Phase-Matched Waveguide Using the Artificial Anisotropic Structure and its Application to a Mode Converter (Short Papers)

Phase matching by the artificial anisotropic structure and its application to a mode converter are proposed for millimeter-wave dielectric circuitry. A phase-matched dielectric planar waveguide is designed and mode conversion characteristics are studied. An experimental result of the nonreciprocal mode converter are presented to show the usefulness of the structure.     

A Level-Crossing Analog-to-Digital Converter With Triangular Dither

In this paper, a level-crossing analog-to-digital converter is described. It can convert audio bandwidth signals with high resolution using few threshold levels and digital interpolation. Samples are generated at nonuniform time intervals and then interpolated to produce uniformly spaced output samples. A periodic triangular dither signal added to the input ensures that low-amplitude or slowly varying signals are sampled and converted accurately. The dither is estimated and removed digitally before interpolation. Simulations show that greater than 10-bit resolution can be achieved with only seven comparators when using a sixth-order polynomial interpolator.     

Nonreciprocal Polarization Converter Consisting of Asymmetric Waveguide With Magnetooptic Cladding: Theory and Simulation

A nonreciprocal polarization converter compatible with InP-based photonic integrated circuits is proposed. The device consists of an asymmetric InGaAsP waveguide combined with a ferrimagnetic cerium-substituted yttrium iron garnet layer. It makes use of the nonreciprocal conversion of the polarization state in the waveguide. A nonreciprocal TE–TM conversion efficiency of 93% at 1.55 $mu{hbox {m}}$ wavelength can be obtained with a device length of 0.27 mm.      

The Design and Optimization of an Ion-Exchanged Polarization Converter Using a Genetic Algorithm

In this work, a genetic algorithm is used for the optimization of the design parameters of an integrated optical polarization converter on a glass substrate. The algorithm is applied to find the minimum possible length for the converter. The required asymmetry for the structure is realized with the aid of a cleaving process following the ion-exchange process. Simulation results show the possibility of realizing such a low-cost integrated converter. The obtained results demonstrate the importance of using such an algorithm in integrated optics problems where several design parameters such as the geometrical dimensions, the temperature, and the time duration are to be optimized.     

Investigation of Waveguide Y-Junction Circulator with a Triangular Ferrite Post

An H-plane waveguide Y-junction circulator with a triangular ferrite post is investigated by a modified analysis of jointly resonance theory and simple field theory. Good agreement between the theoretical obtained performances and experimental results is observed. The circulator exhibits a very low insertion loss and a wide bandwidth.     

Simdified 12-GHz Low-Noise Converter with Mounted Planar Circuit in Waveguide (Short Papers)

A 12-GHz low-noise converter consisting of a planar circuit mounted in waveguide is described. This circuit consists of a metal sheet with proper patterns that is inserted in the middle of a waveguide parallel to the E plane. All circuit elements required for the converter are pressed or etched. This circuit is very useful for low-cost mass production and good performance. A measured noise figure of 4.5 dB was obtained with a 12-GHz signal frequency and a 420-MHz intermediate frequency.     

短路波导法的新应用

本文介绍一种测定不能进行机械加工的“固体材料”（农产品或矿物）微波介电特性的新方法。将这类材料研碎，成为“空气－粒子”混合物，应用短路波导方法，对几种不同的“松密度”混合物测量其介电特性（介电常数和损耗因子）。当已知待测材料的“固体密度”时，利用这些测得特性与混合物“松密度”的线性函数关系进行“外推”，从而获得“固体密度”下的农产品（或矿物）的微波介电特性。     

用多层矩形波导近似计算扁保偏光纤的双折射

本文提出了计算扁保偏光纤双折射的一个近似方法。首先建立了扁保偏光纤的多层矩形介质波导模型,再用类似于Marcatili解矩形介质波导方法,将多层矩形波导分解为两个垂直交叉的多层平板波导,最后求解多层平板波导得到矩形波导的传播常数和双折射。用这一方法计算了双折射与扁保偏光纤结构参数,如应力包层掺硼浓度、椭圆度和归一化频率等的关系曲线,可供设计和工艺人员参考。     

Finite-Element Analysis of Overmoded Waveguide Using Silvester's Algorithm (Short Paper)

A general, high-order finite-element waveguide analysis program originated by Silvester [1], [2] has been used to analyze overmoded waveguides. The algorithm approximates arbitrarily shaped waveguides by triangular subsections and solves the Hehnholtz equation subject to homogeneous Dirichlet or Neumann boundary conditions to obtain the eigenvalues (cutoff wavelengths) and the eigenvectors (scalar potentials). During these investigations of arbitrarily shaped overmoded waveguides, a computer program error was identified. This error resulted in incorrect higher-order mode potential functions. As this algorithms has been rather widely disseminated, it is the purpose of this communication to inform users of a correction which yields the correct higher-order-mode potential functions.     

Asymmetric Fission Transmission of Linear-to-Circular Polarization Converter Using Bi-layer Split Ring Structure

A circular polarizer based on bi-layer split ring structure is proposed that could achieve asymmetric fission transmission of linearly polarized wave at the dual band. Firstly, a new approach of “Fission Transmission of Electromagnetic (FTEM) waves” is introduced to understand the polarization transformation behavior for linear-to-circular polarization. The designed structure achieves broadband circularly polarized wave with an asymmetric transmission over resonance frequencies by the principle of FTEM wave. The electronics circuit of proposed structure demonstrates the transformation behavior of EM waves when the electric and magnetic coupling between the upper and lower patterned SRR is reached at the certain strength. The physics of the giant circular dichroism effect and optical activity is illustrated by the surface currents distribution on the structure. The proposed structure achieves a right-handed circularly polarized wave and left hand circularly polarized wave with high transmission at 13.94–15.70 GHz and at 16.0–17.03 GHz, respectively. The axial ratio bandwidth of 11.76 and 6.86% is obtained at the dual band. The simulated and measured results exhibit good correspondence.     

一种Ku波段波导-微带转换器的研制

本文利用三维高频仿真软件HFSS设计并分析了中心频率为15GHz的波导一微带过渡结构。这种结构的输入输出是直通方向的,与以往的波导-微带过渡结构相比,这种结构体积小、气密性好、更利于小型化。根据测试结果,设计的过渡结构在13GHz-17GHz频率范围内有良好的性能,插入损耗小于0．5dB,端口驻波系数小于1．35。     

Computation of the Reflection Coefficient of a Triangular Semiconductor Prism in a Rectangular Waveguide

In this paper we present a method to solve Maxwell's equations that enables to compute waveguide structure containing a semiconductor triangular prism. The numerical study has showed that the triangular prism in the waveguide has a wider frequency band in comparison with a square rod under equal conditions. The reflection coefficient dependencies on frequency, prism size and its permittivity have been computed. The algorithm and computer programme have been tested and compared with the numerical results and experimental data of the paper [1] with good agreement.     

A Coplanar Waveguide with Thick Metal-Coating (Short Papers)

A theoretical method is presented for the analysis of a coplanar waveguide, with thick metal-coating. Numerical results are given and compared with published data. It is shown that the metal-coating thickness of the coplanar waveguide causes an increase in wavelength and a decrease in characteristic impedance and that the changes are about the same as those of a slot line.     

径向偏振光束经三角形点阵列板衍射的偏振奇点

根据夫琅禾费衍射积分公式推导出径向偏振光束通过三角形点阵列板(TMP)衍射后的传输表达式,通过理论计算模拟并进行实验验证,得到衍射场光强分布图,衍射场光强成周期性排列。并用复Stokes场来分析径向偏振光束衍射场偏振奇点的变化规律。结果表明,衍射场的光强分布随着三角形点阵列板N值的改变而改变,偏振奇点的数目随着三角形点阵列板的N值的增大而增多。另外,光束参数(波长和光束束宽)、传输距离和三角形点阵列板的参数(三角板边长)均对偏振奇点的位置产生影响。改变三角形点阵列板的N值,伴随有偏振奇点的产生和湮灭现象。     

太赫兹超材料极化转换器设计及其特性分析

提出了一种反射型太赫兹超材料极化转换器.该极化转换器结构单元由典型的三层结构组成,上、下两层为金属层,中间为介质层,顶层金属层由一个开口谐振环和一个镂空圆盘组成.研究结果表明:该极化转换器能够将x极化波转换为y极化波,在0.584 0～1.352 0 THz频带上极化转换率大于80％,在0.642 4、0.936 4和1.301 8 THz处极化转换率接近100％.该极化转换器结构简单、便于加工,且能实现宽频带极化转换,在太赫兹波通信、成像等方面有广阔的应用前景.     

Numerical Solution of Surface Waveguide Modes Using Transverse Field Components (Short Papers)

The computation of surface waveguide modes is facilitated by reducing the surface waveguide field problem to a conventional eigenvalue problem that has no spurious solutions. This is achieved by formulating the field problem in terms of transverse field components and by using impedance boundary conditions on an auxiliary boundary with a specified value of the exterior cutoff wavenumber.     

Compact Polarization Mode Converter Monolithically Integrated Within a Semiconductor Laser

The design and realization of a short, passive, single-section waveguide polarization converter monolithically integrated within a Fabry–Perot ridge waveguide laser is reported. The device is fabricated on an unstrained GaAs-AlGaAs double quantum well heterostructure. A predominantly transverse magnetic polarized optical output from the converter facet of greater than 80% is demonstrated for a converter length of 20 $mu$m at an operating wavelength of 867 nm.      

A Higher Order Approximation for Waveguide Circulators (Short Papers)

Earlier work on the analysis and experimental performance of 3-port and 4-port waveguide circulators over the waveguide bandwidth has shown some discrepancies. The computed performance tended to be too optimistic. It is shown that an extension of Davies' analysis to include higher order cylindrical modes and evanescent modes in the waveguide arms yields excellent correlation between theory and practice.