Luminescent properties of YAl3(BO3)4:Eu3+ phosphors

YAL₃(BO₃)₄:Eu³⁺ phosphors were fabricated by the sol-gel method. The structure properties were measured by x-ray diffraction (XRD) and infrared spectra (IR). Doping concentration of Eu³⁺ ions in YAL₃(BO₃)₄:Eu³⁺ phosphors of 0, 1, 3, 4, and 5 mol% were studied. The excitation spectra and emission spectra of YAL₃(BO₃)₄:Eu³⁺ phosphors were examined by fluorescent divide spectroscopy (FDS). The luminescent properties of YAL₃(BO₃)₄:Eu³⁺ phosphors are discussion. The optimal doping concentration of Eu³⁺ ions in YAL₃(BO₃)₄:Eu³⁺ phosphors was found to be approximately 3 mol%.     

自变频激光晶体Nd3+:GdAl3(BO3)4的研究

采用熔盐法生长出尺寸为30mm的Nd3+:GdAl3(BO3)4优质晶体,进行了吸收光谱和荧光光谱的测定研究,计算得到晶体发射截面为σ1061.9e=2.9×10-19cm2和σ1338nme=5.5×10-20cm2.采用染料激光器作为泵浦源,对晶体进行了自变频激光实验研究,在紫外可调谐(378～382nm)、绿光531nm、蓝光(436～443nm)、红光(669nm)和红外可调谐(1305～1365nm)波段实现了激光输出,输出的最大功率分别为:105μJ/脉冲、119.5μJ/脉冲、445μJ/脉冲、19μJ/脉冲和31μJ/脉冲.     

YAl3(BO3)4:TM (TM = Mn, Co, Cr) nanocrystals synthesis for laser operated nonlinear optics

An attempt to synthesize YAB matrices doped with cobalt, manganese, and chromium ions by means of the Pechini method for photo-induced nonlinear optics was performed. The best results were obtained for the Cr doped samples. It may be related with the fact that YAB:Cr main absorption peak is situated near the photo-inducing green second harmonics of Nd:YAG laser at 532 nm. It was established that after 600 s of samples illumination there was observed some maximum of the SHG. With the further treatment of the materials the SHG starts to decrease. The maximal enhancement was achieved at 150 K. After the switching off of the photo-inducing treatment the output SHG was relaxed to initial state during 2–3 min. Local increase of temperature due to heating did not exceed 6 K. For the Mn doped YAB NC the behavior is quite non-monotonic. The SHG changes are within the accuracy of the YAB NC NLO measurements. One can see two slight maxima at 200 and 800 s. At the same time Co suppress the output SHG, which may be caused by specific features of Co ions.     

Morphology, Growth Process and Symmetry of {0001} Face on Yb：YAl3（BO3）4 Crystal

The {0001} face develops on the habit of self-frequency doubling laser crystal Yb: YAl3(BO3)4 (YbYAB) only under high growth rate condition, and its morphology is rough. To study the growth mechanism of {0001} face, we have observed the growth morphology on {0001} polishing section by atomic force microscopy (AFM). A series of AFM images captured in different growth durations on the {0001} polishing section reflect the crystal growth process. It is shown that the growth morphology on the {0001} polishing section was rough with many hillocks at the first growth stage, and it can become smooth finally, although the growth morphology on the {0001} face develoFed naturally on YbYAB crystal habit is always rough. On the smooth {0001} surface formed at the last growth stage, there aresome triangular pits. This fact is different from that of hillocks in most crystal growth morphologies. AFM can easilydistinguish the pits or hillocks on the surface, but differential interfere contrast microscopy (DIC) can not do. Theorientation of the triangular pits is just the opposite to the triangular {0001} faces. The chemical etching patternis also composed of this kind of triangular pits. These growth morphology and etching pattern of the {0001} facesshow 3m symmetry, but the point group of YbYAB crystal is 32. The symmetric contradiction between morphologyand point group does not exist for quartz, although whichsurface morphology we can distinguish the right form ormorphology we can not do. The reason for the symmetricand its point group is not known yet.has the same point group as YbYAB. From quartz {0001}left form of the crystal, but from YbYAB {0001} surfacecontradiction between YbYAB {0001} surface morphology and its point group is not known yet.     

Temperature phase-matching properties for harmonic generation in GdCa4O(BO3)3 and Gd(x)Y(1-x)Ca4O(BO3)3

GdCa4O(BO3)3 has been found to have phase-matching points where the temperature variations of the phase-matching angles become zero for type-1 sum-frequency generation in the zx plane. We also found that the temperature sensitivities of the phase-matching conditions in the zx plane are different along the phi = 0 degrees and phi = 180 degrees directions in this material. In addition, the thermo-optic dispersion formula of this material that reproduces the temperature phase-matching properties of GdCa4O(BO3)3 and Gd(x)Y(1-x)Ca4O(BO3)3 is presented.     

Optical transition probability of Nd3+ ion in α-Ba3Y(BO3)3 crystal

Optical absorption and emission intensities have been investigated for the Nd³⁺ ion in α-Ba₃Y(BO₃)₃ crystal. Based on the Judd-Ofelt theory the spectral parameters were obtained. The intensity parameters Ω_λ are: Ω₂ = 0.62 × 10^–20 cm², Ω₄ = 0.90 × 10^–20 cm², Ω₆ = 1.06 × 10^–20 cm². The radiative lifetime is 1104 μs, and quantum efficiency is equal to 6.9%. The fluorescence branching ratios are: β₁ (0.88 μm) = 0.4050, β₂ (1.06 μm) = 0.4897, β₃ (1.35 μm) = 0.1000 and β₄ (1.88 μm) = 0.0053. Electronic Publication     

Changes of the local magnetic properties of the optically excited Nd3+ ions and their manifestation in the near IR spectra of the Nd0.5Gd0.5Fe3(BO3)4 crystal

Polarized absorption spectra of f–f transitions ⁴I_9/2 → ⁴F_3/2 and (²H_9/2 + ⁴F_5/2) in the Nd³⁺ ion in the Nd_0.5Gd_0.5Fe₃(BO₃)₄ single crystal were studied as a function of temperature in the range of 2–40 K and as a function of magnetic field in the range of 0–65 kOe at 2 K. It was found out that the selection rules for f–f electron transitions substantially changed in the magnetically ordered state of the crystal, and they strongly depended on the orientation of the Fe and Nd ions magnetic moments relative to the light polarization. The splitting of the ground and excited states of the Nd³⁺ ion in the exchange field of the Fe sublattice were determined. It was revealed that the value of the exchange splitting (the exchange interaction) in the excited states did not correlate with the theoretical Landé factors. The Landé factors of the excited states were experimentally found. In general, the local magnetic properties in the vicinity of the excited ion depend substantially on its electron state. In particular: (1) in one of the excited states a weak ferromagnetic moment appears, (2) the changes of type of the local magnetic anisotropy take place in some excited states, and (3) in some excited states the energetically favorable orientation of the Nd³⁺ ion magnetic moment is opposite to that in the ground state. In some excited states the nonequivalent Nd³⁺ centers were found out.     

Low cytotoxicity porous Nd(2)(SiO(4))(3) nanoparticles with near infrared excitation and emission

Porous Nd(2)(SiO(4))(3) nanoparticles were successfully synthesized by a controlled route. This kind of silicate nanoparticle could be excited by near-infrared (NIR) radiation (808 nm) and triggered a NIR emission (1066 nm) at room temperature. By monitoring the 1066 nm emission, the long-lived luminescent lifetime was determined to be 19.5 μs. These NIR nanoparticles with appropriate diameters (<100 nm) were suitable for cell assays. MTT assays showed that the cytotoxicity of the porous Nd(2)(SiO(4))(3) nanoparticles was very low. Therefore, these porous silicate nanoparticles are potential biosafe high-performance NIR biolabeling materials.     

Diode laser absorption measurements of CH(3)Cl and CH(4) near 1.65 microm

Two distributed-feedback (InGaAsP) diode lasers were used to record high-resolution absorption spectra of the parallel and the perpendicular components of the 2nu(4) band of methyl chloride (CH(3)Cl) and the 2nu(3) band of methane (CH(4)) near 1.65 mum. The room-temperature absorption measurements, which were conducted in a multipass cell with a variable path length (878-1020 cm), were used to determine the mole fractions of the constituent gases and thus demonstrate species-specific, nonintrusive concentration measurements of species with overlapping spectra.     

The sol-gel process synthesis of GdAl3(BO3)4:Eu3+ nanophosphors

GdAl3(BO3)4:Eu3+ red phosphors were prepared using citric acid as complex agent by sol-gel technique. The preparation conditions of the precursor synthesis, including crystallization temperature and crystallization time were investigated. Their structure and luminescence properties were characterized by X-ray diffraction (XRD) analysis and fluorescence spectrometry. The results showed that GdAl3(BO3)4:Eu3+ phosphor crystallized at 960 degrees C for 2 h have been synthesized by sol-gel method. The phosphor is distributed into hexagonal system and the lattice parameters are a = 9.2992 nm c = 7.2577 nm. The excitation spectrum of Gd(0.95)Al3(BO3)4:Eu(0.05)3+ samples is complex and the frequency scale is wide. It consists of a number of main excitation transitions namely 8S(7/2) --> 6IJ (270 nm) of Gd3+, and the others 7F0 --> 5L6 (400 nm), 7F0 --> 5D2 (472 nm) and 7F0 --> 5D1 (542 nm) of Eu3+. The main emission peaks are 614 nm and 619 nm, which are the characteristic emission peaks of Eu3+. These emission peaks correspond to the transition from 5D0 to 7F2 of Eu3+. The shape and the wavelength range of the emission spectrum are similar when the sample was excited by different excitation spectrum. Only the relative intensity of the emission peaks is different from each other.     

Emission analysis of Sm3+:Ca4GdO(BO3)3 powder phosphor

This paper reports on the spectral analysis of reddish orange color luminescent Sm³⁺:Ca₄GdO(BO₃)₃ powder phosphor. This phosphor powder has been synthesized by a solid state reaction method. Emission spectrum of it has shown four emission transitions of ⁴G_5/2 → ⁶H_J (J = 5/2, 7/2, 9/2, 11/2) and among them, the transition ⁴G_5/2 → ⁶H_7/2 displays the reddish orange (605 nm) color. Lifetimes of three emissions (⁴G_5/2 → ⁶H_{J=5/2, 7/2 & 9/2}) have been computed based on the measured decay curves. Besides the measurement of emission spectrum of this material, its nature and structural details have also been investigated from XRD, SEM and FTIR studies.     

Spectral parameters of Nd3+ ion in Nd:KLa(WO4)2 crystal

The spectral parameters of Nd³⁺ ions in Nd:KLa(WO₄)₂ crystal have been investigated based on Judd-Ofelt theory. The spectral parameters were obtained: the parameters of oscillator strengths are Ω₂=3.0887×10^–20 cm², Ω₄=1.0375×10^–20 cm², Ω₆=1.0422×10^–20 cm², the radiative lifetime is 685 μs, the quantum efficiency is 30.7%, and the fluorescence branch ratios were calculated: β₁=0.432, β₂=0.475, β₃=0.089, β₄=0.004. Electronic Publication     

Efficient and tunable continuous-wave diode-pumped Yb3+:Ca4GdO(BO3)3 laser

A Yb(3+):Ca(4)GdO(BO(3))(3) (Yb:GdCOB) crystal has been diode pumped for the first time to our knowledge. We obtained 47.5% slope efficiency at 6 degrees C, producing 191 mW of power at 1050 nm, with a 2.4% output coupler. Temperature does not significantly affect the laser performance: At room temperature we still obtained 180 mW of power for the same cavity. We achieved tunability of the Yb:GdCOB laser from 1035 to 1088 nm with a 1.7% output coupler and 100-nm tunability with a low-transmission output coupling (T = 0.03%).     

Spectral characterizations of Nd3+:KLa(WO4)2 crystal

The absorption and emission of Nd³⁺:KLa(WO₄)₂ crystal were investigated. The uniaxial crystal Nd³⁺:KLa(WO₄)₂ shows strong polarization dependence. The intensity of the absorption bands in E//c is about four times than that in E//a. The absorption cross section σ_a is 22.6 × 10^–20 cm² for E//c. The emission cross section at 1.069 μm is 2.09 × 10^–19 cm². The fluorescence lifetime is 157 μs at 300 K. The relationship of Nd³⁺ concentrations with fluorescence intensity and lifetime was discussed. The results show the ca 3 at % Nd³⁺ concentration in Nd³⁺:KLa(WO₄)₂ crystal is appropriate. Electronic Publication     

1.06 μm laser characteristics of γ-Nd3+:LaSc3(BO3)4 crystal

This paper reports the pulse laser characteristics of the new polymorph γ-Nd³⁺:LaSc₃(BO₃)₄ (γ-NLSB) crystal. The maximum laser output of a γ-NLSB rod with dimensions of Φ3.3 mm×15 mm was 83.0 mJ at 1.06 μm, pumped by a single Xenon flash-lamp of Φ3.0 mm×20 mm. The overall and average slope efficiencies were 0.78% and 1.02%, respectively. The laser energy threshold value E_th was lower than 0.2 J, and the extinction ratio of the crystal was 39.38 dB, the output laser of 1.06 μm was the linear polarized light. Electronic Publication