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91.
Far-Field Distributions of Double-Heterostructure Diode Lasers: an Improved Non-Equiphase Model
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A non-equiphase Gaussian model is proposed to simulate the far-field distributions ofdouble-heterostructure diode lasers, which is physically reasonable because the phase along the junction of diode lasers could not be equal, A comparison of the numerically calculated intensity profiles in using the equal phase and non-equiphase models with the experimentally measured intensity profiles given by Nemoto shows that in the x direction perpendicular to the junction plane, the non-equiphase Gaussian model is as good as the equal phase Gaussian model. Specifically, in the y direction parallel to the junction plane and the 45° direction with respect to the x axis in the xoy plane, the numerical results by using the non-equiphase model are in good agreement with the experimental data, as the propagation distance is larger than a certain value. 相似文献
92.
Sub-Doppler spectral resolution has been studied in Doppler-broadened multi-level 87Rb atoms coherently coupled by two strong laser fields. Narrow spectral features of absorption or gain are observed in the center or sides of the Doppler-broadened absorption profile. Analytical and numerical calculations based on a four-level N type model are presented to explain the experimental results. 相似文献
93.
94.
Ch. Andreeva G. Bevilacqua V. Biancalana S. Cartaleva Y. Dancheva T. Karaulanov C. Marinelli E. Mariotti L. Moi 《Applied physics. B, Lasers and optics》2003,76(6):667-675
We investigate the coherent population trapping effect occurring between the Zeeman sublevels of a given hyperfine state of
Cs when excited by a single-mode diode laser, which is frequency modulated in the kHz–MHz range. In the presence of a dc magnetic
field, simultaneous excitation of pairs of ground-state magnetic sublevels to common excited magnetic sublevels is performed.
As a result, coherent population trapping resonance is detected at only a given modulation frequency, whose value gives a
measure of the magnetic field. The parameters of the resonances are measured in order to determine the ultimate accuracy of
the magnetic field measurement.
Received: 6 December 2002 / Revised version: 24 February 2003 / Published online: 2 June 2003
RID="*"
ID="*"Corresponding author. Fax: +39-0577/23-4689, E-mail: biancalana@unisi.it 相似文献
95.
From laser-induced line narrowing to electro- magnetically induced transparency: closed system analysis 总被引:1,自引:0,他引:1
The laser-induced line-narrowing effect, discovered more than thirty years ago, can also be applied to recent studies in high
resolution spectroscopy based on electromagnetically induced transparency. In this paper we first present a general form of
the transmission width of electromagnetically induced transparency in a homogeneously broadened medium. We then analyze a
Doppler broadened medium by using a lorentzian function as the atomic velocity distribution. The dependence of the transmission
linewidth on the driving field intensity is discussed and compared to the laser-induced line-narrowing effect. This dependence
can be characterized by a parameter which can be regarded as “the degree of optical pumping.”
Received: 17 December 2001 / Published online: 15 January 2003
RID="*"
ID="*"Corresponding author. E-mail: hwang.Lee@jpl.nasa.gov
RID="**"
ID="**"Present address: Jet Propulsion Laboratory, MS 126-347, California Institute of Technology, Pasadena, CA 91109, USA 相似文献
96.
97.
The effects of the squeezed vacuum (SV) on the transient optical properties in a ∧-type three-level atomic medium with or without the vacuum-induced coherence (VIC) are investigated in this paper. We find that the oscillatory amplitude of the optical spectra, the transient absorption (gain), and the response time from the transient to the steady situation are remarkably dependent on the SV. When including the VIC, the transient and steady optical properties display a reverse variation with the SV. Additionally, it is interesting to find that the steady population distribution is kept at the same value for different initial conditions in the presence of SV. 相似文献
98.
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
99.
We investigate the group velocity of light in a one-dimensional volume grating inside lithium niobate crystals doped with different impurities. The superluminal and slowdown light propagations are both observed in the crystals. The relationships between the group refractive index and the grating amplitude and phase shift are presented and discussed. 相似文献
100.
N. Simonović P. Grujić 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,42(1):1-10
The semiclassical spectrum of quadruply highly excited
four-electron atomic systems has been calculated for the plane
model of equivalent electrons. The energy of the system consists
of rotational and vibrational modes within the circular skeleton
orbit approximation, as used in a previous calculation for the
triply excited three-electron systems. The full dynamical analysis
is carried out within the Hamiltonian theory, accounting for the
inertial effects and the complete coupling between different
degrees of freedom. Here we present numerical results for energy
spectrum of the beryllium atom. The lifetimes of the semiclassical
states are estimated via the corresponding Lyapunov exponents. The
vibrational modes relative contribution to the energy levels rises
with the degree of the Coulombic excitation. 相似文献