Transmission Modes of Closed Elliptic-Groove Waveguides for Millimeter Waves

In this paper, a new type of horizontal-flat and vertical-flat closed elliptic-groove guides is firstly presented. The field components and characteristic equations for some main transmission modes of the closed elliptic-groove guides are derived by with the help of the mode-matching method and Mathieu function. The variations of the cut-off wavelengths along with eccentricities, widths and lengths of the parallel plates for a number of lower order transmission modes of the closed elliptic-groove guides are also analysed in detail. The calculated results in good agreement with ones in the relevant references are of very important values in theoretical researches and actual applications of closed elliptic-groove guides for millimeter and submillimeter waves.     

Network analyses for transmission characteristics of several kinds of curve-shaped groove waveguides

In this paper, the several kinds of the novel curve-shaped groove guides including the whole elliptic-, whole cosine- and hyperbolic-groove guides as the new millimeter wave transmission lines are presented. The dispersion, cut-off and band characteristics of the dominant mode for the several kinds of the curve-shaped groove guides are analysed by using the equivalent network method with transverse resonance. The obtained results have important values in their theoretical studies and actual applications of the curve-shaped groove waveguides.     

Transmission characteristics of several kinds of closed groove waveguides for millimeter waves

An advantage of closed groove guide over open groove guide is attended. In this paper, the several kinds of closed groove guides including the trapezoidal-, elliptic- and parabolic-groove guides as new types of millimeter wave transmission lines are presented. Their dispersion and cut-off characteristics of the dominant mode are analysed and compared with ones of the closed V-and circular- groove guides by using the equivalent network method. The obtained results have important meaning in theoretical studies and actual applications of groove waveguides.     

Analysis of dispersion characteristics of groove guides with mode-matching method

Groove guide is widely recognized as one of the most promising millimeter wave transmission structures. In this paper, the mode-matching method is used to analyse the dispersion characteristics of single and asymmetrical double groove guides, and the unified formulae of Nth-order approximation dispersion equations are presented. Based on this analysis, a general program for calculating the dispersion characteristrics of single and asymmetrical double groove guides has been completed. Some comparisons between the results obtained by present method and published data show that very good agreement has been seen. The effectiveness and the reliability of the given formulae and program are thus verified.     

A New Fourier''s Expansion-Differential Method for Analyzing Groove Guide with Arbitrary Shape

A new Fourier's expansion-differential method for analyzing groove guide with arbitrary shape is firstly presented in this paper. It is convenient to solve practical application problems of arbitrary groove guides. The calculated results of the guide wavelengths of typical groove guides are in good agreement with ones in references, and its computing precision is fairly high. Hence the computational correctness of the new method is verified. The new method has the advantages of clear conception, direct-viewing expression, simple and easily feasible computation, etc. So it is of important application values for enriching groove guide theory and is solving actual engineering application problems for millimeter waves.     

On the possibility of investigations with very cold neutrons at pulsed sources

The possibility of investigations with very cold neutrons (VCNs) using the example of the IBR-2 pulsed reactor at the JINR FLNP is considered. Possible application areas and specific features of reactor characteristics for these investigations are briefly described. The results of detailed calculations of VCN generation in different cold moderators, VCN transport in neutron guides, and suppressing the contribution of delayed neutrons are presented.     

Analysis for a Novel Cocoon-Shaped Groove Guide with Method of Lines

An arbitrarily cross-sectional groove guide is analyzed by using the method of lines and its characteristic equations are gives for TE and TM modes. Some numerical results show that correctness of the method of lines compared with the relevant results in the references is verified, and it is convenient to solve groove guide with arbitrary shape in practical application problems. A novel cocoon-shaped groove guide is firstly presented and its transmission characteristics are analyzed and discussed. The new type of cocoon-shaped groove guide has the good performances. The obtained results are of important application values in theoretical studies and practical applications of groove guides for millimeter waves.     

Analytical method to measure bending deformations in prismatic optical films

The aim of this work is to provide an analytical method based on experimental measurements in order to obtain the prismatic film deformation for different curvatures of hollow cylindrical prismatic light guides(CPLGs). To conform to cylindrical guides it is necessary to bend the film to guide the light; changes induced by curving the film give rise to deformation shifts. Light losses affected by deformation are experimentally evaluated and numerically analyzed. The effect of deformation on prism angle is especially increased for CPLGs of curvatures higher than 20 m_1. An experimental method for the accurate transmittance of measurements related to bending is presented.     

Radiation losses due to discontinuities in asymmetric three-layer optical waveguides

In this paper, the radiation losses caused by film thickness and refractive index discontinuities in asymmetric slab waveguides are examined theoretically. A technique developed by Mahmoud and Beal for dealing with the continuous part of the radiation spectrum is used. Several numerical examples which show the radiation loss for various waveguide configurations are presented and discussed and, where appropriate, comparisons with other related work made. In the case of asymmetric thickness steps, the radiation losses are found to be appreciably higher than those computed for symmetric guides. The radiation losses for guides having the same thickness were found to decrease as the guide thickness increased. Once the TE₁ mode become guided, the losses decreased rapidly. However, if the two guides had different thickness then it was found that the losses exhibited a minimum.     

基于人工蚁群的红外图像分割算法

基于人工蚁群的红外图像分割方法利用模糊非线性增强算子作为启发信息,与信息素共同指导蚂蚁的行为。通过蚂蚁行走路径上的信息素分布进行更新,使得分布在目标路径上的信息素逐渐增大,逐渐向分割图像收敛,最后根据信息素分布提取分割结果。仿真和实验表明,该算法对真实图像得到了理想的分割结果。     

A full-wave three-dimensional analysis of open dielectric waveguides and periodic structures using an equivalent network model

An accurate fully vectorial wave analysis to calculate the propagation characteristics and field distribution of open dielectric waveguides and optical integrated circuits is presented. Based on the periodic repetition concept and using an equivalent network model, a method to analyze wave propagation in these guides is developed, which is able to take the simultaneous presence of mixed polarizations into account. Compared with conventional approaches like mode matching as well as with other numerical methods, the presented three-dimensional (3D) method shows individual advantages like accuracy, simplicity, and numerical efficiency. To show both validity and usefulness of this approach, some fundamental structures are investigated and the obtained numerical results are presented.     

用三维并行时域有限差分算法研究光子晶体薄板W3波导传输特性

构建了用于高性能并行计算的PC机群环境,将基于此机群环境的三维并行时域有限差分算法用于光子晶体薄板W3波导传输特性研究.性能分析表明：对于大规模问题,机群并行FDTD算法能够获得较理想的加速比.具体计算了W3波导的透射率频谱和光场分布.结果表明：光子晶体薄板W3波导能够实现光的三维约束,其导带中存在着微小禁带（mini-gap）.     

Frequency modulation in the transmittivity of wave guides in elastic-wave band-gap materials

It is shown, for the first time, that the transmittivity of wave guides created as rectilinear defects in periodic elastic band-gap materials oscillates as a function of frequency. The results are obtained using the finite difference time domain method for elastic waves propagating in two-dimensional inhomogeneous media. The oscillations of the transmittivity are due to the richness of modes in the elastic systems and, mainly, due to the periodicity of the potential in the direction of the wave propagation. Results are presented for a periodic array of Pb and Ag cylinders inserted in an epoxy host, as well as for Hg cylinders in an Al host.     

Analytic method of arbitrary cross section open groove guide

Groove guide is one of the waveguides that have been used at millimeter and submillimeter waveband. This paper analyzes arbitrary groove guides by means of the eigen-weighted boundary integral equation method that uses the eigenfunctions of a fictitious regular boundary as weighting functions. In comparison with the theoretical and experimental results published, the numerical results for rectangular, circular and V-groove guides using this method are exact enough with fast convergence and less calculation.The Project Supported by National Natural Science Foundation of P.R. China     

A MEMS Tunable Optical Ring Resonator Filter

In this work, a new architecture for a ring resonator tunable optical filter is proposed. In this architecture, two rings are connected to each other by a directional coupler and tuning is achieved through the control of the separation between the coupler two parallel guides using a micro-electro-mechanical systems (MEMS) actuator. The optical performance of the filter is tested using the FDTD and an analytical model is developed to predict its performances. A good agreement between the analytical and numerical results is obtained. The MEMS design is also presented and verified using an finite element method (FEM) analysis.     

Finite element model for waves guided along solid systems of arbitrary section coupled to infinite solid media

The Semi-Analytical Finite Element (SAFE) method is becoming established as a convenient method to calculate the properties of waves which may propagate in a waveguide which has arbitrary cross-sectional shape but which is invariant in the propagation direction. A number of researchers have reported work relating to lossless elastic waves, and recently the solutions for nonpropagating waves in elastic guides and for complex waves in viscoelastic guides have been presented. This paper presents a further development, addressing the problem of attenuating waves in which the attenuation is caused by leakage from the waveguide into a surrounding material. This has broad relevance to many practical problems in which a waveguide is immersed in a fluid or embedded in a solid. The paper presents the principles of a procedure and then validates and illustrates its use on some examples. The procedure makes use of absorbing regions of material at the exterior bounds of the discretized domain.     

Analysis of closely-spaced index-guided semiconductor laser. I. Multistripe devices

A detailed analysis of triple-stripe lasers incorporating index guides is presented. The relevance of multistripe laser structures for a number of applications is noted and progress in constructing these devices is briefly discussed. The properties of triple-stripe lasers are calculated as a function of stripe width and stripe separation. Light-current characteristics, near-fields and carrier concentration profiles are found for a range of devices and under differing operating conditions.     

Analysis of Loss and Dispersion Characteristics for Groove Guides with Arbitrary Groove Profiles by an Equivalent Active Transmission Line Method*

Loss and dispersion characteristics of groove guide are two practically important factors in the design for millimeter wave system consisting of groove guide. In this paper, a new method is presented for analyzing loss and dispersion characteristics of the groove guides with arbitrary groove cross-sections. The method is based on the combination of an equivalent active transmission line equation and the staircase approximation. Numerical results of dispersion and attenuation properties for some groove guides with different groove profiles are given. The effectiveness and practicality of the present analysis are confirmed by the data given in the literature.*Supported by the National Natural Science Foundation of China (No. 60171019) and (No. 60371010)