Single-mode, singly resonant, pulsed periodically poled lithium niobate optical parametric oscillator

We report single longitudinal mode operation of a pulsed Nd:YAG pumped periodically poled lithium niobate optical parametric oscillator (OPO). The combination of a prism and an etalon provides both coarse and fine spectral resolution, thereby eliminating parasitic resonant oscillation of cascaded signal wavelengths, idler wavelengths, and adjacent longitudinal modes of the signal field. Optical bandwidths of less than 300 MHz have been obtained at signal wavelengths between 1.47 and 1.59 mum. In comparison with broadband operation, the single-mode OPO shows only a 9% reduction in pump depletion with a negligible reduction in extraction efficiency.     

Chaotic RF pulses generated by a periodically driven oscillator

The effect of a periodic drive signal on a chaotic rf oscillator is considered. The possibility to obtain chaotic pulse trains (rf pulses) of a preset duration is experimentally demonstrated.     

Second-harmonic generation in optically trapped nonlinear particles with pulsed lasers

Pulsed lasers are used for simultaneous single-beam three-dimensional optical trapping of and second-harmonic generation in 50-100-nm nonlinear particles. The emission power of the frequency-doubled light, the trapping stability, and the particle degradation are investigated for KTP and LiNbO(3) particles trapped by 25-kHz-repetition-rate Q-switched Nd:YAG and 76-MHz mode-locked Ti:sapphire l a s e r s . Typically 1 pW-10 nW of frequency-doubled light is detected from stably trapped particles. The particles may be used as probes for nonintrusively scanned near-field optical microscopy.     

Resonant dynamics of a periodically driven noisy oscillator

A unified approach to study the dynamics of single degree of freedom systems excited by both weakly periodic and random additive perturbations is developed. The near-resonant motion of such systems is not well understood. This problem is studied with the aim of discovering a common geometric structure in the phase space, and determining the effects of noisy perturbations on the passage of trajectories through the resonance zone. We consider the noisy, periodically driven Duffing equation as a prototypical single degree of freedom system and achieve a model-reduction through stochastic averaging. The solution of the reduced model can be approximated by a Markov process. Depending on the strength of the noise, the reduced Markov process takes its values on a line or on a graph with certain gluing conditions at the vertices of the graph. The reduced model provides a framework for computing standard statistical measures of dynamics and stability such as probability density functions. This work also explains a counter-intuitive phenomenon in stochastic resonance, in which a weak periodic forcing in a nonlinear system can be enhanced by the addition of external noise.     

Fock states generation in a kicked cavity with a nonlinear medium

Abstract

We discuss a model of a cavity filled with a passive nonlinear ?Kerr‘ medium and periodically kicked by a series of ultra-short laser pulses. The nonlinear medium is described by the (2q ? 1)th nonlinearity X ^(2q?1). We find analytical formulas describing the field states inside the cavity. We show that such a system can produce, depending on the order of the nonlinearity, superpositions of several Fock states with the small photon numbers (0,1; 0,1,2; etc). In particular, the one-photon state can be approached during the evolution of the system with X ⁽³⁾ nonlinearity provided the cavity losses are negligible. The purity of states generated in this process, however, can be seriously degraded by the cavity damping. We perform numerical calculations to validate our analytical results.     

Characterization of a periodically poled lithium niobate optical parametric oscillator pumped by a Bessel beam

Abstract

A Bessel beam pumped periodically poled lithium niobate optical parametric oscillator has been characterized. A slope efficiency of 5.4 ± 0.1% was obtained and a threshold pulse energy of 472 ± 12 μJ was measured, which corresponds to a threshold fluence of 0.207 ± 0.005 J cm^?2. The signal output was tuned over ～20 nm by changing the crystal temperature by 50°C. The FWHM bandwidth at each temperature was observed to be 0.3 ± 0.1 nm at each wavelength. The beam profiles of the Bessel pump and Gaussian signal beams were studied in both the near and far field. A beam divergence of 1.14 ± 0.02 mrad was measured.     

Properties of an oscillator slaved to a periodically interrogated atomic resonator

In advanced atomic resonators, such as those using a fountain of cold cesium atoms or an ensemble of stored ions, the atomic medium is interrogated periodically, and the control signal of the slaved oscillator is updated at equally spaced time intervals. We analyze the properties of the output frequency of these frequency standards. We establish the equations that describe the time behavior of this frequency. We give the stability condition and the transient response of the frequency feedback loop, the response to systematic frequency changes of the free running oscillator, the frequency stability for given free-running oscillator noise and given optical detection noise, and the limitation of the frequency stability by down-conversion of the intrinsic oscillator frequency noise (Dick effect). We point out that a second integration in the feedback loop may not improve significantly the rejection of slow perturbations, unless a condition relative to the timing of the atom-field interaction is verified.     

非线性分数阶微分振子的动力学研究

本文结合Zhang—Shimizu法与Newmark法，解决了二次非线性的Riemann—Liouville分数导数中奇异性问题，从而得到了非线性分数微积分求解的单步数值积分算法。在此基础上对某型非线性分数阶微分振子的动力学行为进行研究，分别讨论了振子自由振动及强迫振动下参数变化对振子非线性特性的影响。数值计算结果表明，该数值方法具有较好的稳定好，收敛速度快，精度较高，编程简单容易等优点。     

Chaos in a particular nonlinear oscillator

Summary This paper presents an analysis of new dynamical phenomena using the example of the simple nonsymmetrical anharmonic oscillator. Strange attractors are detected near the critical values of parameters obtained earlier using an approximate analytical method. Long transitional chaotic phenomena, sudden qualitative changes in chaotic dynamics with evolution of chaotic attractors are discussed and illustrated.With 4 Figures     

Noise-induced parametric oscillations in nonlinear oscillator

The onset of stochastic oscillations in a nonlinear oscillator with a noise-modulated frequency is considered. It is demonstrated that these oscillations are characterized by the existence of an attractor (i.e., are independent of the initial conditions), but do not exhibit the phenomenon of synchronization typical of self-oscillatory systems.     

Single-mode near-infrared optical parametric oscillator amplifier based on periodically poled KTiOPO4

A singly resonant, single-axial-mode, optical parametric oscillator (OPO) based on periodically poled KTiOPO(4) (PPKTP) is reported. Signal (1.68 mum) and idler (2.90 mum) optical bandwidths have been narrowed to <400 MHz by use of a diffraction grating at grazing incidence. The OPO generates 370 muJ of signal radiation when pumped by 3.1 mJ of 1.064-mum radiation. We implemented a single-pass PPKTP amplifier to yield 2.15-mJ signal and 1.17-mJ idler radiation without broadening the spectral bandwidths.     

Second generation 50 K dual-mode sapphire oscillator

Low-temperature, high-precision sapphire resonators exhibit a turning point in mode frequency-temperature dependence at around 10 K. This, along with sapphire's extremely low dielectric losses at microwave frequencies, results in oscillator fractional frequency stabilities on the order of 10(-15). At higher temperatures the lack of a turning point makes single-mode oscillators very sensitive to temperature fluctuations. By exciting two quasi-orthogonal whispering gallery (WG) modes in a single sapphire resonator, a turning point in the frequency-temperature dependence can be found in the beat frequency between the two modes. A temperature control technique based on mode frequency temperature dependence has been used to maintain the sapphire at this turning point and the fractional frequency instability of the beat frequency has been measured to be at a level of 4.3 X 10(-14) over 1 s, dropping to 3.5 X 10(-14) over 4 s integration time.     

Frequency stability degradation of an oscillator slaved to a periodically interrogated atomic resonator

Atomic frequency standards using trapped ions or cold atoms work intrinsically in a pulsed mode. Theoretically and experimentally, this mode of operation has been shown to lead to a degradation of the frequency stability due to the frequency noise of the interrogation oscillator. In this paper a physical analysis of this effect has been made by evaluating the response of a two-level atom to the interrogation oscillator phase noise in Ramsey and multi-Rabi interrogation schemes using a standard quantum mechanical approach. This response is then used to calculate the degradation of the frequency stability of a pulsed atomic frequency standard such as an atomic fountain or an ion trap standard. Comparison is made to an experimental evaluation of this effect in the LPTF Cs fountain frequency standard, showing excellent agreement.     

Tunable single-mode operation of a pulsed optical parametric oscillator pumped by a multimode laser

High-quality single-longitudinal-mode (SLM) tunable signal radiation is generated by a pulsed optical parametric oscillator (OPO) pumped by a compact, inexpensive multimode laser. The OPO is based on periodically poled lithium niobate (PPLN) in a ring cavity that is injection seeded at its resonated signal wavelength by a single-mode tunable diode laser. Accurate control of the OPO cavity length and crystal temperature ensures a continuously tunable SLM signal output frequency range of >7.5 THz (>250 cm(-1)); the corresponding idler output remains multimode. High-resolution molecular spectra are recorded to verify OPO performance at wavelengths of ~1.55 mum. The observed signal optical bandwidth of 相似文献   

Two-cell coupled nonlinear chemical oscillator: asymmetric cells

A two-cell coupled chemical oscillator, based on the cubic autocatalator in each cell, isconsidered in the case of different precursor concentrations in each cell. The coupling between the cells is achieved through diffusive interchange of the autocatalyst. It is shown that there is just one stationary state, the stability of which and the positions of Hopf bifurcations are examined for both small and large coupling. In the latter case it isshown that the system is essentially two-dimensional. Numerical results are obtained for general values of the parameters and compared with the previously treated symmetric case.     

Parametrically driven nonlinear oscillator at a few-photon level

Abstract

We consider quantum dynamics of a parametrically driven anharmonic oscillator (PDAO) at a few-photon level. In this scheme the oscillatory mode is excited through the degenerate down-conversion process. This scheme could be experimentally realized in superconducting solid-state devices based on the nonlinearity of the Josephson junction or in cooled nano-mechanical oscillators. We investigate PDAO in the strong quantum regime that means strong Kerr-nonlinearity of the mode with respect to the mode’s dissipation for two cases of excitations: by a monochromatic driving field or by a train of Gaussian pulses. We demonstrate production of the nonclassical oscillatory states with two-fold symmetry in phase-space which are approximately close to the lower pure Fock states. Production of the superposition of the Fock states for time-intervals exceeding the characteristic time of decoherence and dissipation is also shown.     

非线性奇异振子的解析逼近解

利用修正的牛顿-谐波平衡法建立了非线性奇异振子的解析逼近周期和周期解．通过改写控制方程和选取简单、合适的校正项对牛顿-谐波平衡法进行了修正.构造的两个解析逼近周期和周期解不仅在振幅和参数全部取值范围内有效且能快速地收敛到精确解；两个逼近周期与精确周期的百分比误差分别低于0.92%和0.09%，后者比已有结果精度高。     

Evaluating the attractor dimension of a nonlinear oscillator

The correlation dimension of a chaotic attractor of a nonautonomous nonlinear oscillator with variable control parameters is evaluated from experimental data. The dimension of a critical attractor shows good agreement with theoretical data. As the amplitude of the external action is varied, the chaotic attractor exhibits evolution such that the correlation dimension increases from a minimum value, determined by the properties of the critical attractor, to the nearest integer.     

Single-longitudinal-mode scan of a pulsed double-grating Ti:sapphire oscillator

The method of the single-longitudinal-mode (SLM) scan of a pulsed double-grating Ti:sapphire laser oscillator with the grazing incidence cavity configuration was proposed based on the analysis of the optical path length. The SLM scan was experimentally confirmed for this cavity configuration, where the second grating was rotated around an arbitrary point with the translational scan of a back mirror.