Showing papers on "Parametric oscillator published in 1983"

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

Abstract: An oscillator which utilizes the effect of the vortex motion in long Josephson tunnel junctions, i.e., flux flow, has been presented in millimeter and submillimeter wave region. An electromagnetic wave generated by the oscillator is detected with a small tunnel junction as a detector with a refined coupling configuration. Quantitative evaluation of the detected power showed that the detected power attained the value of 10−6 W in the frequency range between 100 and 400 GHz, which is far superior to previous results. Frequency and magnetic field dependences of the present system were also measured, which showed that the output power was able to be controlled by the dc magnetic field. The present oscillator will be promising as the local oscillator in the integrated Josephson receiver systems.

Tunable waveguide oscillator

Abstract: An oscillator formed in rectangular waveguide (1) with both mechanical and electronic tuning comprises an oscillator device (4) spaced from a movable short-circuit termination (2) with a varactor diode (5) therebetween, the effective electrical spacing between the oscillator device (4) and the varactor (5) being approximately an integral number of halv-wavelengths at the operating frequency. The varactor (5) extends into the waveguide (1) from one broad wall thereof and engages a transverse member (10) extending between the narrow walls so that only part of the heigth of the waveguide (1) at that region is obscured. This enables the operating frequency and hence the extent of coupling of the varactor (5) to the oscillator cavity, and thus the electronic tuning range, to be varied by adjusting the position of the short-circuit (2). To enable the operating frequency to be mechanically adjusted without greatly influencing the electronic tuning range, an E-plane stub (11) with a movable short-circuit termination (12) may be branched from the waveguide (1) at the same region as the varactor (5).

On the stabilization of optical isomers through tunneling friction

Abstract: A handed molecule may be represented as a particle in a symmetric double well. When placed in contact with a low temperature medium, the mean position of the particle obeys an equation of motion identical to a damped harmonic oscillator. The standard relaxation theory is used to relate the damping to classical friction, in agreement with recent path integral methods; however, no renormalization of the tunneling matrix element occurs. The stability of handedness is explained in terms of the damped oscillator.

Squeezed states and intensity fluctuations in degenerate parametric oscillation

Abstract: The relationship between the squeezing and photon-number fluctuations in the output of a degenerate parametric oscillator is investigated. The addition of a second driving field at the idler frequency allows the direction of the squeezing to be changed. The squeezing may appear in the amplified quadrature. Photon antibunching or bunching may occur depending on whether the quadrature carrying the coherent excitation is squeezed.

Harmonic oscillator with variable mass

Abstract: A general treatment of the quantal harmonic oscillator with variable mass is given. Various examples additional to those obtained by Colegrave and Abdalla for which a closed form solution is possible are given.

Effect of laser fluctuations on squeezed states in a degenerate parametric amplifier

Abstract: The effect of phase and amplitude fluctuations of the pump mode on the quantum-statistical properties of the signal mode is considered. It is shown that these fluctuations in the laser field tend to decrease the squeezing of the signal field.

Invariants for the time-dependent harmonic oscillator. I

Abstract: Two equivalent families of linear invariants and two equivalent families of quadratic invariants are obtained for a harmonic oscillator with variable mass or with variable frequency. Explicit formulae are obtained for the linear and quadratic invariants in the case of a damped oscillator and the Hamiltonian is seen as a special quadratic invariant.

Non-linear integrated optical coupler and parametric oscillator incorporating such a coupler

Abstract: The invention relates to a coupler in which the coupling between the waveguides is carried out on the one hand, by means of evanescent waves propagating in the medium separating these guides, and on the other hand by means of a non-linear interaction in the substrate, where the waveguides are produced. A first guide is produced by ion exchange of H + ions and a second guide by local titanium diffusion in the substrate.

Resonant Coupling Between Solar Gravity Modes

Abstract: It is shown that in consequence of the parametric resonance, g modes of low spherical harmonic degree l are strongly coupled to the modes of high degree. The coupling limits the growth of lowl modes to very small amplitudes. For gl, l = 1 mode, the final amplitude of the radial velocity is of the order of 10 cm s-1. A mixing of solar core as a result of a finite-amplitude development of linear instability of this mode is thus highly unlikely.

Simulation of the noise rise in three-photon Josephson parametric amplifiers

Abstract: Analog simulations of the three‐photon Josephson parametric amplifier indicate that the noise rise observed in experimental devices arises from occasional hopping between a mode at the pump frequency ωP and a mode at the half‐harmonic ωP/2 . The hopping is induced by thermal noise associated with the shunt resistance.

Microwave oscillator with TM01δ dielectric resonator

Abstract: A microwave oscillator with TM01δ dielectric resonator is disclosed. The oscillator operates with a TM01δ mode as contrasted with prior art techniques of TE01δ mode. This provides for an improved tuning range in excess of 10% of the operating frequency.

Device for generating low-frequency magnetic fields

Abstract: Device for generating low-frequency magnetic fields for therapeutic purposes, having an adjustable, variable-frequency oscillator. The oscillator generates a control signal at a frequency of between 1.5 and 13 Hz. The control signal is cyclically scaled down in a gate downstream of the oscillator, thus producing working and rest periods of the device. The duration of these periods varies as a function of the oscillator frequency between 2 to 3 and 18 to 22 seconds. The control signal is applied to a power stage which generates an alternating current which alternates with the oscillator frequency and feeds a magnet coil. The magnet coil can freely emit the magnetic field, and the connection of an electrically conductive blanket is possible in an alternative operating state.

Stable single axial mode Q switched laser oscillator with injection locking

Abstract: A stable high gain laser includes a Q switched multiple axial mode high gain oscillator, an oscillator for generating a stable optical wave at a first frequency, the first frequency being within the band of the multiple modes of operation, and a coupler for injecting the stable optical wave into the high gain oscillator whereby the axial mode nearest to the frequency of the injected wave selects a single axial mode and through gain saturation suppresses other modes of the high gain oscillator.

Squeezed quantum states of a harmonic oscillator in the problem of gravitational-wave detection

Abstract: A quantum harmonic oscillator subjected to a resonant force action and to a parametric action is considered. Account is taken of the coupling of the oscillator with the thermostat (and with the zero-point oscillations). Explicit solutions of the Heisenberg equations are obtained for the creation and annihilation operators. Various methods of producing squeezed states in the oscillator are considered, and the most suitable for the registration of a weak (gravitational) force are chosen. Concrete estimates are obtained of the improvement of the sensitivity through the use of squeezed states and are obtained. The advantages and shortcomings of the squeezed-states technique and of quantum nondemolition measurements are compared. Possible uses of the squeezed-states technique are discussed.

Waves on the Interface of Two-Liquid Layers in a Vertical Periodic Motion

Abstract: Two-liquid layers which are horizontally bounded by two rigid walls are vibrated vertically with constant frequency and amplitude. In such a case, the standing waves which are formed on the interface of the two-liquid layers are theoretically studied by a linear theory. The lower layer is assumed to be an incompressible ideal fluid and the upper one to be a viscous fluid. The equation governing the amplitude of the wave on the interface is reduced to an equation of the Mathieu type with viscous damping. The two-liquid layers can be made most unstable by the vertical oscillations if their frequency is twice the natural frequency of our system. However, parametric resonance is possible only when the amplitude of the vertical oscillation exceeds a threshold value. Its value depends mainly on the state of the upper layer. The properties of the standing waves on the interface is clarified through a stability diagram and the growth rate of the disturbances.

Diagrammatic solution of the forced oscillator

Abstract: A diagrammatic representation for the S matrix of a forced harmonic oscillator is proposed and illustrated. The method lends itself to a 'physical' picture of each order of perturbation theory.

SQUID parametric amplifier

Abstract: The single junction SQUID was previously shown by analysis and simulation to be an attractive candidate for a parametric amplifier. Further calculations of the noise and saturation behavior of the nearly degenerate parametric amplifier have now been performed by numerical simulation. These simulations clearly show that the amplifier noise temperature will be approximately the device temperature T 0 , and that the amplifier will be completely saturated in the presence of white noise characteristic of 30T 0 . Signal saturation of the amplifier also occurs for an output power 10^{-2}F_{o}\phi_{o}^{2}/2L , strongly limiting the dynamic range, However, a coherent array of N single junction SQUIDs is shown to have a signal saturation level increased by N relative to a single SQUID, with no increase in noise temperature, resulting in an N-fold improvement in dynamic range.

The quantum mechanical linearly damped forced oscillator

Abstract: The solution is obtained to the quantum mechanical linearly damped harmonic oscillator subjected to a time dependent driving force. This solution allows the calculation of interesting quantum quantities such as the Green’s function and the transition amplitudes between harmonic oscillator states. The specific results for a harmonic driving force are given.

Picosecond double-beam absorption spectrometer

Abstract: Apparatus was constructed for investigating fast photophysical and photochemical processes resulting from selective excitation of vibronic molecular states. A single laser pulse emitted from a YAG:Nd mode-locked laser was amplified in a two-stage amplifier, frequency converted in a parametric oscillator, and used to excite molecules. A pulse of the continuum was used as the test pulse. A time resolution of ±3 psec and a precision of ±3×10−3 optical density units were attained in the absorption measurements carried out in a study of primary processes of conversion of the energy of light in photosynthetic reaction centers.

A Low-Drift Oscillator Stabilized by a Highly Sensitive Discriminator

Abstract: A low-drift oscillator stabilized by a highly sensitive discriminator which consisted of a dual-gate FET and a dielectric resonator (DR) is presented. The DR was used in common by both the oscillator and discriminator. The temperature dependence of the oscillating frequency was compensated by means of a microprocessor. The resulting oscillating frequency was between ?7KHZ to +55 KHZfor one oscillator and ?21 KHz to +35 KHz for another oscillator around 11.66 GHz at temperatures from ?20°C to 60°C.

Parametric Instability of Curved Girders

Abstract: The parametric instability of a curved girder subjected to equal and opposite periodic moments at the ends is examined. It is shown that the relationship of the frequencies at which parametric resonance occurs differs from the frequency relationship of ordinary resonance. For small values of the applied couples at the ends, the parametric resonant frequency is twice the natural frequency. The method presented can also be used to determine the natural frequencies and static buckling moment for a curved girder. Special analytical solutions and numerical results are obtained and presented in nondimensional forms.

A New Frequency Temperature Compensation Method for Oscillators

Abstract: Summary Thls paper descrlbes a new frequency temperature compensation nethod for crystal osc~llators. The method is applicable to resonators with second order or third order frequency temperature characteristlcs. Hence, an oscillator with an AT cut, a BT cut crystal unit or a surface acoustic wave resonator !SAWR) can be efficiently compensated. A conventional temgerat'Jre ccmpensated crystal oscillator (TCX3) uses an exper.sive variable capacitance diode (varactor) wlth good linearlty as well as many thermistors. Considerable effijrts have been devoted to developing a new reactance circult to replace the varactor. It was found that a serles circuit, involving a capacitor and a silicon diode, had the same characteristics as a varactor, and its linearity could be easlly ad~usted. In the case of an AT cut crystal unit with third order frequency temperature characteristics, compensation over a wlde temperature range can be achieved by using two series circuits. The compensation in the low temperature range can be accomplished independently from the compensatlon In ttie hlgh temperature range. Component values calculation is simple ard requires no computer. The same method can be applied to a high frequency oscillator which uses a SAWR.

Signal and bias voltage supply for the diode of a parametric amplifier

Abstract: The invention relates to a device for coupling the coaxial signal supply line (3) of a parametric amplifier to one arm (4) of a waveguide circulator isolating the input signal from the output signal. The inside conductor (5) of the coaxial signal supply line, which is contact with the diode (2) of the parametric amplifier, protrudes into the waveguide arm and is provided with a coupling pin to which a source supplying the diode with a bias voltage is connected. At the same time, the coupling pin is used as axially elastic support for the inside conductor.

Aging characteristic of light-modulation quartz-crystal oscillator with glass-bar-mounted plano-convex AT-cut quartz-crystal plate

Abstract: A glass-bar-mounted plano-convex AT-cut quartz-crystal resonator (GMPA resonator) is employed in the oscillator to work as a three-port network device. In this case, the light beam is modulated with the dynamic stress of the oscillating quartz-crystal plate and the modulated-light beam is used as a feedback loop of the oscillation. The experimental results for the frequency/temperature characteristic of the oscillator system are presented. About 5 × 10¯ 9 aging rate for a week was realised in the present oscillator.