Absorption and Emission Spectral Analysis of Sm3 : Bi2O3-B2O3-Li2O Glasses

In order to enhance UV-transmission ability of B₂O₃ based glass, a suitable quantity of Bi₂O₃ and Li₂O salts have been added and hence the UV cut-off wavelength of Bi₂O-B₂O₃-Li₂O glass (abbreviated as BBL glass) has been found to be 268 nm. In this newly developed glass a luminescent rare earth ion namely Sm³⁺ (1 mol.%) has been incorporated to examine its absorption, excitation, emission and lifetimes of different measured emission bands. Under an UV-source, it has displayed a bright orange emission color. Apart from understanding its various optical properties, different physical properties of the un-doped reference glass have been investigated. The XRD profile of this glass has confirmed its amorphous nature. The measured excitation spectrum has shown a bright excitation band at 483 nm with which, the Sm³⁺ glass has been excited and thus obtained four emission bands at 563 nm, 598 nm, 648 nm and 709 nm respectively. An energy level diagram has been shown to explain the emission process involved in the glass system investigated in the present work.

Communicated by Prof. Jinzo Kobayashi     

Tm3+掺杂玻璃光纤研究进展

2 μm波段光纤激光可被广泛应用于激光雷达、生物医疗、环境监测以及光谱学等领域,而Tm³⁺掺杂玻璃光纤是2 μm波段光纤激光重要的增益介质。本文从Tm³⁺掺杂玻璃的发光特性出发,介绍了Tm³⁺掺杂玻璃光纤的制备技术,综述了不同玻璃基质材料掺Tm³⁺光纤的研究进展。最后,指出了制备高性能Tm³⁺掺杂玻璃光纤需要解决的关键问题,提出了可能的解决方法,并对Tm³⁺掺杂玻璃光纤发展趋势进行了展望。     

Luminescent properties of Pr doped ZrSiO4 phosphors

Mixtures of ZrO₂, SiO₂, Pr₂O₃, and H₃BO₃ were fired at the temperature of 1150–1350 °C under H₂ atmosphere. A single phase ZrSiO₄:Pr phosphors could be achieved at the firing temperature above 1150 °C. Crystallinity and PL properties strongly depended on the flux amounts, firing temperature, and dopant concentrations. ZrSiO₄:Pr phosphors showed a strong red emission at 615 nm and a weak red emission at 622 nm with an excitation wavelength of 295 and 450 nm, respectively. Two sets of the emission bands and excitation spectra originated from Pr³⁺ ions at Zr and Si sites, respectively.     

Site-Dependent Study of the Optical Properties of Eu3+ in Pure and Chlorine-Doped Fluorozirconate Glasses

For the present study, the emission spectra and lifetimes of Eu³⁺ in fluorozirconate and fluorochlorozirconate glasses were measured site dependently using the fluorescence line narrowing (FLN) technique. At high excitation energies, two different types of Eu³⁺ sites can be distinguished in fluorozirconate glass. The introduction of chloride into this glass caused a significant effect at low excitation energy.     

B2O3对LTPS用基板玻璃结构和黏温性能的影响

以LTPS用无碱基板玻璃配比料方,探讨B₂O₃对无碱硼铝硅酸盐玻璃结构和黏温性能的影响。通过红外光谱和X射线光电子能谱对玻璃试样进行网络结构分析,并测试了玻璃试样的高温黏度、软化点温度、退火点温度和应变点温度。结果表明:B₂O₃含量较低(0.13%)时,B³⁺以四配位的[BO₄]存在;随着B₂O₃含量升高,满足[BO₄]形成之外的B;逐渐以[BO₃]的形式存在;[BO₃]含量增多,玻璃黏度逐渐下降。     

B2O3-K2O-Sb2O3系统玻璃的光学折射率及带隙

高折射率和非线性光学玻璃可以用于高速光开关、光学存储器、新型光纤和光学运算元件等,其研究受到各国科技工作者的高度重视,本文采用熔融淬冷法制备了组成为(85-x)B₂O₃-15K₂O-xSb₂O₃(x=70, 75, 80, 85)的4组玻璃,测试了玻璃样品的密度、折射率、热学性能、拉曼光谱和吸收光谱,利用玻璃样品的吸收光谱计算了其直接允许光学带隙、间接允许光学带隙及Urbach能量。结果表明：随着Sb₂O₃含量的增加,玻璃样品的密度从4.445g/cm³逐渐增加到4.767g/cm³,折射率从1.9438增加到2.0058,玻璃转变温度从291℃降低到260℃,玻璃析晶温度从463℃降低到370℃,直接光学带隙从3.2775eV降低到3.1379eV,间接光学带隙从3.1444eV降低到3.0256eV,Urbach能量从0.137eV逐渐减小到0.107eV。说明Sb₂O₃-K₂O-B₂O₃系统玻璃可以作为新型的非线性光学玻璃候选材料之一。     

Mechanism of the Blue Up-Conversion in Tm3+/Nd3+-doped Calcium Aluminate Glasses

Blue up-conversion fluorescence from the Tm³⁺:¹ G ₄→³ H ₆ (480 nm) transition has been observed from calcium aluminate glass codoped with Tm³⁺/Nd³⁺. The mechanism for the up-conversion process consists of a two-photon process. An excitation beam with a wavelength of 791 nm first excites Tm³⁺ to the ³ H ₄ level, where Tm³⁺ again absorbs the 1060 nm emission from Nd³⁺:⁴ F _3/2→⁴ I _11/2 to attain the Tm³⁺:¹G₄ level. Lifetime and intensity variations with compositions suggest the presence of an efficient energy transfer from Nd³⁺ to Tm³⁺. The highest 480 nm emission intensity has been obtained from the glass with 0.1 mol% of Nd₂O₃ and 0.2 mol% of Tm₂O₃.     

Physical properties of (100-x) B2O3 xLiF optical glasses

This short note brings out the physical properties of the lithium borate glasses of the composition : (100-x)B₂O₃ + xLiF [where x = 2.5, 5, 10, 20, 30 and 40 in mol %] as the function of Li⁺ ion concentration.     

Tm3+-Doped Gallium–Germanium–Bismuth–Lead Glasses as 1.47 μm Fiber Amplifier Materials

We report the spectroscopic properties of Tm³⁺-doped and Tm³⁺/Ho³⁺-codoped [Ga₂O₃–GeO₂–Bi₂O₃–PbO (PbF₂)] glasses for S-band optical amplifications. The Judd–Ofelt intensity parameters have been determined based on the measured absorption spectra. It is found that PbF₂-modified glasses exhibit a lower Ω₂ value, and the addition of PbF₂ caused the chemical bond associated with Tm³⁺ ions to be more ionic. The PbF₂-free glasses have large peak emission cross-sections in the range of 2.15–2.18 × 10⁻²¹ cm². Meanwhile, the studied glasses exhibit broad 1.47 μm emission with the full width at half-maximum of 119–126 nm. The results indicate that these glasses are useful host material for broadband S-band fiber amplifiers.     

Eu2+-Doped Glass Ceramics Containing BaF2 Nanocrystals as a Potential Blue Phosphor for UV-LED

The Eu²⁺-doped glass ceramics containing BaF₂ nanocrystals were prepared and their luminescence properties were investigated. The excitation spectra of Eu²⁺-doped glass ceramics showed an excellent overlap with the main emission region of an ultraviolet light-emitting diode (UV-LED) centered at 380 nm. The 450 nm emission of Eu²⁺ in glass ceramics under the 385 nm excitation was much stronger than that in glass. The Eu²⁺-doped glass ceramics containing BaF₂ nanocrystals may be used as a potential blue-emitting phosphor for UV-LED.     

Effect of Yb3+-Codoping on the Upconversion Emission Intensity in Er3+-Doped ZBLAN Fluoride Glasses under 800-nm Excitation

The effect of Yb³⁺-codoping on the upconversion emission intensity in Er³⁺-doped ZBLAN fluoride glasses is investigated. The codoping of Yb enhanced the emission intensity for the samples excited by an 800-nm laser diode beam. The enhancement in a constant YbF₃ content (2 mol%) increased with increasing ErF₃ content was about 70% of the initial value at 550 nm for the glasses containing 8 mol% of ErF₃. The emission intensity at 550 nm in a constant ErF₃ content (5 mol%) increased remarkably with the addition of YbF₃ and was maximized around 7 mol% of YbF₃ content, giving an increased ratio of about 200% of the initial value. The reason for the enhancement is discussed and it is derived mainly from two-step excitation of Er³⁺ assisted by Yb³⁺ excited through the energy transfer from Er³⁺.     

Upconversion Luminescence in γ-AlON:Yb3+,Tm3+ Ceramic Phosphors

Upconversion emission properties of γ-AlON:Yb³⁺,Tm³⁺ phosphors were investigated under single-wavelength diode laser excitation of 980 nm. Blue (479 nm) and red (653 nm) emission bands were observed which correspond to the transitions of ¹G₄→³H₆ and ¹G₄→³F₄ of Tm³⁺ ions, respectively. The upconversion spectra show a concentration-dependent luminescence intensity, reaching its peak at a concentration of 1.2 mol% Yb and 0.5 mol% Tm. Pump power dependence of the upconversion emission intensity ( P – I ) revealed that a two-photon process was involved in the blue and red emissions.     

Two micrometer fluorescence emission and energy transfer in Yb3+/Ho3+ co-doped lead silicate glass

Enhanced 2.0 μm and visible up-conversion emissions from Ho³⁺ via Yb³⁺ sensitization in lead silicate glasses have been obtained under the excitation of 980-nm laser diode. The possible energy transfer mechanism has been analyzed based on the photoemission spectroscopy and lifetime measurement. The lifetime of Ho³⁺: ⁵I₇ laser upper level has also been measured. Based on the absorption spectra, Judd–Ofelt parameters, spontaneous emission probability, the absorption, emission cross sections, and gain coefficients have been calculated and analyzed. The results indicate that the Yb³⁺/Ho³⁺ co-doped lead silicate glass has potential application in mid-infrared wavelengths.     

Dispersion and Upconversion Fluorescence of Nd3+ Ions in Zinc Chloride-Based Glasses

Nd³⁺-ion-doped ZnCl₂-based glasses were prepared via the melt-quenching method. The Nd³⁺-ion upconversion excitation mechanism and the ability to disperse Nd³⁺ ions into ZnCl₂-based glasses were investigated using absorption and upconversion fluorescence spectra of Nd³⁺ ions. The ZnCl₂-based glass that had an average cationic radius equal to the ionic radius of Nd³⁺ (98 pm) had the greatest ability to disperse Nd³⁺ ions. The 20KCl·25BaCl₂·55ZnCl₂glass, which had the average cationic radius nearest to 98 pm, dispersed Nd³⁺ ions the most, and it had the strongest upconversion fluorescence.     

Energy Transfer Process for the Blue Up-Conversion in Calcium Aluminate Glasses Doped with Tm3+ and Nd3+

Excitation of Tm³⁺ to ³ H ₄ using the 791 nm pump source showed the frequency up-converted blue emission (∼480 nm) due to the Tm³⁺:¹ G ₄→³ H ₆ transition in Tm³⁺/Nd³⁺ codoped CaO·Al₂O₃ glasses. Intensity and lifetime changes with rare-earth concentrations suggested the efficient energy transfer of Tm³⁺:³ H ₄→ Nd³⁺:⁴ F _5/2 and Nd³⁺:⁴ F _3/2→ Tm³⁺:¹ G ₄. The latter transfer enabled Tm³⁺ to reach its ¹ G ₄ level, and the blue emission became possible through the ¹ G ₄→³ H ₆ transition. Quantitative analysis with rate equations proved that these two transitions were the most efficient among all the possible energy transfer routes between Tm³⁺ and Nd³⁺. Calculated up-conversion efficiency of the Tm³⁺/Nd³⁺ combination in CaO·Al₂O₃ glass was 6.6 × 10⁻³, and it was ∼4 orders of magnitude larger than those reported for other oxide glasses.     

Composition Effects on Optical Properties of Tb3+-Doped Heavy Germanate Glasses

A group of terbium-doped heavy germanate glasses were studied. Glass matrices contained GeO₂, Gd₂O₃, BaO, and/or La₂O₃ with the Tb³⁺ doping concentration ranging from 1 to 5 mol%. The transmission and radioluminescence spectra were measured and their correlations with glass composition are discussed. It is found that the UV cut-off edge of glass matrices is related to the content of the network modifier BaO as well as to the mixed rare earths effect, while the concentration of trapping sites existing in the glass network is essential to the radioluminescence properties of the glass. The latter is also associated with the content of the network modifier BaO that produces unsaturated nonbridging oxygens in the glass lattice. Another important mechanism influencing the luminescence process involves the enhanced energy transfer from Gd³⁺ ions to Tb³⁺ emission centers. A self-sensitizing effect of Tb³⁺ is observed in the Tb³⁺ concentration range studied, which contributes to some extent to the enhanced Tb³⁺ green emission. La₂O₃ additions to the host glass play an active role of partitioning Tb³⁺ in the glass matrix, thereby showing an enhanced blue emission because of the reduced cross-relaxation probability between Tb³⁺ cations.     

Nb2O5对Nd3+掺杂锗酸盐玻璃光谱性能的影响

蓝光激光器在彩色激光显示、高密度光储存、海洋资源探测、水下通信以及生物科技等领域具有广泛的应用前景。目前较为成熟的Yb³⁺掺杂光纤激光器倍频后仅能获得~490 nm蓝绿光,因此如何得到接近450 nm的纯蓝光激光器是目前急需解决的问题。Nd³⁺:⁴F_3/2→⁴I_9/2能级跃迁产生的0.9 μm光经倍频后可获得~450 nm光,并可应用于蓝光激光器,但该跃迁产生的光所占荧光分支比较低。本文系统研究了1%(质量分数)Nd₂O₃掺杂50GeO₂-(20-x)PbO-15BaO-15ZnO-xNb₂O₅(x%=0%,2.5%,5%,10%,15%,摩尔分数)玻璃的吸收光谱、荧光光谱和荧光寿命,计算了相应的Judd-Ofelt强度参数以及增益带宽。研究发现,Nb₂O₅的加入会使Nd³⁺在900 nm荧光峰的吸收截面、发射截面、有效线宽和荧光分支比增加。当Nb₂O₅浓度为10%(摩尔分数)时,Judd-Ofelt强度参数Ω₂=5.91×10^-20 cm²,光谱质量参数χ=1.01,荧光分支比为42.9%。综上所述,Nb₂O₅能提高Nd³⁺ 0.9 μm的荧光分支比,从而倍频获得纯蓝光(450 nm),有利于蓝光激光器的发展及应用。     

Pr3+/Er3+ Codoped Ge-As-Ga-S Glasses as Dual-Wavelength Fiber-optic Amplifiers for 1.31 and 1.55 μm Windows

Fluorescence emissions at both 1.31 and 1.55 μm communication windows were observed from Pr³⁺/Er³⁺ codoped Ge-As-Ga-S glasses with a single wavelength pumping at 986 nm. The lifetime of the Er³⁺:⁴ I _11/2 level decreased as the Pr³⁺ concentration increased, and that of the Pr³⁺:¹ G ₄ level increased as the Er³⁺ concentration increased. Energy transfer from the Er³⁺:⁴ I _11/2 level to the Pr³⁺:¹ G ₄ level was responsible for emission of the 1.31 μm fluorescence from the Pr³⁺:¹ G ₄ level. Ge-As-Ga-S glasses that have been doped with Pr³⁺ and Er³⁺ cations are promising amplifier materials for both 1.31 and 1.55 μm communication windows.     

Absorption and emission spectra of Eu3 doped Fluoroborate glasses

This paper reports the preparation of certain newly developed Eu³⁺ - doped fluoroborate glasses with H₃BO₃ and Na₂CO₃ as the network formers (NWF) and the fluorides of alkali (Na or Li) as the network intermediates (NWL). Further, by adding AIF₃ to the fluoroborate glasses, properties such as glass transparency; hardness; resistivity towards moisture and IR-transmission ability were found improved significantly. Under a UV source, these colourless Eu³⁺ - glasses did reveal brighter red emission. Compositional effects on the absorption and photoluminescence spectra of Eu: fluoroborate glasses were examined from their measured spectrophotometric profiles.     

Determination of the Fe2+/Fe3+ Ratio in Nuclear Waste Glasses

The Fe²⁺/Fe³⁺ ratios of 47 simulated nuclear waste glass samples with ratios varying from 0.01 (oxidized) to 1.6 (reduced) were determined by wet-chemical and Mössbauer spectral analyses. The wet-chemical method involved the spectrophotometric determination of Fe²⁺ and total iron using remote spectroscopy with fiber optic chemical sensing. Interferences from other species present in these glasses were examined and alternative analytical techniques were investigated. Results of wet-chemical and Mössbauer spectral analysis were comparable; however, the wet-chemical method is probably preferable for the analysis of highly radioactive glasses until such glasses have been shown to have satisfactory Mössbauer spectra.