太赫兹传输波导器件研究进展

随着太赫兹技术的发展,太赫兹传输波导器件的研究成为待解决的重要问题之一。太赫兹波位于微波与红外光之间,寻找高效的传输、耦合器件一直是研究人员的目标。主要介绍了太赫兹传输波导研究现状,并总结了各类型太赫兹波导的优势与不足。根据材料与结构分别对金属波导、介质波导的研究进展进行了分析。其中金属波导包括裸金属线波导、微结构波导、空芯波导以及平板波导,介质波导包括介质空芯波导、多孔芯波导以及微结构波导。最后分别对太赫兹传输波导未来需要解决的研究方向进行了展望。     

Progress in Terahertz Waveguides

This paper summarizes the recent progress in Terahertz(THz) waveguides. Many THz waveguides of various sorts have been presented and examined, including dielectric THz waveguides, metal THz waveguides, THz fiber and photonic crystal THz waveguides. Their advantages and limitations are stated, and the perspective of research on Terahertz waveguides is discussed.     

Leaky Waveguide: TE/sup cir//sub 01/ Circular Waveguide Periodic Array of Circular Apertures

This paper describes propagation characteristics of periodic leaky waveguides for helix waveguides and solid metal waveguides carrying a TE/sup cir//sub 01/ mode based primarily on experimental studies. For low-loss leaky waveguides, this type has not been considered feasible, because of the critical problem encountered in mode conversion-reconversion at the circular apertures. Additional loss due to the periodic array of the circular apertures and TE/sup cir//sub 01/ loss/frequency characteristics of the periodic leaky waveguide using helix waveguides and solid metal waveguides are measured by the shuffle-pulse method in the X-band. The periodic leaky waveguides using solid metal waveguides are seen to be acceptable for practical use as a low-loss leaky waveguide system, according to these measurements.     

Nd:MgO:LiNbO_3光波导的制备及其特性

一、引言 目前,LiNbO_3是集成光学系统中使用较为广泛的衬底材料。自从Zhong等人首次报道了掺MgO的LiNbO_3晶体具有抗光损伤效应以来,MgO:LiNbO_3晶体在集成光学系统中得到了越来越广泛的应用。而质子交换MgO:LiNbO_3波导具有比纯LiNbO_3质子交换波导高的抗光损伤能力。把具有较好激光性能的钕离子掺入LiNbO_3中就能制成波导激光器。     

弯曲光波导端面修饰的设计方法

光波导的弯曲损耗一直是集成光学中一个值得人们重视的问题,为有效地减小光波导弯曲损耗,弯曲光波导的设计成为集成光学波导设计中的一个重要内容.本文在弯曲光波导保形变换方法的基础上,应用几何光学分析方法给出了波导弯曲损耗产生的简洁的物理图像,从而深入地分析了弯曲损耗产生的根本原因,并由此提出了弯曲光波导端面修饰的设计方法.理论分析表明,与传统的弯曲的光波导设计相比,该种设计方法可以有效地减小导波的模式泄漏,从而减小波导弯曲损耗.尤其是在弯曲光波导曲率半径、材料折射率等参数被设定的情况下,该种设计方法成为一种有效的设计方法.     

Vectorial wave analysis of dielectric waveguides for optical-integrated circuits using equivalent network approach

A vectorial wave analysis of the propagation characteristics of open dielectric waveguides for optical-integrated circuits using an equivalent network approach is presented. In this approach, all of the contributions from the discrete and continuous parts of the spectrum and from the TE-TM coupling, which are neglected in the earlier equivalent network approach, are taken into account. To show the validity and usefulness of this formulation, examples are computed for optical strip waveguides, rib waveguides, rectangular dielectric waveguides, embossed waveguides, and embedded waveguides.     

太赫兹波导器件研究进展

近年来,太赫兹科学技术的发展极为迅速。与此同时,以波导为基础的、用于太赫兹传输的器件应运而生,其中主要包括：太赫兹金属波导、太赫兹光子晶体波导、太赫兹光子晶体光纤、太赫兹聚合物波导、太赫兹塑料带状波导、太赫兹蓝宝石光纤等。为此,就国际上太赫兹波导器件方面的研究进展和最新动态进行了较详细的分析和归纳总结。     

Low-loss singlemode amorphous silicon waveguides

Amorphous silicon waveguides were obtained by plasma-enhanced chemical vapour deposition and anisotropic plasma etching. Rectangular multimode waveguides as well as singlemode ridge waveguides were fabricated. Scattered light measurements at 1550 nm (1300 nm) wavelength showed a low propagation loss of /spl les/0.5 dB/cm (1.6 dB/cm) for multimode waveguides and 2.0 dB/cm (5.0 dB/cm) for highly-confined singlemode waveguides.     

脊位于窄边的四种加载介质波导传输特性的有限元计算

运用矢量有限元方法对脊位于窄边的四种加载介质双脊波导的主模截止波长和单模带宽特性进行了计算和分析,四种波导分别为脊位于窄边的加载介质双脊矩形波导、加载介质双脊梯形波导、加载介质双脊V形波导以及加载介质双脊椭圆形波导。计算结果表明,脊位于窄边的四种加载介质双脊波导的两种传输特性总体相似,和脊位于宽边相比,脊位于窄边的主模归一化截止波长和单模带宽总体小很多,且脊位于宽边时的特性变化趋势比脊位于窄边时剧烈。这些计算结果将有助于微波器件及微波系统的设计。     

Characterization and Modeling of Laser Micromachined Periodically Corrugated Metallic Terahertz Wire Waveguides

Finite element method simulations of periodically corrugated metal terahertz wire waveguides have been conducted with concurrent analysis done on both the near-field confinement properties and the far-field emission properties at the end of the waveguides. This modeling was used to guide the choice of design parameters for the fabrication of waveguides with laser micromachining. The waveguides were characterized with a fiber-coupled terahertz time-domain spectroscopy and imaging system. The propagation properties as well as the frequency dependent diffraction at the end of the wire waveguides were examined and compared to straight, non-engineered metallic wire waveguides.     

Fabrication and performance analysis of polymer light waveguides in EOPCB

A new method, named as doctor-blaring, is presented to fabricate light waveguides in electro-optical printed circuit board （EOPCB）. This new technology is proven to be suitable for the fabrication of the large size waveguides. The performance parameters of the light waveguides fabricated by the proposed method as well as the influence of the parameters on the performance of the waveguides are analyzed and simulated. The results demonstrate the feasibility of the method to fabricate the polymer waveguides.     

SOI纳米线波导和相关器件研究进展

SOI纳米线波导具有对光场限制作用强、传输损耗低、弯曲半径小、集成度高、与传统CMOS工艺兼容等优点,采用SOI纳米线波导能够大大缩小光子器件的长度和面积,提高器件工作速度和效率,降低器件功耗.介绍了SOI纳米线波导在模式、损耗、偏振等方面与传统大尺寸硅基波导所表现出来的不同特性,评述了当前关于SOI纳米线波导和基于SOI纳米线波导光子器件的最新研究进展.     

激光直写法制备条形光波导中的功率密度阈值

采用溶胶-凝胶法(sol-gel)在Si基SiO2衬底上制备了SiO2-TiO2芯层薄膜,构成了以SiO2为下包层,空气为上包层的平面光波导。利用光纤激光器对平面波导的芯层进行直写,结合后续的化学腐蚀工艺得到了SiO2-TiO2条形光波导,并着重研究了激光直写波导过程中存在的功率密度阈值以及阈值随薄膜预热处理温度的变化关系。研究结果表明,激光直写SiO2-TiO2波导存在起始收缩阈值和烧蚀损伤阈值;随着薄膜热处理温度的提高,两个阈值同时增大,其中损伤阈值的增大趋势要大于收缩阈值;因而薄膜可承受的直写光斑直径变小,所得波导宽度显著减小。最后对直写制得条形光波导的导光性能作了测试分析,验证了波导的三维导光性。     

Attenuation in wall-impedance waveguides: a new approach

The Rayleigh-Schroedinger power expansion of perturbed eigenvalues is used to determine propagation constants in wall-impedance waveguides, the final objective being a design procedure for trunk-communication waveguides. Examples of applications, where corrections up to the fifth order are accounted for, include ideal helix waveguides and thickly dielectric-lined circular waveguides.     

Propagation of TE Modes in Nonuniform Waveguides

The conditions for TE mode propagation in rectangular waveguides with nonuniform dielectric media are established. An equation is derived for determining the capacitivity functions which have equivalent curved waveguides with uniform dielectric media. The types of variable dielectric waveguides which have equivalent curved wall waveguides and a separable wave equation are determined.     

可弯曲的低损耗太赫兹波导研究进展

近年来,随着太赫兹(THz)时域光谱系统的发展,THz波导作为用于THz波传输的器件一直都是研究的重点,而寻找低损耗的材料和可弯曲的结构一直是研究人员的目标。介绍了THz时域光谱系统的现状,并总结了传统波导技术应用于THz领域时的一些不足之处。重点介绍了基于三种不同工作原理的新型THz波导,并对比了各自的优缺点,这三种原理分别是金属面反射、介质界面全反射以及反共振反射。最后简要介绍了可弯曲低损耗THz波导的应用现状及后续工作方向。     

A Combined Method for Dielectric Waveguides Using the Finite-Element Technique and the Surface Integral Equations Method

A combined method employing a finite-element technique in the H/sub x/ - H/sub y/ formulation and the surface integral equations method is proposed to treat the propagation characteristics of inhomogeneous waveguides with single or multiple claddings. The significant features of this combined method are that it does not suffer from any kind of spurious modes, which have been troublesome in applying the finite-element technique to waveguides and it is also capable of treating the cutoff frequencies of arbitrarily shaped, inhomogeneous dielectric waveguides with a single cladding, which is perhaps original. Furthermore, the proposed method is convenient in treating propagation constants close to cutoff and in handling coupled waveguides. Numerical results of inhomogeneous elliptical waveguides, diffusion waveguides, and the corresponding directional couplers are presented, including the cutoff frequencies of the elliptical waveguides.     

弯曲光波导模拟优化研究

用时域有限元差分（FDTD）方法弯曲光波导的优化仿真，减小弯曲光波导损耗。采用OPTIFDTD软件在曲率半径增大到一定的情况下，弯曲损耗在各种损耗中不占优势。在半径一定的条件下，适当选择波导的各个参数进行优化，可以使弯曲损耗达到最低，模拟了弯曲光波导中光的传播，得到了弯曲损耗的变化规律，波导参数不同，弯曲损耗不同，其中有一最佳参数点，由此得到弯曲光波导的参数优化设计值。     

Dispersion and radiation loss characteristics of antiresonantreflecting optical waveguides-numerical results and analyticalexpressions

Propagation characteristics of novel single-mode slab waveguides, ARROW (antiresonant reflecting optical waveguides), ARROW-B, and their modified configurations, are investigated. The dispersion and radiation loss characteristics, field profile, confinement factor, and spot size of these ARROW-type waveguides are analyzed in detail by a mode analysis method using the system interference matrix. Approximate expressions for these characteristics are obtained in simple forms, which provide useful suggestions for the design of these waveguides. Possible combinations of materials and design conditions of ARROW-type waveguides are discussed on the basis of these results     

金属包层渐变折射率平板波导传播特性

本文采用多层线型分割近似，结合欧姆损耗微扰法，分析了金属包层渐变折射率平板波导的传播特性。按此方法计算了几类典型波导的传播常数数值，结果均与精确值相吻合，且物理概念清楚，计算方法简单。