作者机构：
[龙祖强] Department of Physics and Electronics Information Science, Hengyang Normal University, Hengyang 421008, China;[龙祖强; 梁昔明; 阎纲] School of Information Science and Engineering, Central South University, Changsha 410083, China
通讯机构：
Department of Physics and Electronics Information Science, Hengyang Normal University, China
摘要：
采用高温固相法合成了Ca2SnO4∶Tb3+绿色荧光粉。 利用X射线衍射分析了Ca2SnO4∶Tb3+物相的形成。 测量了Ca2SnO4∶Tb3+的激发和发射光谱， 激发光谱由一个宽激发峰组成， 研究了Tb3+浓度对样品激发光谱的影响， 结果显示， 随Tb3+浓度增大， 宽带激发峰发生了红移。 发射光谱由四个主要发射峰组成， 峰值分别位于491， 543， 588和623 nm处， Tb3+以5D4—7F5（543 nm）跃迁发射最强， 低掺杂浓度下， Tb3+的7F6能级出现斯托克劈裂， 劈裂峰(481 nm处)随Tb3+浓度增加， 先增强然后减弱； 在发光强度方面， 随Tb3+浓度的增大呈现先增大后减小的趋势， 当Tb3+摩尔浓度为9%时， 发光强度最大， 根据Dexter理论， 确定了在Ca2SnO4基质中Tb3+自身浓度猝灭机理。 荧光寿命测试表明Tb3+在Ca2SnO4基质中荧光衰减平均寿命为4.4 ms。 A novel green emitting phosphor, Tb3+-doped Ca2SnO4, was prepared by the solid-state reaction. X-ray powder diffraction (XRD) analysis confirmed the formation of Ca2SnO4∶Tb3+. Photoluminescence measurements indicated that the phosphor exhibits bright green emission at about 543 nm under UV excitation. The excitation spectra of Ca2-xTbxSnO4 appear to have a red shift with main peak from 254 to 260 nm. The emission spectra of Ca2-xTbxSnO4 have four peaks ascribed to 5D4—7FJ (where J=6, 5, 4, 3) transitions of Tb3+ ions. Under the condition of low Tb3+ concentration, the 5D4—7F6 transition of Tb3+ showed a stark energy level split to three split peaks and the peak intensity of 481nm firstly increased with increasing Tb3+ concentration, then decreased. The dependence of luminescent intensity of Ca2SnO4∶Tb3+ phosphor on the Tb3+ concentration was studied, and the results show that the luminescence intensity firstly increased with increasing Tb3+ concentration, then decreased, and reached the maximal value at 9 mol% Tb3+. According to the Dexter theory, the authors confirmed the concentration quenching mechanism of Tb3+ in Ca2SnO4. The fluorescence lifetime of phosphor analysis shows that the average lifetime is 4.4 ms. The results indicated that Ca2SnO4∶Tb3+ could be a potential candidate as a green-emitting powder phosphor.
作者机构：
[Xia M.; Yang K.] Wuhan National Laboratory for Optoelectronics, College of Optoelectronics Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China;Department of Physics and Electronic Information Science, Hengyang Normal University, Hengyang, 421008, China;[Tan J.] Wuhan National Laboratory for Optoelectronics, College of Optoelectronics Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China, Department of Physics and Electronic Information Science, Hengyang Normal University, Hengyang, 421008, China
通讯机构：
[Kecheng Yang] W;Wuhan National Laboratory for Optoelectronics, College of Optoelectronics Science and Engineering, Huazhong University of Science and Technology, Wuhan, China
摘要：
Light emitting diode (LED) is one of the most important light sources in the 21st century and has broad prospects in the illumination. Currently, the white LED is used not only for illumination, but also for transmission data. A new technique referred as visible light communication (VLC) is rapidly growing in optical communication. In order to enhance the performance of the communication link, we present optical multiple input and multiple output (MIMO) communication system to achieve high data rate, which can mitigate the shadow effect of indoor communication. Moreover, the MIMO will bring about multi-path effect, which causes inter-symbol interference (ISI) to degrade the performance of the link. Hence, an adaptive equalization technique has been used in the receiver system, which can reduce the ISI when the system is determined to receive symbol. Finally, we have simulated the MIMO system with adaptive equalization. The simulation results show significant improvement in the transmission rate using on off keying (OOK) and the average signal to noise ratio (SNR) in this channel has increased 13.5 dB after equalization.
作者机构：
[龙文] Guizhou Key Laboratory of Economics System Simulation, College of Finance and Economics, Guiyang 550004, Guizhou, China;[李山春; 梁昔明; 龙文] School of Information Science and Engineering, Central South University, Changsha 410083, Hunan, China;[龙祖强] Department of Physics and Electronic Information Science, Hengyang Normal College, Hengyang 421008, Hunan, China
通讯机构：
Guizhou Key Laboratory of Economics System Simulation, College of Finance and Economics, China
作者机构：
[龙文] Guizhou Key Laboratory of Economics System Simulation, Guizhou College of Finance and Economics, Guiyang 550004, China;[梁昔明; Li, Zhaohui; 龙文] School of Information Science and Engineering, Central South University, Changsha 410083, China;[龙祖强] Department of Physics and Electronics Information Science, Hengyang Normal College, Hengyang 421008, China
通讯机构：
[Long, W.] G;Guizhou Key Laboratory of Economics System Simulation, Guizhou College of Finance and Economics, China
作者机构：
[龙文] Guizhou Key Laboratory of Economics System Simulation, Guizhou College of Finance and Economics, Guiyang 550004, China;[龙祖强] Department of Physics and Electronic Information Science, Hengyang Normal College, Hengyang 421008, China;[梁昔明; 龙文; Li, Zhao-Hui] School of Information Science and Engineering, Central South University, Changsha 410083, China
通讯机构：
Guizhou Key Laboratory of Economics System Simulation, Guizhou College of Finance and Economics, China
作者机构：
[唐益群; 王友文; 陆世专; 游开明; 陈列尊; 张登玉] Department of Physics and Electronic Information Science, Hengyang Normal University, Hengyang 421008, China
通讯机构：
Department of Physics and Electronic Information Science, Hengyang Normal University, China
关键词：
非线性传输;啁啾脉冲;宽带激光;时空调制
摘要：
为避免啁啾脉冲堆积宽带激光的空间调制对光学元件的损坏, 数值研究了其非线性传输过程中时域调制对光束空间调制产生与增长的影响。结果表明：光束未叠加空间调制时, 若B积分在实际工作范围内, 堆积子脉冲间干涉引入时间调制外, 叠加与未叠加时间调制, 正反常色散情况下光束空间上均不会产生调制, 因而也没有调制增长, 然而, 当B积分进一步增加时, 光束空间将产生调制, 并能快速增长；当光束引入空间调制后, 在反常色散情况下, 与时间未额外叠加调制相比, 时间额外叠加调制时空间调制增长速度明显加快, 而在正常色散时, 额外添加时间调制与不添加调制, 空间调制增长的差别很小。 To identify the potential risks of spatial modulation of broad-band laser beams stacked by chirped pulses on the safety of optics, this paper numerically investigated the effect of temporal modulation on the generation and growth of spatial modulation during its nonlinear propagation. When there is no additional spatial modulation and the B integral is limited in the practical working range (usually less than 2.0 rad), no spatial modulation will be generated for both normal dispersion and anomalous dispersion; while with the B integral further increasing, spatial modulation will emerge with a rapid growth. When there is additional spatial modulation for anomalous dispersion, the spatial modulation with additional temporal modulation will grow more quickly than that without additional temporal modulation. However, for normal dispersion, the growth of spatial modulation for both cases is similar.
