磁场对非对称量子点中极化子性质的影响

采用线性组合算符和幺正变换方法研究磁场对非对称量子点中弱耦合磁极化子性质的影响.导出了非对称量子点中弱耦合磁极化子的振动频率、基态能量和基态结合能随量子点的横向和纵向有效受限长度、磁场和电子-声子耦合强度的变化关系.数值计算结果表明:非对称量子点中弱耦合磁极化子的基态能量和基态结合能随量子点的横向和纵向有效受限长度的增加而迅速增大.随回旋频率的增加而增大,随电子-声子耦合强度的增加而减小.     

K9和石英玻璃基片上Au膜真空紫外反射特性研究

采用离子束溅射法,分别在经过不同前期清洗方法处理过的K9及石英玻璃光学基片上,选择不同的镀膜参量,镀制了多种厚度的Au膜。对镀制的Au膜在真空紫外波段较宽波长范围内的反射率进行了连续测量。测试结果表明:辅助离子源的使用方式、Au膜厚度对反射镜的反射率有重大影响。基片材料、镀前基片表面清洗工艺等对反射率也有一定影响。采用镀前离子轰击,可显著提高Au膜反射率及膜与基底的粘合力;获得最高反射率时的最佳膜厚与基片材料、镀膜工艺密切相关。对经过离子清洗的石英基片,膜厚在30 nm左右反射率最高;比较而言,石英基片可获得更高的反射率;辅助离子源的使用还显著影响获得最高反射率时对应的最佳膜厚值,且对K9基片的影响更显著。     

Stimulated emission and multi-peaked absorption in a four level N-type atom

Absorption and refraction of the inner transition F₂\leftrightarrow F₃ of the closed four level N-type atom have been investigated under a weak field. The outer transitions F₁\leftrightarrow F₃ and F₂\leftrightarrow F₄ are resonantly interacted with drive field with frequency \omega_c and Rabi frequency \Omega_c, and saturation field with \Omega_s and \Omega_s, respectively. For the suitable Rabi frequencies \Omega_c and \Omega_s, we obtain the Mollow absorption spectrum of probe field. The reason is that the drive field excites the atom to the upper level F_c and simultaneously the saturation field takes the atom out of the lower level F₂, leading to the stimulated emission. Meanwhile, due to the dynamic energy splitting induced by the drive and saturation fields, the two- and four-peaked absorption spectra are observed. At the zero off-resonance detuning of probe field, we also find the transfer of dispersion from negative to positive with an increment of \Omega_s. Finally, the refractive index enhancement is predicted for a wide spectral region.     

Controlling optical responses through local dielectric resonance in nanometre metallic clusters

Optical responses in dilute composites are controlled through the local dielectric resonance of metallic clusters. We consider two located metallic clusters close to each other with admittances \varepsilon₁ and \varepsilon₂. Through varying the difference admittance ratio \eta [ = (\varepsilon₂- \varepsilon ₀) / (\varepsilon₁- \varepsilon₀)], we find that their optical responses are determined by the local resonance. There is a blueshift of absorption peaks with the increase of \eta. Simultaneously, it is known that the absorption peaks will be redshifted by enlarging the cluster size. By adjusting the nano-metallic cluster geometry, size and admittances, we can control the positions and intensities of absorption peaks effectively. We have also deduced the effective linear optical responses of three-component composites \varepsilon_e= \varepsilon₀ \bigl(1 + \sum_n=1^{n_s} [(\gamma_n2+ \eta \gamma_n2)/({\varepsilon₀(s - s_n))]} \bigr), and the sum rule of cross sections: \sum_n=1^{n_s} {(\gamma_n2+ \eta \gamma_n2 ) = N_h1+ N_h2, where N_h1and N_h2 are the numbers of \varepsilon₁ and \varepsilon₂ bonds along the electric field, respectively. These results may be beneficial to the study of surface plasmon resonances on a nanometre scale.     

Polymer-assisted complexing controlled orientation growth of ZnO nanorods

The growth of the oriented zinc oxide (ZnO) nanorods on silicon substrates based on a simple novel chemical transformation and thermal hydrolysis by using polyvinyl alcohol (PVA) as self-assembling complex polymer was introduced in this paper. All the polymers were removed after chemical oxidation and only the carbonized grid backbones remained that confines the ZnO nanorod’s diameter and enhance the absorption and diffusion of ZnO at the tips of the nanorods during growth. The ZnO nanorods are investigated by FTIR, XRD and FE-SEM. The results indicated that these nanorods have fine hexagonal wurtzite crystal structure and their diameter varies from 20 to 90 nm and the length up to about 1 μm. A polymer-localized ZnO growth model is proposed, which well explains the growth behavior of ZnO nanorods.This revised version was published online in August 2005 with a corrected issue number.     

Frequency-stabilized semimonolithic frequency doubler with high output power

We present a semimonolithic frequency-doubler from 1080 to 540 nm with 80% doubling efficiency and up to 849-mW output power of green light.     

基于倏逝波的光纤生物传感器研究

构建了一种以光纤束作为激发光信号和荧光信号传输通道的光纤生物传感器结构.根据光纤探针的倏逝波理论和模式匹配理论对光纤探针的几何形状进行了设计,制作了数组光纤探针并根据需要对其中一部分进行荧光标记.选择了光纤探针置于空气中和水溶液中两种情况,对光纤传感器系统进行了信号检测实验,对比标记了的和未标记的相同几何结构参数的光纤探针两者在系统中被探测的信号差异.从二者的差别区分出系统所探测的倏逝波激发的荧光信号,证明了该光纤传感器系统的可行性.     

监测点波长对高双折射光纤环镜轴向应变灵敏度的影响

研究了高双折射光纤环镜监测点波长对轴向应变灵敏度的影响. 经理论推导得出高双折射光纤环镜轴向应变灵敏度公式. 结果表明: 当高双折射光纤材料选定后, 灵敏度随着监测点波长的增大而增大; 当监测点选定后, 监测点的灵敏度为常数, 波长变化与应变成线性关系. 实验选取不同波长的波峰进行应变灵敏度监测, 对各监测点进行数据拟合, 实验结果与理论分析一致. 研究结果对提高高双折射光纤环镜应变、温度等灵敏度具有指导意义. 关键词： 波长 灵敏度 监测点 高双折射光纤环镜     

基于新型电荷生成层的P-i-N结构白色有机叠层电致发光器件

采用2,9-Dimethyl-4,7-diphenyl-1,10-phenanthroline(BCP): 5 wt.% cesium carbonate(Cs₂CO₃)和N, N'-Bis(naphthalen-1-yl)-N,N'-bis(phenyl)-benzidine(NPB): 20 wt.% molybdenum oxide(MoO₃)分别作为器件的电子注入层和空穴注入层,研究了N型和P-i-N结构有机电致发光器件的载流子传输特性.载流子传输层中BCP: Cs₂CO₃和NPB:MoO₃的引入有效增强了载流子注入能力,从而降低了器件的驱动电压.基于新型电荷生成层BCP: 5 wt.% Cs₂CO₃/ NPB: 20 wt.% MoO₃制备了色稳定、高效率P-i-N结构有机叠层器件.与单元器件相比,引入新电荷生成层有机叠层器件的最大电流效率增大了2.5倍,表明该电荷生成层可以有效地将电子和空穴分别注入到相邻发光单元中.采用该电荷生成层制备了P-i-N结构白色有机叠层器件,器件的上下发光单元分别为橙光和蓝光发射.当发光亮度从500增加到5 000 cd/m²时,器件的色坐标稳定在(0.33, 0.29)附近,接近白光等能点.利用单色发光单元堆叠制备白色有机叠层器件的方法为实现色稳定、高效率的白色有机电致发光器件提供了一种有效的途径.     

基于亚微米光栅透射共振蛋白质检测模型研究

建立了一种基于亚微米光栅透射共振理论的蛋白质检测模型,设计了一种金属光栅型蛋白质检测生物传感器,运用光栅耦合激发表面等离子体共振理论对提出的模型进行了理论分析,通过计算机计算模拟,分析了蛋白质样品折射率、厚度等对透射率的影响。结果表明:透射率与样品折射率、厚度呈二阶多项式关系,并且厚度、折射率都随灵敏度的增加而增加。这种检测模型可应用在蛋白质检测传感方面。基于此方法的蛋白质检测模型具有同时检测蛋白质种类和含量、灵敏度高、实时、无需标记,便于集成芯片化,适用于批量生产、成本低等优点,在蛋白质芯片、生物分析、环境监测、生物器件研发等方面具有广泛的应用前景。