Effects of the periodicity of the subwavelength hole arrays and hole shape of a thin gold film on the optical transmission characteristics

The influence of the periodicity of subwavelength hole arrays and hole shape on transmission frequency and intensity has been studied.The subwavelength hole array sample is prepared on the 220 nm Au film.The transmission characteristics are measured and analyzed.The transmission spectra show that the different transmission peaks depend on the periodicity of hole arrays and the shape of the holes.With the shorter hole array period,the transmission peak shows blue shift,and the ohmic losses of surface plasmon...     

复合型金属孔周期阵列的THz透射特性

利用微细加工技术, 制作出金属矩形孔阵列, 从实验和理论上研究了金属矩形孔阵在THz波段的透射极大值和极小值产生的规律.并利用透射极大值频率随矩形孔长度增大而向低频移动的特性, 在同一层金属上, 利用不同尺寸的金属孔结构形成复合金属孔阵列, 设计出中心频率可调节、频率拓宽的频率选择器件和频率拓宽器件.此研究为太赫兹滤波器等无源器件提供了新的设计思路和加工方法, 对太赫兹波技术的发展具有重要意义.     

复合型金属孔周期阵列的THz透射特性

利用微细加工技术,制作出金属矩形孔阵列,从实验和理论上研究了金属矩形孔阵在THz波段的透射极大值和极小值产生的规律.并利用透射极大值频率随矩形孔长度增大而向低频移动的特性,在同一层金属上,利用不同尺寸的金属孔结构形成复合金属孔阵列,设计出中心频率可调节、频率拓宽的频率选择器件和频率拓宽器件.此研究为太赫兹滤波器等无源器件提供了新的设计思路和加工方法,对太赫兹波技术的发展具有重要意义.     

带有矩形孔阵列的Au-介质-Au多层膜的透射特性

周期性亚波长孔阵列的异常透射性质在亚波长光电器件设计中具有重要意义。两层或更多膜层上周期孔阵列结构,由于层之间电磁场的相互作用可以导致新的光学性质。利用时域有限差分方法理论研究了带有矩形孔阵列的Au-介质-Au多层膜的透射特性。结果表明:该结构在近红外波段的透射谱存在多个透射峰,并且透射峰的数量、位置和强度可以通过改变结构的几何参数和介质膜的材料进行调控。详细分析了介质膜的厚度和折射率、孔阵列的周期、矩形孔的边长等因素对多层膜矩形孔阵列透射谱的影响,为利用多个表面等离子共振设计多波长控制器件提供了一定的参考。     

周期孔状金属薄膜传感器的研究

采用镂空模板法制备了大面积周期孔状金属薄膜,实验揭示了金属小孔阵列在中红外波段的异常透过率增强现象。通过对周期孔状金属薄膜处于不同周围介质下得到的透射谱的研究发现,透射峰随着周围介质折射率的增大会有很明显的红移。比较周期孔状金属薄膜传感器非对称结构和对称结构的灵敏度发现,其对称结构下的灵敏度要高于非对称结构下的灵敏度。通过改变金属薄膜的一些参数,得到金属薄膜厚度和基底折射率为100 nm和1.3时灵敏度最大,分别为12 383 nm/RIU(refractive index unit)和12 667 nm/RIU;灵敏度随周期性孔径的增大而增大;孔的形状与圆的差别越大,灵敏度越高;灵敏度随孔中介质折射率的减小而增大。     

金属孔阵Ku波段透波增强特性研究

用高稳定的辛时域有限差分算法(SFDTD)对金属周期孔阵在Ku波段的透波增强特性进行了研究.数值计算了金属板厚度、孔的大小、孔中填充不同折射率的介质和孔阵的周期等物理参数对孔阵透射系数的影响.得出的研究结果表明:金属周期孔阵在Ku波段的透射系数随孔的增大而增大,随孔阵周期的增大而减小,填充高折射率的介质有利于其透射.     

离子束溅射宽带吸收薄膜设计与制备技术研究

Si薄膜在可见光和近红外波段具有一定的吸收特性,可用于宽带吸收薄膜的制备。采用离子束溅射技术,在熔融石英基底上制备了不同沉积工艺参数的Si薄膜,基于透、反射光谱和椭偏光谱的全光谱数值拟合法,计算了Si薄膜的光学常数,并研究了氧气、氮气流量对其光学特性的影响。选择Si和Ta2O5作为高折射率材料、SiO2作为低折射率,设计了吸收率为2%和10%的宽带（1 000~1 400 nm）吸收薄膜。采用离子束溅射沉积技术,在熔融石英基底上制备了宽带吸收薄膜,对于A=2%的宽带吸收光谱,在1 064、1 200、1 319 nm的吸收率分别为2.12%、2.15%和2.22%;对于A=10%的宽带吸收光谱,在1 064、1 200、1 319 nm的吸收率分别为9.71%、8.35%和9.07%。研究结果对于吸收测量仪、光谱测试仪等仪器的定标具有重要的作用。     

Gold nanohole arrays for biochemical sensing fabricated by soft UV nanoimprint lithography

We report on results of fabrication and optical characterisation of sub-250 nm periodic gold nanohole arrays on glass by using UV nanoimprint lithography (UV-NIL) combined with both reactive ion etching (RIE) and Cr/Au lift-off processes. The transmission spectra of the fabricated nanohole gratings were measured for different hole diameters and periods. We also show preliminary results of chemical sensing after surface modification of the gold hole arrays. In agreement with the theoretical prediction, we found that any change in the dielectric index of the surrounding environment of the metallic array produces a transmission peak red shift.     

（英）基于中红外波段的等离子体金属孔天线

研究了周期性金属孔阵列的光学和远场辐射特性,实验发现所有样品在中红外波段都有两个透射峰,当金属孔径或者孔阵的晶格常数变大时,透过峰的中心频率发生红移.在透过率的中心频率附近,周期性的金属孔阵列表现出偶极子阵列的特性,其远场辐射特性随着孔径的减小或者孔阵列晶格常数的增大而增强.     

含铝的富硅二氧化硅薄膜的发光特性及结构

采用双离子束共溅射技术制备出掺铝的富硅二氧化硅复合薄膜(A1SiO)，采用荧光分光光度计对样品进行PL测试表明：A1SiO复合膜共有三个发光峰，分别在370nm、410nm、510nm处。发光峰的位置随铝含量的变化基本上没有改变，峰强随铝含量有变化，且510nm处的峰强随铝含量增加而增强。PLE结果表明：370nm和410nm的PL峰与样品中的氧空位缺陷有关，而510nm的PL峰则是由于铝的掺入改变了样品中的缺陷状态所致，是Al、Si、O共同而复杂的作用。     

TFT-LCD过孔接触电阻研究

研究了过孔接触电阻变化规律,并进行机理分析,为优化薄膜晶体管的过孔设计提供依据。首先,运用开尔文四线检测法对不同大小、形状、数量的钼/铝/钼结构的栅极和源/漏层金属与氧化铟锡连接过孔的接触电阻进行测试。然后,通过扫描电子显微镜、能量色散X射线光谱仪和聚焦离子束显微镜对过孔内部形貌进行表征。最后,对过孔接触电阻变化规律进行机理分析。实验结果表明:过孔面积越大,接触电阻越小;过孔面积相同时,长方形过孔的接触电阻小于正方形过孔的接触电阻,多小孔的接触电阻小于单大孔的接触电阻,栅极金属与氧化铟锡的过孔接触电阻小于源/漏层金属与氧化铟锡的过孔接触电阻。为了降低钼/铝/钼与氧化铟锡连接过孔的接触电阻,过孔面积尽可能最大化,采用长方形过孔优于正方形过孔,多小过孔优于单大孔设计,同时优化过孔刻蚀工艺,减少过孔内顶层钼的损失。     

孔型对金属介质金属三明治结构超材料的透射率和负折射率的影响

通过改变长方形孔的长度,利用数值模拟研究了金属-介质-金属三明治结构超材料的透射率,负折射(NRI)率和品质因数(FOM)等性质.研究结果表明,随着长方形孔的长度的增大,低频透射峰和最大透射峰都出现了红移现象.长方形孔的负折射率和负折射带宽则随着长方形孔的长度的增大而减小.这意味着可以通过调节金属-介质-金属三明治结构超材料的孔阵列的长度获得较高的透射率或者负折射率.这些结果为开发太赫兹范围的光电器件提供可能的理论.     

双离子束溅射制备SiNx薄膜的光致发光性质

采用双离子束溅射法制备了SiNx薄膜，用XRD、XPS、FTIR等对薄膜的结构进行了表征，并且分析了样品的光致发光(PL)特性。发现在225nm的紫外光激发下，样品在室温下可发射高强度的可见光，峰位分别位于470nm、520nm和620nm，用能隙态模型讨论了可能的发光机理。     

在800~1100nm范围内实现基于狄拉克半金属的多波段超材料波导

提出了一种基于Dirac半金属层的具有四个方孔谐振器的超材料波导,其波长范围为800~1100nm。 在共振波长842nm,921nm,1010nm和1061nm处分别获得四个透射峰（70％,61％,72％和63％）。 这些透射峰源自于分布在主腔和腔1、2、3或4中的磁场的干涉增强作用。通过将费米能量从50meV增加到70meV,可以增加四个透射峰并将其转移到更短的波长。 所提出的超材料波导可能在纳米级滤波器,开关或折射率传感器中应用。     

V2O5薄膜在连续激光防护中的应用研究

用磁控离子溅射法在玻片上沉积了V2O5薄膜,并进行了X射线衍射和常温下光谱透过率测量。分别用1064nm和1319nm连续激光辐照样品,实时测量了V2O5薄膜的温度变化,以及由于温度变化引起相变后对激光透过率的变化。结果表明:在平均入射功率为8.1W、光斑直径2mm时,V2O5薄膜对1064nm激光的透过率由相变前的55%变为相变后的25.5%,响应时间约24ms;在平均入射功率为8.9W、光斑直径2mm时,其对1319nm激光的透过率由相变前的63%变为相变后的27.9%,响应时间约40ms。对实验结果进行了分析并介绍了V2O5薄膜的相变原理及其在激光防护上的应用。     

基于亚波长金属孔阵列的光控太赫兹强度调制器

太赫兹波强度调制器对太赫兹技术的发展至关重要。亚波长金属孔阵列可以激发表面等离子激元,增加入射电磁波的透射效率,极大地提高调制器的调制深度。提出了一种基于表面等离子激元的光控太赫兹波强度调制器。首先给出了器件所依赖的基本原理;其次利用传统的微纳加工技术在半绝缘砷化镓衬底上制作出二维亚波长金属孔阵列;最后搭建了太赫兹时域光谱系统,测试了器件样品对太赫兹波的透过率。结果表明:亚波长金属孔阵列可以引起透射率的异常增强,且透射率随着泵浦光强的增大而减小,在特定频率点实现了较高的调制深度。此研究为实现高调制深度的太赫兹波强度调制器提供了参考。     

基于纳米球镜光刻的选区生长的光子晶体提高InGaN LED光提取效率的研究

We report a new method for the fabrication of two-dimensional photonic crystal(PhC) hole arrays to improve the light extraction of GaN-based light-emitting diodes(LEDs).The PhC structures were realized using nanospherical-lens photolithography and the selective-area epitaxy method,which ensured the electrical properties of the LEDs through leaving the p-GaN damage-free.At a current of 350 mA,the light output power of LEDs with PhC hole arrays of 450 nm and 600 nm in diameter with the same lattice period of 900 nm were enhanced by 49.3% and 72.2%,respectively,compared to LEDs without a PhC.Furthermore,the LEDs with PhC hole structures showed an obviously smaller divergent angle compared with conventional LEDs,which is consistent with the results of finite-difference time-domain simulation.     

Phased arrays based on oscillators coupled on triangular and hexagonal lattices

Phased arrays have been proposed in which a two-dimensional array of voltage-controlled oscillators coupled to nearest neighbors provides excitations for the radiating elements which are properly phased to result in a steerable radiated beam. These arrays have been arranged on a rectangular lattice and the beam is steered by tuning the oscillators along the four edges of the array. Proposed here are similar arrays in which the oscillators are coupled on a triangular lattice or a hexagonal lattice and provide excitations for radiating elements similarly disposed in a planar triangular array. Beam steering is accomplished by tuning the oscillators along the three edges of the array. The dynamic behavior of the arrays is studied via a continuum model and the results compared with those of a full nonlinear discrete analysis and a linearized discrete model.     

Novel densely packed laser diode array

A new GaAs/AlGaAs linear diode laser array with a packing density approaching 90% has been fabricated using chemically assisted ion beam etching. Results are presented for arrays which exhibit single-ended optically coated external quantum efficiencies of 71% and a maximum output power of 23 W (quasi-CW) from a 1 mm aperture.<>     

Isophoric arrays-massively thinned phased arrays withwell-controlled sidelobes

Traditional filled phased arrays have an element placed in every location of a uniform lattice with half-wavelength spacing between the lattice points. Massively thinned arrays have fewer than half the elements of their filled counterparts. Such drastic thinning is normally accompanied by loss of sidelobe control. This paper describes a class of massively thinned linear and planar arrays that show well-behaved sidelobes in spite of the thinning. The term isophoric is derived from Greek roots to denote uniform weight. In isophoric arrays, element placement based on difference sets forces uniformly weighted spatial coverage. This constraint forces the array power pattern to pass through V uniformly spaced, equal, and constant values that are less than 1/K times the main beam peak, where V is the aperture size in half-wavelengths and K is the number of elements in the array. The net result is reduced peak sidelobes, especially when compared to cut-and-try random-placement approaches. An isophoric array will exhibit this sidelobe control even when the array has been thinned to the extent that K is approximately the square root of V. Where more than one beam must be generated at a time, isophoric array designs may be used to advantage even within a traditional filled array. By “interweaving” two isophoric subarrays within a filled array and by appropriate cyclic shifting of the element assignments over time, two independent antenna power patterns can be generated, each with a sidelobe region that is approximately a constant value of 1/(2K) relative to the main beam, where K is the number of elements in the subarray