Study and realisation of dual-composite right/left-handed coplanar waveguide metamaterial in MMIC technology

A novel realisable dual composite right/left-handed (D-CRLH) coplanar waveguide (CPW) transmission line (TL) in GaAs MMIC technology demonstrated by theoretical analysis and experimental results is presented. A D-CRLH TL is the dual of the conventional CRLH TL in the sense that it consists of series LC parallel tanks and shunt LC series tanks. However, an ideal D-CRLH TL cannot be realised because of unavoidable parasitic effects. The measured results indicated that a real D-CRLH TL exhibits a fundamentally different frequency response at higher frequency band in that a real D-CRLH TL cannot provide unlimited left handed (LH) bandwidth. Instead, it has triple bands; right-handed (RH) passband at lower frequencies (DC-2.9 GHz), LH passband at intermediate frequencies (5.1 14.3 GHz) and RH passband at higher frequencies (above 14.3 GHz). The reported fully integrated D-CRLH CPW TL metamaterial has a very compact size of 2.2 mm² which leads to a small loss 1.5 dB within 3 dB LH passband.     

Fast and accurate modeling of waveguide grating couplers

A boundary variation method for the analysis of both infinite periodic and finite aperiodic waveguide grating couplers in two dimensions is introduced. Based on a previously introduced boundary variation method for the analysis of metallic and transmission gratings [J. Opt. Soc. Am. A 10, 2307, 2551 (1993)], a numerical algorithm suitable for waveguide grating couplers is derived. Examples of the analysis of purely periodic grating couplers are given that illustrate the convergence of the scheme. An analysis of the use of the proposed method for focusing waveguide grating couplers is given, and a comparison with a highly accurate spectral collocation method yields excellent agreement and illustrates the attractiveness of the proposed boundary variation method in terms of speed and achievable accuracy.     

Characteristic mode theory of coupled waveguide arrays with periodically varying properties

A method is presented for determining the eigenvalues and eigenvectors (characteristic mode shapes) for coupled waveguide arrays in which the interguide coupling is uniform but where the dephasing varies periodically from guide to guide. It is demonstrated that if the dephasing alternates from guide to guide, a quadratic equation must be solved for the eigenvalues, whatever the number of guides. For dephasing functions of larger period, the eigenvalue equation is of correspondingly higher order. The effect of such functions is to insert additional band gaps into the eigenvalue distribution and to couple together spatial harmonics. Numerical examples illustrating the method are presented where relevant.     

Input waveguide grating couplers designed for a desired wavelength and polarization response

Input grating couplers are used to couple light from free space into a waveguide and can provide additional functions such as focusing and beam splitting of the light into arbitrary desired positions in the waveguide. We show that it is possible to design the couplers so that they perform different desired functions depending on the polarization or wavelength of the incident light. We demonstrate experimentally a number of couplers that may be of interest, e.g., in optical fiber communications. Examples are polarization-independent couplers, designed to have the same response for two orthogonal polarizations of the incident light, and couplers for demultiplexing in wavelength division multiplexing applications, designed to separate and focus different input wavelengths to different positions in the waveguide.     

Design, fabrication, and performance of preferential-order volume grating waveguide couplers

Both a nonfocusing and a focusing preferential-order volume grating waveguide coupler were designed, fabricated, and tested. These volume grating couplers are designed to outcouple a 633-nm wave guided in an adjacent polyimide waveguide film. The slanted-fringe volume gratings are recorded holographically by the interference of two 364-nm waves. The dynamics of the holographic photopolymer HRF600X001 are investigated in relation to the interaction with the guided wave. The fabricated couplers exhibited a preferential coupling of 98%, a spatial coupling rate of 3.6 mm(-1), and a coupling efficiency of 95%. The focusing grating coupler focused the outcoupled beam to a focal line with a full width at half-maximum of 10.49 mum located 25 mm above the grating.     

A grounded coplanar waveguide technique for microwave measurement of complex permittivity and permeability

We present a method for extracting the complex permittivity and permeability of dielectric/magnetic thin films in a grounded coplanar waveguide configuration. The technique is applicable for extraction of these material parameters for lossy and lossless materials over a broad frequency range with high accuracy. For validation, we extracted complex permittivity and permeability, using the scattering parameters obtained from the full-wave electromagnetic simulation for two test cases over a frequency range of 5 to 15 GHz. Accuracy for both dielectric as well as magnetic materials is within 2% error.     

Comparison of mechanical properties of martensite/ferrite and bainite/ferrite dual phase 4340 steels

Different microstructures were produced by heat treatment of 4340 steel. These microstructures are bainite, martensite, ferrite–martensite and ferrite–bainite. Mechanical tests were carried out at room temperature. The results showed that steel with bainite–ferrite microstructure has better ductility and charpy impact energy than steels with martensite–ferrite and full bainite microstructures. But yield and tensile strengths of this steel are less than the yield and tensile strengths of the other two steels. Hardness measurements showed that their hardness is the same. Fracture surface observations of tensile specimens showed increase in toughness of bainite–ferrite in comparison to martensite–ferrite and full bainite microstructures.     

Fast and accurate modeling of waveguide grating couplers. II. Three-dimensional vectorial case.

A boundary variation method for the fast and accurate modeling of three-dimensional waveguide grating couplers is presented. The algorithm is verified by detailed comparisons with the results of a rigorous spectral collocation method, showing excellent agreement. Examples of the modeling of large waveguide grating couplers are given to illustrate the applicability and versatility of the method.     

一种新型腔体式共面波导型微机械射频开关

提出了一种新型的腔体式共面波导型微机械射频开关的结构,可动的金属/电介质的复合膜结构的共面波导既可作射频开关,同时也构成微波信号的传输路径。在普通电阻率(4-8Ω·cm)的硅片上,采用表面微机械加工技术制作出体积大小为:1000μm×600μm×300μm的射频开关,驱动电压为35V,在射频信号频率为50MHz到10GHz的范围内,该开关的插入损耗低于2dB,隔离度高于40dB。     

Solidification mode and residual ferrite in low-Ni austenitic stainless steels

The solidification modes of two new classes of austenitic stainless steels with a low content of Ni are shown. Their chemical composition is similar to that of the standard AISI 304 and AISI 316, except for the content of nickel, manganese and nitrogen. It is found that standard formulas for predicting the residual ferrite can be fairly well used in the prediction of the solidification mode while they do not work in predicting the residual ferrite content. In particular, it is found that ferrite is the first phase to solidify for values of the equivalent ratio (calculated according to the formulas developed by Hammar and Svensson) greater than 1.50, otherwise austenite is the first phase to solidify. A new set of equations for predicting the residual -ferrite in these new classes of materials is determined via multivariable linear regression. The influence of the steel solidification mode on the material structural transformations during heat treatment is also shown.     

Extensions to a lens design program for the ray-optical design of waveguide lenses and prism couplers

Abstract

The design of integrated optical lens systems requires special software because such systems contain both three-dimensional and twodimensional elements (e.g. bulk prisms and planar waveguide lenses), and the waveguides are often anisotropic. We extended the popular optical computer-aided design program OSLO SIX so that it can evaluate and optimize systems that contain coupling prisms and planar waveguide lenses. We describe our software extensions and through examples we demonstrate their usage and benefits. We confirm our computations by measurement results. Finally, we present a ray-optical interpretation of transverse image line inclination and a method for its elimination.     

A theoretical and experimental study of waveguide coupled SAWresonator filters

The coupling-of-modes (COM) formalism is extended to include coupled transducers and applied to the modelling of surface acoustic wave (SAW) coupled resonator filters. The models do not require the derivation of equivalent circuits and they accommodate finger reflections, electromagnetic feedthrough and external matching circuits. Frequency responses for waveguide-coupled devices are computed and compared to experimental results. Longitudinal mode profiles within the resonant cavities are presented     

Annealing behavior of single mode planar waveguide in YVO4 produced by He ion implantation

We report, for the first time to our knowledge, the formation of single mode planar waveguide in z-cut YVO₄ by 400 keV, 500 keV He ion implantation in fluence of 3 × 10¹⁶ ions/cm² at room temperature or at liquid nitrogen temperature (77 K). We investigated annealing behavior of the guiding mode and near-field image in the waveguide by prism-coupling method and end-face coupling method respectively. We found that the effective refractive index of the TE₀ mode was different before and after annealing for the samples implanted at room temperature, while, annealing had nearly no influence on the effective refractive index of the TE₀ mode of the samples implanted at liquid nitrogen temperature (77 K). After annealing at 600 K for 1 h, no guiding mode was observed in the sample implanted by 400 keV He ion in fluence of 3 × 10¹⁶ ions/cm² at room temperature. The Rutherford backscattering/channeling technique was used to investigate the damage reduction after annealing treatments. The minimum yield of the implanted, annealed sample was 5.43%. We reconstructed the refractive index profiles in the waveguide under different condition by applying intensity calculation method.     

Optical properties of a single mode planar waveguide in Nd:YVO4 fabricated by multienergy He ion implantation

We fabricated a single-mode planar waveguide in z-cut Nd:YVO(4) by multienergy He ion implantation in total fluence of 4.5×10(16) ions/cm(2) at room temperature and investigated optical properties of Nd:YVO(4) before and after He ion implantation by measuring transmission, confocal microluminescence, and confocal Raman spectra. Absorption bands and the photoluminescence features of the bulk Nd:YVO(4) crystal have been preserved after He ion implantation. In Raman spectra, most of the peak positions and peak widths had no obvious change before and after He ion implantation. The guiding mode and near-field image in the waveguide were measured by the prism coupling method and end-face coupling method, respectively. We investigated the damage behavior of a Nd:YVO(4) waveguide after implantation, annealing treatment by the Rutherford backscattering/channeling technique. The minimum yield of the virgin z-cut Nd:YVO(4) was 1.98%, which increased to 4.73% after He ion implantation and decreased to 3.20% after annealing at 600 K for 30 minutes.     

Etch-pit investigations of deformed stoichiometric and non-stoichiometric Mn-Zn ferrite single crystals

Etching solutions both for stoichiometric and non-stoichiometric Mn-Zn ferrite crystals have been developed. The hot phosphoric acid method is suitable for nearly stoichiometric compositions and shows an etch memory effect for dislocations nearly parallel to the crystal surfaces. From the etch-pit arrays the slip system of Mn-Zn ferrite crystals is concluded to be of {111}1 0 type independent of the chemical composition and the Schmid factor.     

Synthesis of UHF circulators using quarter-wave coupled triangular resonators on a single substrate above the uniform line

The most widely used topology in the design of the cellular stripline circulator is that comprising a planar gyromagnetic resonator, biased above the uniform mode resonance, symmetrically coupled by quarterwave transformers between ferrite substrates. Its operation is still, however, largely semi-empirical. The purpose is to reconcile, in the case of a side-coupled triangular resonator, its network, magnetic and physical parameters. The magnetic variables of the substrate are uniquely established by the weakly magnetised model of the gyrator circuit and its effective permeability. The procedure outlined here is applicable to the construction of devices below 2 GHz with specifications of up to 25% bandwidth at 1.20 voltage standing wave ratio (VSWR) points (23 dB isolation). This sort of circuit is met in the design of ultra high frequency (UHF) circulators for use in cellular products.     

Exchange coupling controlled ferrite with dual magnetic resonance and broad frequency bandwidth in microwave absorption

Ti-doped barium ferrite powders BaFe_12−xTi_xO₁₉ (x = 0, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7 and 0.8) were synthesized by the sol–gel method. The phase structure and morphology were analyzed by x-ray diffraction (XRD) and scanning electron microscopy, respectively. The powders were also studied for their magnetic properties and microwave absorption. Results show that the Ti-doped barium ferrites (BFTO) exist in single phase and exhibit hexagonal plate-like structure. The anisotropy field H_a of the BFTO decreases almost linearly with the increase in Ti concentration, which leads to a shift of the natural resonance peak toward low frequency. Two natural resonance peaks appear, which can be assigned to the double values of the Landé factor g that are found to be ∼2.0 and ∼2.3 in the system and can be essentially attributed to the existence of Fe³⁺ ions and the exchange coupling effect between Fe³⁺ and Fe²⁺ ions, respectively. Such a dual resonance effect contributes a broad magnetic loss peak and thus a high attenuation constant, and leads to a dual reflection loss (RL) peak over the frequency range between 26.5 and 40 GHz. The high attenuation constants are between 350 and 500 at peak position. The optimal RL reaches around −45 dB and the practicable frequency bandwidth is beyond 11 GHz. This suggests that the BFTO powders could be used as microwave absorbing materials with extraordinary properties.     

Numerical simulation of single and dual pass conventional spinning processes

Due to the complex nature of sheet metal spinning processes, recent trends in analysis of the process are moving toward numerical techniques. These numerical methods, for instance finite element modelling, enable the study of parameters that can not easily be measured directly such as transient strains and stresses. Additionally, it allows a prediction of dynamic instabilities that may be used to control and achieve better product quality. In this investigation, a finite element dynamic explicit model has been used to simulate single and dual pass conventional spinning processes. The initial models are validated against published experimental data and show very good correlation. A variety of roller feed rates, roller passes and roller configurations are then simulated. Effects of roller feed rate on the axial force, radial force and thickness strain are established. The effect of roller pass and roller configuration on the axial force and thickness strain are also assessed.     

Efficient and accurate waveguide mode computation using BI‐RME and Lanczos methods

In this paper, a special purpose algorithm for solving large eigenvalue problems based on the Lanczos method is successfully applied to an engineering problem: the electromagnetic analysis and design of passive waveguide devices. For dealing with such complex problems, the boundary integral‐resonant mode expansion (BI‐RME) technique has been recently proposed. This technique solves integral equations (IEs) through the well‐known method of moments (MoM), thus leading to structured eigenvalue problems. These problems frequently become very large when solving complex arbitrary geometries with high accuracy. In such cases, the eigenvalue problem cannot be efficiently solved with standard methods by means of personal computers, essentially due to CPU time and memory allocation requirements. In this paper, we propose an alternative technique, based on the Lanczos method, for the fast and accurate solution of large BI‐RME generalized eigenvalue problems. The novel theoretical aspects of this approach, as well as the impacton the original BI‐RME formulation, are described. Comparative benchmarks are also successfully presented for the full‐wave analysis and design of real passive microwave devices. Copyright © 2005 John Wiley Sons, Ltd.