光子晶体的制备方法及其应用

光子晶体是一种介电常数不同的、其空间呈周期分布的新型光学材料。由于光子晶体具有光子带隙、光子局域和控制光子态密度等特性,所以它具有广阔的应用前景。简述了光子晶体的主要特征,重点介绍了其制备方法、进展以及实际的和潜在的应用。     

A general method for large-scale fabrication of Cu nanoislands/dragonfly wing SERS flexible substrates

Noble metal nanorough surfaces that support strong surface-enhanced Raman scattering(SERS) is widely applied in the practical detection of organic molecules. A low-cost, large-area, and environment-friendly SERS-active substrate was acquired by sputtering inexpensive copper(Cu) on natural dragonfly wing(DW) with an easily controlled way of magnetron sputtering. By controlling the sputtering time of the fabrication of Cu on the DW, the performance of the SERS substrates was greatly improved. The SERS-active substrates, obtained at the optimal sputtering time(50 min),showed a low detection limit(10~(-6)M) to 4-aminothiophenol(4-ATP), a high average enhancement factor(EF, 1.98 × 10~4),excellent signal uniformity, and good reproducibility. In addition, the results of the 3D finite-difference time-domain(3 DFDTD) simulation illustrated that the SERS-active substrates provided high-density "hot spots", leading to a large SERS enhancement.     

Facile fabrication of SERS-active substrates based on discarded silver compact disks

Surface-enhanced Raman spectroscopy (SERS) as a powerful analytical tool has gained extensive attention. Despite of many efforts in the design of SERS substrates, it still remains a grand challenge for creating a general substrate by a simple and low-cost way. Herein, we report our attempt to address this issue by fabricating SERS-active substrates based on discarded silver (Ag) compact disks (CDs). The revealed Ag layer on the CDs after removing its protective film can be used as SERS substrate directly and exhibited a good SERS activity. The Ag CDs was further roughened by electrochemical oxidation-reduction cycle in 0.1 M KCl and improved its SERS activity greatly. The effects of roughened parameters on the SERS activity were investigated in detail. Moreover, a sandwich structure consisting of Ag nanoparticles, p-aminobenzenethiol and roughened Ag CDs was fabricated as an example to further enhance the SERS activity for detection in ultra-high sensitivity. These SERS-active substrates based on Ag CDs are all low-cost and allowing a “one way use”. The fabrication is also very simple and exhibits great potential for extensive application.     

Coercive field behavior of permalloy antidot arrays based on self-assembled template fabrication

High-density magnetic antidot arrays have been fabricated by deposition of Fe₂₀Ni₈₀ thin films on self-assembled nanoporous alumina membranes (NAM) with high-order hexagonal symmetry. The magnetic properties induced by the size and the geometry configuration of the holes introduced in a Fe₂₀Ni₈₀ thin film are discussed based on hysteresis loops measured as a function of temperature. The precursor NAMs have pore diameters ranging between 35 and 95 nm (55 and 75 nm after the film deposition) and a lattice parameter of 105 nm. An enormous increase of coercitivity, as compared with the corresponding continuous films, was observed for temperatures between 2 and 300 K. This effect depends on the size and surface density of holes in the Fe₂₀Ni₈₀ antidot arrays. Rutherford backscattering spectrometry (RBS) measurements were performed in order to better clarify the magnetic material that was eventually deposited within the NAM pores.     

石墨烯太赫兹波动态调制的研究进展

石墨烯是一种有着独特电学和光学性质的二维材料,近年来在太赫兹波动态调制的研究中有着广泛的应用。本文主要对基于石墨烯的太赫兹波动态调制器件进行了综述,分析了电调制、光调制和光电混合调制3种调制方法的原理和优缺点,介绍了近几年来将石墨烯应用于太赫兹波动态调制所取得的一系列科研成果,着重对不同器件的调制性能进行了对比,分析了优势和不足。石墨烯可调超材料为实现更快速、高效的太赫兹调制器件提供了新的思路。     

光子学太赫兹源研究进展

为了进一步开发、利用高功率、高效率、可调谐且在室温下稳定运转的太赫兹(THz)源,介绍、分析了国内外利用光子技术产生THz波的研究进展,包括THz气体激光器、空气等离子体THz源、光电导天线以及基于非线性光学效应的光学整流、光学差频、参量振荡等THz源,并指出了光子学THz源未来发展所面临的困难和需要解决的关键技术。     

内表面掺硅聚苯乙烯空心微球初步研究

 靶丸内表面掺杂诊断元素可以为内爆压缩界面的研究提供必要的手段。以二甲基二乙氧基硅烷为原料，利用乳液微封装技术和界面聚合技术可以实现单一内表面掺硅的空心聚苯乙烯微球的制备。X光照相和X能谱分析表明：内表面掺硅量比外表面高出2~3个数量级。均匀内表面掺硅层的厚度小于0.3μm，掺杂层厚度越小，均匀性越好。     

The theory of SERS on semiconductor and dielectric substrates

It is demonstrated that the reason for SERS on dielectric and semiconductor substrates is enhancement of the electric field in the regions of the tops of surface roughness with a very small radius or a very large curvature. The enhancement depends on the dielectric constant of the substrate and is stronger for a larger dielectric constant. It is indicated that the enhancement on dielectrics and semiconductors is weaker than on metals with the same modulus of the dielectric constant. The result obtained is confirmed by experimental data on the enhancement coefficients obtained for various semiconductor and dielectric substrates.     

Local field enhancement of pair arrays of silver nanospheres

Local field surface plasmon excitation of pair arrays of silver nanospheres was studied using three-dimensional finite-difference time-domain method. The near-field enhancement was associated with the radius of nanosphere and the incident wavelength, the highest of which always appeared in the penultimate gaps, regardless of the number of the pairs. The surface plasmon resonance could be controlled and tuned by radius of nanosphere and incident wavelength.     

基于OLED显示单元的红外上转换器件研究进展

综述了不同类型上转换器件的的研究进展, 包括性能优化、器件集成以及物理机制。其中基于OLED的红外上转换器件将红外探测器与OLED串联集成起来, 使近红外光首先被吸收, 进而光生电流驱动OLED产生可见光, 可完成近红外-可见光上转换功能。该项研究拓展了OLED在红外夜视方面的应用。     

DNA微阵列制备的新进展

随着人类基因组测序的完成和蛋白组学工程的开展，具有高产出测序的特性的DNA微阵列技术的发展日新月异，其应用已经深入到了生命科学研究的很多方面．与此同时，几种新的DNA微阵列制备技术迅速发展起来，文章介绍了滚轮放大技术、聚酰胺胺表面法、三甲氧基对胺苯基硅烷／重氮化法、化学纳米印迹法等四种制备方法的新进展。     

Exchange bias in nanopatterned Co antidots prepared by self-assembling polystyrene nanospheres

The exchange bias properties of nanopatterned thin films of Co, on top of which a native Co-oxide layer develops spontaneously, are studied by means of magnetic and magneto-resistance measurements. Both continuous and patterned films are investigated, the latter in the form of antidot arrays prepared with the self-assembling polystyrene nanospheres technique. The obtained antidot arrays are in the hexagonal close-packed configuration and cover a surface area of several square millimetres. Nanopatterned samples turn out to have a very good repeatability of their magnetic and magneto-resistive properties. The presence of a native oxide is responsible for the development of an exchange bias effect at temperatures below ~150 K, which has been reported both on hysteresis loops and on magneto-resistance curves; these consist of a superposition of an anisotropic magneto resistance (AMR) effect and a giant magneto-resistance (GMR)-like effect. The determination of the bias field by means of the two different sets of data is consistent and gives a complete picture of the phenomenology in this kind of nanopatterned magnetic systems.     

Facile fabrication of mesoporous ZnO nanospheres for the controlled delivery of captopril

We numerically investigate the surface plasmon resonance (SPR) mode patterns in periodic silver-shell nanopearl arrays and its dimer arrays with the core relative permittivities filled inside the dielectric holes (DHs) by means of finite element method with three-dimensional calculations. Numerical results of resonant wavelengths corresponding to the effects of different period of unit cells, radii of DHs, illumination wavelengths, field propagation, electrical field stream lines, charge distributions, charge densities, half- body charge densities, and the DH core relative permittivities of periodic silver-shell nanopearls are also reported. It can be seen that the periodic silver-shell nanopearl arrays and its dimer arrays with DHs exhibit tunable SPR modes corresponding to the bonding and anti-bonding modes, respectively, that are not observed for the solid silver cases with the same volume. These results are crucial in designing localized SPR sensors and other optical devices based on periodic metal nanoparticle array structures.     

Optical switching in metal-slit arrays on nonlinear dielectric substrates

We propose a scheme for an optical limiter and switch of the transmitted light intensity in an array of subwavelength metallic slits placed on a nonlinear Kerr-type dielectric substrate of finite thickness, where the geometrical parameters are designed for operation at telecom wavelengths. Our approach is based on the abrupt changes of the output light intensity observed in these systems near transmission minima.     

Gold aggregates on silica templates and decorated silica arrays for SERS applications

In this work, we report the fabrication and characterization of size controllable gold nanoparticles (NPs) aggregates for their application in surface enhanced Raman scattering (SERS). Aggregates were prepared using two methodologies: (i) by using silica particles arrays as a template to agglomerate gold NPs between the inter-particle interstices, and (ii) by functionalizing silica particles to be used as support to graft gold nanoparticles and thus to form decorated silica particle arrays. These substrates were used in the detection of Rhodamine 6G producing an enhancement factor (EF) from 10⁴ to 10⁶ that is associated to the increment of hot spot (HS) sites, and the fact that plasmon resonance from aggregates and absorption wavelength of test molecules are closely in resonance with excitation wavelength. The EF was also reduced when the plasmon resonance was red-shifted as a result of the increment of aggregate size. In spite of this, the EF is high enough to make these SERS substrates excellent candidates for sensing applications.     

Recent progress of colloidal quantum dot based solar cells

Colloidal quantum dot(CQD) solar cells have attracted great interest due to their low cost and superior photo-electric properties. Remarkable improvements in cell performances of both quantum dot sensitized solar cells(QDSCs) and PbX(X = S, Se) based CQD solar cells have been achieved in recent years, and the power conversion efficiencies(PCEs) exceeding 12% were reported so far. In this review, we will focus on the recent progress in CQD solar cells. We firstly summarize the advance of CQD sensitizer materials and the strategies for enhancing carrier collection efficiency in QDSCs, including developing multi-component alloyed CQDs and core-shell structured CQDs, as well as various methods to suppress interfacial carrier recombination. Then, we discuss the device architecture development of PbX CQD based solar cells and surface/interface passivation methods to increase light absorption and carrier extraction efficiencies. Finally, a short summary, challenge, and perspective are given.     

Recent progress of infrared photodetectors based on lead chalcogenide colloidal quantum dots

Commercial photodetectors based on silicon are extensively applied in numerous fields. Except for their high performance, their maximum absorption wavelength is not over than 1100 nm and incident light with longer wavelengths cannot be detected; in addition, their cost is high and their manufacturing process is complex. Therefore, it is meaningful and significant to extend absorption wavelength, to decrease cost, and to simplify the manufacturing process while maintaining high performance for photodetectors. Due to the properties of size-dependent bandgap tunability, low cost, facile processing,and substrate compatibility, solution–processed colloidal quantum dots(CQDs) have recently gained significant attention and become one of the most competitive and promising candidates for optoelectronic devices. Among these CQDs, lead chalcogenide CQDs are getting very prominent and are widely investigated. In this paper, the recent progress of infrared(IR) photodetectors based on lead sulfide(PbS), lead selenide(PbSe), and ternary PbS_x Se_(1-x) CQDs, and their underlying concepts, breakthroughs, and remaining challenges are reviewed, thus providing guidance for designing high-performance quantum-dot IR photodetectors.     

非对称GRIN微透镜阵列的设计与制作

针对 L D光束的特点 ,提出利用单个非对称 GRIN微透镜 (双焦距 )对 L D光束进行准直、整形和像散校正。总结出了根据 L D光束参数结合离子交换工艺的设计方法。利用椭圆形掩模孔和电场辅助离子交换工艺制作了非对称GRIN微透镜阵列 ,并对样品的性能进行了测试     

Recent progress of second harmonic generation based on thin film lithium niobate

Recently,nonlinear photonics has attracted considerable interest.Among the nonlinear effects,second harmonic generation[SHG]remains a hot research topic.The rec...