Showing papers on "Parametric oscillator published in 1984"

Squeezing of intracavity and traveling-wave light fields produced in parametric amplification

Abstract: A general input-output theory for quantum dissipative systems is developed in which it is possible to relate output to input via the internal dynamics of a system. This is applied to the problem of computing the squeezing produced by a degenerate parametric amplifier located inside a cavity. The results for the internal modes are identical with those of Milburn and Walls [Opt. Commun. 39, 401 (1981)]. The output field is also found to have only 50% of maximal squeezing. However, by taking the output for a degenerate parametric amplifier inside a single-ended cavity and feeding this into an empty single-ended cavity, one can produce a maximally squeezed state inside this second cavity.

The resonant interaction of disturbances at laminar-turbulent transition in a boundary layer

Abstract: The three-dimensional resonant interaction of a plane Tollmien-Schlichting wave, having a frequency f1, with a pair of oblique waves having frequencies ½ f1, was observed and studied experimentally. In the initial stages, the interaction proved to be a parametric resonance, resulting in the amplification of small random priming (background) oscillations of frequency ½ f1, and of a packet of low-frequency oscillations. The resonant interaction of waves in a boundary layer was investigated also by introducing a priming oscillation with frequency f’ = ½ f1 + Δf for different values of the frequency detuning Δf. The importance of the discovered wave interaction in boundary-layer transition is demonstrated. Causes of realization of different types of laminar-flow breakdown are discussed.

Order within chaos : towards a deterministic approach to turbulence

Abstract: Free Oscillator - Damped Oscillator Forced Oscillator - Parametric Oscillator The Fourier Transform Poincare Sections Three Examples of Dynamical Systems To Chaos: Temporal Chaos in Dissipative System Strange Attractors Quasiperiodicity The Subharmonic Cascade Intermittency Debate Appendixes Index.

AgGaS2 infrared parametric oscillator

Abstract: A report is presented of the first operation of an optical parametric oscillator in a chalcopyrite crystal, AgGaS2. Tuning from 1.4 to 4.0 microns is demonstrated for 1.06-micron Nd:yttrium aluminum garnet pumping. The potential tuning range extends to the 12-micron transparency limit of the crystal.

Flux-flow-type Josephson oscillator for millimeter and submillimeter wave region. II. Modeling

Abstract: A theoretical study is made of a travelling‐wave‐type oscillator, which utilizes a flux flow in a long Josephson junction for use as a local oscillator in the integrated superconducting receiver system. An internal electromagnetic field of the oscillator junction in the flux‐flow state is investigated both numerically and analytically. It is shown that the voltage amplitude of the internal oscillation increases gradually in the direction of the flux flow and reaches a maximum value at the junction end. An equivalent circuit of the oscillator is also obtained, which gives dependences of the emitted radiation on frequency, magnetic field, and load. It is shown that the output power attains the value of the order of 10−6 W in the frequency range between 100 and 500 GHz, and that the output power and the radiation frequency can be controlled by both the bias voltage and the applied magnetic field. These theoretical results explain quantitatively the experimental ones with a Pb‐alloy long junction of length 24 λJ.

The generation of cross-waves in a long deep channel by parametric resonance

Abstract: The evolution equations are obtained which govern the growth of cross-waves generated in a long deep channel by a wavemaker with small amplitude when the waves are modified by finite-amplitude effects. The linearized equations are compared with previous theoretical and experimental work. Some numerical solutions are obtained for illustration.

Squeezing in a detuned parametric amplifier

Abstract: The effect of detuning on the squeezing obtained in a prototype model for squeezing, namely the degenerate parametric amplifier, is investigated. A squeezed minimum uncertainty state is only obtained in a set of variables related to the original variables by a time dependent transformation. The required transformation is obtained using a symplectic decomposition of the dynamic evolution matrix.

Irradiation device for treating living tissue with electro-magnetic waves

Abstract: 1. A radiation device for the treatment of living tissue with electromagnetic waves, with a high frequency oscillator stage (15) for the generation of a high frequency wave train, with a clock generator (19) down-line as a chopper which periodically interrupts the high frequency wave train and with an output amplifier (20) whereto there may be connected a transmitting aerial (13) into whose radiation range there may be positioned the tissue to be treated, or a patient, characterized in that the high frequency oscillator stage (15) produces a frequency which may be set in the range of 100 to 200 Mhz, that provision is made for a low frequency oscillator stage (16) which produces a frequency that may be set within the range of 1 Hz to 1000 Hz that the output of the high frequency oscillator stage (15) and the output of the low frequency oscillator stage (16) are brought together in a modulator unit (17) so that a modulated wave train is generated and that the modulated wave train is passed to the clock generator (19) and that the clock generator (19) may be set to a pulse frequency of 0.5 Hz to 40 Hz.

Coherent states and dissipative systems

Abstract: We study a many-body system consisting of a central harmonic oscillator linearly coupled to a reservoir of a large number of oscillators. To get the quantal description of the central oscillator we use normal-ordering operators and the coherent-state representation in order to solve the Schr\"odinger equation for the complete system. Then, it is shown that the wave function for the total system allows one to obtain the following results: (i) The expectation value of the coordinate of the central oscillator is the same as the classical solution for the damped harmonic oscillator and (ii) the energy of the central oscillator decays towards the correct zero-point energy.

Dynamic stability for a simply supported beam under periodic axial excitation

Abstract: This paper studies the dynamic stability for a simply supported straight beam under periodic axial excitation by using the averaging method and the Routh-Hurwitz stability criteria. By considering the first two modes coupled, we discuss the effect of the stability-instability region and the amplitudes of vibration. Furthermore, by studying the principal parametric resonance i.e. subharmonic order 1 2 , we investigate the effect of the amplitude of the main system by various kinds of non-linearities of the subsystem. Finally, by obtaining the transient results, we describe the beat phenomenon, and harmonic oscillation.

A model for modulated damping or growth of a harmonic oscillator in classical or quantum mechanics

Abstract: A harmonic oscillator with modified damping or growth described by a damping constant multiplied by a certain time-dependent factor is shown to possess an exactly solvable equation of motion. By suitable choice of a second parameter the modification can be made very strong for a short interval of time and this can lead, in the classical case, to a sudden change in motion. In the quantum-mechanical case the solution is given in both the Heisenberg and Schrodinger pictures and the connection between pseudostationary and quasi-coherent states is discussed.

Frequency modulation system for a frequency synthesizer

Abstract: A voltage controlled oscillator includes a main varactor diode coupled to a frequency resonating circuit to produce an output frequency in response to a control voltage. A secondary varactor diode of an appreciably lower voltage to frequency sensitivity ratio is coupled to the main varactor diode. A modulation input circuit is coupled to the secondary varactor diode to enable modulation of the resonating output frequency. A linearizing circuit is coupled to the secondary varactor diode and tracks the main varactor diode capacitance to continuously adjust the bias voltage of the secondary varactor diode to provide constant carrier modulation deviation.

Conservative model for the damped harmonic oscillator

Abstract: A conservative model for the damped harmonic oscillator is constructed by attaching a string of infinite extent to the oscillator’s mass. This system may be used to illustrate, in simple terms, a number of important concepts such as radiation damping, the characteristic impedance of a wave propagating medium, Brownian motion, and the Langevin equation.

On the path integral quantization of the damped harmonic oscillator

Abstract: A time‐dependent canonical transformation is performed in the path integral expression of the propagator for a damped harmonic oscillator to reduce it to a harmonic oscillator with modified frequency. The transformation is carried out in a properly time‐symmetrized expression of the lattice space path integral by making expansions about the midpoint of each time interval.

Intracavity single resonance optical parametric oscillator (I.S.R.O.)

Abstract: The theory of the intracavity single resonance optical parametric oscillator has been studied assuming that the pump- and resonant parametric waves were Gaussian eigenmodes of laser and parametric oscillator resonators. The non-resonant parametric wave has been found by solving a parabolic equation. The resulting equations of motion are parametrized in new terms of integrals that we have discovered. With a given laser and a non-linear crystal, two optimal values for the focusing parameter can be found: the first defines the threshold operation regime of the intracavity single resonance optical parametric oscillator, the other defines the maximum output power of the non-resonant parametric wave. In the latter case, we have demonstrated that in the degeneracy operation regime, this maximum output power of non-resonant wave is equal to the maximum pump laser power when the pump laser works alone (that is without the parametric oscillator) with mirrors having optimal transmission coefficients and when the laser power is twice the threshold value of the pump power. Numerical results have been obtained for an intracavity single resonance oscillator based on a c.w.-YAG-Nd 3+ -laser and a non-linear Ba 2 NaNb 5 O 15 crystal of length 4 mm. In the degeneracy operation regime, the power of the non-resonant wave is 0.35 W when the total laser power in the laser cavity is 35 W, in the absence of the opical parametric oscillator Theorie de l'oscillateur intracavite des ondes optiques parametriques ayant une seule onde resonnante. Theorie faite en supposant que l'onde pompee et l'onde parametrique resonnante sont des modes gaussiens monomodes des resonateurs du laser et de l'oscillateur

The propagator of the time-dependent forced harmonic oscillator with constant damping

Abstract: The work of Montroll in deriving the propagator of a time‐dependent harmonic oscillator is generalized to obtain the propagator of the time‐dependent forced harmonic oscillator with constant damping.

Electromagnetic type conductivity meter

Abstract: PURPOSE: To make it possible to stably measure conductivity up to a lower degree, by forming a resonance circuit by connecting a condenser to a detection coil and performing the positive feedback of the resonant voltage thereof to draw the frequency of an oscillator in resonance frequency. CONSTITUTION: An electromagnetic induction current is flowed to a water loop by exciting a magnetic core W 1 by the output of an oscillator to induce electromotive force in a detection coil L 2 . A condenser C 5 is connected to the coil L 2 to form a resonance circuit and the resonant voltage thereof is supplied to a DC ammeter A through an amplifier Q 1 and a detector D 1 . In this case, the output voltage of the amplifier Q 1 is positively fed back to the oscillator through an amplifier Q 2 and the oscillation frequency of the oscillator is dawn in the frequency of the resonance circuit consisting of L 2 and C 5 to eliminate the difference between both frequencies. Therefore, detection can be performed always in a stable state with high sensitivity. COPYRIGHT: (C)1985,JPO&Japio

Sensitivity of a Hopf Bifurcation to External Multiplicative Noise

Abstract: It has been found experimentally that the properties of oscillatory physical and chemical systems are strongly sensitive to the influence of external multiplicative noise [1–2]. In the case of a well-understood experimental system, namely the electrical parametric oscillator studied by KABASHIMA and coworkers [1], the main effects reported are: (i) The onset of the oscillatory regime is still sharply localized at a well-defined value of the average of the control parameter in spite of the perturbations by the noise, (ii) The noise stabilizes the non-oscillatory regime. In first approximation the threshold of instability is shifted to higher values of the average control parameter by an amount proportional to the intensity of the noise. (iii) There is a slowing down of the relaxation rate of the state variables near the threshold. The theoretical explanation of these experimental findings is based on the properties of the stochastic process xt. given by a stochastic differential equation of the form $$ d{x_t}=\left[{\mu \left({{\lambda_t}} \right){x_t}-{x^3}_t} \right]dt $$ (1) It has been shown indeed by KABASHIMA and coworkers that near the threshold at which the oscillatory regime sets in, the amplitude of the oscillatory current xt is in first approximation given by (1) where $$ \begin{gathered} \mu ({\lambda_t})={\lambda_t} \hfill \\=\lambda+\sigma {\xi_t} \hfill \\ \end{gathered} $$ is proportional to the fluctuating pumping current used as control parameter; λ is the constant average value and ξt is Gaussian white noise with intensity σ

Integrated Tunable Cavity Gunn Oscillator for 60-GHz Operation in Image Line Waveguide

Abstract: The design, construction, and experimental test results of a mechanically tunable Gunn oscillator using a recessed diode metal coaxial cavity coupled to an image line waveguide is described. The oscillator frequency was changed by about 10-percent by varying the bias post length into the coaxial structure. The oscillator is designed so that both the Gunn diode and resonant cavity can be quickly replaced to provide extended frequency coverage and efficiency. This Gunn diode oscillator has provided up to 15-mW CW power at 60 GHz with 10-percent tuning range.

Progress In Optical Parametric Oscillators

Abstract: It is pointed out that tunable coherent sources are very useful for many applications, including spectroscopy, chemistry, combustion diagnostics, and remote sensing. Compared with other tunable sources, optical parametric oscillators (OPO) offer the potential advantage of a wide wavelength operating range, which extends from 0.2 micron to 25 microns. The current status of OPO is examined, taking into account mainly advances made during the last decade. Attention is given to early LiNbO3 parametric oscillators, problems which have prevented wide use of parametric oscillators, the demonstration of OPO's using urea and AgGaS2, progress related to picosecond OPO's, a breakthrough in nanosecond parametric oscillators, the first demonstration of a waveguide and fiber parametric amplification and generation, the importance of chalcopyrite crystals, and theoretical work performed with the aim to understand the factors affecting the parametric oscillator performance.

RF-tuning device comprising a switching mixer stage and a tuning oscillator

Abstract: RF-tuning device comprising a switching mixer stage (M) and a tuning oscillator (0) coupled thereto. According to the invention, so as to reduce the noise contribution of the mixer stage (M) without increasing the oscillator radiation, the slew rate of the oscillator switching signal applied to the mixer stage (M) is increased.

Investigation of the spectral and energy characteristics of a pulsed optical parametric oscillator operating in the regime of external signal injection

Abstract: Experimental and theoretical investigations were made of the operation of a singly resonant optical parametric oscillator made of a lithium niobate crystal and pumped by the fundamental-frequency radiation from a YAG:Nd laser. An external signal was injected into the oscillator. When the source of this signal was another optical parametric oscillator utilizing a crystal of barium sodium niobate, it was possible to generate narrow-band radiation throughout the tuning range of the singly resonant lithium niobate oscillator: the output power obtained in this case was several times higher than that in the absence of injection and the spectral brightness of the radiation was 103 times higher. This was achieved at the expense of a slight loss (< 10%) of the fundamental-frequency radiation used to pump the barium sodium niobate oscillator.

Image line voltage controlled oscillator with replaceable components

Abstract: A millimeter wavelength oscillator combining a mechanically tunable resonating cavity oscillator element with an electronically tunable solid state diode element provides a basic stable steady wave energy source with fine-tuning capabilities not possible with a resonating cavity oscillator alone, and with an apparatus structure which is light in weight, compact, mechanically sturdy, and with easily accessible and quickly replaceable component parts.

Parametric Excitation in the Self-excited Vibration System with Dry Friction : 1st Report, Parametric Resonance

Abstract: An application of solutions of linear Mathieu equation by a new method gives approximate solutions in a parametrically excited self-excitation system with dry friction. Steady solutions and the stability in the regions of parametric resonance of first and second orders are determined. Solutions outside the regions of parametric resonances are approximated by two limit cycles. One corresponds to a stable solution and the other corresponds to an unstable solution. Beyond a certain value of dry friction self-excited vibrations are completely suppressed and a parametric resonance of second order soon disappears, so that only a parametric resonance of first order remains within a certain interval of frequency. Numerical results by the present analysis almost agree with those by Runge-Kutta method and it is seen that the proposed approximate methods have high accuracy.

Picosecond parametric oscillator amplifying radiation from a tunable semiconductor laser

Abstract: The first picosecond optical parametric oscillator based on an LiNbO3 crystal was built. It amplified tunable (near 4 μ) radiation from a semiconductor injection laser.

Motion of a harmonic oscillator with variable sliding friction

Abstract: The velocity of a harmonic oscillator with variable sliding friction is obtained as a function of the displacement. The ultimate stopping position is determined by an iteration procedure.

Performance of an InP MISFET X-Band Oscillator and K-Band Oscillator-Doubler

Abstract: Results for an InP MISFET 1.5 ?m × 300 ?m device used as an oscillator and an oscillator doubler are presented. A fundamental frequency oscillator using the transistor in the reverse channel mode and dielectric resonator stabilised was designed to operate at 9.8 GHz and supplied 80 mW output power at this frequency with RF/dc efficiency of 9%. The second harmonic oscillator gave 12.6 mW at 19.6 GHz with 1.7% RF/dc efficiency.

Parametric Excitation in a Self-exciting System : 1st Report, Behaviors in the Region of Subharmonic Resonance of Order 1/2

Abstract: In a self-exciting system of Van der Pol type with the restoring force expressed as the product of a non-linear function of deflection and a periodic function of time. parametric resonances and moreover subharmonic vibrations can occur. Steady state solutions in the regions of parametric resonance of first order and of subharmonic resonance of order l/2 and the stability are determined by a transformation to the rotating coordinate system and the averaging method. In the neighborhood of these resonances a beat phenomenon occurs and its amplitude is estimated by an approximate limit cycle. By numerical calculations it is ascertained that approximate solutions have high accuracy.