Highly efficient Nd:YAG ceramic CW laser with 59.8% slope-efficiency

In this paper, a highly efficient Ti:sapphire end-pumped 1 at.-% Nd:YAG ceramic laser that is comparable in efficiency with Nd:YAG single crystal lasers has been developed. Optical absorption and emission spectra for Nd:YAG ceramics have been measured. With 673-mW pumping, 295-mW laser output at 1064 nm has been obtained. The laser threshold is only 13 mW. Deducted the transmitted light, the corresponding optical-to-optical conversion efficiency is 58.4%. The lasing characteristics of Nd:YAG ceramic are nearly equal to those of Nd:YAG single crystal.

Síntese e estudo das propriedades luminescentes do SrGa2O4 dopado com íons de Cr3+

Amostras policristalinas de Sr(Ga1-xCrx)2O4 com x = 0,01 foram estequiometricamente preparadas pela mistura dos materiais em pó SrCO3, Ga2O3 e Cr2O3. A estrutura cristalina da amostra dopada foi analisada pelas medidas de difração de raios-X. O padrão de difração revelou uma única fase relacionada a fase monoclínica do SrGa2O4. Os dados foram ajustados usando o Método de Rietveld para refinamento de estruturas e os parâmetros da rede foram determinados. A luminescência do íon de Cr3+ na rede do SrGa2O4 foi investigada pelas espectroscopias de excitação e emissão a temperatura ambiente, através das quais verificamos que os íons de Cr3+ estão localizados em dois sítios diferentes. Os espectros de emissão apresentam bandas largas associadas à transição eletrônica 4T2(4F) → 4A2(4F) para ambos os sítios. Estes resultados são analisados pela teoria de campo cristalino e o parâmetro de campo cristalino Dq e os parâmetros de Racah B e C são determinados pelas posições das bandas de excitação. A partir destes parâmetros determinamos um campo cristalino forte para ambos os sítios. Além disto, foram realizadas medidas de espectroscopia fotoacústica que confirmaram as transições identificadas e estimadas nos espectros de excitação.

掺铒碲-钨-钠玻璃基质的光谱性质研究

制备了用于离子交换法制备光波导器件的掺铒碲-钨-钠玻璃基质。应用扎得-奥菲而特(Judd—Ofelt)理论计算了玻璃样品的三个强度参量，由强度参量计算了Er^3+离子的自发跃迁几率、荧光分支比等光谱参量；应用麦克库玻(McCumber)理论，计算了Er^3+离子在1．5μm的受激发射截面，荧光测试发现Er^3+离子的荧光半峰全宽可达65nm。比较了Er^3+离子在不同玻璃基质中的光谱特性。结果表明，Er^3+离子在碲-钨-钠玻璃中具有较高的受激发射截面和较宽的荧光半峰全宽，可以用于宽带光波导器件的制备。

TeO2-ZnO-Na2O-K2O玻璃中Er^3＋离子掺杂浓度对其发光及荧光寿命的影响

测量了不同掺杂浓度下Er^3+离子在碲酸盐玻璃中的吸收光谱、发射光谱和Er^3+离子的荧光寿命，计算了Er^3+离子的发射截面σc，分析了Er^3+离子掺杂浓度对其发光强度和荧光寿命的影响．结果表明，Er^3+离子掺杂浓度较低时，对其荧光强度和荧光寿命没有显著的影响；掺杂浓度高时，出现了浓度猝灭效应，使Er^3+离子荧光光强度降低，荧光寿命下降．实验确定了掺杂浓度最优值，同时对浓度猝灭机制进行了分析．

X 射线转换屏用Tb3+激活磷酸盐发光玻璃

Phosphate glasses 60P2O5-15CS2O- 15Al2O3-10BaO were made by high temperature melt-annealing method. The absorption spectra, excitation spectra and emission spectra of Gd³⁺-Tb³⁺ and Ce3+-Gd³⁺-Tb³⁺ co-doped phosphate glass 60P2O5-15CS2O- 15Al2O3-10BaO were studied. The experimental results indicate that, the doping of Ce3+ and Gd³⁺ in Tb³⁺ phosphate glass has a good effect on the 545 nm emission of Tb³⁺ at UV excitation. The Ce3+-Gd³⁺-Tb³⁺ co-doped phosphate glass have a good x-ray luminescence at the radiation of x-ray with energy in 50-120 kev, and a high space resolution. The Ce3+-Gd³⁺-Tb³⁺ co-doped phosphate luminescence glass is a promising material for using in the digital radiography system in medical devices.

Characterization of Er3+-doped Na2O-WO3-TeO2 glass for ion-exchanged waveguide amplifiers and lasers

Er^(3+)-doped Na2O-WO3-TeO2 glass consistent with standard ion-exchange technology has been fabricated and characterized. The measured absorption and emission spectra of the glass were analyzed by the Judd-Ofelt and McCumber theories. The intensity parameters are Ω2 = 7.01

Upconversion luminescence of Ce3+ doped BK7 glass by femtosecond laser irradiation

Near-infrared to visible upconversion luminescence was observed in a multicomponent silicate (BK7) glass containing Ce3+ ions under focused infrared femtosecond laser irradiation. The emission spectra show that the upconversion luminescence comes from the 4f-5d transition of the Ce3+ ions. The relationship between the intensity of the Ce3+ emission and the pump power reveals that a three-photon absorption predominates in the conversion process from the near-infrared into the blue luminescence. The analysis of the upconversion mechanism suggests that the upconversion luminescence may come from a three-photon simultaneous absorption that leads to a population of the 5d level in which the characteristic luminescence occurs.

Effect of bismuth oxide introduction on spectroscopic properties of Er3+/Yb3+ co-doped aluminophosphate glasses

The absorption spectra, emission spectra and infrared spectra of Er3+/Yb3+ co-doped xBi(2)O(3)-(65 - x)P2O5-4Yb(2)O(3)-11Al(2)O(3)-5BaO-15Na(2)O were measured and investigated. Spontaneous emission probability, radiative lifetime and branching ratios of Er3+ were calculated according to the Judd-Ofelt theory. The role of substitution of Bi2O3 for P2O5 on luminescence of Er3+/Yb3+ co-doped aluminophosphate glasses has been investigated. The calculated radiative lifetimes (tau(rad)) for I-4(13/2) and I-4(11/2) were decreasing with Bi2O3 content increases, whereas the measured total lifetime (tau(meas)) for I-4(13/2) showed linearly increasing trends. The effect of Bi2O3 introduction on OH- groups was also discussed according to the IR transmittance spectra of glasses. It was found that FWHM of glasses were not affected with the substitution of Bi2O3 for P2O5. The emission spectra intensity increased with Bi2O3 content due to the decreases of phonon energy and OH- content in glasses. (C) 2007 Elsevier B.V. All rights reserved.

Energy transfer between Cr3+ and Ni2+ in transparent silicate glass ceramics containing Cr3+/Ni2+ co-doped ZnAl2O4 nanocrystals

The emission intensity of Ni2+ at 1200 nm in transparent ZnO-Al2O3-SiO2 glass ceramics containing ZnAl2O4 nanocrystals is improved approximately 8 times by Cr3+ codoping with 532 nm excitation. This enhanced emission could be attributed to an efficient energy transfer from Cr3+ to Ni2+, which is confirmed by time-resolved emission spectra. The energy transfer efficiency is estimated to be 57% and the energy transfer mechanism is also discussed. (C) 2008 Optical Society of America.

Effect of Al(PO3)(3) content on physical, chemical and optical properties of fluorophosphate glasses for 2 mu m application

The effect of Al(PO3)(3) content on physical, chemical and optical properties of fluorophosphate glasses for 2 mu m application, such as thermal stability, chemical durability, surface hardness, absorption spectra and emission spectra, is investigated. With the increment of Al(PO3)(3) content, the thermal stability characterized by the gap of T-g and T,, increases first and then decreases, and reaches the maximum level containing 5 mol% Al(PO3)(3) content. The density and chemical durability decrease monotonously with the introduction of Al(PO3)(3) content increasing, while the refractive index and surface hardness increase. Above properties of fluorophosphate glasses are also compared with fluoride glasses and phosphate glasses. The Judd-Ofelt parameters, absorption and emission cross sections are discussed based on the absorption spectra of Tm-doped glasses. The emission spectra are also measured and the 1.8 mu m fluorescence of the sample is obvious indicating that it is suitable to 2 mu m application. (c) 2008 Elsevier B.V. All rights reserved.

Crystal growth and spectroscopic characterization of Yb-doped and Yb, Na-codoped CaF2 laser crystals by TGT

High-quality 2at%-doped Yb:CaF2 and Yb,Na:CaF2 single crystals with diameter of 76mm were grown by the temperature gradient technique. For the first time, distribution coefficients (KO) of Yb in the two crystals were determined to be 1.07 and 0.91, respectively, by measuring the Yb concentrations at the growth starting position in the as-grown boules. Absorption and emission spectra of the two different crystals were measured at room temperature. Experimental results show that Na+ ions codoping with Yb3+ as charge compensators make Yb3+ ions in CaF2 lattice to be a quasi-single-center system, and greatly suppress the deoxidization of Yb3+ to Yb2+ (c) 2005 Elsevier B.V. All rights reserved.

Growth of excellent-quality Nd : LuVO4 single crystal and laser properties

High-quality Nd:LuVO4 single crystal was successfully grown by Czochralski method. The assessment of the crystalline quality by the chemical etching method and Conoscope image was reported. The absorption spectra from 300 to 1000 nm and emission spectra from 960 to 1450 nm of Nd: LuVO4 were measured. Laser performance was achieved with Nd:LUVO4 crystal for the transition of F-4(3/2) -> I-4(11/2) (corresponding wavelength 1065.8 nm) in an actively Q-switched operation, and the average output power reached 5.42 W at a pulse repetition frequency (PRF) of 40 kHz under pump power of 18 W, giving an optical conversion efficiency of 30.1%. The pulse energy and peak power reached 138 mu J and 16.2 kW at PRF of 25 kHz under pump power of 14.2 W, and the pulse duration was 8.5 ns. (c) 2005 Elsevier B.V. All rights reserved.

大尺寸Ce：Lu1.6Y0.4SiO5闪烁晶体的生长和光谱特性

采用中频感应提拉法生长出尺寸为Ф60mm×110mm的Ce：Lu1.6Y0.4SiO5（LYSO）晶体,与LSO晶体相比,LYSO晶体的优势是提高了晶体质量、降低了熔点和原料成本等.在室温下测试了LYSO晶体的透过光谱、激发光谱和发射光谱,结果表明Y的加入使LSO晶体的吸收边向短波方向偏移.Ce^3＋的4f^1→5d^1跃迁吸收导致紫外区产生三个吸收带.发射光谱具有Ce^3＋典型的双峰特征,经Gaussian多峰值拟合,双峰395nm和418nm归属于Ce1发光中心,而435nm的发光峰与Ce2发光中心有

Growth and spectral characterization of beta-Ga2O3 single crystals

Beta gallium oxide (beta-Ga2O3) single crystals were grown by the floating zone technique. The absorption spectra and the luminescence of the crystals were measured. The absorption spectra showed an intrinsic short cutoff edge around 260 nm with two shoulders at 270 and 300 nm. Not only the characteristic UV (395 nm), blue (471 nm) and green (559 nm) lights, but also the red (692 nm) light can be seen in the emission spectra. The deep UV light was attributed to the existing of quantum wells above the valence band and the red light was owed to the electron-hole recombination via the vicinity donors and acceptors. (c) 2006 Elsevier Ltd. All rights reserved.

Cr^3＋：Al2O3透明多晶陶瓷光谱特性分析

对透光性良好的Cr^3＋：Al2O3透明多晶陶瓷的光谱性能进行了研究，其吸收光谱中吸收峰与单晶红宝石相一致，按吸收光谱和Tanabe-Sugano能级图，算出其晶场强度参数Dq及Racah参数B分别为1792cm^-1，689cm^-1，Dq／B=2．6，陶瓷中Cr^3＋离子所处格位的晶体场强比单晶弱一些，但Cr^3＋：Al2O3透明陶瓷仍属于强场晶体材料；当Cr^3＋掺杂浓度到达0．8wt％时，陶瓷的发射谱仍保持较好的R线发射；随Cr^3＋掺杂浓度的增大，激发峰位发生“红移”．在Cr^3＋：Al2O3透