Progress in Solid-State Microwave Power Sources

Recent progress in the following areas is reviewed: high-power UHF and microwave transistors, high-power microwave transistor-oscillator multipliers and transistor-amplifier multipliers, high-power transistor-driven harmonic-generator chains, Gunn-type oscillators, and avalanche diode oscillators.     

2~5 μm中红外飞秒光学参量振荡器研究进展（特邀）

自1994年首次利用克尔透镜锁模钛宝石激光器泵浦RTA光学参量振荡器实现中红外飞秒激光输出以来,在这20多年的时间内,随着高功率近红外泵浦源与各种优质非线性晶体的不断涌现,中红外飞秒光学参量振荡器在平均功率、脉冲宽度、调谐范围等方面都取得了长足的发展,为基础科学研究、生物医疗以及国防安全等领域提供了多样化的应用工具。文中将2~5 μm中红外飞秒光学参量振荡器分为波长可调谐输出型与宽光谱输出型两类,分别重点就这两类中红外飞秒光学参量振荡器的国内外研究进展进行综述,最后对进一步发展趋势进行了展望。高功率、高光束质量中红外飞秒光学参量振荡器和大能量中红外飞秒光学参量振荡器是其中两个重要的发展方向。     

High-power 1-GHz coplanar Gunn-effect oscillators

High peak pulsed output power (up to 100 watts), co-planar, L-band (1 GHz), epitaxial-layer Gunn oscillators are described. Particular emphasis has been given to minimizing surface damage and to effective heat dissipation. These high-power oscillators have been used in both coaxial and stripline circuits. The latter are adaptable to integrated circuitry.     

High-Power 1-GHz Coplanar Gunn-Effect Oscillators

High peak pulsed output power (up to 100 watts), coplanar, L-band (1 GHz), epitaxial-layer Gunn oscillators are described. Particular emphasis has been given to minimizing surface damage and to effective heat dissipation. These high-power oscillators have been used in both coaxial and stripline circuits. The latter are adaptable to integrated circuitry.     

Injected signal characteristics of high-power avalanche diode oscillators

Efficient injection locking results and other injected signal characteristics of high-power avalanche diode oscillators are presented. An injection locking figure of merit as high as 0.145 has been obtained.     

High-power c.w. transferred-electron oscillators

C.W. operation of high-power transferred-electron oscillators (t.e.o.s) is described. A maximum power output of 0.78 W at 8.7 GHz with an efficiency of 2.5% was obtained. This is believed to be the highest c.w. power output reported to date for a single t.e.o. in this frequency range. This high-power output is attributed to improved fabrication technology leading to a thermal resistance of only 8 deg C/W for a 0.015×0.015 in chip.     

Surface High-Energy Laser

We describe a design strategy for high-power solid-state laser oscillators using local correction of thermally induced optical distortion. This offers a potential for scaling lowest order Gaussian mode solid-state laser oscillators directly to high average power, e.g. >100 kW, while using a relatively simple near confocal ring resonator. The waste heat is necessarily produced in the gain region; however, the design strategy facilitates scaling by allowing the laser oscillator to function as though the waste heat was produced in a surface region external to the gain medium.     

Maximum power obtainable in a nonlinear system

This paper presents a new condition to derive a maximum output power from a generator with a nonlinear output conductance to a nonlinear load. This condition is satisfied with a formula that an output differential conductance is equal to the load conductance. This formula would be quite useful for a design of high-power amplifiers and oscillators.     

Six-Port Interferometric Technique for Accurate $W$ -Band Phase-Noise Measurements

An innovative six-port (SP) phase-noise measurement technique for millimeter-wave high-power sources is proposed in this paper. Simulation results using a 94-GHz rectangular waveguide SP circuit model validates the measurement principle for both millimeter-wave oscillators and amplifiers. Phase-noise measurement results of a 100-W extended interaction Klystron amplifier are presented and discussed. Compared to conventional methods, this new method allows accurate low-cost phase-noise measurements.     

国际热核聚变装置用回旋管的现状及技术分析

回旋管是一种具有重要发展前景的高功率毫米波和太赫兹源.本文简要介绍了回旋振荡管的结构和基本原理,并且评述了国际热核聚变装置中所用110,140和170 GHz回旋振荡管的发展现况和趋势.同时指出了回旋振荡管发展中存在的关键问题并给出了可能解决的技术途径.     

Microwave power combination using a bifurcated waveguide and areflecting plate

The coupling circuit is constructed of a bifurcated rectangular waveguide which is especially suitable for high-power combination. In this circuit, there is a thin conductor plate perpendicular to the E plane which acts as a reflector only for higher modes, so that the reflected wave is injected back into oscillators for mutual synchronization. Both analytical and experimental results show that a maximum power-combining efficiency near 100% is achievable     

Operation of transferred-electron oscillators in the ridge-waveguide circuit

Operation of high-power X and K. band transferred-electron oscillators (t.e.o.s) in waveguide circuits is described. An increase in c.w. efficiency from 2.5 to 3.5% by decreasing the impedance of the waveguide circuit is reported. Output powers as high as 1.0 W at 10 GHz with 2.5% efficiency and 500 mW at 20 GHz with 3% efficiency were obtained in a ridge-waveguide circuit.     

Millimeter-Wave Pulsed IMPATT Sources

High-power millimeter-wave pulsed MPATT sources have found a variety of applications as solid-state transmitters in RADAR applications. These applications have been greatly enhanced by the rapidly advancing millimeter-wave technology of which the high-power pulsed IMPATT source is a key element. In this paper the unique IMPATT properties which affect the oscillator spectral purity and coherency are reviewed. Some key considerations for the device design and system applications of the pulsed oscillators are discussed along with the state of the art, recent progress, and future trend.     

Novel Applications of Millimeter and Submillimeter Wave Gyro-Devices

The possible applications of high-power millimeter (mm) and submillimeter waves from gyro-devices span a wide range of technologies. The plasma physics community has already taken advantage of recent advances in applying high-power micro- and mm-waves generated by gyrotron oscillators in the areas of RF-plasma production, heating, noninductive current drive, plasma stabilization and active plasma diagnostics for magnetic confinement thermonuclear fusion research, such as lower hybrid current drive (8 GHz), electron cyclotron resonance heating (ECRH) (28–170 GHz), electron cyclotron current drive (ECCD), collective Thomson scattering and heat-wave propagation experiments. Other important applications of gyrotrons are electron cyclotron resonance (ECR) discharges for generation of multi-charged ions and soft X-rays, as well as industrial materials processing and plasma chemistry. Submillimeter wave gyrotrons are employed in high-frequency broadband electron paramagnetic resonance (EPR) spectroscopy. Future applications which await the development of novel high-power gyro-amplifiers include high resolution radar ranging and imaging in atmospheric and planetary science as well as deep-space and specialized satellite communications and RF drivers for next-generation high-gradient linear accelerators (supercolliders). The present paper reviews the state-of-the-art and future prospects of these recent applications of gyro-devices.     

Recent advances in device processing and packaging of high-power pulsed GaAs double-drift IMPATT's at X-band

High-power multimesa GaAs hybrid double-drift IMPATT's have been developed for pulsed operation at X-band. The diodes are fabricated from GaAs material grown by a novel "infinite" solution liquid phase epitaxial process. The use of specialized rapid thermal processing and packaging techniques has enabled the fabrication of high-power IMPATT oscillators that have delivered peak output powers of over 40 W with 20-percent efficiency under pulsed RF operation at X-band frequencies. The diodes are constructed with an integral heat sink and bounded with a Au-Sn eutectic solder in a microwave package.     

Effects of small-scale phase perturbations on laser oscillator beam quality

A simplified analysis is presented for predicting the effects of small-scale intracavity phase perturbations or scattering centers on the power output and beam quality of high-power laser oscillators. The small-scale perturbations are viewed as scattering energy from the unperturbed lowest order transverse mode of the cavity into numerous higher order transverse modes. These modes are, unfortunately, then regeneratively amplified within the laser cavity. This produces only a small change in the effective output coupling and the total power output from the perturbed laser cavity, but causes a serious deterioration in the far-field brightness and on-axis intensity of the output beam.     

Radiation from planar resonators

Power radiated from microstrip-based resonators is calculated by integration of a Green's function with assumed currents, a method that is convenient and is thought to be more accurate than previous methods used in calculations of radiation Q. Resonators consisting of two coupled microstrips excited in the odd mode are found to radiate much less than conventional single-microstrip resonators or U-shaped hairpin resonators. However, when the resonator is loaded by a semiconductor device, as in an oscillator, radiation increases. Asymmetries in the resonators, arising from output coupling or fabrication errors, introduce even-symmetric currents which radiate much more strongly than odd-mode currents. The effects of such asymmetries on radiated power are estimated. On the basis of these findings, a convenient geometry for high-power planar oscillators with low radiation is proposed     

Nonlinear Design Technique for High-Power Switching-Mode Oscillators

A simple nonlinear technique for the design of high-efficiency and high-power switching-mode oscillators is presented. It combines existing quasi-nonlinear methods and the use of an auxiliary generator (AG) in harmonic balance. The AG enables the oscillator optimization to achieve high output power and dc-to-RF conversion efficiency without affecting the oscillation frequency. It also imposes a sufficient drive on the transistor to enable the switching-mode operation with high efficiency. Using this AG, constant-power and constant-efficiency contour plots are traced in order to determine the optimum element values. The oscillation startup condition and the steady-state stability are analyzed with the pole-zero identification technique. The influence of the gate bias on the output power, efficiency, and stability is also investigated. A class-E oscillator is demonstrated using the proposed technique. The oscillator exhibits 75 W with 67% efficiency at 410 MHz.     

高功率掺镱光纤振荡器:研究现状与发展趋势

近年来,高功率掺镱光纤振荡器的输出功率和光束质量不断提升,在工业、科研等领域得到了越来越广泛的应用。目前,多模掺镱光纤振荡器的输出功率已经突破17.5kW,近单模光纤振荡器输出功率已经突破8kW。本文对掺镱光纤振荡器在科研和工业领域的研究现状进行详细介绍,分析掺镱光纤振荡器未来的发展趋势;对进一步提升掺镱光纤振荡器功率和光束质量的各项关键技术进行剖析,给出了万瓦级近单模高功率掺镱光纤振荡器的技术方案,以期为更高功率光纤振荡器的发展提供技术参考。