Intensities and spectral features of the ~4I_(13/2)-~4I_(15/2) potential laser transition of Er~(3+) centers in CaF_2-CeF_3 disordered crystal

A CaF_2-CeF_3 disordered crystal containing 1.06% of Er~(3+) ions was grown by the temperature gradient technique.Optical absorption and emission spectra recorded at room temperature and at 10 K, luminescence decay curve recorded at room temperature, and extended x-ray-absorption fine structure spectra were analyzed with an intention to assess the laser potential related to the ~4I_(13/2)→~4I_(15/2) transition of Er~(3+). In addition, the thermal diffusivity of the crystal was measured at room temperature. The analysis of room-temperature spectra revealed that the ~4I_(13/2) emission is long-lived with a radiative lifetime value of 5.5 ms, peak emission cross section of 0.73 × 10~(-20) cm~2, and large spectral width pointing at the tunability of the emission wavelength in the region stretching from approximately 1480 nm to 1630 nm. The energies of the crystal field components for the ground and excited multiplets determined from low-temperature absorption and emission spectra made it possible to predict successfully the spectral position and shape of the room-temperature ~4I_(13/2)→~4I_(15/2) emission band. Based on the correlation of the optical spectra and dynamics of the luminescence decay, it was concluded that in contrast to Yb~(3+) ions in heavily doped CaF_2 erbium ions in the CaF_2-CeF_3 crystal reside in numerous sites with dissimilar relaxation rates.     

Spectra properties of Yb~(3+),Er~(3+):Sc_2SiO_5 crystal

The influence of Er3+ ions on the spectra of Yb~(3+),Er~(3+): Sc_2 SiO_5(SSO) single crystal, which was obtained by Czochralski(Cz) method, is discussed. The absorption coefficient at 980 nm was 13.36 cm~(-1) with a peak absorption cross-section of 1.46 × 10~(-20) cm2. The emission cross-sections at 1034 nm and 1062 nm were 5.5 × 10~(-21) cm~2 and4.9 × 10~(-21) cm~2, respectively. The fluorescence lifetime was estimated as 1.24 ms at 1061 nm. The mechanical properties of SSO single crystal were also presented.     

Temperature effect on emission lines and fluorescence lifetime of the 4F3/2 state of Nd:YVO4

By measuring the absorption and fluorescence spectra and the fluorescence lifetime of 4F3/2 state of Nd3+ions in YVO4 12 at.-%)crystal at different temperature,the effects of temperature on the spectra andthe lifetime of F3/2 state have been investigated.As the temperature is increased,the line width of the4F3/2 → 4I11/2 transitions is found to increase and the spectral line toward the longer wavelength,whichare duo to the ion-phonon interaction.The variation fluorescence lifetime of the 4F3/2 state of Nd:YVO4is found to be anomalous in the measured range 8-300 K.It is about 81 /μs at room temperature anddecreases to 30 /μs at 8 K.The experimental results are explained by ascribing to the thermal mixingbetween the two Stark levels of 4F3/2 state with different lifetime.     

Er3＋ ion concentration effect on transient and steady-state behavior in Er3＋ ：YAG crystal

The effect of Er3＋ ion concentration on transient and steady-state behavior in 45-nm Er3＋ ：YAG crystal is investigated. It is shown that by changing the signal field, the coherent field and the concentration of Er3＋ ions in the crystal, the absorption, dispersion, and group index of the weak probe field can be adjusted. Also, it is found that the probe absorption occurs in the presence of population inversion and probe amplification is obtained in the absence of population inversion.     

Multi-photon upconversion luminescence of Er~(3+)-doped Y_2O_3 nanocrystals

Visible upconversion emission intensities are investigated in Er3＋-doped Y203 nanocrystals. We also find that the upconversion intensity varies nonlinearly with the excitation power with a threshold of 110 mW, which indicates that the green and red emissions would be photon avalanche upconversion when the excitation power exceeds the threshold.     

Anti-Stokes laser cooling in Yb(3+)-doped KPb(2) Cl(5) crystal

We report internal laser cooling in Yb(3+) -doped KPb(2)Cl(5) . From the quantum efficiency values measured in the heating and cooling regions by use of the photothermal deflection technique, we have obtained a room-temperature cooling efficiency of 0.2% in a sample doped with ~5x10(19)ions/cm(3) . Excitation spectra obtained under high irradiation fluences show an excess of fluorescence with regard to those obtained at low fluences, which agrees with the prediction of a model based on photon-ion-phonon interaction.     

SBN晶体中Eu~(3+)激发态~5D_0的无辐射跃迁

通过测量~5D_0→~7F_2发射带的荧光寿命与晶体温度的依赖关系,研究了Eu~(3+)激发态~5D_0的无辐射跃迁.结果表明,~5D_0→~7F_2带的温度淬灭效应主要是由于电荷转移态的最低能量太低,~5D_0态易被热激活至电荷转移,然后通过电荷转移无辐射弛豫至~7F_2态.     

SrTiO3：Cr^3＋晶体荧光光谱及荧光寿命的热效应

测量了SrTiO~3:Cr(3+)晶体5～200K的荧光光谱和寿命。并用单声子吸收与发射过程相关的电子振动跃迁理论较好地解释了150K以下荧光寿命随温度变化的规律。     

Spectroscopic and laser properties of Er~(3+), Pr~(3+) co-doped LiYF_4 crystal

In this paper, the absorption and fluorescence spectra of Er~(3+), Pr~(3+)co-doped LiYF_4(Er,Pr:YLF) crystal were measured and analyzed. The Pr~(3+)co-doping was proved to effectively enhance the Er~(3+)∶~4I_(11/2)→~4I_(13/2) mid-infrared transition at the 2.7 μm with 74.1% energy transfer efficiency from Er~(3+)∶~4I_(13/2) to Pr~(3+)∶~3F_4. By using the Judd–Ofelt theory, the stimulated emission cross section was calculated to be 1.834 × 10~(-20) cm~2 at 2685 nm and 1.359 × 10~(-20) cm~2 at 2804.6 nm.Moreover, a diode-end-pumped Er,Pr:YLF laser operating at 2659 nm was realized for the first time, to the best of our knowledge. The maximum output power was determined to be 258 m W with a slope efficiency of 7.4%, and the corresponding beam quality factors M~2_x= 1.29 and M~2_y= 1.25. Our results suggest that Er,Pr:YLF should be a promising material for 2.7 μm laser generation.     

Graphene/MoS_2 heterostructure: a robust mid-infrared optical modulator for Er~(3+)-doped ZBLAN fiber laser

We have prepared the graphene∕MoS_2 heterostructure by a hydrothermal method, and presented its nonlinear absorption parameters and application as a nonlinear optical modulator in the mid-infrared region.Using the nonlinear optical modulator, stable passively Q-switched operation of an Er~(3+)-doped ZrF_4-BaF_2-LaF_3-AlF_3-NaF(ZBLAN) fiber laser at ~2.8 μm can be obtained. The Q-switched Er~(3+)-doped ZBLAN fiber laser can yield per-pulse energy up to 2.2 μJ with the corresponding pulse width and pulse repetition rate of 1.9 μs and 45 kHz, respectively. Our results indicate that the graphene∕MoS_2 heterostructure can be a robust optical modulator for pulsed lasers in the mid-infrared spectral range.     

Tm3+离子掺杂的钨酸钇钠晶体中浓度猝灭效应的研究

测量了Tm3+离子不同浓度(0.5at.%,3 at.%,5 at.%)掺杂的NaY(WO4)2晶体在800 nm激光二极管激发下的上转换发射光谱.结合吸收谱、荧光谱和由Judd-Ofelt理论计算的光谱参数,详细分析了Tm36:NaY(WO4),晶体中上转换能量传递机理和离子浓度对上转换发射的影响.讨论了四种影响上转换发光效率的离子间相互作用机理:3H5+1G4→3H6+1D2,3H5+3H5→3H6+3F3,1G4+3H6→3F4+3F3,1G4+3H6→3F3+3F4,并根据Miyakawa-Dexter理论定量计算了各过程的发生概率.论证了交叉弛豫和共协上转换等浓度猝灭效应是影响Tm3+离子蓝色上转换荧光发射效率的主要因素.     

Sr3SiO5:Eu2+材料光谱特性研究

采用高温固相法制备了用于白光LED的Sr3SiO5:Eu2+材料.研究了合成温度及Sr/Si对样品光谱特性及结构的影响.结果显示,随合成温度的升高或Sr/Si的减小,样品的主发射峰均产生了明显的红移,同时,样品的晶体结构也受到了影响.利用InGaN管芯激发Sr3SiO5:Eu2+材料,表现出显色性较好的白光发射光谱,色坐标为(x=0.348,y=0.326).     

具有高机械强度的掺Er~(3 )∶TeO_2-Nb_2O_5玻璃的光谱性质研究

熔制了掺铒碲铌玻璃样品(100-X)TeO2-XNb2O5(X=5,10,15,20mol%),测试了其密度、折射率、转变温度、析晶温度、维氏机械强度、吸收光谱、荧光光谱、荧光寿命等参量。利用Judd-Ofelt和McCumber理论分别计算了铒离子强度参量Ωt(t=2,4,6)和受激发射截面σemi的大小,研究了掺铒碲铌玻璃样品光谱参量对Nb2O5成分的依赖性,并与典型的碲锌钠玻璃(75TeO2-20ZnO-5Na2O)在热学、机械强度、光谱性质和放大品行四个方面进行了比较.     

Green long-after-glow luminescence of Tb~(3+)in Sr_2SiO_4

The green long-after-glow luminescence from Tb3＋-doped Sr2SiO4 phosphors, which are synthesized by the high temperature solid state reaction in a reductive atmosphere, is observed in this paper. The results show that under ultraviolet excitation, the obtained phosphors produce an intense green-lighting-emission from the Tb3＋, and the green-lighting long- after-glow luminescence related to Tb3＋ can last half an hour after the irradiation source has been removed. Moreover, the effects of co-doping Li＋, Dy3＋, Er3＋, Gd3＋, and Yb3＋ with Tb3＋ on the decay properties and thermoluminescence properties are investigated to confirm the long-after-glow mechanism.     

含铒碲酸盐玻璃的上转换荧光性质研究

在室温下,用804nm波长的半导体激光器作激发源,在TeO_2-PbO基掺铒碲酸盐玻璃中实现了中心波长分别为525nm,550nm和660nm的上转换发射.荧光强度与激发功率呈非线性关系.估测了PbO含量对上转换荧光相对强度的影响.     

Ca8Mg(SiO4)4Cl2:Eu2+,Nd3+的近红外发光

用高温固相法制备了Ca<,8>Mg(SiO<,4>)<,4>Cl<,2>:Eu<'2+>,Nd<'3+>近红外发光材料,通过X射线衍射仪,近红外,可见发射光谱和激发光谱,荧光寿命等对样品进行了测试.研究了Eu<'2+>、Nd<'3+>的掺杂浓度对近红外发光性能的影响及相对强度变化的规律,结果表明,Ca<,8>Mg(Si...     

Tm~(3+)掺杂的LaOF和SiO_2纳米体系中荧光光谱温度特性的研究

研究了不同环境温度下晶体LaOF和非晶体SiO2纳米体系中掺杂Tm3+离子的荧光光谱.结果表明,在20~300 K的温度范围内,荧光谱线的宽度、强度以及谱线位置均随温度的升高而变化.发光离子的局域环境直接影响荧光光谱对环境温度的依赖程度:SiO2中发光离子的荧光寿命受温度影响较小,而位于晶相环境LaOF中离子的荧光寿命...     

Growth and spectral properties of Tm3+-doped NaGd(WO4)2 crystal

Thulium doped sodium gadolinium tungstate crystals with sizes of about 20 mm×45 mm were grown successfully by the Czochralski technique along the (001) orientation. X-ray powder diffraction (XRD) of sodium gadolinium tungstate was described and the linear thermal expansion coefficients for the c- and a-axes were measured as 1.60×10^-5 and 7.89×10^-6 °C^-1. Polarized absorption spectra, and fluorescence spectra, as well as fluorescence decay curves of Tm³⁺-doped NaGd(WO₄)₂, have been recorded at room temperature and used to calculate the absorption and stimulated emission cross-sections. Based on the Judd–Ofelt theory, three intensity parameters were obtained. The luminescent quantum efficiency of the ³ H ₄ level was determined to be approximately 65% for this material. The emission cross-section of the ³ F ₄→³ H ₆ IR transition at about 1.8 μm was estimated by the reciprocity method. PACS 78.55.Hx; 65.40.De; 78.20.-e     

Na_5Eu(WO_4)_4,Na_5Eu(MoO_4)_4和NaEu(MoO_4)_2的振动光谱和Eu~(3+)的~5D_1和~5D_2荧光发射的猝灭

测量了高稀土浓度化学计量基质发光材料Na_5Eu(WO_4)_4,Na_5Eu(MoO_4)_4和NaEu(MoO_4)_2的拉曼和红外光谱。用位置群分析法分析了它们的品格振动模式的对称性分类,并参照有关白钨矿结构材料的结果,对它们的实验振动模确定了归属。这些材料的高能振动模来源于(WO_4)~(2-)或(MoO_4)~(2-)的内拉伸振动,由二个或三个这样的高能声子产生的无辐射弛豫猝灭了Eu~(3+)的~5D_1和~5D_2发射。     

Spectroscopic characteristics of Yb3+-doped Li3Ba2Y3(WO4)8 crystal

This paper reports the spectroscopic properties of Yb³⁺:Li₃Ba₂Y₃(WO₄)₈ crystal. The polarized spectral properties of Yb³⁺:Li₃Ba₂Y₃(WO₄)₈ crystal were investigated. The laser performance parameters β_min, I_sat and I_min of Yb³⁺:Li₃Ba₂Y₃(WO₄)₈ crystals have been also established. Yb³⁺:Li₃Ba₂Y₃(WO₄)₈ crystal has a broad FWHM of the gain cross-section and larger absorption and emission cross-sections. These results may regard the Yb³⁺:Li₃Ba₂Y₃(WO₄)₈ crystal as a tunable laser material.