Pressed waves: Surface-bulk electromagnetic eigenmodes of metal surface

We discovered that in the infrared in conditions of surface electromagnetic waves (SEW) excitiation on finite grating coupler a wave packet consisted of evanescent and bulk waves is generated. This wave packet is conventionally called “pressed wave” by us. The wave packet is demonstrated to satisfy Maxwell equations and boundary conditions on smooth part of a surface outside the grating coupler. Thus the wave packet is a new type of surface-bulk electro-magnetic eigenmodes of metal surface.     

Effects of resonance asymmetries on the conversion of laser phasenoise into amplitude noise in fiber optic ring-resonators

Fiber optic ring resonators constructed from a continuous strand of single-mode fiber and an evanescent wave directional coupler can show an asymmetric resonance characteristic due to coupler losses. The effects of this asymmetry on the conversion of laser phase noise into amplitude noise is discussed. A mathematical model, valid for highly coherent signals, is used to analyze even high-finesse ring resonators with a minimum of CPU time     

Microstrip directional coupler with flat coupling and high isolation

Based on the open-circuited slotline to realise capacitive compensation, a microstrip directional coupler with high isolation is investigated. Meanwhile, by adding external matching networks at the input/output ports, bandwidth is enhanced and a flat coupling is obtained. Centred at 2.4 GHz, a 3 dB directional coupler is designed, fabricated and examined. Both simulated results and measured data are presented, and good agreement between them is observed     

一种基于微带均衡器结构的定向耦合器的研究

提出了一种新颖的基于微带均衡器结构的宽频带高定向性微带线定向耦合器,并对该结构进行了理论分析、设计、制作和测量。该结构的新颖之处是通过对耦合度随频率的变化曲线进行均衡得到宽频带特性。该结构采用三电容补偿的微带线定向耦合器结构,并通过在耦合端集成微带均衡器结构实现。测量结果显示,该结构在2.5～3.5GHz工作频带内的耦合度随频率的变化范围约为1dB,隔离度低于-34dB,较之传统结构的微带线定向耦合器均有大幅的提高。测量结果很好地验证了设计方法的正确性。     

等离子体柱阵列应用于目标隐身的可行性分析

设想了一种等离子体柱阵列技术,并利用CST电磁仿真软件对等离子体柱阵列覆盖金属平板的情况进行了仿真,分析了等离子体柱阵列在2～8GHz频段内对金属平板的散射衰减,并与金属平板覆盖等离子体层的散射特性进行了对比。结果表明,对于TE波,等离子体柱阵列对金属板的散射衰减与等离子体层对金属板的散射衰减相差不大;对于TM波,柱阵列的散射衰减要大于等离子体层的散射衰减,因此,利用等离子体柱阵列覆盖目标来实现目标隐身是完全可行的。     

A novel electromagnetic bandgap metal plate for parallel plate modesuppression in shielded structures

A novel type of metal plate structure incorporated with electromagnetic bandgap holes for use as metal shields with the capability of suppressing the propagation of unwanted parallel plate mode has been proposed. The holes can be of any shape and the periods of those holes should be selected to half the guided wavelength of the parallel plate mode at a desired center frequency of suppression. To show the validity of the proposal, inert electromagnetic wave simulation, results of a shielded microstrip structure designed for application in the 76 GHz frequency band are demonstrated. Experiments are performed with a prototype designed in the 10 GHz frequency band and parallel plate mode suppression is verified successfully with the excellent agreement between experimental and simulation results     

210-320 GHz Multi-Hole Directional Coupler Design and Measurement

The design of a 210-320 GHz multi-hole directional coupler is described. The coupler performance is measured with a millimeter vector analyser across the band 205-350 GHz and compared with simulations. The coupler consists of two waveguides whose broad walls are separated by a thin metal sheet with an array of circular holes according to a Chebyshev distribution of couplings. The coupling is 11 dB with a typical variation of ± 2dB across the WR3 band and the isolation is more than 25 dB.     

In-line single-mode wavelength division multiplexer/demultiplexer

A single-mode fibre optic wavelength division multiplexer/demultiplexer at 1.32 ?m and 1.55 ?m, constructed from a fused evanescent wave coupler, is described. This device has an insertion loss of less than 0.05 dB and a wavelength isolation of 16 dB at 1.32 ?m and 18 dB at 1.55 ?m.     

模式抑制器在Ku波段在线测量系统中的应用

在Ku波段低磁场相对论返波管中,由于阴极发射的角向不均匀性,产生的微波除了TM01模,还有主模TE11等其他微波模式。由于目前设计的圆波导耦合器只能测量TM01模式功率,其他微波模式存在会导致在线微波波形异常,给在线测量带来困难。本文设计了一种模式抑制器,其结构由5个腔组成。通过数值模拟和实测结果得出：TM01模在频率14.8~15 GHz衰减小于0.1 dB,而对其他模式,如主模TE11模式微波能够全反射。模式抑制器置于相对论返波振荡器(RBWO)与圆波导耦合器之间,实验观察在线输出微波与辐射场波形一致,微波功率符合较好。     

Effective power input into quasi-optical cavity with travelling wave

The open three-mirror cavity with a travelling wave, and reflecting diffraction grating on one mirror as a coupler was excited by a wave beam at the frequency 140 GHz. The investigation showed the wave power in the cavity to be about 30 times higher than that at the cavity entrance.     

渐逝波耦合半导体量子点光纤放大器

基于半导体量子点的特性,结合光纤渐逝波耦合器,提出了一种新型的光纤放大器件,它将以溶液形式的硫化铅(PbS)半导体量子点材料沉积于耦合器熔锥区,信号光和抽运光通过渐逝波共同与半导体量子点材料相互作用,实现光的放大作用。PbS量子点材料是采用工艺容易控制的反胶束法制备的,通过透射电镜(TEM)测量得到其粒子尺寸小于10 nm。利用工作波长为980 nm,功率为30 mW的半导体激光器抽运光源对该光纤放大器抽运,在1310 nm波段得到了大于4 dB的增益,这是半导体量子点尺寸效应引起的光谱蓝移现象的体现。因此,这种有源区短、器件结构紧凑的光纤放大器在高速、宽带光纤接入等领域具有重要的实际意义和应用价值。     

Optically pumped submillimeter wave laser with Michelson interferometric output coupling

We report the performance of an optically pumped submillimeter wave laser incorporating a Michelson interferometric output coupler consisting of three mirrors and a metal mesh beam splitter. 10.33-μm radiation from a pulsed CO2TEA laser was used to pump NH3for generating submillimeter wave radiation at 281 μm. Optimum output was achieved by coupling out 59 percent of the radiation per pass using a 250-lines-per-inch mesh at a phase angle of 49°. The submillimeter laser operated in the TEM00mode and was tunable over its free spectral range of about 350 MHz. Translation of the coupling mirror allowed optimization of laser output.     

Engineering Design Method of Energy Coupler and Impedance Transformer for Millimeter Wave Tubes

The engineering design method of heliz-waveguide and rectangular coupled cavitiy-waveguide energy coupler employed in millimeter wave tubes is described. Experiments show that, the former has broadband matching character )VSWR is less than 2 at 26 - 40GHz). And the later has small reflection (VSWR is less than 1.5 at 34-37.5 GHz). Optimum design method of multi-section and linear taper waveguide impedance transformer is also given in this paper. These impedance transformers can operate at wide frequency range in microwave and millimeter wave band. The design method and examples of couplers and impedance transformers can be referred for tube designers.     

Technique for velocity-matched traveling-wave electroopticmodulator in AlGaAs/GaAs

A design for a velocity-matched traveling-wave directional-coupler intensity modulator in AlGaAs/GaAs is proposed. The structure utilizes a thin coating of Ta₂O₅ on the top of the modulator/electrode structure in order to achieve velocity matching between the optical wave and microwave signal. The film does not significantly affect the optical properties or voltage requirements of the modulator. The optical and RF characteristics of the modulator are analyzed using the effective-index and finite-difference methods. The optical bandwidth is calculated numerically, taking into account both the anticipated velocity mismatches due to fabrication tolerances and the calculated frequency-dependent microwave losses. The predicted small-signal bandwidth of a 3 mm long direction coupler biased at a null point is greater than 45 GHz, and exceeds 100 GHz (~50 GHz electrical bandwidth) when the coupler is biased in the linear region. This device is designed to operate at 830 nm with a maximum modulation voltage of 5 V. The figure of merit of the proposed device is therefore at least 10 GHz/V when an electrical bandwidth of 50 GHz is used     

金属网反射面金属丝接触电流仿真分析

基于为了更好的对金属网反射面进行评估的目的,采用平面周期结构的分析方法对金属网反射面金属丝接触电流进行分析,通过Ansoft HFSS软件仿真,得到了金属丝接触电流随金属网网孔、接触状态和馈源信号入射角度的变化规律。得出在选用金属网反射面时网孔不宜过大（如在2 GHz时网孔不大于4 mm）、金属丝与金属丝之间的接触半径不宜处于2-3μm之间的结论,对研究金属网反射面天线无源互调特性及设计金属网反射面天线具有一定的理论指导意义。     

The characteristics and energy coupler of the single row comb circuit for MMW BWO's

In comparision with other slow wave systems, the comb type circuit exists some superior features, such as more large size, easy manufacture and good heat dissipation, so it is suitably used in millimeter wave BWO's. The dispersion equation of the single row comb circuit has been solved. The dispension and impedance as a function of the dimensions of the comb circuit are disscused. The energy coupler is developed for the single row comb circuit. The measurment shows that a broadband match with a VSWR of better than 2.0 is obtained over frequency range from 26.5 to 40 GHz for the coupler.     

串联电容式RF-MEMS开关的研制

研制了一种高电容率的电容式RF-MEMS开关.与普通电容式开关设计不同的是,在CPW信号线上的绝缘层上表面覆盖了一层金属板,使开关在down-state时,上电极能与介质膜紧密接触,而在up-state时,金属板分别与上电极及信号线平面构成一组串联电容,大大降低了Cup值,从而提高了开关的电容率.与相同条件制得的普通电容式开关相比,其电容率要高出一个数量级,达到1000以上.由测试可知,所设计的串联电容式开关其隔离度在8GHz时可达42dB,明显优于普通电容式开关.     

Effects of normal mode loss in dielectric waveguide directional couplers and interferometers

Theoretical arguments and experimental evidence are presented to show that the two fundamental normal modes of a coupled waveguide structure have different attenuations in traversing such a structure. The effects of this phenomenon on evanescent wave directional couplers and interferometers are derived. Parasitic effects in Mach-Zehnder and Sagnac interferometers utilizing directional couplers are described. An asymmetric output for the recently demonstrated all-single-mode fiber resonator is predicted and compared to experimental results. Some qualitative results are presented for integrated optic directional coupler switches.     

电容式微波功率检测系统的灵敏度特性研究

为了提高电容式微波功率检测系统的综合性能,首先建立了MEMS悬臂梁的力学解析模型,研究了MEMS悬臂梁在静电力与弹性力综合作用下的运动规律,并建立了灵敏度的解析模型。研究结果表明,灵敏度主要受悬臂梁至下拉极板的初始间距、梁板长度影响。其中,灵敏度与间距成反相关关系,与梁板长度成正相关关系。在34~36 GHz的Ka波段内,根据力学解析模型和灵敏度模型,灵敏度的仿真结果分别为4.4 fF/W @34 GHz、4.1 fF/W @35 GHz、3.7 fF/W @36 GHz,实验测试结果分别为5.0 fF/W @34 GHz、4.5 fF/W @35 GHz、4.0 fF/W @36 GHz。灵敏度的仿真结果与测试结果比较吻合,这对改善电容式微波功率检测系统的综合性能具有一定的指导意义。     

A new analytic design technique for two- and three-way warped modecombine directional couplers

An analytic technique of designing ultra-wideband warped-mode two way and three-way microwave directional couplers is presented. With this matrix method it is possible to design couplers for any level of coupling by choosing a warping angle appropriate to the desired output amplitudes. The design technique involves obtaining a wave propagation matrix in analytical form as a function of the taper parameter, which in turn is a function of distance along the coupler length. The line parameters and the forward scattering matrix are then determined from the wave propagation matrix at any distance from the beginning of the coupler. The method is demonstrated for couplers using microstrip coupled comblines. The computed and the measured performances of a two-way and a three-way microstrip combline are presented for equal power splitting. These couplers were found to work between 1.5 and 8.5 GHz