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1.
M. Gartz C. Keutgen S. Kuenneke U. Kreibig 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,6(1):127-131
In this paper a detailed experimental study of Coherent Population Trapping (CPT) effect on sodium induced by a dye-laser
operating in a three-mode regime is presented and a detailed analysis of the role of velocity changing collisions is made.
These collisions show a very small relaxation effect on the dark resonances which are visible even at high pressures. For
the first time we demonstrate the persistence of the ground state coherence to pressures up to one atmosphere for a relatively
“heavy” buffer gas like argon. The experimental results have been compared with theory and a very good agreement has been
obtained. Preliminary results on the effect of Na-N2 collisions on Coherent Population Trapping are presented.
Received: 5 October 1998 / Received in final form: 3 December 1998 相似文献
2.
E.A. Korsunsky T. Halfmann J.P. Marangos K. Bergmann 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,23(1):167-180
Four-wave mixing in resonant atomic vapors based on maximum coherence induced by Stark-chirped rapid adiabatic passage (SCRAP)
is investigated theoretically. We show the advantages of a coupling scheme involving maximum coherence and demonstrate how
a large atomic coherence between a ground and an highly excited state can be prepared by SCRAP. Full analytic solutions of
the field propagation problem taking into account pump field depletion are derived. The solutions are obtained with the help
of an Hamiltonian approach which in the adiabatic limit permits to reduce the full set of Maxwell-Bloch equations to simple
canonical equations of Hamiltonian mechanics for the field variables. It is found that the conversion efficiency reached is
largely enhanced if the phase mismatch induced by linear refraction is compensated. A detailed analysis of the phase matching
conditions shows, however, that the phase mismatch contribution from the Kerr effect cannot be compensated simultaneously
with linear refraction contribution. Therefore, the conversion efficiency in a coupling scheme involving maximum coherence
prepared by SCRAP is high, but not equal to unity.
Received 16 August 2002 Published online 4 February 2003
RID="a"
ID="a"e-mail: korsunsky@physik.uni-kl.de 相似文献
3.
F. Plastina F. Piperno 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,6(3):407-413
We examine the decay dynamics of a free four-level system in the -V configuration. Quantum interference strongly manifests itself in this system, as can be seen by looking at the combined spectral
distribution of the two emitted photons and at the time evolution of the intermediate-level populations, whose effective lifetimes
can become very long under certain conditions for the atomic parameters. This effect is attributable to a population transfer
mechanism induced in the time evolution equations by the Fano terms, also responsible for the strong modifications of the
spectral correlation between the emitted photons which we analyze in detail. Finally, population trapping can also occur when
the two intermediate levels are degenerate.
Received: 20 October 1998 相似文献
4.
5.
J. Ruostekoski D.F. Walls 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,5(3):335-339
Two Bose-Einstein condensates in different Zeeman sublevels can be decoupled from driving light fields in coherent population
trapping. A condensate pair with a deterministic entanglement and a controllable value of the relative phase may be prepared
by selecting the phase difference between the coherent light fields. The rate of the condensate phase diffusion may be determined
from the two-photon resonant absorption of radiation.
Received: 29 June 1998 / Revised: 10 October 1998 / Accepted: 19 October 1998 相似文献
6.
H. Xu Z. Dai Z. Jiang 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,17(1):79-83
Ultraviolet and violet upconversion signals at 271 nm, 317 nm, 381 nm and 407 nm were observed when an erbium-doped YAG crystal
was pumped by an Ar+ laser (488 nm). The dependence of intensity of luminescence emitting from the 4S
3/2
state and the 2P
3/2
state on pump power (I) was experimentally investigated. Changes from I1 down to I
1/2
for the 4S
3/2
state and from I2 down to I1 for the 2P
3/2
state were observed. The upconversion mechanism was discussed by means of the rate equations. It appears that energy-transfer
upconversion (ETU) is a dominant process for the Er3+:YAG crystal used in our experiment.
Received 20 March 2001 and Received in final form 11 July 2001 相似文献
7.
C. Ottaviani S. Rebić D. Vitali P. Tombesi 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,40(2):281-296
The interaction of a five-level atomic system involving electromagnetically induced transparency with four light fields is
investigated.
Two different light-atom configurations are considered, and their efficiency in generating large nonlinear cross-phase shifts
compared.
The dispersive properties of those schemes are analyzed in detail, and the conditions leading to group velocity matching for
two of the light
fields are identified. An analytical
treatment based on amplitude equations is used in order to obtain approximate solutions for the susceptibilities, which are
shown to fit well
with the numerical solution of the full Bloch equations in a large parameter region. 相似文献
8.
X.-m. Hu J. Xiong J.-s. Peng 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,13(3):401-413
A theoretical analysis of the spectral linewidth of V-type inversionless and Raman lasers is presented. First, we examine
the effects of the atomic coherence between dressed states and the Autler-Townes splitting on the linewidth. It is demonstrated
that near above threshold, the V inversionless laser has a narrower linewidth than that of the two-level laser. Instead of
the dressed coherence, it is the Autler-Townes splitting that is responsible for the linewidth reduction though the dressed
coherence determines the laser gain. Next, we explore the effects of the generated laser intensity on the linewidth. It is
shown that the linewidths of the V inversionless and Raman lasers follow the usual 1/I decrease for smaller laser intensity I, but a slower decrease than 1/I for larger laser intensity. For the V Raman laser, even more surprisingly, with the laser intensity increasing, the linewidth
appreciably increases as well. As a result, well above threshold, the V inversionless and Raman lasers may have a larger linewidth
than that of the two-level laser. Finally, a comparison is made between the V lasers and the Λ lasers. It is found that the
linewidth of the Λ inversionless laser shows a fast 1/I
2 decay under optimum conditions.
Received 25 October 1999 and Received in final form 10 March 2000 相似文献
9.
F. Levi A. Godone J. Vanier S. Micalizio G. Modugno 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,12(1):53-59
The paper is concerned with the line shapes of resonance phenomena observed in Coherent Population Trapping (CPT) applied
to alkali atoms in a cell containing a buffer gas. Significant asymmetries and departures from a Lorentzian shape have been
observed in connection with the measurement of dark lines and CPT maser emission profiles. Measurements are reported as a
function of the power and frequency tuning of the laser used to create the CPT phenomenon. The paper reports on different
experimental conditions and a comparison between theory and experiments is made for the cases of cesium and rubidium in a
buffer gas.
Received 3 March 2000 and Received in final form 10 April 2000 相似文献
10.
N. Vujičić S. Vdović D. Aumiler T. Ban H. Skenderović G. Pichler 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,41(3):447-454
We present direct observation of the velocity-selective optical pumping of
the Cs ground state hyperfine levels induced by the femtosecond (fs) laser
oscillator centered at either D2 (6 2S1/2↦6 2P3/2,
852 nm) or D1 (6
P1/2, 894 nm) cesium
line. We utilized previously developed modified direct frequency comb
spectroscopy (DFCS) which uses a fixed frequency comb for the excitation and
a weak cw scanning probe laser centered at the 133Cs 6
2S1/2↦6 2P3/2 transition (D2 line) for ground
levels population monitoring. The frequency comb excitation changes the
usual Doppler absorption profile into a specific periodic, comblike
structure. The mechanism of the velocity selective population transfer
between the Cs ground state hyperfine levels induced by fs pulse train
excitation is verified in a theoretical treatment of the multilevel atomic
system subjected to a pulse train resonant field interaction. 相似文献
11.
W.-H. Sun S.-D. Du X.-S. Chen 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,38(2):397-404
We investigate the phase probability distribution (PPD) of a single-mode
micromaser pumped by atoms injected in the most general case, i.e. in the
superposition of the upper, intermediate and lower states by the Monte
Carlo wave function approach. The phase properties of the cavity mode are
greatly influenced by the relative phases and the amplitudes of the
polarized atoms, and the detunings between the atom and cavity. The cavity
field has a single preferred phase if the cavity is pumped by the atoms in
the superposition of the upper and intermediate states or of the
intermediate and lower states. However, a double-peak feature appears in the
PPD of the cavity field when the cavity is pumped by the atoms in the
superposition of the upper and lower states. With appropriate detunings, the
double peaks become narrower and more remarkable, which shows the better
defined phase of the cavity field, as compared to the resonant case. The PPD
displays complicated characteristics when the cavity is pumped by the atoms
in the superposition of the upper, intermediate and lower states. The phase
distribution changes from a single peak to double peaks and to another
single peak when we modulate the phase of the intermediate state, which has
been explained in the semi-classical radiation theory. 相似文献
12.
C. Kohl E. Suraud P.-G. Reinhard 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,11(1):115-122
We analyse theoretically the generation of second and higher harmonics for sodium clusters deposited on an insulating surface.
To this end, we use the time-dependent local-density approximation solved on a three-dimensional grid. We explore the impact
of the various laser parameters (intensity, frequency, polarisation) on the efficiency of second harmonic generation. The
success sensitively depends on a proper tuning of these parameters. We find optimum conditions for which the laser frequency
is half the resonance frequency of the system, if the polarisation is directed orthogonal to the surface of the substrate,
and if the intensity is large but safely below the critical value for destruction of the electron cloud.
Received 22 October 1999 and Received in final form 14 December 1999 相似文献
13.
H.-F. Zhang J.-H. Wu J.-Y. Gao 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,23(3):443-447
A five-level system to control the wavelength of the in-line amplifier by the quantum interference is proposed. It is found
that the gains of the first and the second probe can be adjusted by changing the coherent field and the incoherent pumping.
The new scheme may find its application in optical switch and optical communications.
Received 9 October 2002 Published online 24 April 2003
RID="a"
ID="a"e-mail: qol@mail.jlu.edu.cn 相似文献
14.
J. H. Li X. X. Yang 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,53(4):449-454
We analyze hybrid absorptive-dispersive optical bistability (OB)
behavior via tunable Fano-type interference based on intersubband
transitions in asymmetric double quantum wells (QWs) driven
coherently by a probe laser field by means of a unidirectional
ring cavity. We show that OB can be controlled efficiently by
tuning the energy splitting of the two excited states (the
coupling strength of the tunnelling), the Fano-type interference,
and the frequency detuning. The influence of the electronic
cooperation parameter on the OB behavior is also discussed. This
investigation may be used for optimizing and controlling the
optical switching process in the QW solid-state system, which is
much more practical than that in atomic system because of its
flexible design and the controllable interference strength. 相似文献
15.
G. Huang C. Hang L. Deng 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,40(3):437-444
We study stable propagation of multiple shape-preserving optical
pulses in an inhomogeneously broadened multi-level atomic medium.
By analytically solving the Maxwell-Schr?dinger equations
governing the evolution of N coupled optical fields and atomic
amplitudes we show that N pulsed optical waves coupling to
(N+1)-levels can be automatically matched with the same soliton
waveform and identical yet very slow propagation velocity. Several
sets of coupled soliton solutions for two different (N+1)-level
models are given and their stability is studied by using a
numerical simulation. 相似文献
16.
B. Macke B. Ségard 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,23(1):125-141
This paper deals with the apparent superluminal propagation of electromagnetic pulses in a linear dispersive medium. One specifically
examines the possibility that the pulse leaving the medium may be nearly identical to the incident one (low distortion) and
in significant advance of it (strongly negative group-delays). Favourable conditions are obtained in a dilute medium where
the required anomalous dispersion originates in an ensemble of narrow absorption or gain lines. Analytical expressions of
the advancement of the pulse centre-of-gravity and of the lowest order distortion are established from the transfer-function
of the medium. The experiments already achieved with arrangements involving a single absorption-line or a gain-doublet are
analysed in detail and compared. The considerable difficulties to overcome in order to attain advancements comparable to the
pulse width without important distortion are pointed out. New and promising schemes involving a narrow dip in a gain profile
or absorption-doublets are proposed.
Received 4 July 2002 / Received in final form 8 November 2002 Published online 4 February 2003
RID="a"
ID="a"e-mail: bruno.macke@univ-lille1.fr
RID="b"
ID="b"Unité Mixte de Recherche de l'Université et du CNRS (UMR 8523) 相似文献
17.
P. Sigmund 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,12(1):111-116
Second-harmonic cross-correlation operates a selection in time-phase among the randomly de-phased contributions to an optical
field that propagated through a scattering medium. It can thus be used to selectively detect the weak contribution remaining
coherent with the incident field.
Received 7 May 1999 相似文献
18.
X. J. Fan A. Y. Li S. F. Tian D. M. Tong S. Q. Gong Z. Z. Xu 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,42(3):483-488
We studied effects of the relative phase between the probe and driving fields on the absorption and dispersion properties
in an open three-level ladder system with spontaneously generated coherence but without incoherent pumping. It is shown that
by the phase controlling, switching from absorption to lasing without inversion (LWI) and enhancing remarkablely LWI
gain can be realized; large index of refraction with zero absorption and the
electromagnetically induced transparency can be obtained. We also find that
varying the atomic injection and exit rates has a considerable influence on
the phase dependent-absorption property of the probe field, existent of the
atomic injection and exit rates gives the necessary condition of the
realization of LWI, getting LWI is impossible in the corresponding closed
system without incoherent pumping. 相似文献
19.
Zhuan Li Li-Ping Deng Li-Sen Xu Kaige Wang 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,40(1):147-156
We study a four-level double-Λ atomic ensemble interacting with two
time-dependent signal fields and two stationary control fields. Though, in
each Λ channel, a pair of signal and control fields couple
resonantly with the two lower levels of atoms, the occurrences of
electromagnetically induced transparency (EIT) is affected by the coherence
of the four fields. In the discussion of atomic susceptibilities, we show
that the quantum coherence between the two lower levels can be either formed
or released according to the phase matching of the four fields. We analyze
the propagation equation of the two signal fields, and find two
characteristic solutions: the stationary transmission wave and the transient
decay wave. The former corresponds to a correlated EIT effect in which two
signal pulses are shape-matched. The latter is an opposite effect to the
correlated EIT in which two pulses quench simultaneously, thus named as the
correlated two-signal absorption (CTSA). We propose the CTSA condition in
correspondence with the EIT condition. The numerical simulation shows that
the double-Λ configuration is capable of manipulating synchronous
optical signals and thus provides multiplicity and versatility in quantum
information process. 相似文献
20.
K. Jin Z. C. Wang Q. Zhang 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,42(2):325-332
We study the absorption spectra of a degenerate V-type
atom, where a resonant driving field and a probe field drive
different branches of transitions and a dc field is applied to
drive the transition between two excited states. The effects of
vacuum induced coherence (VIC) on the absorption spectra are
investigated. It is demonstrated that in some special cases the
VIC can lead to the depression of absorption and narrow resonance.
The origin of these features are discussed. When the pump field
and the dc field have the same intensity, it is interesting to
find that the whole absorption spectrum comes mainly from the
absorptions induced by the interferences among different
transitions between dressed states. 相似文献