Showing papers on "Parametric oscillator published in 1978"

A Highly Stabilized Low-Noise GaAs FET Integrated Oscillator with a Dielectric Resonator in the C Band

Abstract: A GaAs FET integrated oscillator stabilized with a BaO--TiO/sub 2/ system ceramic dielectric resonator provides a high-frequency-stabilized low-noise compact microwave power source. The newly developed ceramic has an expansion coefficient and dielectric constant temperature coefficient that offset each other and result in a small resonant frequency temperature coefficient. A stabilized oscillator output of 100 mW with a 17-percent efficiency and a frequency temperature coefficient as low as 2.3 ppm//spl deg/C are obtained at 6 GHz. FM noise level is reduced more the 30 dB by the stabilization. The dynamic properties of the oscillator and resonator are precisely measured to determine equivalent circuit representations. A large-signal design theory based on these equivalent circuit representations is presented to realize the optimal coupling condition between the oscillator and stabilizing resonator. The stabilized oscillator performance is sufficient for application to microwave communications systems.

Bandwidth‐limited operation of a mode‐locked Brillouin parametric oscillator

Abstract: The radiation in the first Stokes component of a fiber Brillouin parametric oscillator is mode locked. The resultant pulses are stable and bandwidth limited.

Mode-locked optical parametric oscillator apparatus

Abstract: Improved mode-locked optical parametric oscillator apparatus comprises a mode-locked pump laser having a cavity with a predetermined effective length l p and a parametric oscillator having a nonlinear crystal, such as lithium niobate (LiNbO 3 ), and singly resonant mirrors spaced apart by an effective distance l o which is substantially less than l p , i.e., l p ≈nl o where n≈5-50. The interaction of the mode-locked pump output with the nonlinear crystal produces parametric outputs at signal (f s ) and idler (f i ) frequencies, the parametric oscillator mirrors being singly resonant at one of those two frequencies. The parametric oscillator may be disposed either externally of or within the pump cavity and the pump laser optionally may be Q-switched. The parametric oscillator apparatus of this invention greatly increases the stability of the mode-locked output under normal operating conditions and enables relatively wide tuning of the apparatus without adjustment of the pump or oscillator cavity lengths.

Thickness-shear mode quartz oscillator with an added non-circular mass

Abstract: A thickness-shear mode quartz oscillator characterized in that an addition mass fitted to a driving electrode of the oscillator for the purpose of adjusting its oscillation frequency has a non-circular shape or the fitting position thereof is deviated from the center of a quartz slice, or both in combination. Such addition mass provides different piezoelectric effects and effects of addition of the mass between the fundamental main vibration and harmonic vibrations and eliminates or restricts a "frequency abnormal phenomenon". Consequently, even when driven by a C-MOS type integrated circuit not having a frequency selection circuit in its oscillation loop, the thickness-shear mode quartz oscillator exhibits stable frequency-temperature characteristics.

X-band singly degenerate parametric amplification in a Josephson tunnel junction

Abstract: Preliminary measurements on a (quasi‐) degenerate parametric amplifier using a single Josephson tunnel junction as the active element is reported. The pump frequency is at 18 GHz and the signal and idler frequencies are both at about 9 GHz. A power gain of 16 dB in a 4‐MHz 3‐dB bandwidth is achieved at the top of the cryostat.

Square‐wave model for a pendulum with oscillating suspension

Abstract: If a sinusoidal oscillation of the point of support of a pendulum is approximated by a square wave, a matrix method may be used to discuss parametric resonance and the stability of the inverted pendulum.

The self-consistent condition for the cranked Harmonic Oscillator Potential

Abstract: When the nuclear field is approximated by an Harmonic Oscillator Potential it is possible to obtain an exact solution when the field is cranked with frequency ω. We have shown that when the energy is minimized, subject to the condition of constant volume, the square of the velocity distribution is not isotropic as previously assumed. The system shows greater stability resulting in a higher cut-off frequency and an expanded energy spectrum.

Electromechanical parametric amplifier for measurement of electric fields

Abstract: The disclosed device is an electromechanical parametric amplifier It utilizes, as the required nonlinear mixing element, the square law force of an electric field on the surface of a conductor In an exemplary device, a wire grid (10) is placed adjacent to a conducting diaphragm (11) The diaphragm (11) is mechanically resonant at the local oscillator (LO) frequency When a signal from the local oscillator (15) is applied to the grid (10), the diaphragm (11) experiences both the electrostatic force from the grid (10) and electrostatic force from the electric field to be measured The amplitude of the vibration of the diaphragm (11) at the LO frequency is a measure of the electric field of interest In an exemplary embodiment the vibration was measured by an electret microphone (12) and a lock-in amplifier (14) The measurement of electric field is important, for example, in industrial environments in which the buildup of static electricity is a problem

Microwave/millimeter wave oscillator

Abstract: In an oscillator of the type producing microwaves, millimeter waves and above, apparatus and a method for increasing the size, so that one or more active devices can be coupled to the oscillator, including a first cavity operating at a higher order mode, which cavity has an output coupled thereto for removing power, and a second cavity operating at a dominant mode and coupled to the first cavity, which second cavity assures efficient and spurious-free operation of the oscillator at the desired frequency.

Temperature compensated integratable RC oscillator

Abstract: A high stability integratable resistance-capacitance oscillator is disclosed which is capable of operating at a stable frequency regardless of changes in ambient temperature or applied voltages. The oscillator uses a temperature compensating impedance and semiconductor junction to compensate for temperature dependent variations in active elements of the oscillator. Constant current bias sources and voltage clamping circuits insure oscillations having predetermined amplitude ranges despite changes in applied voltages. Active transistors in the oscillator are maintained in their linear range by the use of antisaturation transistors connected between their base and collector electrodes.

Nonlinear and parametric effects in atomic rf spectroscopy

Abstract: Nonlinear phenomena occurring during interaction between an atom and a strong rf field of resonant or nonresonant frequency are reviewed. The account is given in both semiclassical and consistently quantummechanical languages. The concept of an atom "dressed by the radiation field" in which not only the optical-frequency field but also the radio-frequency field is quantized is presented in detail. The results are summarized of theoretical and experimental studies of multiphoton transitions, radiative shifts of normal magnetic resonance lines, parametric resonance, and coherent resonances under the conditions of optical pumping. The influence of nonresonance rf fields on magnetic properties and the rate of magnetic relaxation of atoms is discussed.

Inverse Cerenkov Effect and New Phenomena in Non-linear Optics

Abstract: The optical parametric oscillator and amplifier involving the analogue of the inverse Cerenkov effect is considered, the effect being due to the non-linear interaction between the plane wave of pumping (with a frequency yp) incident at an angle onto an optical waveguide and the waves (with frequencies ys, yv satisfying the relation ys + yv = yp) generated in the waveguide. For the oscillator an appreciable non-linear reflection from (transmission through) the waveguide layer of the pumping wave is discovered and shown to appear in new directions compared to those known in optics. Also, the transformation by the reflection (transmission) of the pumping wave into the waves with new frequencies 2 ys, 2yv is predicted. The possible effect of additional (higher-order) non-linear processes on the oscillator dynamics is discussed. A travelling-wave parametric amplifier involving the analogue of the inverse Cerenkov effect is also considered. Here, differing from the usual optical parametric amplifiers the intens...

Optical parametric oscillator dependence on pump laser beam quality

Abstract: Experimentation with a pulsed, angle-tuned LiNbO 3 optical parametric oscillator revealed the dependence of pump power depletion and conversion efficiency on pump laser beam divergence. Mathematical expressions, developed for these parameters, were based on a spherical-wave model. Calculated results and comparison with experimental observations indicate the degree to which phasefront curvature affects parametric oscillator performance.

Nonlinear Dynamic Response of a Wind Turbine Rotor under Gravitational Loading

Abstract: T nonlinear equations of motion for an isolated 3-deg flapping-lagging-feathering rotor blade are derived using Lagrange's equations for arbitrary large angular deflections. The aerodynamic forces and the tower interaction are not considered here. A consistent set of nonlinear equations is obtained by using nonlinear terms up to third order. The limit cycle analysis for forced oscillations and the principal parametric resonance of the flap-lag blade under a periodic gravity field are studied using the harmonic balance method. For a relatively small initial coning angle (about 9 deg), the nonlinearity becomes of the softening spring type, and large coupled responses are possible for rotational frequencies significantly lower than the lagging frequency.

Harmonically tuned high power voltage controlled oscillator

Abstract: In a high power oscillator for frequencies on the order of microwave and above, a method and apparatus for tuning the oscillator in response to a control voltage applied thereto by utilizing a relatively low power varactor diode in a harmonic cavity coupled to the oscillator and without loss of efficiency.

Computer-Aided Design of Highly Linear, High-Power Varactor-Tuned Frequency Modulators

Abstract: A systematic approach to the design of linear high-power varactor-tuned frequency modulators is presented. It is shown that a few simple measurements on the free-running oscillator together with a suitable use of modern general-purpose optimization programs allow the designer to predict and control all aspects of the design problem, including linearity of the frequency-voltage characteristic, the R.F. voltage swing across the varactor junction, and the optimum choice of the varactor diode itself.

Highly Stable, Low Noise Millimeter-Wave IMPATT Oscillator (Technical Notes)l

Abstract: A highly stable and low noise IMPATT oscillator at 75 GHz is realized by using the parametric injection locking technique along with an AFC circuit in which a crystal oscillator is used as a reference. Noise level of this oscillator is lower by 25 dB as compared with that of the free-running IMPATT oscillator and the frequency stability is as good as 10/sup -8/ / /spl deg/C.

Theory of a doubly resonant multimode-pumped optical parametric oscillator

Abstract: A theoretical investigation is made of a doubly resonant multimode-pumped optical parametric oscillator (OPO) in both the cw and pulsed stimulated emission regimes. The conditions for efficient conversion of a broad-band pump wave into a narrow-band signal wave are discussed. Allowance for saturation effects is made in the analysis.

Broadly Tunable, Repetitive Picosecond Laser System and Its Application to Spectroscopy

Abstract: A broadly tunable, repetitive picosecond laser system utilizing the optical parametric effect has been developed for the purpose of studying picosecond spectroscopy. It is possible to produce intense, monochromatic light pulses having 30–40ps duration and a tunable range from 240nm to 3.6μm with a repetition rate as high as 20pps. In a previous paper [1], the construction of an optical parametric oscillator was reported, in which a temperature-controlled LiNbO3 crystal is pumped by the second harmonic of a mode-locked glass:Nd laser with one-shot operation. The same parametric oscillator is used in this paper changing the pumping source to a mode-locked YAG:Nd laser with repetitive operation. To demonstrate the usefulness of this tunable picosecond laser system, results of experiments on the two-photon resonant Raman scattering and luminescence processes associated with excitonic molecules in CuCl are also presented in this paper.

Parameters of a josephson tunnel junction array parametric amplifier

Abstract: The parametric amplification in arrays of small tunnel junctions was turned via a magnetic field The experimental parameters agree well with theoretical estimates