Optical Waveguide Lenses

The development of optical waveguide lenses, i.e. mode-index (including Luneburg), geodesic, Fresnel and Bragg grating lenses is briefly reviewed chronologically. A Bragg lens and a Luneburg lens, fabricated by electron lithography and vacuum deposition respectively, are described. A nearly diffraction-limited lens of the latter type can be obtained by using the shadow mask process.     

Waveguide detachable joints

Conclusions The theoretical formulas (1)-(4) represent correctly the effect of small gaps in waveguides. In the case of longitudinal sections (Fig. 1) with a gap amounting to 0.01 of a waveguide height, the measured attenuation amounts to 0.8 of the computed one. In the case of a transverse section with a gap between flanges of 0.1 of a rectangular-waveguide height or a circular-waveguide radius the attenuation value amounts to 0.8–0.9 of the computed one (rectangular waveguide) and to 1–1.2 of the computed one (circular waveguide).Justification for idealizing the contact connections due to adopting the concept of an effective gap consists of good agreement among gap values obtained in measuring at various frequencies the attenuation of different contact couplers whose contacting surfaces were subjected to the same production technology. The effective gap values were in good agreement with the directly measured deviations from flatness.Translated from Izmeritel'naya Tekhnika, No. 10, pp. 57–59, October, 1978.     

Precision Microwave Waveguide Loss Calibrations

Precision microwave insertion-loss measurements are an important part of the evaluation and calibration of the Jet Propulsion Laboratory-NASA low-noise deep-space communication systems. A study of cooled transmission-line components was initiated with the Rantec Corporation in July 1966. The preliminary work at Rantec involved WR 430 waveguide insertion-loss calibrations using a microwave cavity Q technique. JPL verified the technique by repeating the calibration using a direct insertion-loss measurement technique between matched components. The JPL measurements are described in detail, and the critical areas identified. The difference between the reported JPL (0.00427 dB) and Rantec (0.00414 dB) measurements of 0.00013 dB is within experimental accuracies and adds to the confidence factor of both measurement techniques.     

A General Waveguide Circuit Theory

This work generalizes and extends the classical circuit theory of electromagnetic waveguides. Unlike the conventional theory, the present formulation applies to all waveguides composed of linear, isotropic material, even those involving lossy conductors and hybrid mode fields, in a fully rigorous way. Special attention is given to distinguishing the traveling waves, constructed with respect to a well-defined characteristic impedance, from a set of pseudo-waves, defined with respect to an arbitrary reference impedance. Matrices characterizing a linear circuit are defined, and relationships among them, some newly discovered, are derived. New ramifications of reciprocity are developed. Measurement of various network parameters is given extensive treatment.     

Waveguide spectroscopy of thin films

A waveguide method of measurement of the absorption spectra of thin films in the range of their transparency is considered. The absorption spectra obtained by this method for the thin films of tin oxide and zinc oxide in a wavelength range from 400 to 800 nm are presented. The error of measurement of the absorption spectrum did not exceed 5% for an ∼0.1-μ-thick film with an absorption coefficient of ∼50 cm⁻¹. Possibilities and limitations of the method are discussed.     

Intracavity Waveguide Spectroscopy of Thin Films

The method of intracavity waveguide spectroscopy for measuring low optical losses in thin films is proposed. The method also allows one to distinguish transverse and longitudinal modes in low-gain lasers without introducing considerable losses into the cavity.     

微波波导五端口测量网络设计

介绍了工作于9～10 GHz频带的对称五端口波导网络的设计方法.为了使五端口波导网络能较好地工作于六端口反射计中,要求各端口反射系数的绝对值小于0.1.这里结合了频移法、渐变线分割研究法和数值解法等理论对五端口波导测量网络进行设计.     

玻璃光波导研究进展

介绍了目前国际上主要玻璃光波导的研究热点。阐述了制备光波导的晶体材料、玻璃材料和高分子聚合物材料的优缺点。着重阐述了玻璃材料的研究进展,并简要介绍了采用硫卤玻璃制备非线性光波导的诱人前景。     

基于波导不变量的双阵元被动探测方法研究

利用一种水声信道统计不变特征(波导不变量)实现被动探测。采用双阵元,分别对每一个阵元接收的宽带噪声信号进行LOFAR分析,对LOFAR图利用Hough变换等图像处理方法进行参数估计,得到波导不变量和曲线(文中讨论抛物线)参数估计值,进而运用几何关系估计出运动目标的航向角、速度和距离信息。利用Matlab仿真验证了该方法的正确性。     

Waveguide lasers based on dielectric materials

Fifty years since the invention of the laser have been witness of the development of many different laser systems and designs. Among them, miniaturized versions of solid sate lasers based on rare-earth-doped dielectric materials have been proposed and demonstrated during the last 20 years. They are based on confined radiation provided by optical waveguide structures. Although many materials and techniques have been studied for producing planar and channel waveguides, only a few of them have shown to be adequate routes for fabricating waveguide lasers. Here we summarize the theory and specific technologies developed for characterizing waveguide structures, and we present some common fabrication techniques already successfully applied to fabricate dielectric waveguide lasers, where relevant examples of demonstrated working devices are outlined.     

导波器件的宽带声光叉指换能器

研制了一种用于导波器件的宽带声光Ｂｒａｇｇ偏转叉指换能器，并给出了在Ｙ切Ｔｉ：ＬｉＮｂＯ３光波导上的实验结果。     

光电导型混晶Si1-xGex波导探测器

首次报导了光电导型混晶Ｓｉ－ｘＧｅｘ波导探测器。混晶Ｓｉ１－ｘＧｅｘ是在硅基ＳｉＯＮ／ＳｉＯ２／Ｓｉ上用快速加热超低压化学气相淀积生长并经６５０℃退火３０ｍｉｎ得到的。探测器宽１０μｍ,长２ｍｍ。探测器加２０Ｖ偏置电压是,探测灵敏在０．０２２－０．０１０Ａ／Ｗ之间。混晶Ｓｉ１－ｘＧｅｘ造成探测器的光谱响应曲线发生蓝移。当锗组分ｘ＝０．３５、０．４、０．５、和０．６时,探测器峰值波长分别对应为８７５     

Waveguide IMPATT diode oscillators with cap structure

Abstract

An experimental study of the mechanical properties of graphite/glass/graphite interply hybrid composite laminates subjected to pure tension and pure flexure is reported. The investigation includes single‐graphite, single‐glass and hybrid composite laminates. Straight side test coupons with dimensions of 200 mm × 14 mm and various numbers of layers were fabricated by hand lay‐up molding method. Epoxy resin served as the base matrix material. The types of layup of fabric warp directions include: 0°, 45°, 90°, [0°₃/45°/0°₃] and [0°₃/45°/45°₃].

Emphasis is given to the studying of the strength‐deformation behavior and the associated crack patterns of hybrid composite laminates, for monotonically‐increasing logitudinal elongation and angular deflection. Stress‐strain characteristics and crack patterns distinctive to each type of the specimen tested are presented. Mechanical strength data for hybrid composite laminates indicate the improvement in material characteristics over the single‐graphite fabric laminates.     

Waveguide structures based on two-dimensional photonic crystals

The operation of a waveguide based on a two-dimensional photonic crystal composed of metallic circular cylinders has been experimentally studied. It is shown that the waveguide efficiency can be increased by selecting the optimum height of cylinders. Physical mechanisms responsible for the observed phenomena are analyzed.     

Waveguide properties of gradient periodic fiber lightguides

Propagation of lower surface waves is studied in gradient fibers with longitudinal additive inhomogeneity.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 44, No. 1, pp. 129–135, January, 1983.     

Waveguide thermistor sensors for a microwave multimeter

The design and parameters are described for the sensing element in a transmission guide converter that employs a thermistor probe. Translated from Izmeritel'naya Tekhnika, No. 3, pp. 63–64, March, 1994.