Calculations of longitudinal and transverse velocity structure functions using a vortex model of isotropic turbulence

The longitudinal structure function (LSF) and the transverse structure function (TSF) in isotropic turbulence are calculated using a vortex model. The vortex model is composed of the Rankine and Burgers vortices which have the exponential distributions in the vortex Reynolds number and vortex radii. This model exhibits a power law in the inertial range and satisfies the minimal condition of isotropy that the second-order exponent of the LSF in the inertial range is equal to that of the TSF. Also observed are differences between longitudinal and transverse structure functions caused by intermittency. These differences are related to their scaling differences which have been previously observed in experiments and numerical simulations.

基于成像光通信的时间-空间扩频混合光码分多址编码方案

为了在成像光通信中充分利用时间和空间两种频带资源，以成像光通信为基础，提出一种利用二维光正交Pattern码结合时域扩频实现光码分多址（OCDMA）编码的新方案。分析在该方案中存在的多址干扰噪声，并给出了噪声的概率密度函数，然后讨论由多址噪声引起的误码率与判决门限、用户数、码长积和码重积之间的关系。在相同的码容量下与时域扩频光码分多址编码和空间扩频光码分多址编码方案相比，该方案能降低对相关器件性能（时域码片数量和空间像素规模）的要求，而且还可获得更小的误码率。最后给出编码一解码的光学实现方案。

Influences of radiation trapping on spectroscopic properties of Er3+-doped fluorophosphate glasses

Fluorophosphate glasses with different contents of ErF3 were prepared. Due to the radiation trapping of Er, concentration dependence of the fluorescence lifetime is subject to distortion, and the stimulated-emission cross section calculated by the Fuchtbauer-Ladenburg equation is underestimated. The influence of radiation trapping on the measured fluorescence lifetime and width are investigated quantitatively. By comparing the intensity ratio of the 1556-1532 nm peak in the fluorescence spectrum with that in the stimulated-emission cross-section spectrum obtained according to the McCumber theory, the distortion ratio of fluorescence spectrum due to radiation trapping is obtained. An empirical way to quantitatively evaluate the influences of radiation trapping on fluorescence lifetime and width is proposed. (c) 2007 Optical Society of America.

Holmium laser in-band pumped by a thulium laser in the same host of YAlO3

We report on the room-temperature continuous-wave (CW) operation of a Ho:YAlO3 laser that is resonantly end pumped at 1.94 mu m by a diode-pumped thulium-doped laser in the same host. Through the use of a 1 at % Ho3+-doped 20-mm-long YAlO3 crystal (b cut), the Ho:YAlO3 laser generated 1 W of linearly polarized (E//c) output at 2118 nm and 0.55 W of E//a output at 2128.5 nm for an incident pump power of 5 W, with an output coupler transmission of 14 and 3%, respectively. An optical-to-optical conversion efficiency of 20% and a slope efficiency of 33% were achieved at 2118 nm corresponding to an incident pump power.

云南东方蜜蜂随机扩增多态DNA研究

本文利用随机扩增多枣DN^技术研究r云南 东方童蜂t工蜂)32个个体的遗传变异。帆25个叫物中缔 选出11十引物，其中9个引物扩增出事惫谱带。共检测到 63杀扩增片段，其中46条出现变异。用Nei的片断共事度 盐式计算了，2个个体的遗传距离，用㈣M^聚盎芒构营， 系统发育蝌状图。系统寨娄图中大多数采自同～地匹的样奉 聚在一起．但也存在一宅的交叉，提示地理群体H近期可能 存在一定程度的善因流。

体重对暗纹东方鲀摄食影响的研究

利用室内养殖实验研究了暗纹东方鲀的体重与摄食率的关系以及其日粮的变化规律。结果表明,随着体重由12.3g增加到213.2g,摄食率由12.6%下降到2.6%,由于暗纹东方鲀属于偏肉食性鱼类,其日粮变化一般以2天为一个周期呈振荡型变化。

Triplexers Based on SOI Flattop AWGs

Triplexers are designed based on SOl flattop arrayed waveguide gratings （AWGs）. Three wavelengths （1310, 1490,and 1550nm） operate at three diffraction orders of AWGs. Simulation shows that the 3dB bandwidth,crosstalk, and loss are 6nm,less than -40dB, and 5dB, respectively. The output optical fields of the device fabricated in our laboratory are clear and show a good triplexing function.

An Electroabsorption Modulator Monolithically Integrated with a Semiconductor Optical Amplifier and a Dual-Waveguide Spot-Size Converter

A semiconductor optical amplifier and electroabsorption modulator monolithically integrated with a spotsize converter input and output is fabricated by means of selective area growth,quantum well intermixing,and asymmetric twin waveguide technology. A 1550-1600nm lossless operation with a high DC extinction ratio of 25dB and more than 10GHz 3dB bandwidth are successfully achieved. The output beam divergence angles of the device in the horizontal and vertical directions are as small as 7.3°× 18.0°, respectively, resulting in a 3.0dB coupling loss with a cleaved single-mode optical fiber.

ICP刻蚀参数对SOI脊形波导侧壁粗糙度的影响

研究了以C4F8/SF6/O2为刻蚀气体,利用ICP刻蚀技术制作SOI脊形光波导过程中,刻蚀参数与侧壁粗糙度的关系.实验结果表明偏压、气体比例、压强是影响侧壁粗糙度的关键参数,在低偏压、低C4F8/SF6比和较高压强下更容易获得低粗糙度的侧壁.通过优化刻蚀参数,获得了侧壁粗糙度和传输损耗相对较低的SOI脊形波导.