Enhanced optical transmission through double-layer gold slit arrays

We investigate the relationship between the transmission and the layer distance of double-layer gold slit arrays by using the finite-difference time-domain method.The results show that the transmission properties can be influenced strongly by layer distance.We attribute the two types of resonant modes to surface plasmon resonance and the localised waveguide resonance.We find that the localised waveguide transmission peak redshifts and becomes broader with increasing layer distance D.We also describe and explain the splitting,shift,and degeneration of the surface plasmon resonant transmission peak theoretically.In addition,to clarify the physical mechanism of the transmission behaviours,we analyse the distributions of electric field and total energy for the three transmission peaks with distance D=45 nm for the double-layer system.Light transporting behaviours are mostly concentrated in the region of the slits as well as the interspaces of the two layers,and for different resonant wavelengths the electric field and energy distributions are different.It is expected that the results obtained here will be helpful for designing subwavelength metallic grating devices.     

Plasmonic interactions between a perforated gold film and a thin gold film

Based on the finite difference time domain method,we investigated theoretically the optical properties and the plasmonic interactions between a gold film perforated with periodic sub-wavelength holes and a thin gold film.We showed that the plasmon resonant energies and intensities depend strongly on the thicknesses of the two films and the lattice constant.Based on the distributions of normal electric field component E z,tangential electric field component E y and total energy,we showed that the optical transmission is due to the collaboration of the localized waveguide resonance,the surface plasmon resonance and the coupling of the flat-surface plasmon of the two layers.     

相对论核－核碰撞中产生的Λ粒子的横向极化度与横向动量的关联

对在相对论能量下重核反应中产生的粒子的横向极化度进行了测定．对粒子自旋磁矩与磁场相互作用所造成的自旋进动效应进行了修正，得到了粒子的零横向极化度及其与横动量的无关联关系．与较低能量时核－核反应中产生的粒子的极化情况进行了比较．结果表明，在相对论重核反应下的粒子的产生机制有别于高能质子引起的反应和较低能时的核－核反应中产生粒子的机制．     

塞曼效应实验中等高共轴调节问题探讨

借助带水准仪和三角支架的十字线激光器准确快捷调节塞曼效应实验系统中各光学元件等高共轴,观察到清晰的塞曼分裂图像,准确测量笔型汞灯处的磁场强度大小,大大减小了实验误差。     

基于QR码和算术编码的图像加密无损恢复方法

将QR码作为数据容器引入光学图像加密系统，可以移除光学系统在解密图像时产生的散斑噪声，使得解密图像无损恢复，是一种非常理想和实用的去除噪声的方法。但由于QR码的存储容量有限，只能存储一些字母和简短的句子或者一幅尺寸很小（32×32像素）的灰度图像，严重制约了该技术的进一步应用。为了将一幅更大的灰度图像存入到QR码中，提出一种基于算术编码的图像无损压缩方法。首先将灰度图像以文件的形式读取为二进制数据，然后转换成十进制数据并利用算术编码的方法压缩为二进制数据，最后再转换成十进制数据。实验结果表明，此方法具有较高的压缩效率，能够成功将一幅64×64像素的具有丰富灰度值的图像存入到一张31版QR码中进行加密和解密。     

双随机位相编码信息隐蔽传递过程中的融合和重构图像质量的研究

利用具有高度保密性的双随机位相编码技术,通过灰度迭加方法将编码信息的实部和虚部同时隐藏在一幅足够大的宿主图像中。在提取隐藏图像过程中直接对携带隐藏信息的融合图像进行处理,不需要利用原始宿主图像,且重构图像的质量较好,不受宿主图像的影响。在此基础上进一步对影响融合和重构图像质量的因素进行了讨论,结果表明,对于确定的宿主图像和隐藏图像可通过调整迭加权重得到最佳效果。     

基于二值化计算鬼成像的图像隐藏方法

图像隐藏技术在当今大数据时代扮演着重要角色,尤其在版权保护和保密通信等领域中有着巨大的应用价值.提出了一种基于计算鬼成像的图像隐藏方法,目标图像经过计算鬼成像系统加密,随机散斑作为系统密钥,将密文进行二值化后的结果采用最低有效位算法嵌入到宿主图像中,利用相应的水印提取规则和二阶相关算法恢复目标图像.仿真结果表明,该方法...     

数据偏差对双随机位相解码重构图像噪声特性的影响

双随机位相编码解码技术是应用于图像隐藏领域的一种重要方法。在已编码信息的记录及传递过程中,由于复制、修饰、图像压缩等人为或非人为因素不可避免地会引入各种偏差,这些数据偏差最终反映为重构图像的噪声。分析并数值模拟了满足均匀分布、正态分布的随机偏差及因数据取舍而引入的偏差所导致的重构图像噪声分布。研究表明,这几种类型的数据偏差在重构图像中均会导致灰度值概率分布为高斯型函数的噪声。从理论分析和数值模拟结果来看,实施双随机位相解码运算不会降低图像信噪比,因此重构图像的噪声特性是由已编码信息在记录及传递过程中的信噪比决定的。     

Smoothing potential energy surface of proteins by hybrid coarse grained approach

Coarse-grained(CG) simulations can more efficiently study large conformational changes of biological polymers but usually lose accuracies in the details. Lots of different hybrid models involving multiple different resolutions have been developed to overcome the difficulty. Here we propose a novel effective hybrid CG(hyCG) approach which mixes the fine-grained interaction and its average in CG space to form a more smoothing potential energy surface. The hyCG approximately reproduces the potential of mean force in the CG space, and multiple mixed potentials can be further combined together to form a single effective force field for achieving both high efficiency and high accuracy. We illustrate the hyCG method in Trp-cage and Villin headpiece proteins to exhibit the folding of proteins. The topology of the folding landscape and thus the folding paths are preserved, while the folding is boosted nearly one order of magnitude faster. It indicates that the hyCG approach could be applied as an efficient force field in proteins.