金属波导膜厚测量仪的研制

重点介绍了金属波导膜厚测量仪的制备原理、结构和特点 ,测试表明该装置是一台先进的微波性能检测设备 ,C波段圆极化铁氧体移相器波导膜系的膜厚均匀度不大于 5 %。     

一级衰减标准所用高精密圆截止波导金属壁内部氧化层的影响与分析

现在有许多国家建立的一级衰减标准选用黄铜作为制造截止波导的材料,它长期处于大气环境中在内壁表面上会生成一层薄的氧化层,给测量准确度带来不良影响。 从波导理论角度来看,分析氧化膜的影响要求人们应根据金属波导和介质波导的理论来推导出特征方程,并用电子计算机求解,以得到传输常数的严格值。这里应考虑到波导壁底金属的非理想导电(σ≠∞)、波导内表面非理想光滑以及氧化层膜厚的非均匀分布。以上情况的任何一种均足以使简正波不复存在,而成为混合波型或孪生波型。这是一项极为困难的     

有机-无机复合材料光波导的制备

有机-无机复合光波导在光通信领域具有重要的应用价值,是目前的研究热点之一.采用溶胶-凝胶法分别制备了膜厚达13μm的光滑平整的PMMA膜和具有紫外感光性的膜厚为1.76μm的SiO2/ZrO2凝胶膜,研究了SiO2/ZrO2凝胶膜的感光性及紫外光照对两种薄膜折射率的影响.在此基础上,以PMMA膜为包层膜,SiO2/ZrO2凝胶膜为芯层膜,实现了光波导的包芯层复合.利用SiO2/ZrO2凝胶膜的感光性,结合紫外掩模技术,制备了条形的有机-无机复合光波导,理论分析表明该复合条形光波导能够实现入射波长为1.31μm,模数为0,1的传输.     

掺Er3+:Al2O3平面光波导的溶胶-凝胶制备

掺铒光波导主要用来制作光波导放大器。采用溶胶-凝胶法制备了透明、稳定的掺铒的铝硅酸盐玻璃溶胶;使用浸渍提拉法或旋转涂敷法,并通过放在乙醇蒸汽中干燥,可在玻璃表面得到均匀的凝胶膜;最后样品在一定温度下烧结;通过多次重复涂敷-烧结这一工艺流程可以形成厚的硅酸盐玻璃膜层并得到波导结构。使用显微镜研究了凝胶膜表面性质,通过棱镜耦合法测量了波导的有效折射率Nm,也测定了所制备波导的吸收光谱。溶胶-凝胶法在制作均匀性好、高掺铒浓度的铝硅酸盐玻璃光波导上具有优势。     

锂铁氧体表面沉积Cu-Ti复合金属波导膜系的工艺

采用磁控溅射镀膜方法，在锂铁氧体材料表面，制备了Cu-Ti复合金属波导膜系，本文简单介绍了设备的改造特点，对整个工艺过程进行了分析研究，对制备的Cu-Ti复合金属波导膜系进行了性能测试，结果表明，用该工艺所制备的波导膜系性能指标达到微波器件的要求。     

基于SPR的多层金属膜厚在线纳米测量

通过对于首层金属膜的SPR反射光强曲线的分析利用两峰值点标记角度,同时用柱面光与CCD测量系统建立无机械测角转台的反射光强角度分布测量系统。根据CCD接收的光强与位置对应信息经计算机处理换算为光强角度分布曲线,并通过与库内的曲线数据进行匹配而获得膜厚数值。利用该系统对铬钛银铝等常用金属薄膜进行了在线测控研究,得到了纳米级金属薄膜的膜层蒸镀顺序与相应的膜厚测量范围。     

真空镀膜膜层厚度均匀性计算与工件架的设计

本文介绍了在真空镀膜中膜厚均匀度的理论计算和实际测量，并根据对膜厚均匀度的要求和作者多年的实践经验，提出了真空室内工件架的合理选择和最佳设计原则。     

金属镀层膜厚量值溯源方法的研究

对金属镀层膜厚的不同测量方法进行了比较分析,提出通过设计台阶镀层和测量台阶高度的方法,实现镀层量值的直接溯源,并与X荧光分析测量法进行大量的比对测量试验,验证台阶镀层测量方法的正确性.     

Enhancement of Goos-H(a)nchen Shift with Cascade Optical Waveguides

前期的工作已经证明,由于共振效应和渗透深度的增加,利用毫米尺度对称金属包覆波导和自由空间耦合技术,可获得毫米量级的古斯-汉欣(Goos-H(a)nchen)位移.本文在此基础上,利用一对对称金属包覆波导组成级联型结构,研究了这种结构中古斯-汉欣位移的增强效应.实验结果表明:当激光波长变化43 pm时,由CCD探测器测量得到的古斯-汉欣位移达到了2 215 μm,约为单级波导古斯-汉欣位移的2倍,实验结果与理论推导完全一致.     

级联型波导中古斯-汉欣位移的增强

前期的工作已经证明,由于共振效应和渗透深度的增加,利用毫米尺度对称金属包覆波导和自由空间耦合技术,可获得毫米量级的古斯 -汉欣(Goos-H.nchen)位移。本文在此基础上,利用一对对称金属包覆波导组成级联型结构,研究了这种结构中古斯 -汉欣位移的增强效应。实验结果表明：当激光波长变化 43 pm时,由 CCD探测器测量得到的古斯 -汉欣位移达到了 2 215 μm,约为单级波导古斯 -汉欣位移的 2倍,实验结果与理论推导完全一致。     

Resonances in a semiinfinite waveguide with iris in relation to the excitation of higher-order modes

New types of resonances were discovered in a structure comprising a short-circuited waveguide and a capacitive iris in the case when the distance between the iris and the short is in the order of several hundredths of the waveguide wavelength. The existence of these resonances is explained by the excitation of high-order modes in the iris aperture. It was found that a more complicated shape of the iris aperture results in the frequency characteristic of the electromagnetic structure considered becoming similar to that of a band-pass filter. This fact is explained by the enrichment of the spectrum of high-order modes.     

Analysis of Metallic Waveguides by Using Least Square-Based Finite Difference Method

This paper demonstrates the application of a meshfree least square-based finite difference (LSFD) method for analysis of metallic waveguides. The waveguide problem is an eigenvalue problem that is governed by the Helmholtz equation. The second order derivatives in the Helmholtz equation are explicitly approximated by the LSFD formulations. TM modes and TE modes are calculated for some metallic waveguides with different cross-sectional shapes. Numerical examples show that the LSFD method is a very efficient meshfree method for waveguide analysis with complex domains.     

Optical forces in hybrid plasmonic waveguides

We demonstrate that in a hybrid plasmonic system the optical force exerted on a dielectric waveguide by a metallic substrate is enhanced by more than 1 order of magnitude compared to the force between a photonic waveguide and a dielectric substrate. A nanoscale gap between the dielectric waveguide and the metallic substrate leads to deep subwavelength optical energy confinement with ultralow mode propagation loss and hence results in the enhanced optical forces at low input optical power, as numerically demonstrated by both Maxwell's stress tensor formalism and the coupled mode theory analysis. Moreover, the hybridization between the surface plasmon modes and waveguide modes allows efficient optical trapping of single dielectric nanoparticle with size of only several nanometers in the gap region, manifesting various optomechanical applications such as nanoscale optical tweezers.     

Metallic photonic crystals based on solution-processible gold nanoparticles

We demonstrate the fabrication of metallic photonic crystals, in the form of a periodic array of gold nanowires on a waveguide, by spin-coating a colloidal gold suspension onto a photoresist mask and subsequent annealing. The photoresist mask with a period below 500 nm is manufactured by interference lithography on an indium tin oxide (ITO) glass substrate, where the ITO layer has a thickness around 210 nm and acts as the waveguide. The width of the nanowires can be controlled from 100 to 300 nm by changing the duty cycle of the mask. During evaporation of solvent, the gold nanoparticles are drawn to the grooves of the grating with apparently complete dewetting off the photoresist for channels less than 2 microm in width, which therefore form nanowires after the annealing process. Strong coupling between the waveguide mode and the plasmon resonance of the nanowires, which is dependent on the polarization and incidence angle of the light wave, is demonstrated by optical extinction measurements. Continuity of the nanowires is confirmed by conductivity properties. Simplicity, high processing speed, and low cost are the main advantages of this method, which may have a plethora of applications in telecommunication, all-optical switching, sensors, and semiconductor devices.     

Measurement of the electroconductivity of nonmagnetic metallic nanofilms at ultra-high frequencies

It is shown that the electroconductivity of nonmagnetic metallic films may be measured by means of coaxial and waveguide impedance measurement instruments.     

A slab optical waveguide with negative effective thickness

Two new asymmetric slab optical waveguides with a left-handed media (LHM) cover or substrate are studied. The effective thickness is derived by using normalized waveguide parameters. An analytical method is then proposed to calculate the universal effective thickness. We show that negative effective thickness exists in the waveguide with a LHM substrate, unlike in conventional waveguide or other LHM waveguides studied previously. However, for the waveguide with a LHM substrate, the shape of high-order mode behaves like that of a traditional slab waveguide, and neither the fundamental mode nor the other higher order modes have the novel phenomena of negative effective thickness. Both TE and TM modes are discussed.     

AgI-coated silver-clad stainless steel hollow waveguides for infrared lightwave transmission and their applications

We fabricated silver iodide (AgI)-coated silver hollow waveguides to transmit a wide range of infrared (IR) light. Silver-clad stainless steel pipes were used as a supporting pipe. Since this type of metallic hollow waveguide has high mechanical strength and heat resistance, it is suitable as a rigid lightwave probe for various applications such as dental or medical laser treatment, IR spectroscopy, thermal radiometry, and laser processing. Considering these applications, we estimated the hollow waveguides with different thicknesses of the AgI layer. By optimizing the AgI layer thickness according to the wavelength of propagating light, we succeeded in efficiently transmitting Er-YAG and CO(2) laser light. We also studied the optical characteristics of a wide range of incoherent light for IR spectroscopy and radiometry applications using these metallic hollow waveguides as lightwave probes.     

Waveguide structures based on two-dimensional photonic crystals

The operation of a waveguide based on a two-dimensional photonic crystal composed of metallic circular cylinders has been experimentally studied. It is shown that the waveguide efficiency can be increased by selecting the optimum height of cylinders. Physical mechanisms responsible for the observed phenomena are analyzed.     

太赫兹量子级联激光器波导数值模拟

采用传输矩阵法(TMM)计算比较了太赫兹量子级联激光器两种波导限制方式(单面等离子波导和双面金属波导)的特点.结果表明双面金属波导的限制因子较单面等离子波导的限制因子有明显的提高,具有良好的模式限制作用,可以有效地降低波导层的厚度.     

A tunable waveguide to cavity coupler for high power accelerator cavities

The end iris ridge waveguide couplers are used to couple power to accelerator cavities through a reduced size coupling port. However, higher electric and magnetic fields due to reduced size lead to strict requirements on dimensional tolerances during coupler fabrication process. It is shown by detailed parametric analysis that even small dimensional changes during manufacturing or operation can lead to undesired shift in design frequency and deterioration of return loss. Hence, transmitted power testing of two couplers connected back to back without an intermediate cavity cannot be carried out. Here, we propose cylindrical static tuners on impedance matching section to relax the dimensional tolerance requirements. It is also shown that an iris coupled coupler-cavity system is more tolerant towards coupler dimensional changes than a stand-alone coupler. However, same tuners can find use for tuning the coupling coefficient of coupler-cavity system. The proposed tuning scheme is expected to reduce the coupler manufacturing costs and provide an useful alternative for coupling coefficient tuning over iris machining.