The dominant mode in closed circular groove guide

The structure of closed circular groove guide is similar to that of open circular groove guide, but it can prevent energy from leaking out of the guide. In this paper, the dominant mode in closed circular groove guide is considered. The characteristic equation is derived and solved and the results are discussed.     

Millimetric V-groove guide and components

A characteristic equation of single V-groove guide has been derived using the transverse resonance technique. This equation is much less complex and tedious to solve when compared with that obtained by the conformal mapping technique. The computed results are within 1% of the published experimental values for the cut-off wavelengths at X-band and 100 GHz. The present analytical approach is to approximate the central groove region by a large number of rectangular steps and the previously derived analytical solution for the rectangular-groove guide are applied to predict the propagation characteristics of single V-groove guide. A number of components in V-groove guide which have very similar characteristics to those of the rectangular-groove counter-part have been reviewed. It is noted that both the E-plane and H-plane cylindrical bends in both rectangular-groove and V-groove guides had unacceptably high-loss and a satisfactory solution have yet to be reached.     

Optimisation of dimensions of single V-groove guide

The optimum dimensions of a single V-groove guide for a frequency band were found to be more critical than that at a fixed frequency. The dimensions of this guide were optimised at X-band (8?12.4 GHz).     

The V-groove multijunction solar cell

A new type of silicon photovoltaic converter has been developed called the V-Groove Multijunction (VGMJ) solar cell. The VGMJ solar cell consists of an array of many individual diode elements connected in series to produce a high-voltage low-current output. All the elements of the cell are formed simultaneously from a single silicon wafer by V-groove etching. The results of detailed computer simulations predict a conversion efficiency in excess of 24 percent for this cell when it is operated in sunlight concentrated 100 or more times. The advantages of this cell over other silicon cells include the capability for greater than 20-percent conversion efficiency with only modest bulk carrier lifetimes, a higher open-circuit voltage, a very low series resistance, a simple one-mask fabrication procedure, and excellent environmental protection provided by a glass front surface.     

Study of a new leaky-wave antenna for millimeter waves based on the V-groove guide

Journal of Infrared, Millimeter, and Terahertz Waves - In this paper a new type of leaky-wave antenna for millimeter waves using an asymmetric strip in the V-groove guide is presented. The...     

Studies on the closed circular groove guide

When the circular-groove guide is closed at the two side ends by metal, its dispersion characteristic is studied in this paper, and theoretical values are presented. The eigen-weighted boundary integral equation method was used here.     

Coupling performance of closed double circular groove guide

Double circular groove guide is a simple structure which can be used to construct directional coupler. In this paper, the coupling property of two uniformly coupled circular groove guides is studied based on the transverse resonance analysing results of closed double circular groove guide.     

Characterisation of electrical and optical base controlled switching in the V-groove isolated punch through mode mist

The base controlled switching characteristic of the isolated, punch through mode metal-insulator (tunnel)-silicon thyristor is examined under various base inputs. It is shown that an excitation threshold and sensitivity are sufficient to characterise the electrical and optical base controlled switching modes. A simple model is presented which adequately explains the observed switching characteristics for both electrical and optical excitations. Furthermore for the optical case, the responsivity is derived and measured in order to provide a basis for comparison with existing photodetectors.     

An efficient image guide mode launcher

A three section efficient mode launcher for converting TE₁₀ mode of rectangular wave guide to dielectric image guide mode has been designed and tested experimentally. The transmission loss of the trapped image guide and insulated trapped image guide are also evaluated experimentally using this transition.     

Dominant mode characteristics of circular groove guide

Circular groove guide is a kind of waveguide for millimeter waves with low loss, large dimensions, and low dispersion. In this paper, the dominant mode characteristics of it is analysed. The technique that mode macthing method combines with point matching method is used to derive the Nth-order characteristic equation of the guide. The 1st order, 2nd order and 3rd order approximate curves that the normalized cutoff wavelength of circular groove guide varies with c/a are given. The attenuation curves are given at 1mm, 1.5mm and 3mm wavelength. The numerical results are in well agreement with the experimental results published.     

Fiber misalignment in silicon V-groove based optical modules

The use of anisotropically etched silicon optical benches (SiOB) and optical adhesives have attracted much attention for the low cost assembly of optical modules. In this paper, the effect of attachment process parameters (such as the amount of bulk adhesive, and the thickness/symmetry of the adhesive layer between the fiber and V-groove walls) on the alignment of the fiber with the laser diode assembled on SiOB, is studied. Finite element analysis (FEA) on the fiber displacement within the V-groove at a given temperature, increases significantly for different thicknesses of adhesive layers, present on either side of the fiber but does not change much with the total amount of adhesive in the module. Validation of the FEA data was accomplished by the use of in situ micro moiré interferometry, involving determination of the displacement of the centre of the fiber in the V-groove exposed to a temperature excursion ranging from room temperature to 125 °C. Maximum displacements of the fiber centre in the vertical and horizontal directions relative to the SiOB were found to range between 0.69–1.21 and 0.36–0.42 μm, respectively at 100 °C. The misalignment results obtained by moiré interferometry matched favorably with the finite element data. The simulation and experimental data in this study indicates that fiber misalignment due to temperature cycling can be reduced significantly if the fiber is located equidistant from the two inclined walls of the Si V-groove.     

基于主导—主体教学模式的机器人教学研究

本篇文章以机器人教学的实际内容,详细探讨一下主导——主体的机器人教学模式内容,从而为后续进一步提升机器人教学水平提供一定的理论基础.     

脊槽波导主模截止特性研究

为了研究脊槽波导主模截止特性,采用亥姆霍兹方程的有限差分格式,计算在窄边与宽边比为0.45、槽的高度与窄边比为0.4的条件下,脊槽波导中脊和槽的几何尺寸在中间位置连续变化时的归一化截止波长。并且计算了当脊宽为0、脊槽间距为窄边长度加槽高度,即脊槽波导的脊消失,成为单槽波导的归一化截止波长。并将计算结果与单槽波导和单脊波导的进行对比。结果表明,脊槽波导的截止特性较单脊波导和单槽波导更加良好。     

Regenerative switching in V-groove metal oxide semiconductor field-effect transistor structure

Anomalous regenerative switching has been observed in a power V-groove MOSFET with the drain terminal of the MOSFET at the top surface of the chip. This switching phenomenon is attributed to a rectifying junction formed at the drain terminal due to a thin oxide between the drain metal and the n-type drain diffusion. Because of the regenerative switching, the device characteristic changes from the MOSFET I(V) characteristic to a turned-on thyristor characteristic as the gate voltage is increased to a critical voltage. The ON-resistance of the device in the thyristor mode is found to be one-tenth of that in the MOSFET mode. Based on the explanation of the experimental results, an insulated gate controlled thyristor structure with substrate as the cathode is proposed.     

矩形波导中主模电磁波传播特性研究

矩形波导主模电磁波是波导传输中使用最多的模式。为了能深入了解其传播特征。从波导的截至波长入手,讨论了电磁波单模传播的条件。得出结论：主模传播需要电磁波波长和波导尺寸之间满足一定关系。推导出主模电磁波的场方程,利用该场方程,结合一定尺寸的矩形波导管,模拟出一定频率的主模电磁波分布图,进而总结了主模电磁波传播的主要特征。这...     

Enhanced dominant mode operation of a shielded multilayer coplanarwaveguide via substrate compensation

The cutoff frequency of the first higher-order even mode in a shielded multilayer coplanar waveguide (CPW) is studied using the spectral domain approach (SDA). The effective dielectric constant for the dominant odd and first higher-order even mode in a shielded multilayer CPW is computed and compared to other published numerical results. Dielectric constant and substrate height are varied with respect to even mode cutoff frequency and plotted for several CPW structures. Different combinations of internal substrates are shown to produce even mode cutoff frequency maximization for increased odd mode operation bandwidth     

Leakage of the dominant mode on stripline with a small air gap

In addition to the expected bound (proper) dominant mode, an independent leaky, (improper) dominant mode has been found to exist on a conventional stripline that has a small air gap above the conducting strip. Such an air gap often occurs during the fabrication process, and has in the past been suspected as the cause of spurious performance. This newly discovered leaky dominant mode leaks into the fundamental TM ₀ parallel-plate mode of the background structure, which is a parallel-plate guide with an air gap. Furthermore, it is found that the leaky dominant mode, not the bound dominant mode, is the continuation of the stripline TEM mode that exists with no air gap. Hence, it is the leaky mode that is excited predominantly by a conventional feed for the small air-gap structure. The general properties of both the bound and leaky dominant modes are obtained by using a full-wave spectral-domain approach. The primary purposes of this paper are to discuss the nature of the leaky dominant mode, and to show that its presence is indeed responsible for spurious transmission-line performance, such as unexpected loss and crosstalk, and interference between the bound and leaky dominant modes. These conclusions are verified experimentally     

超薄金属膜V-型槽等离子波导的定向耦合研究

分析了在 1 550 nm 波长下超薄金属膜(金膜厚t=10 nm)V-型槽等离子波导间长程沟道等离激元导模的定向耦合。通过计算不同波导间距下的模式分布,得出了定向耦合器中奇、偶模有效折射率实部和传播长度随波导间距的变化情况,并进一步计算了相邻波导间的耦合长度、最大串扰与波导间距的关系曲线。计算结果表明:在波导间距较小时,耦合长度小于各模式的传播长度,随着波导间距的增加,耦合长度随之增加,最大串扰随之减小。对超薄金属膜V-型槽等离子波导的定向耦研究在集成光路的实际应用中具有重要的价值。     

3D-to-1D carrier scattering in GaAs V-groove quantum wires

Epitaxial growth on nonplanar substrates is an attractive method for producing high quality quantum wire structures for applications in low-threshold lasers. However, a crucial factor in this application is the transfer of carriers between extended (3D) three-dimensional and confined (1D) one-dimensional states. In this paper we present a joint theoretical and experimental investigation of 3D-to-1D scattering in GaAs V-groove quantum wires confined either, within GaAs/AlAs short-period superlattice or bulk GaAlAs barriers. The scattering rates were computed using accurate wavefunctions for both the one-dimensional and the extended three-dimensional states. The rates are in good agreement with time-resolved luminescence measurements.     

Analysis of threshold conditions for generation of a closed mode in a Fabry-Perot semiconductor laser

Threshold conditions for generation of a closed mode in the crystal of the Fabry-Perot semiconductor laser with a quantum-well active region are analyzed. It is found that main parameters affecting the closed mode lasing threshold for the chosen laser heterostructure are as follows: the optical loss in the passive region, the optical confinement factor of the closed mode in the gain region, and material gain detuning. The relations defining the threshold conditions for closed mode lasing in terms of optical and geometrical characteristics of the semiconductor laser are derived. It is shown that the threshold conditions can be satisfied at a lower material gain in comparison with the Fabry-Perot cavity mode due to zero output loss for the closed mode.