Characteristics of the crystalline and luminescence properties of a-plane GaN films grown on γ-LiAlO2 （302） substrates

A method of clarifying bioaerosol particles is proposed based on T-matrix. Size and shape characterizations are simultaneously acquired for individual bioaerosol particles by analyzing the spatial distribution of scattered light. The particle size can be determined according to the scattering intensity,while shape information can be obtained through asymmetry factor(AF) . The azimuthal distribution of the scattered light for spherical particles is symmetrical,whereas it is asymmetrical for non-spherical ones,and the asymmetry becomes intense with increasing asphericity. The calculated results denote that the 5 –10 scattering angle is an effective range to classify the bioaerosol particles that we are concerned of. The method is very useful in real-time environmental monitoring of particle sizes and shapes.     

混合界面对溶液制备的磷光OLED器件性能的影响

利用混蒸的方法、将空穴阻挡材料2,9-Dimethyl-4,7-diphenyl-1,10-phenanhroline及电子传输材料Tris(8-hydroxy-quinolinato)aluminium混合,在电子传输层及空穴阻挡层之间制备了薄层的混合界面.在相同驱动电压下,采用混合界面的器件比常规器件的电流密度和亮...     

Fabrication and characterization of CdS-sensitized TiO<Subscript>2</Subscript> nanotube photoelectrode

CdS quantum dot (Qd)-sensitized TiO₂ nanotube array photoelectrode is synthesised via a two-step method on tin-doped In₂O₃-coated (ITO) glass substrate. TiO₂ nanotube arrays are prepared in the ethylene glycol electrolyte solution by anodizing titanium films which are deposited on ITO glass substrate by radio frequency sputtering. Then, the CdS Qds are deposited on the nanotubes by successive ionic layer adsorption and reaction technique. The resulting nanotube arrays are characterized by scanning electron microscopy, X-ray diffraction (XRD) and UV–visible absorption spectroscopy. The length of the obtained nanotubes reaches 1.60 μm and their inner diameter and wall thickness are around 90 and 20 nm, respectively. The XRD results show that the as-prepared TiO₂ nanotubes array is amorphous, which are converted to anatase TiO₂ after annealed at 450 °C for 2 h. The CdS Qds deposited on the TiO₂ nanotubes shift the absorption edge of TiO₂ from 388 to 494 nm. The results show that the CdS-sensitized TiO₂ nanotubes array film can be used as the photoelectrode for solar cells.     

用于光纤法布里-珀罗传感器腔长互相关解调的光楔的数学模型研究

光楔是实现光纤法布里-珀罗(F-P)传感器互相关解调的重要光学元件.根据互相关解调的原理分析了造成光楔和光纤F-P传感器F-P腔的反射光相位不同的因素,进而建立了光楔的干涉光强的数学模型,在此基础上对具有不同反射率的光楔的干涉光强进行了数值仿真,和相同反射率的光纤F-P传感器F-P腔的干涉光强对比之后建立了光楔的简化数...     

只需一个解调器的偏分复用差分相移键控系统实验实现

偏分复用技术是提高系统传输速率的有效方法之一.搭建了被称为双偏振态差分相移键控(Dual-Pol.DPSK)码的新型偏分复用实验系统,它与具有相同的比特波特比的差分正交相移键控(DQPSK)调制方式相比,接收机要简单很多.与传统的偏振分解复用(POLMUX)技术相比,它无需偏振控制或偏振跟踪,只需一个解调器和一个平衡探...     

Gain evaluation of compact designing on Er/Yb codoped germanate glass channel waveguide

Bent waveguide structures (U- and F-bend) based on UV-sensitive Er³⁺/Yb³⁺ codoped germanate glass substrates have been designed to achieve high-gain C-band amplification. Using simulated-bend method, the optimal radius for curved structure is offered to be 1.90 cm with loss coefficient of 0.0015 dB/cm, as the substrate size is minimally schemed. In the wavelength range of 1528–1559 nm, obvious gain enhancement for the bent structure waveguides is anticipated, while, for the F-bend waveguide, the internal gain at 1533.8 nm wavelength is derived to be 22.55 dB, which is much higher than the value of 14.06 dB in the U-bend waveguide, and over three times higher than that of the straight one, after compensating both the bend loss and the transition loss. The simulation results indicate that the bent structure designing is beneficial in attaining high optical gain in Er³⁺/Yb³⁺ codoped germanate glass substrates, which assures that long-period grating can be applied to implement practical C-band gain-flattened amplification.     

ZnO-doped LiNbO<Subscript>3</Subscript> single crystals studied by X-ray and density measurements

Energy Dispersive X-ray Fluorescence Spectroscopy, X-ray diffraction and density measurements were conducted on undoped and ZnO-doped congruent LiNbO₃ single crystals grown by the Czochralski method. Based on the experimental results, an intrinsic defect evolution model was proposed. When ZnO was doped into the congruent LN crystals, the Zn ions replaced first the Li ions and increased the density. Then, the Zn ions simultaneously replaced the Li ions and the antisite Nb_Lis until all Nb_Li ions were replaced, which increased the density further. After that, the Zn ions substituted Nb ions in the Nb-sublattice sites with the reduction of the Li vacancies as self-compensation and thus reduced the density. When the Li vacancies disappeared completely, the Zn ions substituted simultaneously both Li ions in the Li-sublattice sites and Nb ions in the Nb-sublattice sites. The simultaneous substitution might finally lead to the generation of oxygen vacancies and decreased the density further. PACS 61.72.-y; 06.30.Dr; 61.10.-i     

The influence of exciton behavior on luminescent characteristics of organic light-emitting diodes

We used N,N′-bis-(1-naphthyl)-N,N′-1-diphenyl-1,1′-biphenyl-4,4′-diamine (NPB), 4,4′-N,N′-dicarbazole-biphenyl (CBP) and tris(8-hydroxyquinoline) aluminum (Alq₃) to fabricate tri-layer electroluminescent (EL) device (device structure: ITO/NPB/CBP/Alq₃/Al). In photoluminescence (PL) spectra of this device, the emission from NPB shifted to shorter wavelength accompanying with the decrease of its emission intensity and moreover the emission intensity of Alq₃ increased relatively with the increase of reverse bias voltage. The blue-shifted emission and the decrease in emission intensity of NPB were attributed to the polarization and dissociation of NPB excitons under reverse bias voltage. The increase of emission intensity of Alq₃ benefited from the recombination of electrons (produced by the dissociation of NPB exciton) and holes (injected from the Al cathode).     

High-energy scale revival and giant kink in the dispersion of a cuprate superconductor

In the present photoemission study of a cuprate superconductor Bi1.74Pb0.38Sr1.88CuO6+delta, we discovered a large scale dispersion of the lowest band, which unexpectedly follows the band structure calculation very well. Similar behavior observed in blue bronze and the Mott insulator Ca2CuO2Cl2 suggests that the origin of hopping-dominated dispersion in an overdoped cuprate might be quite complicated. A giant kink in the dispersion is observed, and the complete self-energy containing all interaction information is extracted for a doped cuprate. These results recovered significant missing pieces in our current understanding of the electronic structure of cuprates.