1.55μm光纤放大器用掺Er3+碲酸盐玻璃光谱性能研究

制备了TeO2-BaO(Li2O,Na2O)-La2O3掺铒碲酸盐玻璃系统,测量玻璃的密度、折射率和DSC曲线,以及玻璃的吸收光谱和荧光光谱.由测得的密度和折射率等参数,应用Judd-Ofelt理论和McCumber理论,计算出碲酸盐玻璃的各光学性能参数与受激发射截面.且从测得热稳定性能较好的TBLE3荧光发射谱图中得到该碲酸盐玻璃荧光半高宽(FWHM)为～60nm,σepeak×FHWM值高达～600,明显大于掺铒硅酸盐玻璃和磷酸盐玻璃,表明该种碲酸盐玻璃是光纤发大器用的理想基质材料.     

Er~(3+)掺杂透明微晶玻璃光谱性质的研究

通过高温熔融法和热处理制备了含有-γBi2WO6纳米晶的Er3+掺杂透明硼铋酸盐微晶玻璃.根据X射线粉末衍射结果和Scherrer公式计算得到-γBi2WO6晶粒大小约为15 nm.由于部分Er3+离子取代Bi3+进入-γBi2WO6纳米晶相中,使得Er3+离子在1.5μm的有效发射带宽由78 nm增加到85 nm,同时Er3+离子在4I13/2能级的荧光寿命由0.67 ms增加到1.43 ms.此外,与原始玻璃相比,在Er3+掺杂硼铋酸盐微晶玻璃中观察到强烈的绿光上转换发光,其上转换发光机制可以归为双光子过程.     

Emission properties of highly doped Er3+ fluoroaluminate glass

Er³⁺-doped fluoroaluminate (AYF) glass was compared with fluorozirconate (ZBLAN) and tetraphosphate (PE) glass as a host material for 1.54-μm emission. Experimental results show that the Er³⁺:AYF glass has a smaller concentration quenching and much stronger intensity for the 1.54-μm emission. In high dopant, the 1.54-μm emission is two times stronger in Er³⁺/AYF glass than in ZBLAN glass, and 10 times stronger than in PE glass.     

Energy transfer and energy level decay processes of Er3+ in water-free tellurite glass

This report details the fundamental spectroscopic properties of a new class of water-free tellurite glasses studied for future applications in mid-infrared light generation. The fundamental excited state decay processes relating to the ⁴I_11/2 → ⁴I_13/2 transition in singly Er³⁺-doped Tellurium Zinc Lanthanum glass have been investigated using time-resolved fluorescence spectroscopy. The excited state dynamics was analyzed for Er₂O₃ concentrations between 0.5 mol% and 4 mol%. Selective laser excitation of the ⁴I_11/2 energy level at 972 nm and selective laser excitation of the ⁴I_13/2 energy level at 1485 nm has established that in a similar way to other Er³⁺-doped glasses, a strong energy-transfer upconversion by way of a dipole–dipole interaction between two excited erbium ions in the ⁴I_13/2 level populates the ⁴I_11/2 upper laser level of the 3 μm transition. The ⁴I_13/2 and ⁴I_11/2 energy levels emitted luminescence with peaks located at 1532 nm and 2734 nm respectively with luminescence efficiencies of 100% and 8% for the higher (4 mol.%) concentration sample. Results from numerical simulations showed that a population inversion is reached at a threshold pumping intensity of ∼57 kW cm⁻² for a CW laser pump at 976 nm for [Er₂O₃] = 2 mol.%.     

Gold nanoparticles assisted structural and spectroscopic modification in Er3+-doped zinc sodium tellurite glass

Achieving enhanced spectroscopic properties of rare earth doped inorganic glasses by embedding metallic nanoparticles of controlled sizes is a challenging task. We report the gold (Au) NPs assisted modifications in structural and spectroscopic properties of melt-quench synthesized Er³⁺ doped zinc sodium tellurite glass. The growth of NPs is stimulated via time varying heat treatment at 300 °C. XRD patterns confirm the amorphous nature of glasses and TEM images manifest the growth of gold NPs with sizes between 6.1 and 10.7 nm. The heat treatment time dependent variations in physical properties are ascribed to the alteration in bonding of non-bridging oxygen ions. The UV–VIS–NIR spectra reveal six absorption peaks centered at 488, 523, 655, 800, 973 and 1533 nm corresponding to the transition from ground state of ⁴I_15/2 to ⁴F_7/2, ²H_11/2, ⁴F_9/2, ⁴I_9/2, ⁴I_11/2, and ⁴I_13/2 excited states of Er³⁺ ions, respectively. Surface plasmon resonance (SPR) bands are observed in the range of 618–632 nm. Judd–Ofelt analyses demonstrate a significant increase of spectroscopic quality factors (0.86–1.05) and branching ratio (0.62–92.38%). The up-conversion emission spectra of Er³⁺ exhibit three prominent peaks of reasonable green (502 nm), a moderate green (546 nm) and a strong red (629 nm). An enhancement in the red band luminescence intensity by a factor of 8.19 and 8.54 times are achieved for 2 and 4 h of heat treatments, respectively. This enhancement is attributed to the SPR effects of gold NPs producing an intense local field in the proximity of Er³⁺ ions and subsequent energy transfer between RE ions and NPs. The FTIR spectra display the presence of vibrational modes for ZnO₄ bonds, Te–O bond in TeO₃ (tp) and TeO₄ (tbp) units and the hydroxyl groups. Excellent features of the results suggest that our method constitute a basis for tunable growth of gold NPs which is exceedingly useful for the optimization of optical and structural properties.     

Fluorescence dynamics and rate equation analysis in Er3+ and Yb3+ doped double tungstates

The fluorescence dynamics in Er3+ and Yb3+ doped KGd(WO4)2 and KY(WO4)2 has been investigated. Lifetimes have been measured for the Yb (2F(5/2)), Er (4I(13/2)), and Er (4S(3/2)) levels around 1, 1.5, and 0.55 microm, respectively. The Yb (2F(5/2)) lifetimes show a decreasing trend toward the limiting Er (4I(11/2)) lifetime with increasing Er-to-Yb concentration ratio, whereas the Er (4I(13/2)) lifetimes are mostly unaffected by the doping concentrations. A rate equation analysis has been performed to explain the observed behavior and gain is calculated for a continuous-wave laser at 1.53 microm to find the optimum doping concentrations for high gain.     

Crystallization and spectroscopic properties investigations of Er3+ doped transparent glass ceramics containing CaF2

Transparent oxyfluoride glass ceramics with composition of 45SiO₂–25Al₂O₃–5CaCO₃–10NaF–15CaF₂–0.5ErF₃ (in mol%) were developed through controlled crystallization of melt-quenched glass. Non-isothermal crystallization kinetics investigation showed that the average apparent activation energy E_a and Avrami exponent n are about 283 kJ/mol and 2.22, respectively, indicating the crystallization a three dimensional crystal growth process controlled by the diffusion with a decreasing nucleation rate. X-ray diffraction (XRD) analysis and transmission electron microscopy (TEM) observation revealed the precipitation of CaF₂ crystallites sized about 15 nm among the glass matrix after heat-treatment at 650 °C for 2 h. For as-made glass, no upconversion signals were detected when excited with a 30 mW diode laser at 980 nm, while strong upconversion emissions at 545, 660 and 800 nm were obtained for transparent glass ceramic under similar excitation condition.     

Effect of Ag nanoparticles on the radiative properties of tellurite glasses doped with Er3+, Yb3+ and Tm3+ ions

The present work is devoted to the characterization of the thermal and spectroscopic properties of tellurite glasses, codoped with Er³⁺, Yb³⁺ and Tm³⁺ rare-earth ions and silver nanoparticles (NPs). The techniques used for this investigation were UV–visible and infrared absorption, time-resolved luminescence and thermal lens. Time-resolved luminescence studies indicate efficient Yb³⁺ → Er³⁺ and Yb³⁺ → Tm³⁺ energy transfers and intense Er³⁺ and Tm³⁺ mid-infrared emissions around 1550 nm and 1860 nm, respectively. The presence NPs is found to increase the thermal diffusivity of the materials and to shorten the mid-infrared emission lifetime of both the Er³⁺ and Tm³⁺ ions.     

Crystallization and spectroscopic properties in Er3+ doped oxyfluorogermanate glass ceramics containing Na

The Er³⁺ doped oxyfluorogermanate glasses, with a composition containing Na element, were synthesized by the conventional melting–quenching technique. When Na element was introduced into the composition of oxyfluorogermanate glass, the crystals behavior was investigated in details. Depending on the annealing procedure supplied, thermal annealing of precursor glasses in the system GeO₂/BaF₂/AlF₃/Na₂O/NaF/ZnO/GdF₃/ErF₃ led to the precipitation of different crystal phase nanocrystals. It was confirmed the nanocrystals in GC600 is orthorhombic NaBaAlF₆ which led to enhance obviously in the UC luminescence of Er³⁺. However, the nanocrystals in G585 led to decrease in the UC luminescence, which indicated few Er ions enter into the lattice of this nanocrystal phase. The reason of the decrease in UC emission intensity of GC585 was analyzed.     

Multicolor upconversion of Er3+/Tm3+/Yb3+ doped oxyfluoride glass ceramics

Er³⁺/Tm³⁺/Yb³⁺ tridoped oxyfluoride glass ceramics was synthesized in a general way. Under 980 nm LD pumping, intense red, green and blue upconversion was obtained. And with those primary colors, multicolor luminescence was observed in oxyfluoride glass ceramics with various dopant concentrations. The red and green upconversion is consistent with ⁴F_9/2 → ⁴I_15/2 and ²H_11/2, ⁴S_3/2 → ⁴I_15/2 transition of Er³⁺ respectively. While the blue upconversion originates from ¹G₄ → ³H₆ transition of Tm³⁺. This is similar to that in Er³⁺/Yb³⁺ and/or Tm³⁺/Yb³⁺ codoped glass ceramics. However the upconversion of Tm³⁺ is enhanced by the energy transfer between Er³⁺ and Tm³⁺.     

Er3+单掺与Er3+/Yb3+共掺Y2SiO5的上转换发光

报道了一种新的上转换发光材料X2型Y2SiO5:Er, Yb并研究了Yb3 浓度和泵浦功率对样品的上转换发光特性的影响:(1)随着Yb3 浓度的增加,绿、红光发射均呈先增强后减弱的变化,但相对于绿光发射,红光发射受Yb3 浓度的影响更剧烈,并且当12%(摩尔分数)Yb3 时,可以得到很纯的红光发射;(2)上转换发光强度与泵浦功率的关系表明,双光子吸收贡献样品的上转换发射.此外,讨论了可能的上转换机制.认为随着Yb3 浓度增加,Er3 的激发态吸收、Yb3 到Er3 的能量传递和Er3 的交叉弛豫对上转换发光的作用依次逐渐加强.     

Photoluminescence and energy transfer study of Er3+ and Dy3+ codoped tellurite glasses

Photoluminescence properties of the Er(3+)-Dy3+ codoped tellurite glasses were studied by absorption and visible emission spectra, which revealed luminescence bands of both Er3+ and Dy3+ when pumping with the wavelength of 325 nm. The concentration quenching occurred as Dy3+ concentration increased beyond 3 mol%. The dependence of Er3+ characteristic emission on Dy3+ concentration indicated energy transfer process between Er3+ and Dy3+. The chromaticity coordinates of these glasses are close to white light, which implies that these glasses might be potential candidates for white lighting through an appropriate combination.     

掺Er3+:Al2O3平面光波导的溶胶-凝胶制备

掺铒光波导主要用来制作光波导放大器。采用溶胶-凝胶法制备了透明、稳定的掺铒的铝硅酸盐玻璃溶胶;使用浸渍提拉法或旋转涂敷法,并通过放在乙醇蒸汽中干燥,可在玻璃表面得到均匀的凝胶膜;最后样品在一定温度下烧结;通过多次重复涂敷-烧结这一工艺流程可以形成厚的硅酸盐玻璃膜层并得到波导结构。使用显微镜研究了凝胶膜表面性质,通过棱镜耦合法测量了波导的有效折射率Nm,也测定了所制备波导的吸收光谱。溶胶-凝胶法在制作均匀性好、高掺铒浓度的铝硅酸盐玻璃光波导上具有优势。     

Luminescence quantum efficiency at 1.5 μm of Er3+-doped tellurite glass determined by thermal lens spectroscopy

Erbium doped tellurite glasses (TeO₂ + Li₂O + TiO₂) were prepared by conventional melt-quenching method to study the influence of the Er³⁺ concentration on the luminescence quantum efficiency (η) at 1.5 μm. Absorption and luminescence data were used to characterize the samples, and the η parameter was measured using the well-known thermal lens spectroscopy. For low Er³⁺ concentration, the measured values are around 76%, and the concentration behavior of η shows Er–Er and Er–OH⁻ interactions, which agreed with the measured lifetime values.     

Absorption spectra of Er3+ ions in Li6Y(BO3)3 crystals

The optical absorption spectra of Li₆Y(BO₃)₃:Er³⁺ crystals have been studied. The absorption lines corresponding to intraconfiguration electronic transitions from the ⁴I_15/2 ground state to the levels of excited states of Er³⁺ ions have been found in the spectral range of 370–700 nm. The transitions to the ⁴F_9/2, ⁴S_3/2, ²H_11/2, ⁴F_7/2, ⁴F_5/2, ⁴F_3/2, ²H_9/2, and ⁴G_11/2 levels have been investigated in detail at 2 K. The number of lines observed for these transitions corresponds to the theoretical maximum for the f-f electronic transitions in Er³⁺ ions located in the noncubic crystal field. The narrowness of the lines observed and their number indicate that erbium occupies one regular position (specifically, the yttrium position). The energy levels of the excited states have been determined for the transitions under study.     

Emission properties of polymer composites doped with Er3+:Y2O3 nanopowders

In this work we report the recent results of our investigation on visible emission properties of the PMMA-based polymer nanocomposites doped with Er³⁺:Y₂O₃ nanopowders. The set of active nanopowders, and polymer films, differing in active ions concentration, was characterized with respect of their luminescent properties in the green spectral range, available to a limited extent for semiconductor lasers. In particular – the concentration dependent emission spectra and fluorescence dynamics profiles were measured under direct (single photon) and up-converted excitation, enabling the comparison of luminescent properties of developed nanocomposite materials and original nanopowders, optimization of erbium dopant concentration as well as discussion of excitation mechanisms and analysis of the efficiency of depopulation processes.     

Laser stimulated piezoelectricity in Er3+ doped GeO2–Bi2O3 glasses containing silicon nanocrystals

We report the first observation of the laser stimulated piezoelectricity in Er³⁺ doped GeO₂–Bi₂O₃ glasses containing silicon nanocrystals, prepared using the simple well known melt quenching technique. Two split beams originated from the same nanosecond lasers were used for the performance of the bicolor laser treatment.The fundamental (λ = 1064 nm) and the doubled frequency (λ = 532 nm) signal of a pulsed nanosecond Nd:YAG laser, as the fundamental (λ = 1540 nm) and the doubled frequency (λ = 770 nm) signal of an Er:glass laser were used.The ratio of power densities between the fundamental and the doubled frequency beams has been varied from 4:1 to 8:1. This value was chosen to achieve the maximum output photoinduced piezoelectric response. The present photoinduced piezoelectricity effect opens a new road for obtaining optically operated piezoelectric devices in germanate composites doped with rare-earth ions.     

Thermal analysis of a diffusion bonded Er3+,Yb3+:glass/Co2+: MgAl2O4 microchip lasers

The analysis of thermal effects in a diffusion bonded Er³⁺,Yb³⁺:glass/Co²⁺:MgAl₂O₄ microchip laser is presented. The analysis is performed for both wavelengths at 940 nm and at 975 nm as well as for two different sides of pumping, glass side and saturable absorber side. The heat sink effect of Co²⁺:MgAl₂O₄, as well as the impact of the thermal expansion and induced stress on the diffusion bonding are emphasised. The best configurations for reducing the temperature peaks, the Von Mises stresses on the diffusion bonding, and the thermal lensing are determined.