分布式布喇格反射镜的穿透深度计算

采用特征矩阵法分别计算奇、偶数层布喇格反射镜的反射相移,利用反射时延与反射相移的关系给出了其穿透深度的表达式.采用电子束热蒸发的方法制备了结构为[HL]2H的布喇格反射镜,并制作了有机微腔器件,测量和计算了其透射光谱、反射相移和穿透深度,得到了微腔的有效腔长,测量值与实验值吻合较好,验证了该穿透深度公式的正确性.     

分布式布喇格反射镜的穿透深度计算

采用特征矩阵法分别计算奇、偶数层布喇格反射镜的反射相移,利用反射时延与反射相移的关系给出了其穿透深度的表达式.采用电子束热蒸发的方法制备了结构为[HL]2H的布喇格反射镜,并制作了有机微腔器件,测量和计算了其透射光谱、反射相移和穿透深度,得到了微腔的有效腔长,测量值与实验值吻合较好,验证了该穿透深度公式的正确性.     

Compton散射下太赫兹波段介质微腔光学特性

应用Compton散射模型、1维等离子体光子晶体模型和数值计算方法,研究太赫兹波段介质微腔光学特性,给出了系统反射率、反射相移和相位穿透深度修正方程和实验验证。结果表明：与散射前相比,系统中心波长左移15 ,这是因散射使等离子体层中电子与光子碰撞频率增大效应导致系统振荡频率增大的缘故;反射相移在截止区与波长呈准线性关系,中心波长处相对 有一定偏离,这是因散射使等离子体层中电子辐射阻尼增强效应导致系统振荡频率减小的缘故;禁带区相位穿透深度增大,这是因散射与入射光形成的耦合光与入射光在禁带区的相位不同,导致入射光禁带对于耦合光产生局部失效的缘故。谐振峰左移15 ,强度提高了22倍,这是因散射产生的等离子体频率和电子辐射阻尼增大效应使系统中心波长左移,透射几率增大,从而导致透射禁带两个谐振峰左移和谐振峰强度提高的缘故。     

Compton散射下太赫兹波段介质微腔光学特性

应用Compton散射模型、1维等离子体光子晶体模型和数值计算方法，研究太赫兹波段介质微腔光学特性，给出了系统反射率、反射相移和相位穿透深度修正方程和实验验证。结果表明：与散射前相比，系统中心波长左移15 ，这是因散射使等离子体层中电子与光子碰撞频率增大效应导致系统振荡频率增大的缘故；反射相移在截止区与波长呈准线性关系，中心波长处相对 有一定偏离，这是因散射使等离子体层中电子辐射阻尼增强效应导致系统振荡频率减小的缘故；禁带区相位穿透深度增大，这是因散射与入射光形成的耦合光与入射光在禁带区的相位不同，导致入射光禁带对于耦合光产生局部失效的缘故。谐振峰左移15 ，强度提高了22倍，这是因散射产生的等离子体频率和电子辐射阻尼增大效应使系统中心波长左移，透射几率增大，从而导致透射禁带两个谐振峰左移和谐振峰强度提高的缘故。     

Compton散射对太赫兹波介质微腔光学特性影响

应用Compton散射模型、1维等离子体光子晶体模型和数值计算方法,研究太赫兹波段介质微腔光学特性,给出了系统反射率、反射相移和相位穿透深度修正方程和实验验证.结果表明:与散射前相比,分布式布拉格反射镜系统中心波长左移15μm,这是因散射使等离子体层中电子与光子碰撞频率增大效应导致系统振荡频率增大的缘故;反射相移在截止区与波长呈准线性关系,中心波长处相对π有一定偏离,这是因散射使等离子体层中电子辐射阻尼增强效应导致系统振荡频率减小的缘故;禁带区相位穿透深度增大,这是因散射与入射光形成的耦合光与入射光在禁带区的相位不同,导致入射光禁带对于耦合光产生局部失效的缘故.谐振峰左移15μm,强度提高了22倍,这是因散射产生的等离子体频率和电子辐射阻尼增大效应使系统中心波长左移,透射几率增大,从而导致透射禁带两个谐振峰左移和谐振峰强度提高的缘故.     

单层介质膜反射棱镜式光学相位延迟器件研究

反射式介质膜光学相位延迟器件在具有波片的功能的同时,还可用作光束保偏(或相移)转向器件及光束保偏(或相移)平移器件等,是光学领域中近10多年出现的新型器件,在科研与光学工程中有广泛的应用与需求.本文从理论上系统地研究了各相关因素对单层介质膜反射棱镜式光学相位延迟器件相位特性的影响,探讨了该类光学相位延迟器件的设计方法,给出了一个设计实例及相应的实验结果.     

太赫兹波段介质微腔光学特性研究

采用匀胶法制备了厚度在微米量级的 Si/[TiO₂/Al₂O₃]²TiO₂和Si/[TiO₂/MgO]²/TiO₂ 多层介质膜反射镜. 采用太赫兹(THz)时域透射光谱系统获得了多层膜的时域透射谱. 用传输矩阵法模拟了Si/[TiO₂/Al₂O₃]²TiO₂ 和Si/[TiO₂/MgO]²/TiO₂两种分布式布拉格反射镜 (DBR)的反射相移和相位穿透深度等光学特性. 设计了两种结构为 DBR/LT-GaAs/DBR的对称THz光学微腔结构并模拟了腔结构的辐射光谱. 结果表明:通过引入谐振腔, 两种DBR组成的微腔器件在谐振波长处的强度分别提高了19和14倍. 其中Si/[TiO₂/Al₂O₃]²TiO₂/LT-GaAs (12 μm)/ [TiO₂/Al₂O₃]²TiO₂腔的辐射光谱存在两个峰, 分别位于208和248 μm, 并分析了出现两个谐振峰的原因. 探讨了通过引入介质谐振腔实现对THz源的辐射特性进行调控的可行性. 关键词： 分布式布拉格反射镜 光子晶体 穿透深度 太赫兹微腔     

基于Ag/Ge/Ag阳极的as

通过在Ag层中引入一层Ge薄膜, 获得了具有低反射率和高反射相移的Ag/Ge/Ag复合阳极, 并制备了基于该阳极的蓝光顶发射有机电致发光器件.阳极高的反射相移使得器件在有机层厚度为100 nm时获得了顶发射蓝光发射, 且阳极较低的反射率减弱了器件内的微腔效应, 使得其电致发光光谱在不同视角下具有良好的稳定性.当Ge的厚度为20 nm时, 器件性能表现最为优良, 最高亮度和最大电流效率分别可达3 612 cd/m²和5.4 cd/A, 且色坐标在视角从0°变化到60°时仅移动了(0.007, 0.006).     

宽带多层高反射膜相位色散的干涉法测量

在超短脉冲技术中,腔内元件的相位色散效应起了重要影响,本文介绍了一个测定宽带多层高反射膜的相位色散的实验方法,同时计算了反射膜的相位二阶导数,实验表明宽带多层反射膜相移和相位二阶导数与膜层设计和工艺过程有密切关系.     

液晶法布里-玻罗滤波器可调谐特性分析

分析了液晶法布里－玻罗可调滤波器中介质反射镜反射相位引起的峰值波长漂移. 液晶法－玻滤波器通过外加电压调谐峰值波长, 反射相位会导致峰值波长漂移使器件不能达到DWDM系统的使用要求. 本文推导了一套计算反射镜反射相位的公式,将它应用于液晶法-玻可调滤波器的理论设计, 模拟结果定量表示了反射相位对峰值波长造成的影响. 这对确定液晶可调滤波器峰值波长和设计器件电驱动装置具有重要意义. 由此设计了一个在光通讯波段可单调调谐的液晶法-玻滤波器.     

Effect of Ag underlayer thickness on the microstructure and magnetic properties of L10-FePt films

FePt/Ag films were deposited on thermally oxidized Si(100) substrates by magnetron sputtering at room temperature and then the as-deposited films were annealed at 500 ^°C. The microstructure and magnetic properties of the films have been investigated by X-ray diffraction and vibrating sample magnetometry. The results indicate that introduction of the Ag underlayer promotes an ordering transformation of the FePt phase due to thermal tensile stress between the Ag underlayer and the FePt film. The in-plane tensile stress induced by the Ag underlayer should stretch the horizontal lattice parameter of FePt; thus, it is helpful for the ordering transformation. With increasing Ag underlayer thickness, the ordering parameter and coercivity first increase and then decrease. When the Ag underlayer thickness is 12 nm, the ordering parameter and coercivity of the film reach the maximum values, respectively. The Ag underlayer thickness also affects the magnetization reversal mechanism.     

ZnO/Ag/ZnO多层结构薄膜的光电性质

通过磁控溅射方法生长了不同银层厚度的ZnO/Ag/ZnO多层结构的薄膜,并对其形貌、光吸收谱、光致发光和光响应特性进行了比较研究.结果表明ZnO薄膜中银薄层的加入使得光致发光的强度增强.银层厚度为6 nm样品制成的器件在350 nm处的光响应度为0.06 A/W,相对于ZnO薄膜提高了一个数量级.而当银层厚度达到15 ...     

环形狭缝腔阵列光学特性的研究

设计了一种六角密排的二维环形纳米腔阵列结构, 利用时域有限差分算法对该结构的光学特性进行了探究. 仿真结果表明, 在线性偏振光入射时, 环形腔内可以形成多重圆柱形表面等离激元谐振, 谐振波长的个数和大小与环形腔的结构参数相关. 根据透、反射光谱, 电场矢量的模式分布及截面电荷密度的分布, 谐振波长处形成圆柱形表面等离激元, 谐振波长处入射光能量大部分在环形腔内损耗, 此时反射率为极小值, 环形腔内的电场增强效应为极大值(光强增强可达1065倍). 谐振波长与环形腔的结构参数(狭缝内径、狭缝外径、膜厚、环境介质折射率、金属的材质)相关, 通过调节结构参数, 谐振波长在350–2000 nm范围内可调. 通过对比相同结构参数的单个环形腔和环形腔阵列的仿真结果, 周期排布对环形腔内的圆柱形表面等离激元吸收峰位置影响不明显. 该结构反射光谱对入射光电矢量偏振方向不敏感. 谐振波长的可调控性对于表面拉曼增强和表面等离激元共振传感器的设计与优化具有指导性意义, 且应用于折射率传感器时灵敏度可达1850 nm/RIU.     

New surface structure analysis of Ag-Si phase by quantitative auger electron spectroscopy method

Ag or Au was deposited on a clean Si substrate at room temperature. These systems, Ag/Si and Au/Si, were annealed at various temperatures or various heating times. Due to the annealing, Ag or Au diffused into Si and/or Si diffused into the metal. The changes of the surface composition are analyzed by a quantitative Auger Electron Spectroscopy (AES) method which is newly developed as a non-destructive method. In the case of Ag/Si, Ag migrated into the Si substrate and/or Si diffused into Ag. Then, Ag-Si solid solution was produced. After the annealing, the Ag/Si system is changed into Ag/(Ag-Si)/Si of the three-phase structure. In the case of Au/Si (Au film thickness < 15 Å), the Au film thickness became thinner by annealing. The Au/Si system always keeps the Au/Si phase after annealing, while there was no Au-Si solution area. The difference between the Ag/(Ag-Si)/Si and the Au/Si structure is attributed to the reason that Au diffuses more quickly than Ag into the Si substrate. AES results after annealing cannot be explained by the model of the formation of the three-dimensional island structure which is commonly referenced.     

Interface effects on the quantum well states of Pb thin films

Using scanning tunneling spectroscopy, we have studied the interface effect on quantum well states of Pb thin films grown on various metal-terminated (Pb, Ag, and Au) n-type Si(111) surfaces and on two different p-type Si(111) surfaces. The dispersion relation E(k) of the electrons of the Pb film and the phase shift at the substrate interface were determined by applying the quantization rule to the measured energy positions of the quantum well states. Characteristic features in the phase shift versus energy curves were identified and were correlated to the directional conduction band of the silicon substrate and to the Schottky barrier formed between the metal film and the semiconductor. A model involving the band structure of the substrate, the Schottky barrier, and the effective thickness of the interface was introduced to qualitatively but comprehensively explain all the observed features of the phase shift at the substrate interface. Our physical understanding of the phase shift is critically important for using interface modification to control the quantum well states.     

Glancing-incidence X-ray diffraction of Ag nanoparticles in gold lustre decoration of Italian Renaissance pottery

Lustre is known as one of the most significant decorative techniques of Medieval and Renaissance pottery in the Mediterranean basin, characterized by brilliant gold and red metallic reflections and iridescence effects. Previous studies by various techniques (SEM-EDS and TEM, UV-VIS, XRF, RBS and EXAFS) demonstrated that lustre consists of a heterogeneous metal-glass composite film, formed by Cu and Ag nanoparticles dispersed within the outer layer of a tin-opacified lead glaze. In the present work the investigation of an original gold lustre sample from Deruta has been carried out by means of glancing-incidence X-ray diffraction techniques (GIXRD). The study was aimed at providing information on structure and depth distribution of Ag nanoparticles. Exploiting the capability of controlling X-ray penetration in the glaze by changing the incidence angle, we used GIXRD measurements to estimate non-destructively thickness and depth of silver particles present in the first layers of the glaze. PACS 61.10.Nz; 61.10.Eq; 81.70.-q; 61.46.+w     

Infrared and photoelectron spectroscopy study of vapor phase deposited poly (3-hexylthiophene)

Poly (3-hexylthiophene) (P3HT) was thermally evaporated and deposited in vacuum. Infrared spectroscopy was used to confirm that the thin films were indeed P3HT, and showed that in-situ thermal evaporation provides a viable route for contaminant-free surface/interface analysis of P3HT in an ultrahigh-vacuum (UHV) environment. Ultraviolet photoelectron spectroscopy (UPS) as well as X-ray photoelectron spectroscopy (XPS) experiments were carried out to examine the frontier orbitals and core energy levels of P3HT thin films vapor deposited in UHV on clean polycrystalline silver (Ag) surfaces. UPS spectra enable the determination of the vacuum shift at the polymer/metal interface, the valence band maximum (VBM), and the energy of the π-band of the overlayer film. The P3HT vacuum level decreased in contrast to that of the underlying Ag as the film thickness increased. XPS and UPS data confirmed the chemical integrity (stoichiometry) of the polymer at high coverage, as well as the shift of the C 1s and S 2p binding energy peaks and the secondary-electron edge with increasing film thickness, indicating that band bending is present at the P3HT/Ag interface and that the measured onset of the valence band is about 0.8 ± 0.05 eV relative to the Fermi level.     

Surface resistance measurements at the metal/electrolyte interface of Ag(100) and Ag(111) thin film electrodes

The conductivity of thin film metal electrodes with a thickness of the order of the mean free path of the conduction electrons (50 nm at 300 K) is sensitive to several processes on the metal surface (e.g. adsorption and desorption of ions). We developed epitaxially grown Ag(100)/MgO(100) and Ag(111)/TiO₂(110) electrodes of 20 nm thickness. The change in the surface resistance of Ag(100) thin film electrodes during adsorption of the halide ions Cl⁻, Br⁻ and I⁻ shows the different strengths of specific adsorption. We investigated the phase transition of thiocyanate (SCN⁻) on Ag(100) electrodes by combining the surface resistance method with voltammetric, capacitance and ex-situ XPS measurements. The influence of adsorbed uracil on the resistance of Ag(100) films was demonstrated. The surface resistance is very sensitive to small concentrations of metal cations (e.g. Tl⁺). The surface resistance of Ag(100) and Ag(111) thin film electrodes shows the typical difference in the stripping potential of Tl⁺ of about 100 mV.     

90°反射式相位延迟器的设计

铜蒸气激光反射镜在非正入射的时候 ,两个不同的偏振态之间会产生不同的相移。通过优化设计 ,在4 90～ 5 30nm之间p、s波获得了 90°的相移 ,同时也使反射率在 99 998%以上。Ag层的厚度对于相移不敏感 ,并且当其厚度大于一定值的时候 ,对反射率没有影响。根据误差分析 ,制备薄膜时其沉积速率精度控制在± 1%以下 ,在光谱范围内能达到± 15 2 8°的相移误差 ,相移均在 5 0 4nm处附近存在有一个收敛值。折射率的变化控制在± 1%以下 ,在光谱范围内能达到± 12 77°的相移误差。最外一层厚度变化± 1% ,其相移变化达到± 5 5°,2～ 5层和 9～ 16层对相移的影响也在 0 .5°之上 ,其余各层对相移影响非常的小。使用时的入射角控制在± 1°时 ,在光谱范围内能达到± 2 .86°的相移误差。在 5 30nm附近的波段对入射角不敏感。