High sensitivity SPR refractive index sensor with high resolution based on anti-resonance fiber

We proposed a surface plasmon resonance (SPR) refractive index sensor based on hollow-core anti-resonance fiber (HC-ARF). Gold was filled in two symmetric cladding tubes of the fiber, while the analyte was filled in central air holes. The sensing performance was investigated by the finite element method (FEM). Results show that two resonance peaks (a crossing point around 1 030 nm and an anti-crossing region around 1 065 nm) appear for x-polarization (x-pol) core mode coupling with the surface plasmon polariton (SPP) mode. Moreover, the sensitivity was also analyzed. The sensitivity increased with the increase of cladding tube thickness t. The sensor with thickness t=1.7 μm gave a wavelength sensitivity of 7 350—14 790 nm/RIU in the refractive index range of 1.33—1.45 with resonance wavelength from 1 900 nm to 450 nm. Meanwhile, the resolution of 10-6 RIU was achieved. Thanks to high sensitivity and resolution, the proposed sensor has potential applications in glucose detection.     

A high sensitivity localized surface plasmon resonance sensor based on D-shaped photonic crystal fiber for low refractive index detection

In this paper, a localized surface plasmon resonance (LSPR) refractive index sensor based on photonic crystal fiber (PCF) is proposed to solve the problem of low refractive index analyte detection. 31 silver nanowires are placed on the surface of the D-shaped PCF, which increases the contact area between the plasma material and the analyte. The simulation results indicate that the maximum sensitivity of the sensor reaches 16 400 nm/RIU, and the refractive index detection range is 1.26—1.33. It is proved that the sensor has a good prospect in low refractive index detection.     

皮秒激光烧蚀7075铝合金数值模拟与实验研究北大核心CSCD

为了解超快激光与材料相互作用的机理,优化激光金属烧蚀能力,以达到理想的烧蚀效果,本文在二维轴对称模型中引入了适用于超快激光烧蚀的双温模型,模拟了皮秒激光对于以7075铝合金为代表的低熔点合金的烧蚀行为。通过更改皮秒激光的功率密度和冲击次数,确定皮秒激光各参数对于7075铝合金的影响并与实验结果相对照。结果表明,激光烧蚀的深度小于通过双温模型计算出的金属熔化温度层,同时激光的烧蚀深度与激光密度线性相关,当烧蚀深度大于一定数值时,激光烧蚀深度几乎不随着烧蚀次数的增加而增大。     

一种长焦大变倍连续变焦光机组件结构设计及装调

介绍了一种基于长焦大变倍比连续变焦红外热像仪的结构设计及装调方法。可用于各类红外热像仪的变焦结构设计中,在保证图像清晰的前提下,能够明显改善连续变焦过程中的光轴晃动,提高红外热像仪的光轴一致性和光轴稳定性,控制焦距精度,降低红外热像仪装调难度。该结构采用双导轨配合步进电机组件化设计,相对于其他变焦结构的设计,该结构变焦过程中光轴一致性好,光轴晃动量小,通用性强。     

基于稀疏迭代的非连续谱高频雷达信号处理方法

在拥挤频谱环境中,雷达系统在多个非连续频段发射信号并在接收端进行综合相干处理,是一种获得等效大带宽的方式. 本文专门就非连续谱调频连续波(discontinuous spectrum-frequency modulated continuous wave, DS-FMCW)及其在高频雷达中的应用展开研究. 首先提出采样点平移方法,建立DS-FMCW快时间维的非均匀采样序列谱估计模型;随后,进一步建立DS-FMCW距离-多普勒二维谱估计模型,提出解决距离徙动的方案;最后为解决距离高旁瓣问题,基于一种适用于单次快拍的迭代式稀疏重构算法提出DS-FMCW的距离与距离-多普勒谱估计方法,并提出相应的快速谱求解方法. 仿真试验表明:所提DS-FMCW距离-多普勒处理方案能有效补偿距离徙动;当频带利用率大于20%时,所提谱估计方法能够稳定地分辨距离维间隔为雷达固有距离分辨率的1/3的两个目标,且距离估计精度优于经典最小二乘算法以及正交匹配追踪算法;所提快速算法单次迭代运算量低,适用于实时系统.     

自适应调节滤波强度的SAR图像非局部平均抑斑算法

为提升对SAR图像乘性相干斑的抑制水平与边缘保护性能,该文提出了一种可自适应调节滤波强度(AFS)的SAR图像非局部平均(NLM)抑斑新算法(AFS-NLM).该算法利用Frost滤波图像计算的局部均值与方差来改善SAR图像场景参量的估计,形成了一种能更好刻画SAR图像同质区与边缘区的改进Kuan滤波系数.利用局部均值比与改进Kuan滤波系数分别作为新的相似性测量参量与自适应衰减因子,构建了一种更适应SAR图像乘性噪声特性的改进NLM滤波.利用偏平滑参数与偏边缘保护参数控制下的改进NLM滤波,分别替代经典Kuan滤波模型中的像素局部均值与自身灰度值作为加权项,并采用由改进Kuan滤波系数构建的自适应调节因子对二者进行加权平均,从而形成了一种可自适应调节滤波强度的加权滤波新模型.实验表明,该文算法与近期多种先进算法相比,具有更好的相干斑抑制与边缘保护性能.     

MULTIPHOTON EXCITATION OF A WATER MOLECULE IN INTENSE LASER FIELDS

A stretch vibration Hamiltonian of H_2O has been derived by using the second quantization, unitary transformations and the optimization of coefficients. The energy spectrum obtained from this Hamiltonian is in good agreement with that of experiments. The multiphoton excitation and the energy absorption of H_2O in intense laser fields have been calculated.     

稀土高分子发光材料研究的新进展

介绍了稀土高分子发光材料的发光机理及其发展历程，对其合成方法以及研究方向进行了综述，着重阐述了掺杂型和键合型稀土高分子发光材料研究的最新进展，并对其发展方向和应用前景作了展望。