端面附近缺陷在掺铒光纤中引起的振荡

实验研究了由于掺铒光纤（ＥＤＦ）端面附近存在缺陷引起光反射而导致的振荡，这种振荡发生在掺铒光纤放大的自发辐射（ＡＳＥ）谱的峰值波长处，由于较长掺铒光纤的放大的自发辐射谱近似于其小信号增益谱，因此也可以认为发生在掺铒光纤放大器（ＥＤＦＡ）的最大增益处，对其增益产生不良影响。     

大间隙速调管放大器中二极管寄生振荡及其抑制

利用三维高频电磁软件和三维粒子模拟软件,对大间隙强流相对论速调管放大器中的二极管寄生振荡机制进行了模拟研究,发现由于6.18 GHz频点的高阶TM31模式在二极管区截止,故形成了谐振腔结构,进而对电子束产生强烈的调制,干扰了速调管的正常工作。结合模拟结果,提出了优化和改进措施。粒子模拟结果表明:二极管结构改进后,寄生振荡消失,束流调制效果得到显著改善。     

Current-mode current-tunable four-phase quadrature oscillator

A current-mode current-tunable four-phase quadrature oscillator (QO) using current differencing transconductance amplifiers (CDTA) is presented in this paper. The proposed QO consists of three CDTAs and two grounded capacitors, which can provide four quadrature current outputs at high impedance nodes. The proposed QO has the advantages of electronically and independently control of oscillation condition and oscillation frequency. Moreover, the active and passive sensitivities of the QO are low. Cadence IC Design Tools 5.1.41 post-layout simulation results are included to confirm the theory.     

Toward a theory of stability of resonant amplifiers with distributed interaction

It is shown that stochastic instability can arise in the amplification of a real multifrequency signal in resonant amplifiers with distributed interaction that are stable under the influence of a harmonic oscillation. Necessary conditions for the onset of chaos are determined analytically by means of running Lyapunov exponents. Specific results of numerical and analytic studies of the stability or orotron amplifiers are presented.Radio-Astronomy Institute, Academy of Sciences of Ukraine. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 35, Nos, 3, 4, pp. 285–294, March–April, 1992.     

板条激光放大器中寄生振荡的研究

寄生振荡的存在使得放大器在信号光到达之前消耗了大量的反转粒子数,降低了放大器的激光增益和储能效率,严重地影响了激光放大器的性能,尤其对高功率激光放大器。在理论分析和实验研究的基础上,以Nd∶YAG晶体板条为例,用8条半导体激光阵列对晶体进行双侧抽运,研究了高功率激光放大器的寄生振荡现象,分析了板条晶体寄生振荡产生的原因,并详细比较了晶体在不同的抽运功率和表面处理下的放大效果,得到了2倍的单程放大,当输入能量为140 mJ时,获得了278 mJ的激光输出。     

Analysis of the transmission,reflection and noise properties of distributed feedback laser amplifiers

The transmission and reflection characteristics of distributed feedback (DFB) laser amplifiers are determined. Near the oscillation threshold of a DFB mode a relation is found between gain and bandwidth which can be used to obtain an expression for an intrinsic noise linewidth that is analogous to that found by Schawlow and Townes.     

BEPC储存环束流振荡频率测量

在加速器的运行和机器研究过程中,需要经常对束流振荡频率进行测量.BEPC储存环束流振荡频率测量系统包括一台频谱仪,两个条形电极装置,两个电压放大器和一个束流振荡检测器.本文介绍了经过改进的BEPC储存环束流振荡频率测量系统.     

Demonstrationsversuche zur Parameterverstärkung

Parametric amplifiers have been developed during the last years to get a low noise amplification of weak electromagnetic signals. This paper describes simple experiments to demonstrate the basic principles by an electrical arrangement with variable capacity and by a mechanical set-up with capillary-gravity waves on a water surface. An explanation of the parametric oscillation and amplification is given in connection with these experiments.     

忆阻混沌电路的分析与实现

具有记忆功能的忆阻器是除电阻器、电容器和电感器之外的第四种基本二端电路元件. 提出了由φ-q平面上的一条三次单调上升的非线性曲线来确定的光滑磁控忆阻器,它有着斜"8"字形的类紧磁滞回线的伏安特性曲线. 采用此忆阻器和负电导构成的有源忆阻器替换蔡氏混沌电路中的蔡氏二极管,导出了一个基于忆阻器的混沌振荡电路. 此外,利用常规的运算放大器和乘法器等元器件给出了有源忆阻器的等效电路实现形式. 理论分析、数值仿真和电路仿真结果一致,均表明忆阻混沌电路的动力学行为依赖于忆阻器的初始状态,在不同初始状态下存在混沌振荡、周期振荡或稳定的汇等不同的运行轨道. 关键词： 忆阻器 混沌电路 初始状态 等效电路     

Gain and bandwidth of the gyro-TWT and CARM amplifiers

Issues concerning the interpretation of gain and bandwidth from the dispersion relation are examined for the gyrotron traveling wave tube (gyro-TWT) and the cyclotron auto-resonance maser (CARM) amplifiers. A general method for the determination of the critical current for oscillation is illustrated. Despite the broad bandwidth predicted for the CARM amplifier by the commonly employed dispersion relation, it is seen in particle simulation that single-particle interaction. Rather than collective amplification, prevails over much of the band. Reasons for the discrepancy are analyzed     

Hysteresis phenomena of the parametric oscillations

Parametric amplifiers have been described which are based on the magnetoelastic interaction of the oscillation of a torsional pendulum and an electrical circuit. When the inverting amplifier is driven overcritically, selfexcitation of the pendulum occurs. Because of the nonlinear magnetoelastic damping, it may happen that the pendulum oscillates only in a certain range of amplitudes. Varying the intensity of the magnetic pumping field, hysteresis effects of the oscillation appear which can be explained by damping measurements. Oscillation measurements of other authors can now be understood.The author thanks Prof. Dr. G.Dietz for many valuable remarks to this paper and Prof. Dr. H.Happ in whose institute the experiments were performed.     

Stable 1 MW, third-harmonic gyro-TWT amplifier

The concept that the relatively weak harmonic gyro-TWT interactions allow high values of electron beam current for stable operation has been extended to design two extremely high power, 140 GHz, third-harmonic TE₃₁ gyro-TWT amplifiers. One device is driven by an axis-encircling electron beam from a cusp gun and the other employs a magnetron injection gun (MIG). These devices are predicted by a self-consistent nonlinear numerical simulation code to yield, respectively, output powers of 775 kW and 937 kW with 15.5% and 18.7% efficiency, saturated gains of 27 dB and 30 dB, and saturated bandwidths of % and 6.5%. The stability of the amplifiers is ensured by limiting the length of the interaction section(s) to the shortest starting oscillation length as determined by linear theory. The cylindrical waveguide circuits of both amplifiers have been sliced to suppress modes without a threefold azimuthal symmetry. The amplifier utilizing a MIG yields superior performance because the dominant competing interaction is minimized for the choice of the beam's guiding center radius. The advantages as well as limitations of this approach for high power microwave generation are also addressed     

Slow and fast light in quantum dot based semiconductor optical amplifiers

Recent progress in the field of quantum dot/dash based semiconductor optical amplifiers (SOAs) for slow and fast light is discussed. Room temperature fast light has been obtained in InAs/InP QDash based SOAs by means of coherent population oscillation and four wave mixing (FWM) effects. Typical optical delays amount to 55 ps at 2 GHz. Growth optimization of the QDashes allowed us to achieve high modal gain, leading to very similar performances, e.g. gain and FWM efficiency, to those of a bulk SOA. A novel approach based on linear spectrograms is also introduced to measure the phase shift induced by wave mixing in an SOA.     

流动激光非稳定振荡器,放大器基本特性比较分析

根据流动激光腔中流动的非平衡混合气体各能态布居数和强辐射相互作用达到稳定振荡的过程和相应的三维分布状态的数值模拟计算结果,发展了相应的振荡器和放大器基本特性的简化计算公式.其计算结果与多种器件、多种腔体的实测结果相符.具体比较分析了流动激光振荡器与放大器的基本特性,得到一些基本原则,为相应器件的优化设计提供理论依据.     

LD泵浦光纤激光放大器实现13 kW高光束质量输出

光纤耦合半导体激光器（LD）泵浦的光纤激光放大器具有体积小、功质比高、稳定性好等优点,在工业加工和军事国防等诸多领域都有着广泛且重要的应用。然而,受限于器件制作工艺水平及光纤中的受激拉曼效应和模式不稳定效应,LD泵浦的光纤激光放大器难以同时实现高功率及高亮度激光输出。为实现更高功率、更高亮度的光纤激光输出,需要结合现有的器件工艺水平并同时实现对放大器中的受激拉曼散射效应和模式不稳定效应的有效抑制。报道了基于单位自研大模场增益光纤成功实现13 kW功率、高光束质量激光输出。激光器采用主振荡功率放大结构,放大级采用单后向981 nm泵浦自研大模场增益光纤,在总泵浦功率为15 kW时,输出功率达到12.94 kW,光束质量M2因子约为2.85。通过进一步优化器件性能及光纤模式控制,有望实现更高功率、更高亮度的光纤激光输出。     

Ultra-high-frequency chaos in a time-delay electronic device with band-limited feedback

We report an experimental study of ultra-high-frequency chaotic dynamics generated in a delay-dynamical electronic device. It consists of a transistor-based nonlinearity, commercially-available amplifiers, and a transmission-line for feedback. The feedback is band-limited, allowing tuning of the characteristic time-scales of both the periodic and high-dimensional chaotic oscillations that can be generated with the device. As an example, periodic oscillations ranging from 48 to 913 MHz are demonstrated. We develop a model and use it to compare the experimentally observed Hopf bifurcation of the steady-state to existing theory [Illing and Gauthier, Physica D 210, 180 (2005)]. We find good quantitative agreement of the predicted and the measured bifurcation threshold, bifurcation type and oscillation frequency. Numerical integration of the model yields quasiperiodic and high dimensional chaotic solutions (Lyapunov dimension approximately 13), which match qualitatively the observed device dynamics.     

高增益相对论速调管放大器相位特性的模拟与实验研究

为实现高功率微波的相干功率合成, 开展了S波段高增益相对论速调管放大器输出微波相位特性的粒子模拟和实验研究, 粒子模拟与实验结果均表明电子回流是影响输出微波相位特性的主要因素. 在有效控制电子回流的情况下, 实验实现输出微波相位抖动小于± 10°, 锁相时间达90 ns. 以此计算, 若相位抖动在± 10° 内满足均匀分布, 十台该高增益相对论速调管放大器的功率合成效率将大于99%.     

大能量全固态再生放大器研究进展

在固体激光脉冲放大器中,再生放大器具有增益高、光束质量好以及结构简单等优点,得到了广泛的关注和应用。经过几十年的不断发展,再生放大器已经能够实现数百mJ脉冲能量以及数kW均值功率的稳定输出。增益材料特性、腔型结构、泵浦能力、热效应、元器件性能等诸多方面都会影响再生放大器的输出特性,其中增益材料特性是最根本的因素。由于特性不同,基于不同增益材料体系的再生放大器在结构和功能上都会有较大的差异。基于不同的材料体系,介绍了各类体系下的再生放大器在发展过程中遇到的关键共性问题,以及几类典型的再生放大器及其特点。讨论了再生放大器未来的发展趋势。     

Principal modes in fiber amplifiers

The dynamics of the state of polarization in multimode fiber amplifiers is presented. The experimental results reveal that although the state of polarizations at the output can vary over a large range when changing the temperatures of the fiber amplifiers, the variations are significantly reduced when resorting to the principal states of polarization in single-mode fiber amplifiers and principal modes in multimode fiber amplifiers.     

Spectral hole burning measurement thulium-doped fiber amplifiers

An accurate technique was implemented to measure spectral hole burning in rare-earth amplifiers at room temperature, showing that thulium-doped fiber amplifiers exhibit hole depths four times lower than those of C -band erbium-doped fiber amplifiers.