太阳能电池基本特性测定实验 --一个与能源利用有关的综合设计性实验

“太阳能电池基本特性测定”是与能源利用有关的新的综合性设计实验．本文简述了该实验的原理、实验方法及测量结果,得出了太阳能电池基本参数短路电流Iac,开路电压Uoc与太阳能电池接收到的相对光强度J／Jn的近似函数关系。     

加速器高频D电路Q值的计算与测量

 介绍了回旋加速器高频单D型盒D电路Q值的计算与测量方法。重点对Q值的理论计算进行推导，并对计算原理进行说明。然后对计算结果和测量结果进行比较。得出的计算和测量结果基本吻合。误差产生的主要原因是计算过程中的近似和短路片接触电阻的取值，其中短路片接触电阻是一个重要因素，在设计腔体时应引起足够的重视。     

Sensitive linear response of an electron-hole superfluid in a periodic potential

We consider excitons in a two-dimensional periodic potential and study the linear response of the excitonic superfluid to an electromagnetic wave at low and high densities. It turns out that the static structure factor for small wavevectors is very sensitive to a change of density and temperature. It is a consequence of the fact that thermal fluctuations play a crucial role at small wavevectors, since exchanging the order of the two limits, zero temperature and vanishing wavevector, leads to different results for the structure factor. This effect could be used for high accuracy measurements in the superfluid exciton phase, which might be realized by a gated electron-hole gas, for instance, in coupled quantum wells or double layer materials. The transition of the exciton system from the superfluid state to a non-superfluid state and its manifestation by light scattering are discussed.     

基于宽度可调节的线缺陷平板型光子晶体的空气槽微腔

研究了一种空气槽光子晶体微腔,这种腔是由在平板型光子晶体上引入一条宽度可以调节的线缺陷空气槽形成的.腔模的电场被强烈局限在空气槽中,由于介电常量的不连续性,电场得到很大的提高,同时模体积被大大地降低.数值模拟与分析了微腔的能带结构和场分布,考虑到腔模的谐振频率和对称性,发现一阶偶膜同时具有较高的品质因子和较小的模体积;应用有限时域差分法,得到腔模的品质因子可以高达10⁶,模体积仅为0.02(λ/n)³.计算了一阶偶模谐振波长随空气槽宽度以及空气孔半径的变化,发现随着宽度的增加,波长越来越短.而随着空气孔半径的增加,波长近似线性地减小;当空气孔半径为170 nm时,可以获得最高的腔品质因子.     

透射式能见度仪动态范围扩展方法

提出了一种利用光学衰减片与电机组合,扩展透射式能见度仪动态范围的方法。通过改变加载到LED光源的调制信号的幅度,控制LED光源的发射光强;设计测量系统,选择固定透过率的衰减片;设置合理的系统阈值完成数据测量。对测量数据作拟合分析,结果表明:采用透过率为60%的中性密度衰减片,系统动态范围扩展了0.6倍;透过率为12%时,系统动态范围扩展了6.9倍。同时,通过选择不同透过率的中性密度衰减片,可实现系统动态范围的灵活扩展。     

抽运光与信号光的光强重叠因子和掺铒玻璃波导放大器的增益特性

在掺铒玻璃波导放大器（EDWA）的三能级速率-传输方程中,考虑两次离子交换工艺中波导掩模窗口宽度w不同所导致的抽运光、信号光模场与光强分布的不同,讨论不同w对EDWA增益特性的影响,得到光强分布的数值解.引入描述波导中抽运光和信号光的归一化光强重叠因子,对EDWA的传统近似解提出修正,得到了修正解,使其更加接近光强分布的数值解.模拟结果表明,在条波导长度为4 cm、抽运光波长为980 nm、功率为80 mW、信号光波长为1534 nm、功率为-10 dBm条件下,不同w所导致EDWA的增益差别可达297 dB.修正解的结果比传统近似解更加接近光强分布的数值解.修正解对于EDWA的理论研究、器件设计具有指导作用. 关键词： 集成光学 掺铒玻璃波导放大器 重叠积分因子 增益     

Analysis on electrical characteristics of high-voltage GaN-based light-emitting diodes

<正>In order to investigate their electrical characteristics,high-voltage light-emitting-diodes(HV-LEDs) each containing four cells in series are fabricated.The electrical parameters including varying voltage and parasitic effect are studied. It is shown that the ideality factors(IFs) of the HV-LEDs with different numbers of cells are 1.6,3.4,4.7,and 6.4.IF increases linearly with the number of cells increasing.Moreover,the performance of the HV-LED with failure cells is examined.The analysis indicates that the failure cell has a parallel resistance which induces the leakage of the failure cell.The series resistance of the failure cell is 76.8Ω,while that of the normal cell is 21.3Ω.The scanning electron microscope(SEM) image indicates that different metal layers do not contact well.It is hard to deposit the metal layers in the deep isolation trenches.The fabrication process of HV-LEDs needs to be optimized.     

Dynamic compensation temperature in the mixed spin-1 and spin-2 Ising model in an oscillating field on alternate layers of a hexagonal lattice

The dynamic behavior of a mixed spin-1 and spin-2 Ising system with a crystal-field interaction in the presence of a time-dependent oscillating external magnetic field on a hexagonal lattice is studied by using the Glauber-type stochastic dynamics. The lattice is formed by alternate layers of spins σ=1$\sigma =1$ and S=2. The Hamiltonian model includes intersublattice, intrasublattice and crystal-field interactions. The set of mean-field dynamic equations is obtained by employing the Glauber transition rates. Firstly, we study time variations of the average sublattice magnetizations in order to find the phases in the system, and the thermal behavior of the average sublattice magnetizations in a period or the dynamic sublattice magnetizations to obtain the dynamic phase transition points as well as to characterize the nature (continuous and discontinuous) of transitions. Then, the behavior of the dynamic total magnetization as a function of the temperature is investigated to find the dynamic compensation points as well as determine the type of behavior. We also present the dynamic phase diagrams for both presence and absence of the dynamic compensation temperatures in the nine different planes. According to the values of Hamiltonian parameters, besides the paramagnetic (p), antiferromagnetic (af), ferrimagnetic (i) and non-magnetic (nm) fundamental phases, eight different mixed phases and the compensation temperature or L- and N-types behavior in the Néel classification nomenclature exist in the system.     

Dynamic Analysis of Vibrating Systems with Nonlinearities

The max-min approach is applied to mathematical models of some nonlinear oscillations.The models are regarding to three different forms that are governed by nonlinear ordinary differential equations.In this context,the strongly nonlinear Duffing oscillator with third,fifth,and seventh powers of the amplitude,the pendulum attached to a rotating rigid frame and the cubic Duffing oscillator with discontinuity are taken into consideration.The obtained results via the approach are compared with ones achieved utilizing other techniques.The results indicate that the approach has a good agreement with other well-known methods.He's max-min approach is a promising technique and can be successfully exerted to a lot of practical engineering and physical problems.