Experiments of a Discrete Reflecting Beam Waveguide with Parabolic Cylindrical Reflectors

The new beam waveguide with parabolic cylindrical reflectors, analyzed in another paper, has been constructed and experimentally investigated. The measurement of the attenuation is in fairly good agreement with the theoretical attenuation constant if surface roughness and installation error of the reflector are taken into account. By the fundamental experiment for train RADAR application, with various obstacles placed inside this beam waveguide, it is shown that the measured reflection from metallic obstacles is in good agreement with theoretical calculations.     

A Theoretical Analysis of Discrete Reflecting Beam Waveguide with Parabolic Cylindrical Reflectors

A discrete reflecting beam waveguide with parabolic cylindrical reflectors, proposed by M. Kamimura, is theoretically analyzed. Electric field elementary waves on the reflector and the exciting primary electric field from the launcher are represented in the elliptic cylindrical coordinate system, and boundary conditions on the reflector are introduced to derive simultaneous integral equations regarding the reflector current. By solving these integral equations approximately, the integral representation of the secondary electric field in the beam waveguide is obtained, and poles and residues of the integrand are calculated to obtain the propagation constant of the beam waveguide and beam waveguide modes. The beam waveguide mode reflected toward the transmitting side when an obstacle is placed in the beam waveguide is obtained.     

Phase Step Beam Waveguide

Experimental tests on a new type of beam waveguide constituted by a series of equispaced dielectric frames are described. Field-pattern and power-loss measurements have been performed on short-circuited sections of the waveguide working at 10 GHz and on the 37-GHz prototype constituted by Teflon square frames. In comparison with the more common iris and lens beam waveguides, it presents advantages concerning diffraction, reflection, and dissipation losses. In addition, it is lightweight and compact. The experimental results confirm these advantages, along with a low sensitivity to assembling and constructive imperfections. Design criteria are suggested as a result of the optimization for the lowest losses obtained through numerical computations performed on the equivalent open resonator.     

非球面反射型扩束器的研究

非球面反射型扩束器由于其独特的优点得到了广泛的应用.本文分析了两种最常用形式的结构和像差特点,提出了一种利用两个不同锥体反射镜的组合实现光束转换的办法,从而消除了系统由于中心遮拦而带来的能量损失.文章还对各种非球面反射型扩束器和折射型扩束器的特点进行了比较.     

应用高斯波束理论设计波束波导天线

以高斯波束理论为基础,根据天线基本参数要求,分析确定出波束波导系统中各反射面尺寸、反射面彼此间距及各部件相对位置。以此系统为实例,给出各个反射面处高斯波束特征参数值,并分析比较了反射面之间距离、反射面辐射口径等参数对截获效率的影响。波束经过两反射面反射后均会产生交叉极化模,给出计算反射效率公式,得出结论为:两反射面姿态对称条件下彼此产生的交叉极化模可以互相抵消。     

Loss Measurements of the Beam Waveguide

The diffraction loss of a new low-loss waveguide for millimeter and shorter wavelength, called the beam waveguide, was measured. The loss measurements were made using a resonator technique. The beam waveguide resonator derived from the beam waveguide consists of confocal paraboloids and is itself a very useful millimeter and sub-millimeter wave circuit component having already found application in some optical masers. Measurements made to determine the reflection loss of the resonator end plates also resulted in information on the loss of 90/spl deg/ bends in the beam waveguide. The results of the loss measurements made on the beam waveguide, in the frequency range near 9 Gc, are in good agreement with theoretical values given by Goubau.     

离子束辅助沉积真空镀膜技术制备阵列波导光栅波导材料

采用离子束辅助沉积(IBAD)真空镀膜技术制备阵列波导光栅(AWG)波导材料。以固体石英玻璃材料作为衬底,采用离子束辅助沉积真空镀膜制备SiO2膜层,以实现偏振不敏感的阵列波导光栅。实验表明器件的偏振相关性大大改善,其双折射B约为1.4077×10-5,远小于二氧化硅-硅基波导结构阵列波导光栅的双折射B=2×10-4。器件的热稳定性也得以改善,当工作环境的温度变化范围为-10~70℃时,采用此方法研制的阵列波导光栅最大波长漂移为1.144 nm,小于普通的二氧化硅-硅基波导结构阵列波导光栅的波长漂移1.368 nm。     

Photonic Crystal Slab Waveguides Based on Antiresonant Reflecting Optical Waveguide Structures

A novel two-dimensional photonic crystal slab waveguide based on an antiresonant reflecting optical waveguide (ARROW) structure is proposed and designed. Lightwaves propagating in this waveguide are confined by antiresonance reflection vertically and the photonic band gap laterally. In order to obtain the characteristics of the ARROW-based photonic crystal waveguides, the three-dimensional finite-difference time-domain simulations are performed. With a lateral adiabatic taper, a coupling efficiency of 80.3% from a single-mode fiber to the ARROW-based photonic crystal waveguide of a single-line defect is obtained. In addition, propagation losses less than 10 dB/mm and bend losses of 0.23 and 0.39 dB/bend for the designed 60$^{circ}$ and 120$^{circ}$ bends are achieved at an operating wavelength of $1.55~mu{hbox {m}}$.      

A Light Beam Waveguide Using Hyperbolic-Type Gas Lenses

This paper is concerned with the optimum design of a light beam waveguide constructed with a proposed lens-like medium, namely, a hyperbolic-type gas lens which has a hyperbolic temperature distribution on its transverse cross section. In such a medium, the temperature distribution is ideally quadratic in the transverse directions, and so the mode conversion due to the higher order variation of the dielectric constant can be minimized. Moreover, this guide has the following merits; the design procedure is simple, the mode matching at the input part is easy, and it is possible to construct a waveguide using ordinary air as the lens medium. And this consideration can be easily extended to the guide with curved configuration. It was shown that the experimental convergency of this gas lens was in agreement with the theoretical one.     

Metallic Frame Beam Waveguide (Short Papers)

Experimental tests performed on metallic frame beam waveguides are described. Two types of metallic structures have been considered. The first one constituted by thin annular frames has the same attenuation value as that of an iris beam waveguide (infinite slit) of the same aperture, but presents guiding properties which are polarization sensitive. The second type of a more complex structure is essentially a dielectric frame beam waveguide in which the dielectric of suitable refraction index is simulated by metallic parallel plate waveguide sections.     

赋形波束波导馈电网络的研制

波导馈电网络具有损耗小、功率容量高、幅相分布精度容易控制等优点,广泛应用于波导裂缝阵列天线中.文中介绍了一种波导赋形波束馈电网络的工程设计,对研制过程中的关键技术如波导窄边裂缝耦合器、波导宽边裂缝耦合器及宽带配相波导等进行了详细论述.测试结果表明,馈电网络幅相精度良好,已成功应用于天线系统中.     

Bistabilities of Birefringent Vertical-Cavity Semiconductor Optical Amplifiers With Antiresonant Reflecting Optical Waveguide

Bistable characteristics of birefringent antiresonant reflecting-optical-waveguide (ARROW) vertical-cavity semiconductor optical amplifiers (VCSOA) under external optical injection with multi-mode profile and arbitrary polarization orientation are investigated theoretically. It is found that the presence of ARROW can realize stable single-mode bistable switching in VCSOAs. Furthermore, with suitable design of the bias current profile, it can be shown that ARROW VCSOAs with a large core diameter (i.e., ${ge 50}~mu{hbox {m}}$) can sustain stable single-mode bistable switching.      

Optical Flip-Flop Using Bistable Vertical-Cavity Semiconductor Optical Amplifiers With Anti-Resonant Reflecting Optical Waveguide

Flip-flop operations of anti-resonant reflecting-optical-waveguide (ARROW) vertical-cavity semiconductor optical amplifiers (VCSOAs) under the influence of undesired high-order injection modes are investigated theoretically. Three types of flip-flop operations, namely: (1) flip-flop triggered by optical injection, (2) inverse flip-flop triggered by optical injection, and (3) flip-flop triggered by injection current, are to be considered in the studies. It is found that with the presence of ARROW, all three types of optical flip-flop are insensitive to high-order injection modes, and stable single-mode flip-flop can be maintained in the operation.     

波束波导馈电的新型偏置近场卡塞格伦天线

提出一种新型偏置近场卡塞格伦天线,天线的主副镜均由具有圆口径的抛物面镜构成,给出了主副镜的几何参数和设计方程。采用非传统且适应高功率应用的波束波导进行馈电,天线系统（含波束波导）采用了几何光学和去极化的设计方法。根据照射锥削角和高斯束腰设计了方向图圆周对称的波纹喇叭馈源。在此馈源喇叭的基础上,根据高斯波束法得到波束波导各镜面尺寸。采用物理绕射理论对一个设计实例的方向图进行分析,证明该天线系统具有极低的交叉极化电平和旁瓣电平。     

基于有限差分的大角度交叉波导光束传输法

采用有限差分光束传输法(FDBPM)分析光波在大角度交叉区域的传输过程,利用pad近似解决大角度传输问题;利用透明边界条件弥补边界光波反射现象,通过追赶法编程计算有限差分方程组,得到在一定光波导结构条件下传输损耗与交叉角度之间的关系。在此基础上,利用低压化学气相沉积技术在硅衬底上制作了二氧化硅交叉波导结构,实验结果表明有限差分光束传输法在分析大角度交叉时具有比较高的计算精度。     

输出实心光束的环波导激光器

本文介绍了一种结构新颖的、具有环形增益介质的环波导CO2激光器。该激光器采用了一个结构简易的光束变换系统,可使出射的环状平行光束转换为实心平行光束。从而大大地拓宽了该激光器的应用范围。     

消除中心遮拦的反射式激光扩束新方案

反射型扩束器由于其独特的优点得到了广泛的应用,但系统存在的中心遮拦现象,使得高斯光束在扩束过程中有４０%左右的能量损失．本文提出了一种采用两个不同锥体反射镜构成的激光扩束新方案,消除了这种由于中心遮拦而带来的能量损失,并分析了对这种结构形式进行变化后得到的其他几种方案．