离子交换铒掺杂磷酸盐玻璃波导特性研究

给出有关离子交换铒掺杂磷酸盐玻璃波导的制备以及发光特性的基本结果。用Ag+ Na+ 离子交换在含有适量氧化钠的铒掺杂磷酸盐玻璃上很容易实现低损耗平面波导 ,并且离子交换过程对这种玻璃的光谱特性没有影响。     

Ultra‐Low‐Loss Acrylate Polymers for Planar Light Circuits

We have developed a materials system composed of liquid multifunctional fluorinated acrylate monomers that achieves very low absorption losses within both datacom and telecom wavelength ranges. Identified structure–property relationships have guided the design of polymers that are optimized with respect to their inherent materials properties and their ability to be processed into low‐loss optical waveguides. Together these co‐developed materials and processes combine to produce waveguides that have propagation losses equivalent to planar glass guides, and significantly reduced polarization dependence and improved thermal response needed for the performance of thermo‐optic devices. Extensive environmental studies have demonstrated robustness well beyond that required for normal operating conditions.     

Three‐dimensional printing technologies for terahertz applications: A review

Three‐dimensional (3D) printing technologies enables fast prototyping of complex 3D objects with ever improving printing qualities. To date, 3D printing has been found useful in areas such as manufacturing, industrial design, aerospace, dental and medical industries, and many others. In this article, we review recent advances of 3D printing technologies for terahertz (THz) applications. Different 3D printing technologies and printable materials are first discussed and compared. 3D‐printed THz components and devices, which are categorized as waveguides/fibers, antennas, and quasi‐optical components, are further demonstrated. It is found that the performances and functionalities of 3D‐printed THz devices have been greatly enhanced, while the operating frequencies have been increased from the lower end of THz range to over 1 THz region. With further development of novel materials and printing techniques, it is believed that 3D printing technologies will play an important role in the realization of THz components for efficient control and manipulation of THz waves.     

Padé近似在光子晶体模拟中的应用

为了节省时域有限差分(FDTD)法的计算时间,提出了许多将FDTD的时域结果转换到频域的方法.文中介绍了一种基于Baker算法的Pade近似,并展示了其在光子晶体模拟中的应用.对频率为160THz,品质因子为5000的简单谐振子,结果显示Padé近似用28时间步数据得到的强度谱比快速傅里叶变换用220时间步数据得到的强度谱更精确.采用这一Padé近似,光子晶体平板结构中不同波矢对应的模式频率和品质因子及其能带结构可以在很短的FDTD输出结果下得出.另外,Padé近似也用于计算光子晶体微腔的模式频率和品质因子.     

Very accurate and simple CAD models based on neural networks for coplanar waveguide synthesis

Very accurate and simple neural models for coplanar waveguide (CPW) synthesis are proposed. The results obtained from these neural models are compared with the results of quasi‐static analysis, the other synthesis formulas, and other experimental works. The accuracy of the neural models is found to be better than 0.4% for 11,206 CPW samples. © 2005 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2005.     

增量参数法计算的差分格式

给出了增量参数法中所需的导数计算的任意阶差分格式。通过计算一些实例,表明了采用较高阶差分格式可获得较高的精度。     

利用缓冲质子源制作LiNbO3光波导:光学特性及稳定性研究

利用缓冲质子源(苯甲酸中掺入一定量的苯甲酸锂)在Z切LiNbO3基底上制作了质子交换平面光波导，得到了不同掺杂摩尔分数(0．5％，1．0％和1．5％)的缓冲质子源质子交换波导的有效扩散系数及折射率分布。随着质子源中苯甲酸锂的摩尔含量逐渐增加，质子交换的有效扩散系数呈指数衰减，同时波导表面折射率增量线性递减。研究了有效折射率的稳定性特征，并与用纯苯甲酸制作的光波导进行了比较，发现利用缓冲质子源制作的LiNbO3光波导的稳定性明显优于纯苯甲酸制作的光波导。     

Preliminary investigation of near-field nondestructive testing of carbon-loaded composites using loaded open-ended waveguides

Composite materials are being utilized in a multitude of industrial and commercial applications. This is due to their desirable features such as light weight, durability and strength. This presents quite a challenge to the field of nondestructive testing and evaluation (NDT&E). Due to the material complexity associated with these materials, many techniques have been shown to be ineffective when inspecting these materials. The ability of microwaves to penetrate deeply inside such dielectric materials and composites makes microwave NDT techniques very attractive for interrogating such materials. Microwaves are also sensitive to the presence of dissimilar layers in these materials which allows for accurate thickness variation measurement in the range of a few micrometers at frequencies as low as 10 GHz. Near-field microwave inspection techniques were successfully used for detecting and locating defects and voids of different sizes and shapes in composites. For optimal detection, the standoff distance between the sensor and the composite and frequency of operation were used as optimization parameters to improve the detection capability. Carbon-loaded composites present a challenge to microwave NDT because of the lossy nature of carbon, especially at high microwave frequencies. Lower frequencies penetrate more (deeper) in carbon-loaded composites, however, the size of the waveguide sensor increases drastically at lower frequencies and consequently the resolution degrades rapidly as well. To overcome this dilemma, open-ended rectangular waveguides loaded with a dielectric material will be used to inspect carbon-loaded composites. The loading of the waveguide reduces the frequency of operation and keeps the small size of the waveguide (i.e. increases the penetration depth and maintains the resolution). Carbon-loaded composites with disbonds will be inspected and the ability of utilizing loaded rectangular waveguides for carbon-loaded composites inspection will be assessed.     

矩形弱吸收介质波导光学特性的微分增量法分析

运用微分增量法分析了矩形弱吸收介质波导的光学特性,数学处理简捷,所得公式精确度高,对于文中的计算实例,本方法的计算结果与波导模复特征方程的数值结果之间的相对误差,对于模有效折射率小于3×10~(-6),对于模吸收系数小于6×10~(-4).