005 91 K~(-1)。     

Optical thermometry using FIR of two close lying levels of different ions in Y2O3:Ho3+–Tm3+–Yb3+ phosphor

The possibility of combustion synthesized Ho³⁺–Tm³⁺–Yb³⁺ codoped Y₂O₃ phosphor as temperature sensor using fluorescence intensity ratio (FIR) technique under a 980 nm excitation has been reported. The variation in FIR of blue upconversion emissions generated from two closely spaced levels of the Tm³⁺ and Ho³⁺ ions (¹G₄ and ⁵F₃) as a function of temperature has been monitored up to 703 K. The maximum relative sensitivity has been found to be 3.38 × 10^?3 K^?1 which indicates that the present phosphor material can play a vital role for high optical thermometric purpose. The results imply that the FIR of two closely spaced levels of two different rare earth ions can also be used as temperature sensor.     

Phase evolution and morphology of nanocrystalline BaCe0.9Er0.1O3−δ proton conducting oxide synthesised by a novel modified solution combustion route

Pure BaCeO₃ and 10 mol% Er₂O₃ doped BaCeO₃ (BCE) was synthesised by a novel modified solution combustion synthesis (MCS) route wherein the pH of the precursor solution was varied and the phase formation and morphology were compared with those obtained in conventional solution combustion synthesis (SCS). X-ray diffraction (XRD) studies confirmed the presence of the undesirable BaCO₃ phase in the calcined powders prepared using SCS route whereas the powders synthesised with the modified (MCS) route exhibited a single perovskite phase after calcination. Variation in the pH of the precursor solution resulted in a morphology change from a mix of irregular and globular at pH 4 to more spherical at pH 6 and 8. Fourier transform infrared spectroscopy (FT-IR) studies revealed that calcination time has more pronounced effect on phase formation than calcination temperature. A calcination time of 10 h at 1000 °C resulted in negligible amount of BaCO₃. Such prolonged calcination treatment resulted in substantial grain growth in the SCS sample while the MCS samples were still in the nanocrystalline form. Absence of the ceria peak (464 cm^–1) in the Raman spectra confirmed the presence of a single perovskite BaCeO₃ phase in the sintered pellets as well.     

Er3+单掺及Yb3+/Er3+双掺LaLiP4O12玻璃光谱性质研究

制备了Er3 +单掺杂及Yb3+/Er3+双掺杂四磷酸盐玻璃 ,测量了吸收光谱、荧光光谱 ,用McCumber理论计算Er3 +的发射截面 ,研究了其荧光特性、浓度猝灭及其机制、以及OH基对荧光强度和能量传递的影响 ,研究发现对四磷酸盐玻璃Yb3+的最佳浓度约为 1.82× 10 2 1ions/cm3,Er3+最佳浓度约为 0 .96× 10 2 0 ions/cm3。     

Manifestation of up-conversion in Yb3+/Tm3+ doped Li2O–Y2O3–SiO2 glass system

In this study, we have investigated the principal role of Y₂O₃ on the emission features of Tm³⁺ ion and up-conversion phenomenon in Tm³⁺ and Yb³⁺ co-doped Li₂O–Y₂O₃–SiO₂ glass system. The concentration of Y₂O₃ is varied from 0 to 5 mol% while that of Yb³⁺ and Tm³⁺ is fixed. When the glasses are doped with Tm³⁺ ions, the intense blue and red emissions were observed, whereas Yb³⁺ doped glasses exhibited NIR emission at about 980 nm. When the glasses are co-doped with Tm³⁺ and Yb³⁺ ions and excited at 900 nm, the blue and red emission lines were observed to be reinforced and strengthened with increase in the concentration of Y₂O₃. The IR emission band detected at about 1.8 μm due to ³F₄ → ³H₆ transition of Tm³⁺ ions is also observed to be strengthened due to co-doping. The reasons for enhancement in the intensity of various emission bands due to co-doping have been identified and discussed with the help of rate equations for various emission transitions.     

Sol-gel法制备Er3+掺杂Yb2Ti2O7粉末上转换发光特性

采用溶胶-凝胶法制备了8 mol%Er3+掺杂单一Yb2Ti2O7相粉末.976 nm半导体激光器激发Er3+掺杂Yb2Ti2O7粉末获得中心波长524、548 nm的绿色和660 nm的红色上转换发光,绿色和红色上转换发光强度(Igreen、Ired)随激光泵浦功率的增大而增强,且绿色和红色上转换发光均为双光子吸收过...