An Optical Labeling Scheme with Novel DPSK/PPM Orthogonal Modulation

A novel differential-phase-shift-keying （DPSK）/pulse-position-modulation （PPM） orthogonal modulation is pro- posed for optical labeling applications, with PPM data as the high-speed payload and DPSK signal as the optical label. The systematic setup for the proposed scheme and research on bit-error rate is presented. The results show that at the bit-error rate of 10-~, the power penalties for 70kin fiber transmission are in the range of 1-3 dB to DPSK label and 5-6 dB to PPM payload in our simulation system. This is under the condition that the large extinction ratio of 18-19 dB is used for the intensity modulators of the PPM payload, with a well received DPSK label. Thus the feasibility of the proposed scheme for all optical transmission networks is clearly verified.     

Focusing of Time Reversal Lamb Waves and Its Applications in Structural Health Monitoring

The focusing of time reversal acoustic fields for dispersive and multimodal Lamb waves is theoretically investigated and experimentally verified. It is demonstrated that the time reversal Lamb wave signal will reach the maximum amplitude when the observation point is located at the damage location. Based on the time reversal focusing theory, a damage imaging method is proposed for structural health monitoring using Lamb waves. The experiments employ a transducer network consisting of four piezoelectric transducers as actuators and as well sensors for excitation and measurement of Lamb waves. The results show that this method is able to accurately predict damage location and provides an estimation of the possible area even for damage close to one of the transducers or even slightly outside the transducer network.     

A Geometrical Model for Tortuosity of Tortuous Streamlines in Porous Media with Cylindrical Particles

We present a three-dimensional geometry model for tortuosity of streamlines in porous media with randomly placed cylindrical particles. The proposed model is expressed as functions of porosity and geometrical parameters with no empirical constant. This might be helpful for understanding the physical mechanism for tortuosity of streamlines in three-dimensional porous media. The model predictions are found to be in good agreement with the experimental data available.     

A Novel Ce3＋/Tb3＋ Codoped Phosphate Glass as Down-Shifting Materials for Enhancing Efficiency of Solar Cells

For the purpose of improving conversion efficiency of solar cells by applying the effect of the wavelength conversion of rare earth ions, photo-luminescence and excitation spectrums of Ce3＋-Tb3＋ doped phosphate glass are investigated. Results show that incorporating Ce3＋ ions to Tb3＋-doped phosphate glass can greatly increase the absorption coefficient in the range 300-400 nm and then the energy transfer （ET） from Ce3＋ to Tb3＋ occurs. In addition, increasing Tb3＋ concentration in Ce3＋/Tb3＋ co-doped phosphate glass can greatly enhance the ET efficiency and 545 nm emission intensity. This shows that Ce3＋/Tb3＋ co-doped phosphate glass would be a promising down-shifting material for enhancing the efficiency of solar cells.     

求解(H^)=5/3(a^)+(a^)+2/3((a^)2+(a^)+2)量子系统能谱新方法

通过对形如(H^)=5/3(a^)+(a^)+2/3((a^)2+(a^)+2)哈密顿量的分析、还原和改造,给出求解该量子系统量子化能谱的两种新方法.     

太阳能驱动全天候监控系统的实验设计

研发了一套太阳能全天候监控系统设计性实验。该实验通过对太阳能电池板基本物理性能的测定,了解其工作原理,然后选择合适的控制器件与负载,设计电路,最后形成一套由太阳能电池板提供能量,实现全天候监控的应用系统。该实验不仅能够作为设计性实验用于大学物理实验,而且可以应用于许多工程领域。     

微波消解-FAAS测定6种龙胆科植物花中微量元素的含量

选用硝酸和双氧水(5∶1)的混合消解液对样品进行微波消解,采用火焰原子吸收光谱法测定了云雾龙胆,管花秦艽,线性龙胆,黄管秦艽,麻花秦艽,蓝玉簪龙胆花这6种龙胆科植物花中的Ca、Mg、Cu、Fe、Mn、Zn6种微量元素的含量。该方法的加标回收率为96.53%—100.11%,相对标准偏差(RSD)小于3%,具有良好的准确度和精密度。研究结果显示,6种龙胆科植物花微量元素含量丰富,其中Mg、Ca、Fe的含量普遍较高,不同龙胆花中各元素的含量均有一定差异。本试验为这些龙胆花药材的合理药用及进一步的开发利用提供了可靠依据。     

新型苯基吡唑铱(Ⅲ)配合物的合成及光物理性能研究

合成了4种新型铱配合物(ppz)₂Ir(LX)(ppz＝1-苯基吡唑,LX＝2-(2’-羟基苯基)苯并噻唑(BTZ),2-(3’-甲基-2’-羟基苯基)苯并噻唑(3-MeBTZ),2-(4’-甲基-2’-羟基苯基)苯并噻唑(4-MeBTZ),2-(4’-三氟甲基-2’-羟基苯基)苯并噻唑(4-TfmBTZ)),并对其分子结构和光物理性能进行了表征。结果表明,4种配合物的最大发光峰分布在583～615 nm,并都在400 nm左右出现一个弱发射带。400 nm的弱发射被认为是金属离子微扰的辅助配体BTZ的单重态激子的辐射跃迁,长波段的光发射被认为是Ir(BTZ)的3MLCT三重态激子的辐射跃迁。而Ir(ppz)₂的3MLCT的三重态激子在室温下被猝灭。最强激发带位于250～310 nm,表明这些配合物的发射主要源于ppz和BTZ配体的跃迁,而不是3MLCT跃迁。与Ir(ppz)₃相比,不仅实现了室温磷光,也通过第二配体的修饰实现了对发光颜色的调制。     

光子晶体环形谐振腔异质结构超微多路光分束器

基于直波导和环形谐振腔的耦合特性,设计了一种新型、高效的二维光子晶体异质结构光分束器.时域有限差分法模拟表明,该设计仅仅通过改变介质柱的折射率,使光场发生重新分布,便可实现输出能量的均分或自由分配.在通信波长范围,该设计结构尺寸小、分束角度大、分束率高,这些特性使其在光通信领域具有重要的应用前景.     

锂铌比对铪铁铌酸锂晶体全息存储性能的影响

以掺杂4mol%Hf4+的LiNbO3:Fe:Hf系列晶体([Li]/[Nb]比变化)为研究对象,研究了系列晶体的可见吸收光谱,在632.8nm的写入光下晶体的衍射效率、灵敏度和抗光散射能力在不同[Li]/[Nb]下的变化规律.研究发现Hf4+的浓度达到阈值浓度后,随着[Li]/[Nb]比的增大,晶体的可见吸收边会发生红移,而且晶格中[Fe2+]/[Fe3+]也会增加,这就导致随着[Li]/[Nb]比的增加,样品的衍射效率逐渐减小,写入时间缩短,灵敏度增大.同时,在晶体中,随着[Li]/[Nb]的增大,陷阱中心Fe2Li+数量增大会使得晶体抗光散射能力减弱.