Er~(3 ),Ho~(3 )和Tm~(3 )在硫氧化钆中的余辉发光

非放射性长余辉磷光粉作为美化和清洁光源在发光陶瓷、交通安全标志、紧急突发事件的照明设施、工艺美术涂料等众多领域得到越来越广泛的应用,引起人们的重视.到目前为止,文献报道的稀土长余辉磷光体的激活离子主要有铕离子(Eu3+和Eu2+[1-4]、三价铈离子(Ce3+)[5]、三价铽离子(Tb3+)[6]、三价镨离子(Pr3+)[7]、三价钐离子(Sm3+)[8].Ho3+,Er3+,Tm3+等稀土离子作为红外上转换发光材料的激活离子[9～12],而关于它们的长余辉发光的报道极少.最近,雷炳富等在Tm3+离子[13]激活的硫氧化钇体系中发现了长余辉发光.在此,我们通过高温固相法合成了Er3+,Ho3+和Tm3+掺杂的硫氧化钆长余辉磷光粉,观察到该体系中迄今未见文献报道的Er3+,Ho3+和Tm3+离子的长余辉发光.     

沉淀法合成纳米晶长余辉材料Y2O2S∶Eu3+，Ti

The long-lasting phosphorescent materials, yttrium oxysulfides doped by Eu and Ti, were systhesized by coprecipitation with their subsequent thermal decomposition in the presence of sulphur. The products were characterized by XRD, TEM, phosphorescent spectra, and thermoluminescence. The XRD results indicate that the lowest synthesis temperature is 700 ℃. From the TEM, the average diameter of particles was in the range of 60～120 nm, and augmented with the increase of temperature. The materials under UV excitation presented well afterglow from the transition of ⁵D_0,1 → ⁷F_J of Eu³⁺, and the persistent time was about 2 h. The long-lasting afterglow mechanism was discussed, too.     

Er3+，Ho3+和Tm3+在硫氧化钆中的余辉发光

The new Er^3 , Ho^3 and Tm^3 doped gadolinium oxysulfide phosphors with the long afterglow emission were synthesized by solid-state reaction method. The synthesized phosphors were characterized by X-ray diffraction. The excitation and photolumineseenee spectra, afterglow spectra and afterglow decay curve were examined by fluorescence spectroscopy. The afterglow spectra of Gd2O2S:Er^3 , Mg, Ti showed typical transitions of Er^3 at 528(2H11/2→4I15/2), 548 (^4S3/2 →^4I15/2) and 669 nm (^4F9/2→^4I15/2). In the afterglow spectra of Gd2O2S: Ho^3 , Mg, Ti,typical transitions of Ho^3 at 546 nm (^5S2→^5I8), 651 and 661 nm (^2F5→^5I8) were observed. In Gd2O2S:Tm^3 , Mg,Ti, the afterglow emission at 800 nm (^1G4→^3H5) of Tm^3 was seen. The meehnism and model of afterglow energy transfer were proposed.     

沉淀法合成纳米晶上转换发光材料Y_2O_2S:Yb,Er

采用沉淀法在不同温度下合成了纳米上转换发光材料Y2O2S∶Yb,Er,运用XRD、TEM和上转换发光光谱对其进行表征。结果表明,使用该法在700℃即能合成纳米上转换发光材料Y2O2S∶Yb,Er,随着合成温度的升高,产物的粒径从60到120nm逐渐增大。上转换发光光谱显示该材料主要有2个发射带,其中红光发射的中心波长位于668nm,绿光发射的中心波长位于525和550nm。此外,对材料的上转换发光过程进行了探讨。     

新型环树融合的无源光网络的应用研究

随着接入网带宽需求和业务支持需求的快速发展,环形结构的无源光网络(PON)的应用越来越重要,更长距离、支持更多光网络单元、与环形网络无缝融合已经成为PON在城域网中继续发展的3大要求.文章详细论述了新型环树融合拓扑结构的PON的原理及关键技术,讨论了这种新型结构的典型应用,总结了不同方案的优缺点,为未来接入网与城域网更深层次的融合发展的研究提供参考.     

基于光纤传送网的5G移动通信前传关键技术

移动前传网络是C-RAN(集中式/云无线接入网)技术中的重要部分。随着现代无线接入网络的发展演进,用户带宽需求的快速增长对网络的传输速率提出了更高的要求。文章回顾了移动前传网络的基本内容,分析了前传网络需要满足的各项需求,并对当前提出的各种前传网络的解决方案进行了详细的介绍。     

V形微带缝隙天线

提出了一种新颖的V形微带缝隙天线,地板上开一个直角V形缝隙,在V形缝隙的顶角处附加一个小直角三角形补偿隙,通过改变三角形补偿隙面积的大小可以对天线阻抗匹配进行优化,由基片另一侧的箭形微带线终端对缝隙单元馈电。这种天线易于实现宽带特性,设计简单,便于加工。文中给出了天线阻抗和方向图的计算结果,并给出了反射损耗和增益的实验结果。实测结果表明,该天线的阻抗带宽达到了43%,覆盖了1146~1776MHz的频率范围,-10dB阻抗带宽内增益值在4.5~6.5dB之间,平均增益约为5.5dB。     

一种副载波单边带分插复用的OFDM-PON模型

提出并证明了一种基于副载波单边带分插复用的正交频分复用无源光网络(OFDM-PON)系统的新型结构.该结构的下行传输是基于单边带的OFDM-4-正交幅度调制(QAM),传输速率为10 Gbit/s;而上行传输则是利用下行信号中保留的另一条边带进行2.5 Gbit/s速率的幅移键控(ASK)调制,采用时分多路接入方式.该方案可以较好地避免双向传输中的后向瑞利散射,考虑后向散射情况下,下行信号功率代价＜0.8 dB,上行信号功率代价＜1.8 dB.     

High speed optical transmission utilizing constant envelope modulation based on frequency shift keying and minimum-shift keying

A novel 40-Gb/s constant envelope optical frequency shift keying （FSK） transmitter and the transmission characteristics are investigated both by simulation and experiment. Meanwhile, to increase the spectrum efficiency of FSK, we propose a novel optical minimum-shift keying （MSK） scheme and analyze its per-formance compared with other MSK schemes and other traditional modulation formats. Simulation and experimental results show that the novel FSK scheme could be a potential candidate for the future high speed transmission and label switching systems. And the novel MSK scheme deserves future deep research for its potential excellent performance.