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Showing papers on "Parametric oscillator published in 1992"


Patent
28 Apr 1992
TL;DR: In this article, a wide pulling voltage controlled crystal oscillator (12) operates at one third the transmit frequency followed by a frequency tripler/filter/amplifier chain that can be quickly switched on and off.
Abstract: An RF transceiver achieves a fast switching time between transmit and receive modes by leaving the transmit oscillator (12) on all the time. The transmit chain comprises a wide pulling voltage controlled crystal oscillator (12) that operates at one third the transmit frequency followed by a frequency tripler/filter/amplifier chain that can be quickly switched on and off. By operating the transmit oscillator at one third the transmit frequency, only the third harmonic of the oscillator falls into the sensitive receive frequency band. Further isolation during the receive mode is achieved by gating off the frequency tripler, pulling the frequency of the oscillator out of the receive band, electronically detuning the harmonic filter (16) and switching off the transmitter's power amplifier (18).

108 citations


Journal ArticleDOI
TL;DR: In this paper, the linear stability of unbounded strained vortices in a stably stratified fluid is investigated theoretically and the problem is reduced to a Floquet problem which is solved numerically.
Abstract: The linear stability of unbounded strained vortices in a stably stratified fluid is investigated theoretically The problem is reduced to a Floquet problem which is solved numerically The three‐dimensional elliptical instability of Pierrehumbert type [Phys Rev Lett 57, 2157 (1986)] is shown to be suppressed by the stable stratification and it disappears when the Brunt–Vaisala frequency exceeds unity On the other hand, two classes of new instability mode are found to occur One appears only when the Brunt–Vaisala frequency is less than 2, whereas the other persists for all values of the Brunt–Vaisala frequency The former mode is related to a parametric resonance of internal gravity waves, and the latter modes are related to superharmonic parametric instability

73 citations


Book ChapterDOI
01 Jan 1992
TL;DR: In this article, a case study in the bifurcation theory of Hamiltonian systems with or without certain discrete symmetries is presented, in which structure preserving normal form or averaging techniques are used, as well as equivariant singularity theory and theory of flat perturbations.
Abstract: Generic nonlinear oscillators with parametric forcing are considered near resonance. This can be seen as a case-study in the bifurcation theory of Hamiltonian systems with or without certain discrete symmetries. In the analysis, among other things, structure preserving normal form or averaging techniques are used, as well as equivariant singularity theory and theory of flat perturbations.

65 citations


Journal ArticleDOI
TL;DR: The beat frequency of the signal and idler subharmonic outputs of a tunable cw KTP optical parametric oscillator was phase locked to a microwave reference frequency source, which permitted precise determination of the output frequencies at approximately half the input pump frequency.
Abstract: We report the experimental demonstration of a novel optical parametric oscillator approach to tunable optical frequency division. The beat frequency of the signal and idler subharmonic outputs of a tunable cw KTP optical parametric oscillator was phase locked to a microwave reference frequency source, which thus permitted precise determination of the output frequencies at approximately half the input pump frequency.

60 citations



Journal ArticleDOI
TL;DR: P pulsed squeezed-light generation by means of an optical parametric downconverter that is pumped by the second harmonic of a mode-locked Q-switched laser and 2-dB squeezing is observed for a parametric gain of 1.5.
Abstract: We report pulsed squeezed-light generation by means of an optical parametric downconverter that is pumped by the second harmonic of a mode-locked Q-switched laser. Using the fundamental beam of the laser as a local oscillator, we observe 2-dB squeezing for a parametric gain of 2.0. This local oscillator, however, is nonoptimal because of its spatiotemporal mode mismatch with the squeezed mode generated by the downconverter. We describe an experiment in which a matched local oscillator is generated with the use of an optical parametric amplifier that is pumped by the same laser as is the downconverter. In this case, 2-dB squeezing is observed for a parametric gain of 1.5. The present experimental setup is limited by the uncontrollable phase fluctuations that prohibit us from making squeezing measurements at higher parametric gains.

34 citations


Journal ArticleDOI
TL;DR: In this article, the authors discuss recent progress in the study of the nonclassical properties of light beams generated by non-degenerate parametric splitting in χ(2) nonlinear birefringent crystals, with special emphasis on their quantum correlation.
Abstract: We discuss recent progress in the study of the non-classical properties of light beams generated by non-degenerate parametric splitting in χ(2) nonlinear birefringent crystals, with special emphasis on their quantum correlation (“twin beams”). We describe experimental results using successively pure parametric fluorescence, parametric amplification of a weak signal beam pumped by a pulsed laser, and parametric oscillation in a cavity pumped by a cw laser. In this review, we compare the respective advantages and drawbacks of the different approaches.

30 citations


Journal ArticleDOI
TL;DR: A theory of two-mode phase-sensitive amplification by a three-level atomic system in the cascade configuration is presented, within the framework of the theory of multiwave mixing.
Abstract: A theory of two-mode phase-sensitive amplification by a three-level atomic system in the cascade configuration is presented, within the framework of the theory of multiwave mixing. Two photons of a strong external pump field induce coherence between the top and bottom levels. It is shown that both quadratures of the field modes acquire unequal gain and added noise. For large values of the dimensionless pump intensity, with a particular choice of its phase, and zero side-mode detuning, the system behaves as a nondegenerate parametric amplifier.

29 citations


Journal ArticleDOI
TL;DR: Continuous-wave operation of a mode-locked optical parametric oscillator has been achieved with the use of an all-solid-state laser pump and the performance of the oscillator may be enhanced significantly through optimization of the design parameters.
Abstract: Continuous-wave operation of a mode-locked optical parametric oscillator has been achieved with the use of an all-solid-state laser pump. The oscillator, based on a 5-mm-long KTP crystal, is synchronously pumped at 523.5 nm by a continuous train of picosecond pulses at 352 MHz obtained by frequency doubling the output of a cw mode-locked, diode-laser-pumped Nd:YLF laser in an external enhancement cavity. The doubly resonant oscillator has a pump power threshold of 150 mW, corresponding to a peak mode-locked pumping intensity of 4 MW/cm2. At 3.8 times above threshold, the oscillator converts ~7% of the pump power into externally usable signal and idler outputs at 1.020 and 1.075 μm. The performance of the oscillator may be enhanced significantly through optimization of the design parameters.

27 citations


Journal ArticleDOI
TL;DR: In this article, higher-order digital statistical analysis techniques are used to investigate the nonlinear and parametric mechanisms responsible for the energy transfer to the subharmonic, and the results show that the dominant interaction is a parametric resonance mechanism between the fundamental and the sub-harmonic modes which leads to a pronounced growth of the sub harmonic.
Abstract: An experimental investigation is conducted in order to quantify the nonlinear and parametric resonance mechanisms that are associated with the subharmonic growth in the transition to turbulence in plane mixing layers. Higher-order digital statistical analysis techniques are used to investigate the nonlinear and parametric mechanisms responsible for the energy transfer to the subharmonic. The results show that the dominant interaction is a parametric resonance mechanism between the fundamental and the subharmonic modes which leads to a pronounced growth of the subharmonic. Measurements also indicate that the fundamental, besides interacting with the subharmonic, is also engaged in redistributing its energy to the other Fourier components of the flow via nonlinear three-wave interactions. Local wavenumber measurements verify that frequency—wavenumber resonance matching conditions exist between the fundamental and subharmonic in the region where the subharmonic gains its energy by parametric resonance. The results are in general agreement with theoretical models by Kelly (1967), and Monkewitz (1988) on subharmonic growth.

27 citations


Journal ArticleDOI
TL;DR: In this paper, the authors used quantum-optical master equations to model the communications systems and solved numerically for systems with either laser amplifiers or parametric amplifiers, with and without the nonlinear Kerr effect.
Abstract: Gordon and Mollenauer [ Opt. Lett.15, 1351 ( 1990)] have shown that the nonlinear Kerr effect limits the range of coherent communications systems using laser amplifiers. We show that parametric amplifiers avoid this limitation. Our method is novel in that we use quantum-optical master equations to model the communications systems. These are solved numerically for systems with either laser amplifiers or parametric amplifiers, with and without the nonlinear Kerr effect. Parametric amplifiers perform better because they preserve the signal-to-noise ratio and decrease the phase noise.

Journal ArticleDOI
TL;DR: In this article, a widely tunable 90° phase-matched KTP parametric oscillator pumped by a tunable dye laser was described, and the device emitted stable IR pulses that had a linewidth of ~0.2 nm in the 1.04-1.38-μm range and 1 2 n in the 2.15-3.09-m range when the pump wavelength was scanned from 0.7 to 0.95 μm.
Abstract: A widely tunable 90° phase-matched KTP parametric oscillator pumped by a tunable dye laser is described. The device emitted stable IR pulses that had a linewidth of ~0.2 nm in the 1.04–1.38-μm range and 1–2 nm in the 2.15–3.09-μm range when the pump wavelength was scanned from 0.7 to 0.95 μm.

Patent
11 Jun 1992
TL;DR: The tunable, small band laser unit uses an optical parametric oscillator that has a pair of mirrors (14, 16) forming a resonator and having a crystal (18) between them.
Abstract: The tunable, small band laser unit uses an optical parametric oscillator (10) that has a pair of mirrors (14, 16) forming a resonator and having a crystal (18) between them. The crystal can be of beta bamium borate or littium borate. The crystal may be tilted through an angle (alpha) for tuning. Two such parametric oscillators are used to generate the coherent emission and located between them is an optical system inducing a wavelength selective element (28) in the form of a reflection grating (28). The spectral bandwidth of the first oscillator is typically 0.2 to 3 nm. ADVANTAGE - Provides ease of adjustment for stable operation.

Journal ArticleDOI
TL;DR: The effect of the bistability on the two-time correlation function and the transmitted-field spectrum is calculated and the measurable steady-state probability distribution at the output of a homodyne detector is calculated, in order to investigate whether one can experimentally distinguish between quentum-superposition and classical states.
Abstract: The degenerate parametric oscillator operating above threshold exhibits bistability, and recent work suggests that it might also exist as a quantum-superposition state. We calculate the effect of the bistability on the two-time correlation function and the transmitted-field spectrum. The measurable steady-state probability distribution at the output of a homodyne detector is also calculated in a particular limit, in order to investigate whether one can experimentally distinguish between quentum-superposition and classical states

Proceedings ArticleDOI
13 Apr 1992
TL;DR: In this article, an experimental investigation into the response of a nonlinear continuous system with many natural frequencies in the range of interest is presented, where the system is a flexible cantilever beam, whose first four natural frequencies are 0.65 Hz, 5.65 GHz, 16.19 Hz, and 31.91 Hz, respectively.
Abstract: An experimental investigation into the response of a nonlinear continuous system with many natural frequencies in the range of interest is presented. The system is a flexible cantilever beam, whose first four natural frequencies are 0.65 Hz, 5.65 Hz, 16.19 Hz, and 31.91 Hz, respectively. The fourth natural frequency is about fifty times the first natural frequency. Several cases were considered with this beam. For the first case, the beam was excited with periodic base motion along its axis. The excitation frequency fe was near twice the thud natural frequency f3, which for a uniform isotropic beam corresponds to approximately the fourth natural frequency fq. Thus the thud mode was excited by a principal parametric resonance (i.e., fe=2f3) and the fourth mode was excited by an external resonance (i.e., fe=f4) due to a slight curvature in the beam. Modal interactions were observed involving the first, third, and fourth modes. Through a stationary frequency sweep the response transitions from a periodic, to a periodically modulated, to a chaotic motion. For the second case, the beam was excited with band limited random base motion transverse to the axis of the beam. The first and second modes were excited through nonlinear interactions. For the third case, the beam was excited with base excitation along the axis of the beam at 138 Hz. The corresponding response is dominated by the second mode.

Journal ArticleDOI
TL;DR: In this article, the exact solution of the time evolution for the generalized parametric oscillator, both in the Schrodinger and in the Heisenberg representation, was found by exploiting the SU(1, 1) structure of the Hamiltonian.

Journal ArticleDOI
Robert M. Shelby1, Michael Rosenbluh1
TL;DR: In this article, a nonlinear crystal in a cavity which is resonant for both signal and idler waves and which is synchronously pumped by the second-harmonic of an acousto-optically mode-locked cw Nd: YAG laser is discussed.
Abstract: The generation of pulsed squeezed light using an optical parametric oscillator (OPO) is discussed. This mode-locked optical parametric oscillator consists of a nonlinear crystal in a cavity which is resonant for both signal and idler waves and which is synchronously pumped by the second-harmonic of an acousto-optically mode-locked cw Nd: YAG laser. The fundamental wavelength of the pump laser provides local oscillator pulses for balanced homodyne detection of squeezed vacuum pulses emitted by the oscillator when operated below oscillation threshold. Photocurrent noise reduction to 30% below the classical shot-noise limit is observed, corresponding to squeezing of the field to a level approximately a factor of two below the mean square vacuum noise.

Journal ArticleDOI
TL;DR: In this article, the effect of an alternating magnetic field of low frequency ω on a cylindrical tank of liquid metal was analyzed and the stability regions associated with this system were discussed and it was shown that the most easily excited transition to a non-axisymmetric mode is subharmonic.
Abstract: This paper analyses the effect of an alternating magnetic field of low frequency ω on a cylindrical tank of liquid metal. Previous work with higher-frequency fields has focused attention on the mean recirculating motion, but in the low-frequency limit periodic motion and surface waves become important. We show that a system of forced standing axisymmetric waves of frequency 2ω is established, and that the growth of non-axisymmetric modes is governed by a coupled system of Mathieu-type equations. The stability regions associated with this system are discussed and it is shown that the most easily excited transition to a non-axisymmetric mode is subharmonic, with frequency ω. Comparison with experiment shows that the theory gives qualitatively correct predictions.

Journal ArticleDOI
TL;DR: In this paper, an analytic theory of nonlinear effects in the Z-oscillation (axial motion) during off-resonance excitation is proposed based on a representation of electric potential in an ion cyclotron resonance cell in the fourth order approximation.
Abstract: An analytic theory of nonlinear effects in the Z-oscillation (axial motion) during off-resonance excitation is proposed. This theory is fbased on a representation of electric potential in an ion cyclotron resonance cell in the fourth-order approximation. Z-oscillation is considered as a parametric oscillation with a defined motion in the plane of the magnetic field. It is shown that a peculiarity of ion motion due tocoupling of axial and radial motions can be understood in terms of the stability of the Mathieu equation common to the dthree-dimensional quadrupole ion trap (quistor). Analytic expressions relating parameters (A, Q) of the dMathieu equation to the coefficients of electric potential expansion in the cell are obtained. The strongest coupling effects arise when the frequency of excitation differs from the base cyclotron frequency bytwice the value of the effective frequency of Z-oscillation that correof parametric resonance in Z-oscillations.


Journal ArticleDOI
TL;DR: In this article, a resonant tunnel diode (RTD) oscillator can be optically tuned, frequency modulated, and injection locked over a 150 kHz bandwidth with a laser diode via fibre optics.
Abstract: Preliminary results indicate that a resonant tunnel diode (RTD) oscillator can be optically tuned, frequency modulated, and injection locked. Experiments were performed in which a 2.8 GHz RTD oscillator was frequency modulated from DC to 100 MHz and injection locked over a 150 kHz bandwidth with a laser diode via fibre optics.

Book
01 Jan 1992
TL;DR: In this article, the authors presented a prototype of a tunnel junction made of high-Tc superconductors for high-temperature superconducting transformers with high-frequency noise.
Abstract: I High-Tc Superconducting Devices.- Toward a Technology of Electronic Circuits with High-Tc Superconductors.- Physics of Josephson Junctions Made of High-Tc Superconductors.- Towards Real HTS Tunnel Junctions.- NS Boundaries and the Proximity Effect in Metal - YBCO Junctions.- In-Situ YBa2Cu3O7/SrTiO3/YBa2Cu3O7 a-b Plane Josephson Edge Junctions.- Fine Structure in the Tunneling Characteristis of Bi-Sr-Ca-Cu-O:Pb.- Suppression of Magnetic Flux Noise in YBa2Cu3O7?x Flux Transformers.- Anomalous Properties of Weak-Link-Containing Superconductors: Flicker Noise.- Exotic Manifestations of Intrinsic High-Tc Interferometer Loops.- Percolation and Josephson Effects in High-Tc Polycrystalline Thin Films.- Observation of Magneto-Thermoelectric Effects in High-Tc Superconducting Tl2Ba2CaCu2Ox Single Crystals.- Enhancement of the Superconducting Transition Temperature of Y-Ba-Cu-O Thin Films by Silver Over-Layer Deposition.- High-Temperature Ceramic RF-SQUIDs.- A Compact High-Tc RF-SQUID System with Reduced Tank Circuit Damping.- High-Tc RF-Biased SQUID Magnetometers.- Performance of BSCCO Thick Film RF-SQUIDs.- Two-Loop Y-Ba-Cu-O RF-SQUID Magnetometer.- YBCO/PBCO/YBCO Edge Junctions and DC-SQUIDs.- Reproducible High-Tc SNS Josephson Junctions and DC-SQUIDs.- High-Tc Epitaxial Junctions and DC-SQUIDs.- Multilayer YBa2Cu3Ox Structure - An Approach to SQUID Applications.- DC-SQUID with Step Edge Junctions on (100) SrTiO3.- YBa2Cu3Ox DC-SQUIDs on Y-ZrO2 Bicrystals.- YBCO Thin Films SQUIDs Fabricated on Bicrystal Substrates.- Sub-Micron YBa2Cu3O7-? Grain Boundary Junction DC-SQUIDs.- Thin Film BiPbSrCaCuO DC-SQUIDs Operating at 78 K.- Thin Film High-Temperature Superconducting Flux Transformers Coupled to SQUIDs.- YBa2Cu3O7-? Thin Film Flux Transformers Made by Wet Etching.- Progress Towards an Integrated HTS SQUID Magnetometer.- Light Detection Using High-Tc Microstrip Lines.- The Superconducting Flux How Transistor: Models and Applications.- Preliminary Studies of HTS Far-Infrared Micro-Bolometers.- Current Injected Thick Film HTS Magnetic Sensors.- II Low-Tc Devices.- Comparative Study on Two All-Refractory Josephson Tunnel Junctions: Nb/AlOx/NB and Nb/NbN/MgO/NbN/Nb.- Preparation and Characteristics of Full-Epitaxial NbCxN1?x/MgO/NbCxN1?x Josephon Tunnel Junctions.- Lead/Bismuth- and Niobium-Based SIN Tunnel Junctions.- Relation Between Tunnel Junction Quality, Anodization Profiles, and Low-Frequency Noise.- Submicron Sized, High Current Density Nb/PbBi Window Tunnel Junctions.- Barrier-Properties of All-Niobium Tunnel Junctions.- Fabrication and Performances of NbZr/Oxide/NbZr Thin Film Josephson Junctions.- Some Aspects in the Tunneling Behavior of Photosensitive Junctions.- Construction and Performance of Wire-Junction RF-SQUIDs.- Self-Consistent Theory of the Voltage-Current Characteristic and Intrinsic Noise of the Hysteretic RF-SQUID.- An Analysis of Non-Linear Behaviour in the Radio Frequency SQUID Magnetometer.- Low Noise UHF Thin Film SQUID with Cryogenic HEMT Preamplifier.- Design and Fabrication Considerations for Extending Integrated DC-SQUIDs to the Deep Sub-Micron Regime.- Nb-AlOx-Nb SNAP Technology for 125 mm Wafers Developed in Partnership with Silicon Technology.- DC-SQUIDs Fabricated with Nb/Al-oxide/Nb Tunnel Junctions.- A Compact Very Low Noise DC-SQUID Magnetometer.- A Low Noise DC-SQUID Based on Nb/Al-AlOx/Nb Josephson Junctions.- DC-SQUID with Aluminium Microbridges far from Tc.- Accurate Determination of the Electrical Parameters of Thin Film SQUID Structures and Simulation of DC-SQUIDs with Coupling Coils.- RF Properties of a DC-SQUID Coupled to a Multiturn Input Coil.- Resonances in All-Niobium DC-SQUIDs.- Noise in All-Niobium DC-SQUIDs.- Noise Measurements on DC-SQUIDs with Varied Design.- Noise Properties of NbN-MgO-NbN SQUIDs.- Noise Studies of Uncoupled DC-SQUIDs.- The Laser Switch in SQUID Measurements: Fundamental Experiments and Low Frequency Noise Reduction.- A New DC-SQUID System with 2f-Demodulation.- Relaxation Oscillating SQUIDs Using Nb/AlOx/Nb Josephson Tunnel Junctions.- DC-SQUID Electronics Based on Adaptive Noise Cancellation and a High Open-Loop Gain Controller.- Investigation of a Double-Loop DC-SQUID Magnetometer with Additional Positive Feedback.- Switching Probability and Performance in Single-Chip SQUIDs.- Digital CMOS Circuits Below 100 K.- III Applications.- Fluxons in Josephson Transmission Lines.- Phase Locking in Long Josephson Junctions.- Soliton Chains in Annular Josephson Junctions: Experiments.- Coupled Josephson Soliton Oscillators.- A 500 GHz Quasi-Optical Slot Antenna SIS Mixer.- Numerical and Experimental Results on Josephson Junctions Irradiated by a Biharmonic Drive.- Phaselocked States in Josephson Junction Resonator Systems.- Microwave Properties of Josephson Junctions Strongly Coupled to Microstrip Resonators.- Multiloop Integrated DC-SQUID Low Noise RF Amplifiers.- Subharmonic Pumping and Noise Properites of the Josephson Parametric Amplifier.- Imaging of Self-Resonant and RF-Induced States in Josephson Junctions.- 1 V and 10 V Josephson Voltage Standards.- Ratio Standard for DC Resistance Using a Second Generation of Josephson Junction Arrays.- Superconducting Instrumentation for Precision Measurement and Control.- Use of a Resistive SQUID for Noise Thermometry.- Analysis of a Josephson Junction Noise Thermometer with a DC-SQUID Preamplifier.- Review on Superconducting Tunnel Junctions as Ionizing-Radiation Detectors.- Particle Detection with Superconducting Tunnel Junctions-Modelling the Non-Equilibrium State Generated by Particle Interactions.- A Calorimetric Particle Detector Using a SQUID Monitored Transition Edge Thermometer.- Multichannel Instrumentation for Biomagnetism.- Design and Operation of a Biomagnetic Multichannel System.- Biomagnetic Multi-Channel System Consisting of Several Self-Contained Autonomous Small-Size Units.- A Modular 19-Channel SQUID System for Biomagnetic Measurements.- On the SQUID-Modules for the UT Multichannel Neuromagnetometer.- 11-Channel Multipurpose Biomagnetic System for Operation in Unshielded Environment.- A New Method of Adjusting Bias Currents of Neuromagnetometers.- Active Shield with SQUID for Biomagnetic Measurement.- Active Magnetic Shielding Support for Biomagnetic Instruments.- Performance of an Electronic Gradiometer in Noisy Environments.- Gradiometer Response Analysis for Current Multipole Sources.- Analyzing Multichannel Magnetometer Data.- Measurements on Magnetic Samples with a DC-SQUID Working at mK Temperatures in Magnetic Fields up to 6 mT.- A Miniature DC-SQUID Magnetometer with Current Injection Feedback.- The DC-SQUID Amplifier for the NAUTILUS Gravitational Wave Detector at CERN: Preliminary Measurements.- An Improved System for the Nondestructive Evaluation of Steel.- Improved Techniques for Structural NDT Using SQUIDs.- Application of DC-SQUID Magnetometers for Nondestructive Testing of Multilayer Electronic Cards.- Characterization of Normal/Superconducting Interfaces: A Novel Technique.- Transistor Action in Three-Terminal Structures Having Nb Electrodes on an Insulating SrTiO3 Substrate.- IV Summary and Conclusions.- Summary and Conclusions.- Index of Contributors.

Journal Article
TL;DR: In this article, the authors derived quantum solutions of a generalized inverted or repulsive harmonic oscillator with arbitrary time-dependent mass and frequency using the quantum invariant method and linear invariants, and wrote its wave functions in terms of solutions of the second-order ODE that describes the amplitude of the damped classical inverted oscillator.
Abstract: We derive quantum solutions of a generalized inverted or repulsive harmonic oscillator with arbitrary time-dependent mass and frequency using the quantum invariant method and linear invariants, and write its wave functions in terms of solutions of a second-order ordinary differential equation that describes the amplitude of the damped classical inverted oscillator. Afterwards, we construct Gaussian wave packet solutions and calculate the fluctuations in coordinate and momentum, the associated uncertainty relation, and the quantum correlations between coordinate and momentum. As a particular case, we apply our general development to the generalized inverted Caldirola–Kanai oscillator.

Journal ArticleDOI
01 Apr 1992-Chaos
TL;DR: A new path to chaos, called a disruption bifurcation, is the source for intermittency in the ACRO when the amplitude of internal resonances is excited to the degree that existing limit cycles are disrupted.
Abstract: If a harmonic oscillator is embedded in a relaxation oscillator, the resulting system may behave like an autonomous chaotic relaxation oscillator (ACRO). The discharge transient of the relaxation oscillator excites sinusoidal oscillations in the harmonic oscillator and these sinusoids affect when the next discharge occurs. This can lead to chaotic intervals in the oscillator periods. A simple electronic model of the ACRO is studied over a wide range of parameters using numerical, analytic, and experimental techniques. The dynamics of the ACRO is found to be determined by three parameters: (1) tuning, (2) coupling, and (3) damping. Complex, intermittent outputs can always be inhibited by increasing the damping of the harmonic oscillator. For weak damping, strong coupling yields chaotic periods. With weak damping and weak coupling, complex behavior only occurs if the relaxation oscillator is tuned near a resonance of the harmonic oscillator. A new path to chaos, called a disruption bifurcation, is the source for intermittency in the ACRO. This bifurcation occurs when the amplitude of internal resonances is excited to the degree that existing limit cycles are disrupted.

Patent
04 Dec 1992
TL;DR: In this paper, a cylindrical cavity resonator and a coil 14 modulating the magnetic field are provided, and a micro-wave f generated from a microwave oscillator 16 is supplied through an isolator 18 and a subsequent attenuator 20 and then a circulator 24 to the cavity resonance, where the oscillation output of a modulating frequency oscillator 42 is supplied to the coil 14.
Abstract: In a fixed polarized magnetic field generated by permanent magnets 10, a cylindrical cavity resonator 12 and a coil 14 modulating the magnetic field are provided. A micro-wave f generated from a micro-wave oscillator 16 is supplied through an isolator 18 and a subsequent attenuator 20 and then a circulator 24 to the cavity resonator. The oscillation output of a modulating frequency oscillator 42 is supplied to the coil 14. A movable end plate 60 is moved by a driving feature 58 to vary the resonance frequency f 0 for a detection thereof and a subsequent negative feed back to a micro-wave oscillator 16 through a circuit comprising a low frequency amplifier 48, a phase detector 50, a low frequency oscillator 54, a phase shifter 56 and a micro-wave oscillator power source 52 thereby the micro-wave frequency f is so swept as to be maintained to be equal to the resonance frequency f 0 .

01 Jan 1992
TL;DR: In this paper, the authors describe the design of a synthesized local oscillator for a rubidium [Rb] passive frequency standard pumped by radiation from a diode laser, which operates at room temperature.
Abstract: We describe the design of a synthesized local oscillator for a rubidium [Rb] passive frequency standard pumped by radiation from a diode laser. The design goals for this new oscillator are: 1) To operate at room temperature,

Proceedings ArticleDOI
10 Jun 1992
TL;DR: In this article, an injection-locked parametric oscillator based on a nonlinear LBO crystal pumped by XeCl- and dye-laser systems was developed for femtosecond pulses at high intensity.
Abstract: The parametric down conversion of femtosecond pulses at high intensity is discussed. An injection-locked parametric oscillator based on a nonlinear LBO crystal pumped by XeCl- and dye-laser systems is developed. The nonlinear refractive index n2 approximately equals 1.7 10-16 cm2/W and the optical surface breakdown threshold Ibr approximately equals 3.8 1013 W/cm2 of LBO crystal for approximately 400 fsec pulses were measured. The spatial dispersion of effective nonlinearity deff2/n3 for parametric amplification in LBO crystal is calculated. The design and performance of femtosecond dye- laser system and XeCl-excimer-laser system capable of producing a focused intensity in excess of 1016 W/cm2 are described.© (1992) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Patent
02 Oct 1992
TL;DR: In this paper, the arrival of a photon pulse at a parametric amplifier is synchronized by a system clock which also clocks the generation of the data photon pulses in the optical circuits.
Abstract: Amplification and synchronization of photon pulses in optical computing chips is accomplished by placing parametric amplifying devices at predetermined spatial locations in the light conductive paths that make up the optical circuits in the chip. The laser pumping signal for the parametric amplifiers is clocked by a system clock which also clocks the generation of the data photon pulses in the optical circuits. By synchronizing the arrival of a pumping pulse with the arrival of the photon pulse at a parametric amplifier, the data pulse can be amplified, reshaped and resynchronized. The pumping pulse can be directed to the spatially located parametric amplifiers on the chip in a number of different ways. The chip could be masked except for the parametric amplifiers, and the entire chip could be illuminated by the pumping laser though collimating lens. If the chip is not masked, then pumping light must be directed only to the parametric amplifiers. This could be done with a hologram to spatially distribute the light beams to the amplifiers. Alternatively, the beam from the pumping laser could be piped by light conducting fibers to the parametric amplifiers with light pipes. Further, the light pipes for the pumping pulses could be light conducting channels in a second optical chip, or an additional optical circuit layer.

Journal ArticleDOI
TL;DR: In this paper, it was shown that the virtual cathode can generate narrowband (03% bandwidth) microwave pulses when the virtual cathode is surrounded by a resonant cavity and is driven by an appropriate electron beam.
Abstract: Experiments at the microsecond pulse length have demonstrated that the virtual-cathode oscillator generates narrowband (03% bandwidth) microwave pulses when the virtual cathode is surrounded by a resonant cavity and is driven by an appropriate electron beam This result is a significant departure from the behavior of a free-running virtual-cathode oscillator where the frequency depends on the (current density)/sup 1/2/ The long-pulse experimental results are described >

Journal ArticleDOI
TL;DR: A novel mechanism for strong ion heating inside magnetized sheaths, formed at plasma-wall interfaces in radio-frequency-driven plasmas, is studied.
Abstract: A novel mechanism for strong ion heating inside magnetized sheaths, formed at plasma-wall interfaces in radio-frequency-driven plasmas, is studied. The ion gyration frequency is modulated by the oscillating charge density inside the sheath, resulting in a Hill-type parametric equation of motion. The gyration velocity is unstable when the time-averaged gyrofrequency Ω is near a subharmonic nω/2 of the rf frequency. Large energy absorption occurs within only a few gyrations because of the initial exponential growth