结构参量对左手材料通带位置影响的研究

基于金属短板对和连续金属线(short-slab pair and continuous wires)复合结构,从理论上系统地研究了在THz波段结构参量对左手材料通带位置的影响.数值模拟结果表明,改变金属板宽度或厚度、连续金属线的长度或厚度都会引起左手材料通带位置向较高频段偏移. 关键词： 负折射 左手材料 结构参量 通带     

LD-end-pumped 60 pm linewidth Tm:YLF laser

Narrow linewidth continuous-wave Tm:YLF laser at room temperature with a Volume Bragg grating and double Fabry-Perot etalons by using the end-pumping configuration was presented. The Tm:YLF laser operates at 1907.3 nm with FWHM of approximately 60 pm. We achieved the maximum output power of 1.92 W when the incident pump power of 13.9 W, corresponding to the optical-to-optical conversion efficiency of 13.8% and slope efficiency of 16.4%.     

基于相变原理模拟红色顶发射有机电致发光器件的出光性能

研究了有机发光器件(organic light emitting diodes, 简记为OLED)半透明电极上形成的反射相移对OLED光谱产生调制现象.以红色微腔结构顶发射OLED(top emitting OLED,TOLED)为例,基于微腔理论和传输矩阵理论建立物理模型,采用计算机数值模拟方法,得出结果表明器件发光光谱的调制作用不只局限于有机层厚度,也和反射相移有关.通过改变覆盖到顶电极表面的有机层厚度的简单方法,可以实现对顶电极反射相移的调节,从而改变TOLED光学性能.这一结果为进一步改善器件的性 关键词： 反射相移模拟 红色微腔 顶发射有机发光     

霍尔推进器中磁化二次电子对鞘层特性的影响

为进一步研究霍尔推进器壁面二次电子发射对推进器性能的影响,采用流体模型数值模拟了二次电子磁化效应的等离子体鞘层特性.得到二次电子磁化鞘层的玻姆判据.讨论了不同的磁场强度和方向、二次电子发射系数以及不同种类等离子体推进器的鞘层结构.结果表明:随器壁二次电子发射系数的增大,鞘层中粒子密度增加,器壁电势升高,鞘层厚度减小;鞘层电势及粒子密度随着磁场强度和方位角的增加而增加;而对于不同种类的等离子体,壁面电势和鞘层厚度也不同.这为霍尔推进器的磁安特性实验提供了理论解释. 关键词： 霍尔推进器 磁鞘 二次电子     

Instantaneous frequency measurement based on complementary microwave photonic filters with a shared Mach-Zehnder interferometer

A novel configuration using only one Mach-Zehnder interferometer (MZI) for photonic-assisted instantaneous microwave frequency measurement is proposed. The amplitude comparison function (ACF), related to the input microwave frequency while independent of the input optical power and modulate index, is achieved by using a ratio of low-pass to bandpass frequency responses introduced by intensity and phase modulation with a shared MZI. The microwave frequency can be estimated by the measured ACF. A proof-of-concept experiment for measurement of RF from 5 to 10 GHz is successfully demonstrated with the measurement errors less than ± 0.2 GHz.     

Diffusion and ballistic contributions of electron-electron interaction to the conductivity in an Al0.26Ga0.74N/AlN/GaN heterostructure

The results of an experimental study of quantum correction of electron-electron interaction (EEI) to the conductivity of two-dimensional electron gas (2DEG) in an undoped heterostructure are reported. A small but significant decrease of the Hall slope with the increase of temperature was discovered. This is not due to the increase of electron concentration as temperature increases but to the EEI effect. Both diffusion and ballistic contributions of EEI to the conductivity of 2DEG were observed. As the temperature increases, the negative diffusion EEI correction to the conductivity increases in an absolute value while the ballistic EEI correction reduces to a renormalization of the transport mobility.     

Propagation properties of vectorial elliptical Gaussian beams beyond the paraxial approximation

Starting from the vectorial Rayleigh diffraction integral formula and without using the far-field approximation, a solution of the wave equation beyond the paraxial approximation is found, which represents vectorial non-paraxial elliptical Gaussian beams in free space. The far-field expressions for non-paraxial Gaussian beams and elliptical Gaussian beams can be regarded as special cases treated in this paper. Some basic propagation properties of vectorial non-paraxial elliptical Gaussian beams, including the irradiance distribution, phase term, beam widths and divergence angles are studied. Numerical results are given and illustrated.     

贵金属（Cu、Ag、Au）掺杂ZnO电子结构和光学性质的第一性原理研究

采用基于密度泛函理论的总体能量平面波超软赝势方法,对贵金属（Cu、Ag、Au）掺杂ZnO进行了几何结构优化,并计算了相应的能带结构、受主能级、形成能、电子态密度和光学性质. 结果表明：贵金属掺杂后带隙增加且体系费米能级附近电子态密度主要来源于Cu3d、Ag4d和Au5d态电子的贡献. 与未掺杂ZnO相比,介电函数虚部、反射峰强度和吸收系数在可见光和紫外区域增强. 能量损失谱计算表明,贵金属（Cu、Ag、Au）掺杂后ZnO的等离子体共振频率峰发生蓝移.     

领结形中空表面等离子体波导的传输特性

设计了一种领结形中空表面等离子体波导.采用频域有限差分法,对这种波导所支持的基模的能流密度分布、有效折射率、传播长度和模式面积随几何结构参数和工作波长的依赖关系进行了分析.结果表明,沿纵向的能流主要分布在两个上下突起所形成的中间区域.通过调整几何参数及工作波长,可以调节模式的有效折射率、传播长度和模式面积.在工作波长确定的条件下,有效折射率随突起半径的增大呈减小趋势,而传播长度和模式面积则随着突起半径的增大呈增大趋势,四个角上的圆弧半径对波导的传输特性有微调作用,左右扇形区域的半径对波导的传输特性有较明显 关键词： 集成光学 光波导 表面等离子体波导