非临界相位匹配RTP晶体1.6 μm光参量振荡器

采用非临界相位匹配切割,尺寸4 mm4 mm20 mm的磷酸钛氧铷（RTP）晶体作为非线性光学晶体,进行了半导体激光端面抽运Nd:YAG/RTP的内腔式光参量振荡获得人眼安全激光的实验研究。对比了不同声光调Q重复频率下的信号光输出特性。在10.5 W的抽运功率和15 kHz的重复频率下,获得了最高900 mW的1.62 m人眼安全激光输出,光光转换效率达8.6%。1.62 m信号光和对应的1.06 m基频光的脉冲宽度分别为4.6和8.2 ns。信号光中心波长在1618 nm,谱线宽度小于0.5 nm。     

LBO-类非临界相位匹配腔内倍频671nm激光器

报道了利用珋类非临界相位匹配的ＬＢＯ晶体腔内倍频、激光二极管泵浦的ＮｄｖＹＶＯ４ 激光器, 在吸收泵浦功率５．４４ Ｗ 时, 获得２４０ ｍ Ｗ 的６７１ ｎｍ 激光输出, 光－光转换效率约４．４％ 。     

ErxY1-xAlO3晶体的荧光动力学研究

本文详细计算了辐射跃迁几率、无辐射跃迁几率、交叉弛豫几率和其他光谱参数。并且在考虑上述三种辐射过程的情况下,讨论了Er³⁺离子的荧光动力学过程,研究了荧光发射特征与Er³⁺离子浓度的关系,给出了它们的规律。 关键词：     

LBOⅠ类非临界相位匹配腔内倍频671 nm激光器

报道了利用１类非临界相位匹配的ＬＢＯ晶体腔内倍频、激光二级管泵浦的Ｎｄ：ＹＶＯ４４激光器,在吸收泵浦功能５．４４Ｗ时,获得２４０ｍＷ的６７１ｎｍ激光输出,光－光转换效率约４．４％。     

高效率Nd:YVO4/LBO临界相位匹配脉冲绿光激光器

报道了一种利用激光二极管（LD）端面泵浦Nd:YVO4晶体,声光调Q,LBO临界相位匹配腔内倍频的高效率、小体积、风冷绿光激光器。分析了不同偏振光泵浦的情况下,激光晶体对泵浦光的吸收特性。由分析得出,采用部分偏振光泵浦,可以提高激光晶体对泵浦光吸收均匀性,改善基波畸变,获得高转换效率激光输出。实验中,在泵浦光功率为33 W、声光调Q重复频率为20 kHz时,得到脉宽为23.96 ns、平均功率为15 W的1064 nm基频光输出。经倍频后,得到平均功率为11.2 W的绿光输出,倍频效率为74.6%,总体光-光转换效率为34%。在输出功率为10 W时,测得1 h内输出功率不稳定度为0.512 2%,水平方向和竖直方向的光束质量因子M2分别为1.2和1.1。     

非临界相位匹配KTP光学参量振荡器的研究

对电光调Q(Ce,Nd):YAG激光抽运内腔非临界相位匹配(NCPM)光参量振荡器(IOPO)进行了实验研究,实验发现IOPO输出光波长为532 nm、632 nm、1 064 nm、1 100 nm和1 571 nm 5种。OPO输出镜对信号光反射率较大时,信号光出现多脉冲,可以通过控制信号光反射率,使信号光为单脉冲。信号光能量随着抽运能量增加到一定值后出现饱和。     

产生蓝色相干辐射和实现Nd∶YAG 1.0642μm倍频90°非临界相位匹配的Nb∶KTiPO_4(英文)

本文报道了用熔盐顶部籽晶法生长Ｎｂ浓度（０～１３）ｍｏｌ％的Ｎｂ∶ＫＴＰ晶体的倍频的Ⅱ型相位匹配的截止波长和Ｎｄ∶ＹＡＧ１．０６４２μｍ及Ｎｄ∶ＹＡ１Ｏ３１．０７９５μｍ激光在这些晶体中倍频的最佳相位匹配角的测量结果．从中可看出,由于Ｎｂ５＋的引入使ＫＴＰ晶体倍频的Ⅱ相位匹配的截止波长有效蓝移,目前已使截止波长蓝移至９３７ｎｍ且有效产生４６８．５ｎｍ的倍频蓝光．同时Ｎｂ５＋的引入使Ｎｄ∶ＹＡＧ１．０６４２μｍ激光和Ｎｄ∶ＹＡ１Ｏ３倍频的最佳相位匹配方向产生很大的变化,目前已使Ｎｂ∶ＫＴＰ晶体倍频的最佳相位匹配方向为θ＝８８．３２°、Φ＝０°,非常接近于９０°非临界相位匹配方向     

Gd1-xEuxAl3(BO3)4纳米晶的合成及其发光性能

以高温固相反应法合成了Gd_1-xEu_xAl₃(BO₃)₄:Eu³⁺纳米荧光粉。使用XRD分析确定了样品的物相,并根据谢乐公式计算出其微晶的纳米粒度。采用了“粉末悬浮法”以甘油为分散介质,在RF540荧光光度计上测试了纳米晶荧光粉的激发光谱和发射光谱。GdAl₃(BO₃)₄基质本身发光,GdAl₃(BO₃)₄:Eu纳米荧光粉表现了Eu³⁺的特征发射光谱,其中最强峰为⁵D₀→⁷F₂发射,表明晶体结构中没有对称中心格位。实验表明在GdAl₃(BO₃)₄:Eu纳米晶荧光粉中,存在Gd³⁺对Eu³⁺发光的基质敏化作用。     

产生蓝色相干辐射和实现Nd:YAG 1.0642μm倍频90°非临界相位匹配的Nb:KTiPO4

本文报道了用熔盐顶部籽晶法生长Nb浓度(0～13)mol%的Nb:KTP晶体的倍频的Ⅱ型相位匹配的截止波长和Nd:YAG1.0642μm及Nd:YA1O₃1.0795μm激光在这些晶体中倍频的最佳相位匹配角的测量结果.从中可看出,由于Nb⁵⁺的引入使KTP晶体倍频的Ⅱ相位匹配的截止波长有效蓝移,目前已使截止波长蓝移至937nm且有效产生468.5nm的倍频蓝光.同时Nb⁵⁺的引入使Nd:YAG1.0642μm激光和Nd:YA1O₃倍频的最佳相位匹配方向产生很大的变化,目前已使Nb:KTP晶体倍频的最佳相位匹配方向为θ=88.32°、Φ=0°,非常接近于90°非临界相位匹配方向.     

RECa4O(BO3)3 thin films as new Luminescent materials screened by the combinatorial method

A new phosphor material, Y_1−xTb_xCa₄O(BO₃)₃ (0≤x≤1) film was grown on SiO₂ substrates by the combinatorial pulsed laser deposition (PLD) method, which enabled us to fabricate continuous composition spread film libraries. Photoluminescence (PL) and PL decay were measured for these film libraries to identify the optimum composition as well as to determine the luminescence mechanism. The film libraries showed strong dependence of luminescence intensities on the chemical composition of Tb ion. The optimum concentration of Tb ions in Y_1−xTb_xCa₄O(BO₃)₃ was experimentally and theoretically determined to be x=0.2-0.3.     

预注入对Si1-xCx合金形成的影响

室温下在单晶Si中注入(0.6—1.5)at%的C原子,部分样品在C离子注入之前在其中注入²⁹Si⁺离子产生损伤,然后在相同条件下利用高温退火固相外延了Si_1-xC_x合金,研究了预注入对Si_1-xC_x合金形成的影响.如果注入C离子的剂量小于引起Si非晶化的剂量,在950℃退火过程中注入产生的损伤缺陷容易与C原子结合形成缺陷团簇,难于形成Si_1-xC关键词： 离子注入 固相外延 1-xC_x合金')" href="#">Si_1-xC_x合金     

Magnetic properties and magnetoresistance effect of Y1-xGdxMn6Sn6 (x=0－1) compounds

The magnetic properties and magnetoresistance effect of Y_1-xGd_xMn₆Sn₆ (x=0－1) compounds have been investigated by magnetization and resistivity measurements in the applied field range (0－5 T). Compounds with x=0.4－1 display ferrimagnetic behaviours in the whole magnetic ordering temperature range, while compounds with x=0－0.2 display a field-induced metamagnetic transition, and the threshold fields decrease with increasing Gd content. The compounds with x=0.1－0.2 undergo an antiferromagnetic to ferromagnetic transition with increasing temperature. The cell-parameter a and c and cell-volume V of compounds (x=0－1) increase with increasing Gd content. It was found that the saturation magnetization M_s of the compounds (x=0.4－1) decreases, while the ordering points of the compounds (x=0－1)increase with increasing Gd content. A large MR effect was observed in the compound with x=0.2, and the maximum absolute value of MR at 5 K under 3 T is close to 19.3%.     

Crystal structure and magnetic properties of Nd（Mn1-xFex）2Si2 compounds

X-ray powder diffraction,resistivity and magnetization studies have been performed on polycrystalline Nd(FexMn1-x)2Si2 (0 ≤ x ≤ 1) compounds which crystallize in a ThCr2Si2-type structure with the space group I4/mmm.The field-cooled temperature dependence of the magnetization curves shows that,at low temperatures,NdFe2Si2 is antiferromagnetic,while the other compounds show ferromagnetic behaviour.The substitution of Fe for Mn leads to a decrease in lattice parameters a,c and unit-cell volume V .The Curie temperature of the compounds first increases,reaches a maximum around x = 0.7,then decreases with Fe content.However,the saturation magnetization decreases monotonically with increasing Fe content.This Fe concentration dependent magnetization of Nd(FexMn1-x)2Si2 compounds can be well explained by taking into account the complex effect on magnetic properties due to the substitution of Mn by Fe.The temperature’s square dependence on electrical resistivity indicates that the curve of Nd(Fe0.6Mn0.4)2Si2 has a quasi-linear character above its Curie temperature,which is typical of simple metals.     

Structure, dielectric and magnetodielectric properties of Bi1-xGdxFeO3 Ceramics

Different magnetodielectric effects were observed in Bi1-xGdxFeO3 ceramics depending on gadolinium content. A positive one was observed in the samples with x ≤0.10 at 295K and 16K, and a negative one in the sample with x = 0.4 at 16 K. Structure analysis by x-ray diffraction (XRD) reveals that the samples crystallize in the R3c structure (ferroelectrics) for x<0.08 and in the Pbnm structure (paraelectrics) for x≥0.3 at room temperature. Temperature-dependent dielectric response and x-ray diffraction confirm the occurrence of a structural transition in the Pbnm phase at low temperature for the samples with x ≤0.4. While the positive magnetodielectric effects can be attributed to a coupling of magnetic and crystallographic structures of the R3c phase, the observed negative magnetodielectric effect in the Pbnm phase can be associated with a low-temperature modification of the Pbnm structure. The observed dualsigned magnetodielectric effects suggest that the Bi1-xGdxFeO3 oxides are a good prototype for understanding the magnetodielectric coupling mechanism in this kind of materials.     

第一原理研究Sn(O1-xNx)2材料的光电磁性质

基于第一原理的密度泛函理论, 以量子化学从头计算软件 为平台研究了Sn(O_1-xN_x)₂材料的光电磁性能, 分析了体系的态密度、 能带结构、 磁性、 介电虚部及折射率. 计算结果表明, N替代O后, 随着掺杂浓度的增加, 体系的带隙先减小后增大, 掺杂量为12.50%时带隙最窄. 由于N 2p轨道电子的贡献, 在0.55-1.05 eV范围内产生了浅受主能级, 价带和导带处的能级均出现了劈裂及轨道的重叠现象, Sn-O键的键强大于N-O键的键强. 从磁性来看, N原子决定了磁矩的大小. 从介电虚部可知, 掺杂后体系的光学吸收边增宽, 主跃迁峰发生红移, 反射率和介电谱相对应, 各峰值与电子的跃迁吸收有关.     

Temperature and pressure dependences of EPR spectra of Gd ion doped in the EuAl3(BO3)4 monocrystal

The ground state of Gd³⁺ ions substituting for trivalent europium in the EuAl₃(BO₃)₄ single crystal was studied by electron paramagnetic resonance (EPR) over the temperature range of 300-4.2 K and at pressures up to 9 kbar. The EPR spectra were analysed using the spin Hamiltonian of axial symmetry. The following parameters are reported: g=1.981±0.002, b₂⁰=280.18±0.12, b₄⁰=−12.95±0.08 and b₆⁰=0.61±0.12 (at Т=298 K). The distortions of the nearest environment of Gd³⁺ ion were analysed within the framework of the superposition model of crystal field.     

Cd1-xZnxTe晶体退火条件的选择及Zn压对退火晶体质量的影响

采用传统Bridgman方法和加入accelerated crucible rotation technique的Bridgman(缩写为ACRT-B)方法生长的Cd_1-xZn_xTe(x=0.04)晶体中存在有点缺陷、位错、杂质和Te沉淀等缺陷.为了减少甚至消除这些缺陷,必须将生长后的CdZnTe晶片在Cd气氛下退火.从Cd-Te和Cd_0.96Zn_0.04Te的PT相图出发,详细讨论了CdZnTe晶体的气固平衡条件,并 关键词： 1-xZn_xTe')" href="#">Cd_1-xZn_xTe 退火 气-固平衡     

R3(Fe1-xCox)29-yCry(R=Gd,Sm)化合物相稳定性研究

在制备出Gd₃(Fe_1-xCo_x)_29-yCr_{y化合物基础上，成功制备出Sm3(Fe1-xCox)29 -yCry化合物，通过x射线衍射和热磁分析对R3(Fe1-x< /sub>Co x)29-yCry 关键词： 3(Fe1-xCox)29-yCry化合物')" href="#">R3(Fe1-xCox)29-yCry化合物 相结构 单轴磁晶各向异性}