我国马铃薯价格波动的定量分析

研究了我国马铃薯价格波动的影响因素,利用多项式拟合、线性回归、ARIMA模型等方法分析了我国马铃薯的价格波动,得出了有关我国马铃薯价格的总体趋势、年内变化、年间变化特点的结论.     

β,β-偶氮桥连双卟啉的合成

用硼氢化钠/钯-碳还原2-硝基-5,10,15,20-四苯皋卟啉得到一种新型β,β-偶氮桥连双卟啉.通过UV-vis,1H NMR,IR,MS,拉曼光谱,元素分析等手段对化合物进行了结构表征.采用凝胶电泳法,初步考察了化合物在光照和无光照条件下对pBR322质粒DNA的切割能力.     

十二重准晶光子结构中的负折射与成像

最近实验证明周期性的光子晶体中存在电磁波的负折射现象,并且观测到亚波长成像.然而,这些研究主要集中在周期性结构中,对非周期结构的研究还没有相关的报道.文章报道了一种新的理论和实验结果：非周期性十二重准晶光子结构同样存在负折射,并且可以实现超透镜的远场成像.具有这些特性的光子准晶可以广泛的应用于光集成器件中.     

Defect Modes in Multiple-Constituent One-Dimensional Photonic Crystals Examined by an Analytic Bloch-Mode Approach

Defect modes in one-dimensional photonic crystals (PCs) can be readily detected from the solution of the trans-mission spectra via the standard transfer-matrix method. We adopt an analytic Bloch-mode approach to examine this problem in terms of eigenmode solutions and investigate the dispersion behaviour of localized defect modes supported by a defect layer sandwiched within two symmetric semi-infinite PCs that are made from multiple constituents. The results show that the number of defect modes grows when the dielectric constant and width of the defect layer increase.     

Systematic study on visible light collimation by nanostructured slits in the metal surface

We present a systematic experimental investigation on visible light collimation by a nanostructured slit flanked with a pair of periodic array of grooves in gold thin film. A wide variety of aspects are considered, such as the polarization state, the transport path of incident light, the groove--groove spacing, the groove width and depth. Our results clearly show that the relationship between the collimation wavelength and the periodicity of the slit-groove structure accords well with the surface plasmon dispersion model proposed by previous researchers. Furthermore, the surface plasmon wave phase retardation effect induced by the surface structure is also verified via the measurement for samples with different groove widths and depths. These results indicate that the detailed geometry of the groove structure has obvious impacts on the collimation effect and the angular distribution of the diffraction light in the subwavelength plasmonic system.     

Optical properties of the direct-coupled Y-branch filtersby using photonic crystal slabs

We fabricated a new type of two-dimensional photonic crystal slab filter. The resonant cavities were directly put into the waveguide arms. The optical transmissions of the filters were measured and the results show that the optimized two-channel filters give good intensity distribution at the output ports of the waveguide. A minimum wavelength spacing of 5~nm of the filter outputs isrealized by accurately controlling the size of the resonant cavities.     

Simulation of the Weakly Nonlinear Rayleigh–Taylor Instability in Spherical Geometry

The Rayleigh-Taylor instability at the weakly nonlinear(WN) stage in spherical geometry is studied by numerical simulation.The mode coupling processes are revealed.The results are consistent with the WN model based on parameter expansion,while higher order effects are found to be non-negligible.For Legendre mode perturbation Pn(cos B),the nonlinear saturation amplitude(NS A) of the fundamental mode decreases with the mode number n.When n is large,the spherical NSA is lower than the corresponding...     

电光聚合物在全光技术实现THz波产生与检测中的研究进展

研究和开发基于超短波和低能量激光系统的高振幅、宽频带的太赫兹系统一直是太赫兹应用领域的一个热点。与传统电光晶体材料相比,以电光聚合物薄膜作为太赫兹波产生和检测的最大的优势在于： 一方面电光聚合物不具有晶格结构相应的不存在声子的吸收和太赫兹折射率的散射问题,避免光谱间隙的产生;另一方面电光聚合物薄膜与已用于宽频太赫兹系统中的超薄电光晶体材料相比,更易于加工和处理。另外,可以自行设计得到低相位失配和高电光系数的电光聚合物材料,得到高效率和宽频带的太赫兹辐射源。可以预见,电光聚合物在这一领域的应用必将有宽阔的发展空间和学术研究意义。介绍电光聚合物的电光效应及二阶非线性生色团合成等相关理论问题基础上,综述了近二十多年来,电光聚合物在基于全光技术实现太赫兹波产生与检测系统中的研究进展,主要包括: 掺钛蓝宝石飞秒激光激发下,共聚型和主客体型电光聚合物实现太赫兹波产生与检测;光纤飞秒激光激发下,主客体型电光聚合物实现太赫兹波的产生与检测。     

十二重准晶光子结构中的负折射与成像

最近实验证明周期性的光子晶体中存在电磁波的负折射现象，并且观测到亚波长成像．然而，这些研究主要集中在剧期性结构中，对非周期结构的研究还没有相关的报道。文章报道了一种新的理论和实验结果：非周期性十二重准晶光子结构同样存在负折射，并且可以实现超透镜的远场成像。具有这些特性的光子准晶可以广泛的应用于光集成器件中。     

Near-field optical observations of surface plasmon wave interference at subwavelength hole arrays perforated in Au film

We image optical near-field patterns at subwavelength circular hole arrays in Au film by using scanning near-field optical microscopy in near-infrared wavelengths.Periodical oscillation features are found in the near-field images at the air/Au interface and exhibit two typical kinds of standing wave oscillation forms at the wavelengths corresponding to the transmission minimum and maximum in the transmission spectrum,and the latter one originates from the excitation and interference of a surface plasmon wave at the metallic hole arrays.Our work indicates that monitoring optical near-field patterns can help to reveal many interesting properties of surface plasmon waves at metallic nanostructures and understand their underlying physical mechanisms.