Pulse-time modulation of mutually coupled arrays of oscillators

This paper specifies the coupling parameters for multioscillator arrays (2" in number) such that nondegenerate symmetric and antisymmetric states may be sequentially accessed by electronic control of the coupling parameters. A requirement of this coupling configuration is that, when mutually locked, the oscillator amplitudes are identical to one another. Thus, when the oscillator signals are combined with a series of magic-T's, the output power is the sum of the oscillator powers in the array minus some small loss in the coupling circuit for the symmetric state and zero for the antisymmetric state. Switching from one state to the other is accomplished by control of the feedback phase delay between oscillators. Ideal oscillator cases are analyzed for two, four, and higher numbers of oscillators by induction. By this electronic-mode control of mutually locked oscillators, we have been able to generate pulse-time modulation (PTM) signals which are useful for communication systems. We describe some results of an X-band PTM signal generator     

Stabilization and modulation of laser oscillators by internal time-varying perturbation

The paper reviews the application of internal time-varying perturbation to the problem of laser mode control and stabilization. The spectral characteristics and time domain behavior obtained by means of phase type and loss type perturbations are considered. Two techniques which allow the attainment of high single frequency output powers from normally multimode lasers are described. A method for the absolute frequency stabilization of an FM laser is considered, and a brief discussion of an efficient method of internal modulation, termed coupling modulation, is given.     

Hybrid-tee coupled oscillators

When two oscillators are coupled by a hybrid tee, if properly adjusted, combined power is greater than the sum of individual maximum power. For example, at 7 GHz, when two reflex klystrons, of 1.4 W and 1.2 W respectively, are combined, 3.4 W output is produced.     

Frequency modulation characteristics of coupled stripe laser diode array

Time-dependent changes in the cavity resonance frequency were measured in a ten-element gain-guided coupled stripe array using a new technique based on injection locking. Sensitivity of the frequency to changes in the array current was 0.7 GHz/mA at dc and 0.04 GHz/mA for 1.0 MHz sine-wave modulation. The current-to-frequency modulation transfer function for the array was determined, and it was concluded that the transition from thermal to carrier-induced frequency modulation occurs in the region between 10⁵and 10⁶Hz.     

Field-induced coupled quantum-well oscillators

A study of field-induced coupled quantum-well oscillators due to the interwell coherent oscillation is presented. The evolution of an electron wave packet in an asymmetric coupled quantum-well structure is described by the application of the time-development operator of the time-dependent Schrodinger equation. By adjusting the applied field, various resonant conditions giving rise to different oscillation frequencies can be obtained in a single device. Direct frequency tuning, amplitude variation, and dipole matrix element due to the external field are also investigated     

Injection locking of oscillators

An oscillator can be locked in frequency by an external signal which is injected into the oscillator. In the oscillator model developed by Adler [1], the mechanism of the locking process depends upon the following. 1) The initial frequency difference between the oscillator and external signals. 2) The relative amplitude between the injected and the oscillator signals. 3) The circuit parameters. There are cases when the time required for locking must be known, particularly when an oscillator is being locked to a pulsed signal. In this paper, the work of Adler is extended to develop an equation which is useful for higher levels of locking signal, a case often encountered when an oscillator is being injection locked by a pulsed signal. Because the solution of this equation is unwieldy and difficult to understand intuitively, except in very special cases, curves describing the locking mechanism were obtained using a digital computer. These curves enable a designer to construct oscillators which will provide a desired performance. The curves were checked experimentally and showed a close agreement between predicted and measured results. The experimental data indicates that the theory describes the locking time remarkably well even at high levels of locking signal.     

Frequency modulation of Gunn-effect oscillators

Electronic tuning in CW X-band Gunn effect oscillators is reported. Several mechanisms which may account for the effects observed are discussed and discounted on the basis of simple models. An explanation in terms of growing domains is proposed.     

Precise delay generation using coupled oscillators

A new delay generator based on a series of coupled ring oscillators has been developed; it produces precise delays with subgate delay resolution for chip testing applications. It achieves a delay resolution equal to a buffer delay divided by the number of rings. The coupling employed forces the outputs of a linear array of ring oscillators oscillating at the same frequency to be uniformly offset in phase by a precise fraction of a buffer delay. The buffer stage used in the ring oscillators is based on a source-coupled pair and achieves high supply noise rejection while operating at low supply voltages. Experimental results from a 2-μm N-well CMOS implementation of the delay generator demonstrate that it can achieve an output delay resolution of 101 ps while operating at 141 MHz with a peak error of 58 ps     

Dispersion-induced instability in CW laser oscillators

A CW-pumped laser with a short photon cavity lifetime may show an unstable output in the form of spontaneous pulsations or noise. In this paper, a model is developed which reconciles previous studies of unstable behavior in homogeneously and inhomogeneously broadened lasers. Specific regions of instability are predicted for xenon lasers, and it is concluded that some degree of inhomogeneous broadening makes the instability much more likely to be observed.     

Spontaneous coherent pulsations in laser oscillators

A coherent pulsation effect is reported in which the output of a CW laser oscillator is localized in periodic short bursts of energy. The experimentally observed pulse trains resulting from this instability are in agreement with solutions of the governing quantum mechanical equations and cannot be predicted from the usual rate equation models.     

Transverse-mode distortions in giant-pulse laser oscillators

It is shown that high-gain giant-pulse lasers can have transverse intensity profiles differing greatly from the steady-state transverse-mode patterns. The transient effects of gain saturation may cause the intensity profile at the output mirror to change rapidly with time. This can lead to non-Gaussian output intensity profiles, short-duration intense regions ("hot spots"), and irregular time behavior. Shortening the cavity length, i.e., increasing the resonator Fresnel number, which is often done to reduce the number of longitudinal resonances, will only enhance these effects.     

Injection locking of microwave solid-state oscillators

Injection locking of microwave solid-state oscillators is discussed, based on the familiar theorem that the total impedance times the current is equal to the applied voltage. Both quasi-static and dynamic analyses of the locking range, large-signal injection, locking stability, and AM and FM noise are given, and recent experimental work is reviewed briefly. No applications of injection locking are discussed in detail.     

Injection locking of punched-through-injection transit-time oscillators

Injection-locking experiments have been conducted with the punched-through-diode oscillator, and the results have agreed well with theory. This confirms the nature of oscillations to be of a negative-resistance type and not of a relaxation type.     

Angle modulation of frequency locked Gunn oscillators

It is shown experimentally and theoretically that frequency modulation through the bias circuit of free-running Gunn oscillators at low modulation frequencies can be converted to an equivalent phase modulation by frequency locking. Judicious choice of locking bandwidth causes the low-frequency phase-modulation coefficient to be of the same order of magnitude as that measured at high modulation frequencies. The phase-modulation coefficient at high frequencies is unaltered by frequency locking.     

Synchronization of oscillators coupled through narrow-band networks

The ability of two coupled oscillators to synchronize depends critically on the coupling network. Previous analyses have accurately predicted the performance of quasi-optical microwave oscillator arrays for both weak and strong coupling, but have been limited to coupling networks with bandwidths considerably larger than the locking bandwidths of the oscillators. In this paper, the authors develop a method for deriving a suitable system of nonlinear differential equations describing the oscillator amplitude and phase dynamics using a generalization of Kurokawa's method. The method is applied to the case of two Van der Pol oscillators coupled through a resonant network for a wide range of coupling strengths and bandwidths. Simple approximate formulas are developed for the size of the frequency locking region as functions of the basic circuit parameters     

Antiphase synchronization of chaos in symmetrically coupled self-sustained oscillators

Antiphase chaotic synchronization in symmetrically coupled oscillators with a negative resistance is studied. The domains of existence and stability of synchronous modes are determined. The desynchronization process caused by variation of coupling is considered.     

High-speed phase and amplitude modulation of Gunn oscillators

Linear phase and amplitude modulation of X band Gunn oscillators up to 3 GHz modulating rates has been observed. The modulating signal was applied through the bias circuit, and typical sensitivities were 0.1 rad/V and 10% depth of modulation/volt, respectively. A simple theoretical explanation of the results is given.     

Surface-acoustic-wave oscillators: mode selection and frequency modulation

The letter discusses various aspects of the design and performance of surface-acoustic-wave oscillators, including two proved solutions to the mode-selection problem and a demonstration of the wide frequency-modulation capability.     

耦合式光电振荡器的理论与实验研究

为了研究耦合式光电振荡器,阐述了耦合式光电振荡器的模式选择理论,给出了维持最佳锁模状态的相位匹配条件,分析了影响射频信号相位噪声的因素,进行了基于保偏机制的耦合式光电振荡器的实验研究。采用分别调节光环形腔和光电微波振荡环路中的保偏可变光纤延迟线可改变腔长的方法,获得了腔长与振荡频率的关系。同时,采用鉴频法测量了不同条件下5GHz射频信号的相位噪声,研究了影响射频信号相位噪声的因素。结果表明,耦合式光电振荡器的振荡模式取决于光环形腔的腔长,射频信号相位噪声受到光信号偏振态、相位匹配、环路长度等因素的影响。实验中获得了偏移频率10kHz处相位噪声达到-136dBc/Hz的5GHz射频信号,是目前国内已知的相位噪声最低的耦合式光电振荡器。