Temperature-dependent fluorescence characteristics of an ytterbium-sensitized erbium-doped silica fiber for sensor applications

The characteristics of temperature-dependent fluorescence of an ytterbium (Yb³⁺)-sensitized erbium (Er³⁺)-doped silica fiber are presented. A 10-cm long double-clad Yb³⁺/Er³⁺-codoped fiber is diode-pumped at 915 nm and the individual fluorescence intensities from Yb³⁺ and Er³⁺ ions are measured with varying the fiber temperature. The ratio of the dual fluorescence intensities varies exponentially with temperature in the range of room temperature to ∼300 °C. This dual-dopant system has dual emission bands that emit comparable fluorescence powers. Particularly, the self-referencing fluorescence intensity ratio is insensitive to external perturbations in the fiber, which is useful for sensors that are used in a harsh environment without any use of additional referencing techniques. This scheme allows a compact, long-life, and low-cost temperature sensor and can also be combined with a wide range of existing fiber-optic multiplexing schemes that can simultaneously detect multiple physical parameters.     

Yb:ZnWO4激光晶体的光谱特征

采用Czochralsk i法生长出光学质量较高的Yb:ZnWO4单晶,通过偏振吸收光谱、荧光光谱的测量计算出其吸收截面为3.0×10-20cm2、发射截面为2.0×10-20cm2和荧光寿命为1.15ms,并推导Yb3+的Stark分裂能级。实验表明,Yb:ZnWO4在近红外972nm处有强吸收峰,发射光谱是从914nm到1055nm的宽带,荧光寿命长,是一种新型LD抽运的可调谐激光晶体。     

Influence of the melting atmosphere on Yb3+/Al3+ co-doped silica glass with powder melting technology

We demonstrated the formation of Yb²⁺ ions in Yb³⁺/Al³⁺ co-doped silica glass using the powder melting technology based on the high-frequency plasma furnace. The Yb³⁺ ions can be deoxidated into Yb²⁺ ions under the atmosphere of N₂ or Ar. The appearance and optical properties of the Yb³⁺/Al³⁺ co-doped silica glass are also changed.     

Electrospinning Preparation and Drug‐Delivery Properties of an Up‐conversion Luminescent Porous NaYF4:Yb3+, Er3+@Silica Fiber Nanocomposite

Up‐conversion (UC) luminescent porous silica fibers decorated with NaYF₄:Yb³⁺, Er³⁺ nanocrystals (NCs) (denoted as NaYF₄:Yb³⁺, Er³⁺@silica fiber) are prepared by the electrospinning process using cationic surfactant P123 as a template. Monodisperse and hydrophobic oleic acid capped β‐NaYF₄: Yb³⁺, Er³⁺ NCs are prepared by thermal decomposition methodology. Then, these NCs are transferred into aqueous solution by employing cetyltrimethylammonium bromide (CTAB) as secondary surfactant. The water‐dispersible β‐NaYF₄:Yb³⁺, Er³⁺ NCs are dispersed into precursor electrospinning solution containing P123 and tetraethyl orthosilicate (TEOS), followed by preparation of precursor fibers via electrospinning. Finally, porous α‐NaYF₄:Yb³⁺, Er³⁺@silica fiber nanocomposites are obtained after annealing the precursor fibers containing β‐NaYF₄:Yb³⁺, Er³⁺ at 550 °C. The as‐prepared α‐NaYF₄:Yb³⁺, Er³⁺@silica fiber possesses porous structure and UC luminescence properties simultaneously. Furthermore, the obtained nanocomposites can be used as a drug delivery host carrier and drug storage/release properties are investigated, using ibuprofen (IBU) as a model drug. The results indicate that the IBU–loaded α‐NaYF₄:Yb³⁺, Er³⁺@silica fiber nanocomposites show UC emission of Er³⁺ under 980 nm NIR laser excitation and a controlled release property for IBU. Meanwhile, the UC emission intensity of IBU–α‐NaYF₄:Yb³⁺, Er³⁺@silica fiber system varies with the released amount of IBU.     

Improvement of 1.53 μm emission and energy transfer of Yb3+/Er3+ co-doped tellurite glass and fiber

To improve the 1.53 μm band emission of Er³⁺, the trivalent Yb³⁺ ions were introduced into the Er³⁺ single-doped tellurite glass with composition of TeO₂–ZnO–La₂O₃, a potential gain medium for Er³⁺-doped fiber amplifier (EDFA). The improved effects were investigated from the measured 1.53 μm band and visible band spontaneous emission spectra together with the calculated 1.53 μm band stimulated emission (signal gain) spectra under the excitation of 975 nm laser diode (LD). It was found that Yb³⁺/Er³⁺ co-doping scheme can remarkably improve the visible band up-conversion and the 1.53 μm band fluorescence emission intensity, and meanwhile improves the 1.53 μm band signal gain to some extent, which were attributed to the result of the effective energy transfer of Yb³⁺:²F_5/2 + Er³⁺:⁴I_15/2 → Yb³⁺:²F_7/2 + Er³⁺:⁴I_11/2. The quantitative study of energy transfer mechanism was performed and microscopic energy transfer parameters between the doped rare-earth ions were determined. In addition, the spectroscopic properties of Er³⁺ were also investigated from the measured absorption spectrum according to the Judd–Ofelt theory, and the structure behavior and thermal stability of the prepared tellurite glass were analyzed based on the X-ray diffraction (XRD) and differential scanning calorimeter (DSC) measurements, respectively.     

Design of large-core single-mode Yb3+-doped photonic crystal fiber

The effective index of the cladding fundamental space-filling mode in photonic crystal fiber (PCF) is simulated by the effective index method. The variation of the effective index with the structure parameters of the fiber is achieved. For the first time, the relations of the V parameter of Yb3+-doped PCF with the refractive index of core and the structure parameters of the fiber are provided. the single-mode characteristics of large-core Yb3+-doped photonic crystal fibers with 7 and 19 missing air holes in the core are analyzed. The large-core single-mode Yb3+-doped photonic crystal fibers with core diameters of 50 μm, 100 μm and 150 μm are designed. The results provide theory instruction for the design and fabrication of fiber.     

掺Yb3+硅酸盐玻璃的制备和光谱特性

为了研究用于高功率激光器的掺Yb3+激光玻璃的制备和光谱特性,采用高温熔融工艺制备了两块碱金属元素含量不同的掺Yb3+硅酸盐激光玻璃,利用相应的光谱仪器测试了两块玻璃样品的吸收光谱和荧光光谱;分析了不同碱金属离子对吸收系数和荧光强度的影响;比较了倒易法和Fuchtbauer-Ladenburg(F-L)法两种不同方法得到的受激发射截面图,得到了Yb3+掺杂玻璃的各个光谱参量和激光参量。结果表明,随着碱金属离子半径的增大,吸收系数和荧光强度减小;样品的吸收截面图与倒易法计算所得的受激发射截面图相似,而与F-L法计算所得的受激发射截面图差别较大,并且倒易法发射截面图中主峰波长较F-L法发射截面图的主峰波长蓝移;最终样品1的增益性能比较好。     

Yb3+掺杂锂硅酸盐玻璃的近红外发光特性

为了研制高功率光纤激光器的掺镱纤芯材料,采用高温熔融法制备了0.70SiO₂-0.18Li₂CO₃-0.04MgCO₃-0.04BaCO₃-0.02Al₂O₃-0.02Yb₂O₃（摩尔分数）锂硅酸盐玻璃样品,测试了其吸收光谱和858nm激发下的荧光光谱,进一步对光谱和激光性能参量进行了理论计算。结果表明,样品的主荧光峰位于1036nm附近,荧光有效线宽为94.1nm,吸收截面为1.143pm2,发射截面为1.024pm2,荧光寿命为0.98ms,激发态最小的粒子数仅为0.042,最小抽运强度为0.76kW·cm-2。与近年来相关文献中报道的镱掺杂玻璃相比,该掺镱锂硅酸盐玻璃在光谱及激光性能上比较有优势,有望在研制镱掺杂光纤中得到应用。     

Yb3+掺杂氟铝酸盐玻璃的光谱性质

根据测得的Yb^3 离子在氟铝酸盐玻璃中的吸收光谱和荧光光谱，分析了Yb^3 离子在氟铝酸盐玻璃中的吸收和发射特性，计算了Yb^3 离子的发射截面，讨论了Yb^3 离子的荧光自吸收效应和浓度猝灭效应。结果表明，自吸收效应使Yb^3 离子实测发射截面与计算所得发射截面存在较大差异并使荧光强度降低，高掺杂时Yb^3 向杂质Er^3 的能量传递是导致浓度猝灭的另一重要原因。     

Strong Self-Trapped Exciton Emission and Highly Efficient Near-Infrared luminescence in Sb3+-Yb3+ Co-doped Cs2AgInCl6 Double Perovskite

Yb³⁺ doped lead-free double perovskites (DPs) with near-infrared (NIR)-emitting have attracted extensive attention due to their wide application prospects. Unfortunately, they still suffer from weak NIR emission due to undesirable resonance energy transfer between the sensitizers and Yb³⁺ ions. Herein, a new effective NIR-emitting DP is developed by co-doping Sb³⁺ and Yb³⁺ into Cs₂AgInCl₆. Experiments and theoretical calculations reveal that induced by co-doping Sb³⁺ ions, the self-trapped excitation (STE) emission intensity of Cs₂AgInCl₆ is greatly enhanced by 240 times, and the STE emission shifts from 600 nm to 660 nm, which contributes to a larger spectral overlap between STE emission and the absorption of Yb³⁺ ions. As a result, the absolute NIR photoluminescence quantum yield reaches an unprecedented 50% in lead-free DPs via high-efficiency STE sensitization (>30%). The excellent optical performance of Cs₂AgInCl₆: Sb, Yb with high ambient, thermal and light stability makes it suitable for application in night-vision devices. Moreover, an ingenious dual-modal optical information encryption based on the combination of visible and NIR fluorescence printing patterns utilizing Cs₂AgInCl₆: Sb and Cs₂AgInCl₆: Sb, Yb respectively is successfully demonstrated. This study provides inspiration for designing highly efficient NIR-emitting Ln³⁺-doped DPs and illustrates their great potential in versatile optoelectronic applications.     

Performance of Er3+-doped chalcogenide glass MOF amplifier applied for 1.53 μm band

A model of Er3＋-doped chalcogenide glass （GasGe20Sb10S65） microstructured optical fiber （MOF） amplifier under the excitation of 980 nm is presented to demonstrate the feasibility of it applied for 1.53 μm band optical communications. By solving the Er3＋ population rate equations and light power propagation equations, the amplifying performance of 1.53 μm band signals for Er3＋-doped chalcogenide glass MOF amplifier is investigated theoretically. The results show that the Er6＋-doped chalcogenide glass MOF exhibits a high signal gain and broad gain spectrum, and its maximum gain for small-signal input （-40 dBm） exceeds 22 dB on the 300 cm MOF under the excitation of 200 mW pump power Moreover, the relations of 1.53 μm signal gain with fiber length, input signal power and pump power are analyzed. The results indicate that the Er3＋-doped Ga5Ge20Sb10S65 MOF is a promising gain medium which can be applied to broadband amplifiers operating in the third communication window.     

Pr3+‐ and Pr3+/Er3+‐Doped Selenide Glasses for Potential 1.6 μm Optical Amplifier Materials

1.6 µm emission originated from Pr³⁺: (³F₃, ³F₄) → ³H₄ transition in Pr³⁺‐ and Pr³⁺/Er³⁺‐doped selenide glasses was investigated under an optical pump of a conventional 1480 nm laser diode. The measured peak wavelength and full‐width at half‐maximum of the fluorescent emission are ~1650 nm and ~120 nm, respectively. A moderate lifetime of the thermally coupled upper manifolds of ~212 ± 10 µs together with a high stimulated emission cross‐section of ~(3 ± 1)×10^??20 cm² promises to be useful for 1.6 µm band fiber‐optic amplifiers that can be pumped with an existing high‐power 1480 nm laser diode. Codoping Er³⁺ enhances the emission intensity by way of a nonradiative Er³+: ⁴I_{13/2 →} Pr³⁺: (³F₃, ³F₄) energy transfer. The Dexter model based on the spectral overlap between donor emission and acceptor absorption describes well the energy transfer from Er³⁺ to Pr³⁺ in these glasses. Also discussed in this paper are major transmission loss mechanisms of a selenide glass optical fiber.     

Structure and spectroscopic properties of Er3+/Ce3+ co-doped TeO2-Bi2O3-TiO2 glasses modified with various WO3 contents for 1.53 μm emission

The Er^3＋/Ce^3＋ co-doped tellurite-based glasses （TeO2-Bi2O3-TiO2） modified with various WO3 contents are prepared using conventional melt-quenching technique. The X-ray diffraction （XRD） patterns and Raman spectra of glass sam- ples are measured to investigate the structures. The absorption spectra, the up-conversion emission spectra, the 1.53 /am band fluorescence spectra and the lifetime of Er3＋：4113/2 level are measured, and the amplification quality factors of Er3＋ are calculated to evaluate the effect of WO3 contents on the 1.53 μm band spectroscopic properties. With the in- troduction of WO3, it is found that the prepared tellurite-based glasses maintain the amorphous structure, while the 1.53 μm band fluorescence intensity of Er3＋ is improved evidently, and the fluorescence full width at half maximum （FWHM） is broadened accordingly. In addition, the prepared tellurite-based glass samples have larger bandwidth qual- ity factor than silicate and germanate glasses. The results indicate that the prepared Er3＋/Ce3＋ co-doped tellurite-based glass with a certain amount of WO3 is an excellent gain medium applied for the 1.53 μm band Er3＋-doped fiber ampli- fier （EDFA）.     

Effect of SiO2 on the thermal stability and spectroscopic properties of Er3+-doped tellurite glasses

Er3＋-doped tellurite glass （TeO2-ZnO-Na2O） prepared using the conventional melt-quenching method is modified by introducing the SiO2, and its effects on the thermal stability of glass host and the 1.53 μm band spectroscopic properties of Er3＋ are investigated by measuring the absorption spectra, 1.53 μm band fluorescence spectra, Raman spectra and differential scanning calorimeter （DSC） curves. It is found that for Er3＋-doped tellurite glass, besides improving its thermal stability, introducing SiO2 is helpful for the further improvement of the fluorescence full width at half maximum （FWHM） and bandwidth quality factor. The results indicate that the prepared Er3＋-doped tellurite glass containing an appropriate amount of SiO2 has good prospect as a candidate of gain medium applied for 1.53 μm broadband amplifier.     

Spectral properties and energy transfer in Er3+/Yb3+ co-doped LiYF4 crystal

Laser crystals of LiYF4 (LYF) singly doped with Er3+ in 2.0% and co-doped with Er3+/Yb3+ in about 2.0%/1.0% molar fraction in the raw composition are grown by a vertical Bridgman method. X-ray diffraction (XRD), absorption spectra, fluorescence spectra and decay curves are measured to investigate the structural and luminescent properties of the crystals. Compared with the Er3+ singly doped sample, obviously enhanced emission at 1.5 μm wavelength and green and red up-conversion emissions from Er3+/Yb3+ co-doped crystal are observed under the excitation of 980 nm laser diode. Meanwhile, the emission at 2.7 μm wavelength from Er3+ singly doped crystal is reduced. The fluorescence decay time ranging from 18.60 ms for Er3+ singly doped crystal to 23.01 ms for Er3+/Yb3+ co-doped crystal depends on the ionic concentration. The luminescent mechanisms for the Er3+/Yb3+ co-doped crystals are analyzed, and the possible energy transfer processes from Yb3+ to Er3+ are proposed.     

Yb3+掺杂硅酸盐激光玻璃的制备及其特性研究

为了制备Yb3+掺杂硅酸盐激光玻璃,并对其激光特性进行分析,采用富氧气氛下的非化学气相沉积高温熔融工艺,通过Fuchbauer-Ladenburger方法,进行了理论分析和实验验证,取得了所制备硅酸盐激光玻璃的吸收光谱和荧光光谱数据。结果表明,在850nm～1100nm近红外波段为吸收区域,有一宽带吸收峰;吸收主峰位于978nm,次峰位于919nm;其荧光主峰位于1018nm,次峰位于970nm,并理论计算了Yb3+的吸收截面面积、受激发射截面面积及其荧光寿命等特征参量。这一结果对硅酸盐激光玻璃的特性分析是有帮助的,所制备的玻璃材料能够满足激光玻璃的使用要求。     

Er3+/Yb3+双掺光纤放大器理论模型

本文在分析一些文献的基础上,仿照掺Er3+光纤放大器的理论模型,尝试建立了一个Er3+/Yb3+双掺光纤放大器的理论模型。利用本模型,可以模拟双掺光纤中信号、泵浦及放大的自发辐射(ASE)的变化情形,并得到一些有意义的数值结果。     

Enhanced cooperative near-infrared quantum cutting in Pr3+-Yb3+ co-doped phosphate glass

Pr3+and Yb3+co-doped phosphate glasses are prepared to study their optical properties.Excitation and emission spectra and decay curves are used to characterize their luminescence.We demonstrate that upon excitation of Pr3+ion with one high energy photon at 470 nm,two near-infrared(NIR)photons are emitted at 950-1100 nm(Yb3+:2F 5/2 →2F 7/2)through an efficient cooperative energy transfer(CET)from Pr3+to Yb3+.The maximum energy transfer efficiency(ETE)and the corresponding quantum efficiency approach up to 90.17%and 190.17%,respectively.The glass materials might find potential application for improving the efficiency of silicon-based solar cells.     

Nd3+ doped fluorochlorozirconate glass:3.9 μm MIR emission properties and energy transfer

The Nd3+ doped fluorochlorozirconate (FCZ) glass was prepared by melt-quenching method. The 3.9 μm emission from Nd3+ ions is attributed to the two-photon absorption process. The strong emission transition at 3.9 μm fluorescence peak intensity, corresponding to the 4G11/2→2K13/2 transition, is directly proportional to the NaCl concentration. With the increase of the Cl- ions amount, the mid-infrared (MIR) luminescent intensity is significantly enhanced. Additionally, the Judd-Ofelt (J-O) parameter Ω2 is larger than that of the fluorozirconate (FZ) glass, which indicates the covalency of the bond between RE ions and ligand is stronger as Cl- ions substitution of F- ions in chloride FZ glass. The X-ray diffraction (XRD) patterns show that the amorphous glassy state keeps the FZ glass network structure. In brief, the advantageous spectroscopic characteristics make the Nd3+-doped FCZ glass be a promising candidate for application of 3.9 μm emission.     

Ag纳米颗粒对Er3+/Tm3+/Yb3+共掺铋锗酸盐玻璃上转换发光特性的影响

采用传统熔融淬冷法制备了系列Er³⁺/Tm 3+/Yb³⁺共掺复合Ag纳米颗粒的铋锗酸盐玻璃样品。从吸收光谱中 确定了Ag纳米颗粒表面等离子体共振(SPR)峰位于545nm附近;透射 电镜(TEM)图像中观察到均匀分布的Ag纳米颗粒,尺寸 约为6～18nm。研究了纳米Ag含量对Er3＋/Tm3＋ 共掺复合Ag纳米颗粒铋锗酸盐玻璃上转换发光特性的影响,结果表 明,Tm³⁺离子472nm处的上转换蓝光、Er³⁺离子525nm处的上转换绿光、543nm处的上转换 绿光和661nm处的上转换红光发光强度在AgCl含量的质量百分数为 1%时达到最大值,与未掺杂AgCl的基质玻璃相比,分别提高了约3.2、3.8、5.4倍。