The b-type rotational transitions of HNCO in the lowest excited vibrational state

In the microwave and millimeter wave spectra of HNCO, the b-type transitions between the K_a = 0 and 1 levels in the lowest excited vibrational state have been observed. Because of strong a-type Coriolis resonances among the three bending excited states the energy difference between the levels for K_a = 0 and 1 is much smaller in the lowest excited state than in the ground state. The subband origin of these b-type transitions has been found in the millimeter wave region at 275 697.309 MHz (9.1963 cm^?1). The effect of the Coriolis resonances is discussed in relation to the molecular quasi-linearity and is compared with the case of HNCS.     

Frequency synthesizers up to 370 GHz

A new generation of frequency synthesizers up to 370 GHz is described. The main parts of them are microwave frequency synthesizer covering 11–15 GHz band, effective frequency multipliers-mixers using an opposite pair of planar Shottky diodes and a lock-in loop of a backward-wave oscillator tube covering millimeter and longer part of submillimeter wave bands with tens of milliwatts of output power. The ways of further increase in the operating frequency of such synthesizers are discussed.     

Diode laser heterodyne spectroscopy on the ν1 band of sulfur dioxide

Diode laser heterodyne techniques have been used to obtain the frequencies of 55 ir absorption lines of ³²S¹⁶O₂. From these data and from previous microwave and millimeter wave measurements, new spectroscopic constants for the ν₁ band have been determined. The new constants have been used to predict new optically pumped submillimeter wave emissions.     

填充等离子体的介质同轴波导中的切伦科夫辐射

 利用自洽线性场理论，导出了薄环形相对论电子注通过填充等离子体的介质同轴波导中的注波互作用色散方程，得到了注波互作用产生切伦科夫辐射的同步条件和波增长率。分析了填充等离子体后的波与电子注之间的能量交换及等离子体密度对色散特性、波增长率和注波能量交换的影响。分析结果表明：切伦科夫辐射是由沿介质同轴波导传播的慢波与沿薄环形相对论电子注传播的负能空间电荷波耦合所致，且其耦合强度与电子注的密度成正比；输出频率和波增长率随着填充等离子体密度的增大而提高；保持一定的输出频率，增大电子注的束流可得到高的微波输出功率。     

The development of a diamond switch for RF pulse compressionsystems

The use of a diamond RF switch for super-highpower microwave/millimeter wave generation has been evaluated. An X-band chemical vapor deposition (CVD) diamond window package was theoretically analyzed, designed, and built. Thirty-eight percent of an injected microwave signal with a frequency of 11.424 GHz was reflected from a 100-μm thick, 22-mm-diameter CVD diamond window when activated by a 160-mJ, 266-nm Nd:YAG laser. The details of the CVD diamond window design and experimental results are presented. The results have high application potential for building super-high-power microwave systems     

内开槽矩形波导栅慢波电路高频特性的数值分析

 介绍了用德国CST公司提供的MWS 4.2软件模拟计算色散特性和耦合阻抗的理论方法，对内开槽矩形波导栅结构的高频特性进行了数值模拟。结果表明：在传统矩形波导栅结构的基础上，开槽后的矩形波导栅结构比开槽前的相速更低，用作行波管的慢波结构时，可降低工作电压，工艺上容易实现，而且耦合阻抗均在45 W以上，满足毫米波行波管的要求；在内开槽宽度一定的前提下，槽深、栅间距和栅周期的增大对降低系统相速有利。     

Band structure,group velocity,effective group index and effective phase index of one dimensional plasma photonic crystal

In this present communication, we study the reflection behavior of electromagnetic in one-dimensional photonic crystal of electromagnetic waves in microwave region of electromagnetic spectrum. The Plasma Photonic Crystal structure is composed of alternate layers of thin micro-plasma and dielectric material electromagnetic (EM) spectrum in one-dimensional Plasma Photonic Crystals (PPCs). In order to obtain the characteristic equation (dispersion relation), we have solved the Maxwell scalar wave equation. Beside this we study the anomalous behavior of group velocity and effective index of refraction of PPCs in microwave region. We have adopted Transfer Matrix Method (TMM) for calculating reflectance and dispersion relation of PPCs. In order to calculate the expression for effective refractive index inside the PPCs structure we have used the concept of the group velocity instead of phase velocity.     

Guided surface modes in a hollow slab waveguide with a left-handed material substrate or cover

The structural dispersion characteristics of guided surface modes in a hollow slab waveguide with a left-handed material substrate or cover are investigated. Dispersion relation is derived by using normalized parameters, and universal dispersion curves have been obtained analytically, by solving transcendental dispersion equations in a reverse way. Existence condition, mode degeneracy and other dispersion properties of guided surface modes have been discussed for different ? or μ of three layers for this substrate or cover layer.     

Tunable microwave generation based on a Brillouin fiber ring laser and reflected pump

A simple approach for photonic generation of a tunable microwave signal is proposed and successfully demonstrated. By mixing the output from a single-longitudinal-mode Brillouin fiber ring laser with the reflected laser pump at photodetector, a microwave signal at the Brillouin shift can be obtained. Since the Brillouin shift can be changed by tuning the pump wavelength, tunable microwave can be generated. As a result a microwave signal tunable from 10.39 to 10.67 GHz has been achieved, with linewidth less than 600 KHz.     

Study on BMT Millimeter Wave Dielectric Resonators

The microwave dielectric properties and microstructures of Ba(Mg_1/3Ta_2/3)O₃ (BMT) ceramics were investigated. In order to reduce the evaporation of MgO at high temperature, burying in MgO powders sintered BMT ceramics. The relationship between the composition and Q value of BMT ceramics was discussed. Dielectric resonators using in millimeter wave band have been designed and fabricated. Their attenuations at central resonation frequency (_f) are less than 35dB. Temperature coefficients of resonant frequency are adjustable and less than 2 ppm/°C.     

耦合腔慢波结构冷测特性的计算方法

 对几种用3维MAFIA仿真软件以及利用其准周期边界条件和后处理模块计算耦合腔行波管慢波结构的色散和耦合阻抗等冷测特性的方法进行了讨论，另外还对两种阻抗＿总阻抗和Pierce耦合阻抗的定义进行了充分讨论。考虑到休斯结构耦合腔行波管的电子是与耦合腔慢波结构的负一次谐波发生作用和耦合阻抗应该是电子注截面上的平均值等，指出总阻抗和Pierce耦合阻抗之间相差一个因子，考虑了这个修正因子之后，其结果将更接近实际情况。用这些方法计算耦合腔行波管的冷测特性，得到了与实验冷测值十分接近的结果。     

Dispersion Characteristics of Dielectric Loaded Multiple V-Ridge Waveguide

A new kind of V-ridge waveguide is presented in this paper. The transmission problem is solved by edge element for the first time. The field patterns of the waveguide with single, double and triple V-ridge for different values of dielectric constant have been presented. Variations of the cutoff wavelength, single-mode bandwidth with the ridge dimensions for different values of dielectric constant are investigated in detail. The results will be of practical significance in designing ridge waveguide components in microwave and millimeter wave engineering.     

Optically Controlled Broadband Millimeter Wave Beam-Splitter-Type Coupler

Recently, Laser-controlled four-port beam-splitter-type couplers with photoinduced plasma layer and band-limited coupling characteristics at millimeter wave frequencies have been proposed for use in dielectric and image guides and circuits. In order to achieve a large dynamic range regarding the optical control of the coupling coefficient narrowband destructive interference in the dark state has been used. In this paper an ultra-broadband coupler for applications at millimeter wave band is proposed. This configuration requires waveguides to be transparent for the optical excitation. Numerical examples for the lowest order modes are presented and discussed considering fused quartz for the dielectric strips of the guides and a 50 m GaAs film for the active layer.     

基于偏振稳定双波长保偏光纤光栅激光器的可调谐微波/毫米波产生技术

首次提出了一种基于偏振稳定双波长保偏光纤光栅激光器的可调谐微波/毫米波产生技术, 利用保偏光纤光栅选频产生两个偏振稳定的激光信号, 采用扰偏器确保激光输出的两个正交偏振态功率的一致性, 最后输入高速光电探测器产生微波/毫米波. 通过对保偏光纤光栅施加不同大小的侧向应力, 可以灵活调谐输出的毫米波频率. 实验制作了基于偏振稳定双波长保偏光纤光栅激光器的可调 谐微波/毫米波产生装置, 通过对保偏光纤光栅施加不同的轴向拉力分别产生了20.407 和22.050 GHz的微波信号. 仿真产生了60 GHz的毫米波信号, 并分析该毫米波在光纤无线通信下行链路的传输性能, 结果表明该毫米波作为副载波调制到光波上从中心站传输80 km至基站后经天线发射至用户端, 解调后仍然得到很好的眼图, 充分证明了本方案的优越传输性能.     

基于注入半导体激光器的微波副载波相位调制信号产生

光载无线技术是解决终端超宽带无线通信的重要方法,光信号与微波/毫米波信号的融合处理技术在光-无线的数据格式转换中至关重要.提出了一种基于相位调制信号光注入Fabry-Perot型半导体激光器实现微波副载波相位调制信号产生的方法.光学注入半导体激光器的输出光场会产生一周期(P1)振荡效应, P1振荡产生的边带实现了相位调制信号光的调制分量的放大,被放大的调制分量与注入光载波在激光器腔内拍频形成微波副载波.注入光相位的变化导致新产生的微波副载波相位变化, 实现了注入信号光相位信息转化为微波副载波相位信息.本系统完成1.3 Gb/s, 2.7 Gb/s, 2 Gb/s光相位调制信号到微波副载波相位调制信号的转换,并测量了微波的单边带相位噪声. 通过光电转换和电域混频将还原出的光基带信号与原信号进行逻辑对比,证明了数据信息转换的正确性.     

Theoretical Analysis of the Biological Thermal Effect of Millimeter Waves in Layered-Dielectric-Slabs

The theory is presented for one method of determining the biological thermal effect of millimeter waves in microwave radiometry. It has been studied theoretically that millimeter waves propagation and absorption in a human body. The model is a plane straticulate homogeneous slab of tissues under the irradiance of normal incidence plane wave. It has been discussed by obtaining the electromagnetic field, absorbent power, specific absorption rate, temperature field and their distributions in the human trunk model. Also, the principle of thermal therapeutics of millimeter waves to cancer has been discussed preliminarily.     

Minimal position-velocity uncertainty wave packets in relativistic and non-relativistic quantum mechanics

We consider wave packets of free particles with a general energy-momentum dispersion relation E(p). The spreading of the wave packet is determined by the velocity v=∂_pE. The position-velocity uncertainty relation is saturated by minimal uncertainty wave packets Φ(p)=Aexp(-αE(p)+βp). In addition to the standard minimal Gaussian wave packets corresponding to the non-relativistic dispersion relation E(p)=p²/2m, analytic calculations are presented for the spreading of wave packets with minimal position-velocity uncertainty product for the lattice dispersion relation E(p)=-cos(pa)/ma² as well as for the relativistic dispersion relation . The boost properties of moving relativistic wave packets as well as the propagation of wave packets in an expanding Universe are also discussed.     

A Model for Millimeter Wave Attenuation by Atmospheric Gases in China Area

The earth's atmosphere plays an important role in microwave remote sensing and millimeter wave propagation. In this paper, we study the measurements of the attenuation due to atmospheric gases have been made in China, put forward a empirical model for the atmospheric attenuation of millimeter wave in China area.     

Six‐wave mixing induced by free‐carrier plasma in silicon nanowire waveguides

Nonlinear wave mixing in mesoscopic silicon structures is a fundamental nonlinear process with broad impact and applications. Silicon nanowire waveguides, in particular, have large third‐order Kerr nonlinearity, enabling salient and abundant four‐wave‐mixing dynamics and functionalities. Besides the Kerr effect, in silicon waveguides two‐photon absorption generates high free‐carrier densities, with corresponding fifth‐order nonlinearity in the forms of free‐carrier dispersion and free‐carrier absorption. However, whether these fifth‐order free‐carrier nonlinear effects can lead to six‐wave‐mixing dynamics still remains an open question until now. Here we report the demonstration of free‐carrier‐induced six‐wave mixing in silicon nanowires. Unique features, including inverse detuning dependence of six‐wave‐mixing efficiency and its higher sensitivity to pump power, are originally observed and verified by analytical prediction and numerical modeling. Additionally, asymmetric sideband generation is observed for different laser detunings, resulting from the phase‐sensitive interactions between free‐carrier six‐wave‐mixing and Kerr four‐wave‐mixing dynamics. These discoveries provide a new path for nonlinear multi‐wave interactions in nanoscale platforms.