共查询到20条相似文献,搜索用时 15 毫秒
1.
P. Mathey M. Grapinet H. R. Jauslin B. Sturman D. Rytz S. Odoulov 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,39(3):445-451
A general analysis of the threshold behavior for the
photorefractive semi-linear oscillator is performed within the
linear approximation on the basis of the classical wave-coupling
model. This analysis shows that the well known particular results
on the frequency degenerate oscillation are valid only within a
restricted range of the external parameters. The theory specifies
the conditions for onset and properties of the frequency
non-degenerate oscillations, including the necessary values of the
coupling strength, pump intensity ratio, the increments of the
instability, and the frequency splits. Important generalizations
of the basic model are considered. 相似文献
2.
P. Mathey 《Applied physics. B, Lasers and optics》2005,80(4-5):463-469
The oscillation intensity of a semilinear photorefractive oscillator with reflection gratings is calculated for different cavity losses, different pump intensity ratios and different crystal orientations. Distinct from an oscillator with transmission gratings, this oscillator always has a soft excitation in the vicinity of the threshold. The theoretical results are in reasonable agreement with that of experimental studies with BaTiO3:Co as a photorefractive crystal.This revised version was published online in March 2005. In the previous version, the published online date was missing 相似文献
3.
B.I. Sturman A.S. Gorkunova K.H. Ringhofer 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,23(2):291-297
We investigate analytically and numerically the influence of the type of the photorefractive nonlinear response on the periodic
states (attractors) which occur during feedback controlled 2W-coupling and correspond to almost 100% diffraction efficiency
of the dynamic index grating. In addition to the case of the local response typical, for example, for LiNbO3 crystals we consider the cases of nonlocal (diffusive) response (BaTiO3, SBN) and resonant response (DC-biased BSO, BTO, and BGO crystals). It is shown that the conditions for the transition to
the periodic states and their apparent characteristics are strongly different for the two limiting cases above.
Received 16 July 2002 / Received in final form 29 October 2002 Published online 4 March 2003 相似文献
4.
S. S. Hassan H. A. Batarfi R. Saunders R. K. Bullough 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,8(3):403-416
A time-independent theoretical and numerical analysis of an optical bistable model of two-level atoms in a ring cavity, driven
by a coherent field and in contact with a squeezed vacuum field is presented in the two cases of absorptive and dispersive
optical bistability (OB). In the former case, a suitable choice of the phase of the squeezed vacuum field reduces the threshold
for OB to occur compared with the normal vacuum case. In the latter case, regions of OB are identified as one or two disconnected
simple closed curves depending on the cooperation parameter [0pt] : is the maximum possible value of the critical value of C at fixed values of the squeezed vacuum field parameters. Phase switching effects between different (output) states of the
system is investigated in detail. In the absorptive case, one- or two-way optical switching is possible depending on [0pt]
. We also present results which demonstrate more complicated switching behaviour in the dispersive case.
Received 12 March 1999 and Received in final form 20 August 1999 相似文献
5.
H. A. Batarfi S. S. Hassan R. Saunders R. K. Bullough 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,8(3):417-429
Linear stability analysis and (numerical) investigation of the periodic and chaotic self-pulsing behaviour are presented for
the Maxwell-Bloch equations of a bistable model in contact with a squeezed vacuum field. Effect of the squeeze phase parameter
on the period doubling bifurcation that preceeds chaos is examined for the adiabatic and non-adiabatic regimes. 相似文献
6.
We show theoretically that thermomechanical effects in dye-doped nematic liquid crystals when illuminated by laser beams,
can become important and lead to molecular reorientation at intensities substantially lower than that needed for optical Fréedericksz
transition. We propose a 1D model that assumes homogenous intensity distribution in the plane of the layer and is capable
to describe such a thermally induced threshold lowering. We consider a particular geometry, with a linearly polarized light
incident perpendicularly on a layer of homeotropically aligned dye-doped nematics. 相似文献
7.
M. Darwish 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,41(3):547-556
Theoretical investigations of dynamical behavior in optical
parametric oscillators (OPO) have generally assumed that the cavity
detunings of the interacting fields are controllable parameters.
However, OPOs are known to experience mode hops, where the system
jumps to the mode of lowest cavity detuning. We note that this
phenomenon significantly limits the range of accessible detunings
and thus may prevent instabilities predicted to occur above a
minimum detuning from being evidenced experimentally. As a simple
example among a number of instability mechanisms possibly affected
by this limitation, we discuss the Hopf bifurcation leading to
periodic behavior in the monomode mean-field model of a triply
resonant OPO and show that it probably can be observed only in very
specific setups. 相似文献
8.
S. Zhu J. Fang X. Luo 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,18(1):123-128
A linear array of three lasers that are coupled mutually in space is investigated. It is shown that the phase of the laser
fields is locked with intermediate coupling while the laser intensities are totally chaotic and chaotically synchronized.
When the intensities of lasers reenter the regime of chaotic synchronization at smaller coupling constant, the laser fields
show low degree of phase locking. The phase differences in the fields between three lasers show rich patterns when the coupling
is changed.
Received 3 August 2001 and Received in final form 27 September 2001 相似文献
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11.
We study theoretically the dynamical reorientation phenomena when a long-pitch cholesteric liquid-crystal film with homeotropic alignment is illuminated by a circularly polarized lightwave. In the present case, the natural cholesteric pitch is of the order of (or larger than) the film thickness. The helical cholesteric structure is thus frustrated by the boundary conditions without illumination. However, above a light intensity threshold reorientation occurs and the bifurcation scenario depends strongly on the natural cholesteric pitch. Recalling that a long-pitch cholesteric is achieved in practice by adding a small amount of chiral agents in a nematic liquid crystal, the observed dynamics can be viewed as the result of the competition between intrinsic and extrinsic unidimensional helical patterns. The intrinsic part consists of the helical deformations induced by the chirality of the dopant, whereas the extrinsic part is related to the chirality induced by the optical field through the non-uniform angular momentum transfer of light to a nematic. The all-optical analog in the case of a pure nematic (without chiral dopant), is also discussed. 相似文献
12.
F. Bassani V. Lucarini 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,12(3):323-330
The nonlinear oscillator model is useful to basically understand the most important properties of nonlinear optical processes.
It has been shown to give the correct asymptotic behaviour and to provide the general features of harmonic generation to all
orders, in particular dispersion relations and sum rules. We investigate the properties of pump and probe processes using
this model, and study those cases where general theorems based on the holomorphic character of the Kubo response functions
cannot be applied. We show that it is possible to derive new sum rules and new Kramers-Kr?nig relations for the two lowest
moments of the real and of the imaginary part of the third order susceptibility and that new specific contributions become
relevant as the intensity of the probe increases. Since the analytic properties of the susceptibility functions depend only
upon the time causality of the system we are confident that these results are not model dependent and therefore have a general
validity, provided one substitutes for the equilibrium values of the potential derivatives the density matrix expectation
values of the corresponding operators.
Received 25 January 1999 and Received in final form 26 April 1999 相似文献
13.
M.L. Ramón R. Meucci M. Ciofini A. Labate L. Calero 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,11(1):137-141
The formation and stabilization of spatio-temporal patterns in an annular CO2 laser is studied. We give experimental and numerical evidence of the role of a small spatial perturbation (consisting of
a thin metallic wire inserted in the optical cavity) in the selection and stabilization of patterns.
Received 15 December 1999 相似文献
14.
M.L. Ramón R. Meucci E. Allaria S. Boccaletti 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,12(2):329-337
Competition among modes in an annular CO2 laser has been experimentally and numerically analyzed. During the coexistence of different patterns, each of them resulting
from the interaction of two transverse modes with opposite angular momentum, chaos has been experimentally detected. A numerical
model, derived from the Maxwell-Bloch equations and including symmetry breaking terms, enables the interpretation of the main
experimental features.
Received 10 March 2000 相似文献
15.
L. K. Jha S. Kumar B. N. Roy 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,39(1):101-106
Stable two-mode, and three-mode oscillations due to the spatial hole burning
effect were observed experimentally with the increase of the pump power
ratio in a laser-diode pumped sub-nanosecond microchip Cr,Yb:YAG
self-Q-switched multimode laser. The stability of the output pulse trains
was attributed to the mode coupling through antiphase dynamics between
different modes. Modified multimode rate equations including the spatial
hole-burning effect in the active medium and the non-linear absorption of
the saturable absorber were proposed. Numerical simulations of the antiphase
dynamics of such a laser were in good agreement with the experimental data,
and the antiphase dynamics were explained by the evolution of the inversion
population and the bleaching and recovery of the inversion population of the
saturable absorber. 相似文献
16.
L. Wu S. Zhu Y. Ni 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,41(2):349-354
Combination of two basic types of synchronization, anticipatory
synchronization and lagged synchronization, is investigated
numerically between two coupled semiconductor lasers. It is found
that lagged synchronization produced by a backward coupling with a
suitable delay can combine with the originally hidden anticipatory
synchronization and produce a type of synchronization overcoming the
original lagged synchronization produced by a forward coupling. We
study the combination synchronization phenomenon when the delay of
the backward coupling is different from that of the original
anticipatory synchronization. Our results suggest that the
synchronization combination phenomenon might allow an interpretation
of an experimental observation by Sivaprakasam et al. [Phys.
Rev. Lett. 87, 154101 (2001)] that the anticipating time is
irrespective of the external-cavity round trip time, which to date remains to be understood. 相似文献
17.
C. Szwaj G.-L. Oppo A. Gatti L.A. Lugiato 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,10(3):433-448
Quantum images, that is inhomogeneous field distributions purely generated by quantum fluctuations, persist when passing from
the degenerate to the non-degenerate case of optical parametric oscillators (OPO). Below the threshold for parametric oscillation
where the near-field distributions are homogeneous both in intensity and phase, appropriate spatial correlation functions
anticipate the transverse spatial pattern that appears above threshold. In particular, the angular dependence of the far field
spatial correlation function is able to reveal the travelling-wave nature of the phase pattern above threshold typical of
nondegenerate OPOs. Cross-correlation functions between signal and idler intensities show clear evidence of the non-classical
nature of the output light.
Received 8 October 1999 相似文献
18.
The effects of pump phase modulation on noise characteristics of
fiber optical parametric amplifiers
M. Gao C. Jiang W. Hu J. Wang H. Ren 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,40(3):431-436
This paper investigates the effects of pump phase
modulation (PM) on the noise characteristics of fiber optical parametric
amplifiers (FOPAs) theoretically. The results show that the effect of the
pump PM on the noise of FOPAs can be diminished by adjusting the structural
parameters of amplifiers properly. The parameters of the pump phase
modulation are optimized with several methods to reduce the noise of FOPAs. 相似文献
19.
The pulse shape of a passively Q-switched microchip laser 总被引:2,自引:0,他引:2
T. Erneux P. Peterson A. Gavrielides 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,10(3):423-431
The shape of the intensity pulse of a passively Q-switched microchip laser is investigated numerically and analytically. Our
analysis is motivated by independent microchip laser experiments exhibiting nearly symmetric pulses in the case of a semiconductor
saturable absorber and asymmetric pulses in the case of a solid state saturable absorber. Asymptotic methods are used to determine
limiting behaviors of the pulse shape for both symmetric and asymmetric pulses. In the first case, we determine a sech2 solution parametrized by one parameter which can be determined by solving two coupled nonlinear algebraic equations. In the
second case, the pulse solution is decomposed into two distinct approximations exhibiting different amplitude and time scales
properties. We review earlier approximations of the repetition rate and the pulse width.
Received 2 August 1999 相似文献
20.
S. Longhi 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,17(1):57-66
Multiphase patterns are found in a mean-field model of a singly-resonant optical parametric oscillator that converts a pump
field at frequency 3ω into signal and idler fields at frequencies 2ω and ω. A complex Ginzburg-Landau equation without diffusion
and with a quadratic phase-sensitive nonlinear term is derived under single-longitudinal and paraxial propagation approximations.
Owing to the phase-matched multistep parametric process ω + ω = 2ω, phase locking of the resonated signal field is possible
with three distinct phase states. Three-armed rotating spirals, target patterns and light filamentation are found by a numerical
analysis of the mean-field equation.
Received 19 April 2001 and Received in final form 21 June 2001 相似文献