共查询到20条相似文献,搜索用时 52 毫秒
1.
We apply the expanded basis method (EBM) to investigate the behavior of light in polaritonic photonic crystal (PC) slabs with losses. The influence of losses on transmissivity is studied. It is found that the transmissivity is significantly lowered with the increase of losses, in particular, it is abruptly decreased in the vicinity of transverse-optical-phonon frequency. The electromagnetic (EM) dissipation is mainly dominated by the imaginary part of dielectric constant of PC. The larger the imaginary part of the dielectric constant, the more the EM energy depletion is. The variation of EM dissipation with the number of period layers in the PC slab is approximately linear or oscillatory increase with the number of period layers. 相似文献
2.
B. Zhang M. Y. Li 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,45(2):321-323
An optimized surface modification structure for
suppressing the reflections at the surfaces of photonic crystal slab lens is reported in this paper. The total reflection
of the slab lens with proposed anti-reflection surface structure is reduced to below 0.3% for the incident angle of light
less than 48 degrees. The image efficiency of the slab lens for the normal incident Gaussian beam with waist width equal to
the wavelength is near 99%. 相似文献
3.
O.N. Gadomsky S.V. Sukhov Yu.Yu. Voronov 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,11(2):185-190
The self-consistent problem is solved for the interaction of two dipole atoms situated at arbitrary distance from one another
with the field of quasiresonant light wave. Atoms are considered to be linear Lorenz oscillators. Polarizing fields inside
the system include both Coulomb and retarding parts. The solutions obtained are investigated for the case when atoms have
the same polarizabilities and interatomic distance is much less than external light wavelength. Formulas for electric fields
inside and outside of small object are obtained. It is shown that longitudinal and transverse optical oscillations are possible
to exist inside small two-atom object. Dispersion laws of these oscillations depend upon interatomic distance and upon angle
between axis of the system and the direction of propagation of external wave. The field outside the small object in wave zone
is linearly polarized with the choice of linear polarization of external field. However, the directions of polarization of
these waves are different and depend essentially upon frequency. The amplitude of field outside small object in wave zone
is shown to depend essentially on the frequency of external field and interatomic distance. The results obtained are treated
as near-field effect in the optics of small objects making it possible to investigate the structure of small objects with
optical radiation.
Received 26 October 1998 and Received in final form 26 January 2000 相似文献
4.
Arkhipkin VG Gunyakov VA Myslivets SA Zyryanov VY Shabanov VF 《The European physical journal. E, Soft matter》2007,24(3):297-302
A one-dimensional ZrO2/SiO2 photonic crystal with a 4-n -pentyl-4' -cyanobiphenyl (5CB) nematic defect layer was used to investigate the transmission spectra of light polarized
parallel and perpendicular to the liquid-crystal director at different angles of incidence. The spectra of the photonic crystal
were shown to split into four polarized components Tij at oblique incidence. When the incident angle increased, the bandgap edges and the defect modes shifted towards short wavelengths,
while the amplitudes of the defect modes increased for the transverse magnetic polarization and decreased for the transverse
electric polarization. The observed discrepancy between the defect mode amplitudes in the center and near the edges of the
photonic bandgap was found to be related to the radiation losses inside the defect layer of a non-ideal photonic crystal.
The simulated transmission spectra obtained using recurrence relations and taking into account the decay of defect modes are
in good agreement with the experimental data. 相似文献
5.
Xiangdong Zhang 《Physics letters. A》2008,372(19):3512-3516
A new transport regime of photon in two-dimensional photonic crystal near the Dirac point has been demonstrated by exact numerical simulation. In this regime, the conductance of photon is inversely proportional to the thickness of sample, which can be described by Dirac equation very well. Both of bulk and surface disorders always reduce the transmission, which is in contrast to the previous theoretical prediction that they increase the conductance of electron at the Dirac point of graphene. However, regular tuning of interface structures can cause the improvement of photon conductance. Furthermore, large conductance fluctuations of photon have also been observed, which is similar to the case of electron in graphene. 相似文献
6.
N. D. Lu Y. Q. Zhou T. G. Shen P. L. Ji J. Sun B. G. Yuan F. C. Yu 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,54(3):707-710
The paper investigated a composite photonic crystal patch antenna by using the method of finite difference time domain (FDTD).
The results show that there exists a wave resonance state at 2.635 GHz, where the real part of the permittivity and permeability
are all negative; its refraction index is –1. The effect has largely enhanced the electromagnetic wave’s resonance intensity,
and has improved the localized extent of electromagnetic energy obviously in such photonic crystal structure (PBG), resulting
in a higher antenna gain, a lower return loss, and a better improvement of the antenna’s characteristics. Due to such the
advantages, the use of patch antennas can be extended to such fields as mobile communication, satellite communication, aviation,
etc. 相似文献
7.
A. A. Zemlyanov Y. E. Geints 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,42(2):349-357
The generic scenario of intense femtosecond laser pulse propagation in the
air from the viewpoint of evolution of its integral effective parameters
(energy transfer coefficient, effective radius, effective duration, limiting
angular divergence) is considered. The analysis of variation of the
effective parameters along the propagation path in the single and multiply
filamentation scenarios based on numerical calculations is presented. It is
shown that the process of self-action of the ultrashort radiation is
characterized by the formation in a medium of the nonlinearity layer, after
which optical pulse propagates quasi-linearly with the limiting angular
divergence that depends mainly on initial pulse power. The effective pulse
temporal duration and the effective beam radius increase after the passage
through the nonlinearity layer, and their values are mostly determined by
the initial beam power also. The coefficient of energy transmission of
femtosecond laser radiation is lower than in the linear medium and has a
tendency to decrease with the increase of the pulse power. 相似文献
8.
J.M. Luck T.M. Nieuwenhuizen 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,7(3):483-500
No direct imaging is possible in turbid media, where light propagates diffusively over length scales larger than the mean
free path .The diffuse intensity is, however, sensitive to the presence of any kind of object embedded in the medium, e.g. obstacles or defects. The long-ranged effects of isolated objects in an otherwise homogeneous, non-absorbing medium can be
described by a stationary diffusion equation. In analogy with electrostatics, the influence of a single embedded object on
the intensity field is parametrized in terms of a multipole expansion. An absorbing object is chiefly characterized by a negative
charge, while the leading effect of a non-absorbing object is due to its dipole moment. The associated intrinsic characteristics
of the object are its capacitance Q or its effective radius ,and its polarizability P. These quantities can be evaluated within the diffusion approximation for large enough objects. The situation of mesoscopic
objects, with a size comparable to the mean free path, requires a more careful treatment, for which the appropriate framework
is provided by radiative transfer theory. This formalism is worked out in detail, in the case of spherical and cylindrical
objects of radius R, of the following kinds: (i) totally absorbing (black), (ii) transparent, (iii) totally reflecting. The capacitance, effective
radius, and polarizability of these objects differ from the predictions of the diffusion approximation by a size factor, which
only depends on the ratio .The analytic form of the size factors is derived for small and large objects, while accurate numerical results are obtained
for objects of intermediate size .For cases (i) and (ii) the size factor is smaller than one and monotonically increasing with ,while for case (iii) it is larger than one and decreasing with .
Received: 7 August 1998 / Accepted: 3 September 1998 相似文献
9.
J. P. Xu Y. P. Yang 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,49(1):135-145
Recently, Liu et al. [Phys. Rev. B 74, 075314 (2006)] pointed out that the atomic instant decay rate in one dimensional photonic crystal (1DPC) showed a series
of pulse-like peaks with time. In this paper, we continue their work, and adopt a special 1DPC, in which the refractive indexes
of both constitution layers in a period are the same, to perform the analysis in detail. Our results show that the pulse-like
peak of instant decay rate originates from the interaction between the atom and the sub-reservoir, the latter of which corresponds
to the group of reflected fields having the same optical distance. The atom interacts with such a sub-reservoir mainly after
the time needed for propagation. However, near the arrival time of the reflected field, the atomic level is broadened and
couples to all frequency components of the sub-reservoir, and the pulse-like peak of instant decay rate appears. Although
our conclusion is deduced with the special 1DPC, it is also valid for more general cases and might be useful to measure the
quantum Zeno and anti-Zeno effect, since the interval of repeated measurements may be expanded to several optical cycles in
1DPC, which will facilitate the observation of the quantum Zeno or anti-Zeno effect. 相似文献
10.
J. P. Xu Y. P. Yang N. H. Liu S. Y. Zhu 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,41(2):403-411
Inserting left-handed material (LHM) layers into a one dimensional structure
can influence the spontaneous emission (SpE) of a two-level atom. This has
been investigated, starting from the simplest case of a three-layer
system, where we find the reflected field (atom can “see”) passing through
LHM layer is stronger than that through the corresponding normal layer.
Indeed the induced decay is more strongly influenced by reflected field
passing through LHM layer.
Based on this and after further analysis of reflectivity, we find that, a
quarter photonic crystal (PC) composed of alternately LHM and RHM can
inhibit the atomic spontaneous emission more intensely compared to an
ordinary PC. 相似文献
11.
12.
H. Xiao D. Z. Yao C. X. Wang S. Chen 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,64(2):219-229
The absolute photonic band gap (PBG) in two-dimensional (2D) photonic crystal with excentric core-shell rods is studied in
this paper. The core rod shifts away from the core-shell rod center, and its position is decided by two new introduced parameters
— the shift angle θ and the offset ρ. We use the FDTD algorithm to calculate the photonic bands of the photonic crystal, and analyze how the offset and shift
angle affect the photonic bang gap of excentric core-shell photonic crystal for different core rod size. It has been shown
that the variation of the photonic band gap is quite peculiar. 相似文献
13.
D. Benredjem V. Bommier H. Guennou C. Möller A. Sureau 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,2(1):83-87
In order to solve the radiative-transfer equation for polarized beams propagating in plasmas a matrix approach is applied.
The solution is the four-components Stokes vector, and the effect of the medium on the state of the radiation is represented
by an amplification operator. Our approach is applied to the neon-like germanium 23.6 nm line, when a right-circularly polarized
beam is injected into an amplifying plasma. The conditions governing the recovery of the initial polarization state are investigated
over the entire spectrum of the output.
Received: 10 October 1997 / Revised: 12 January 1998 / Accepted: 27 January 1998 相似文献
14.
M. Cheng R. Chen S. Feng 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,50(1):81-85
The lateral shift of a light beam at the surface of an anisotropic
metamaterial slab is investigated. Analytical expressions of the lateral
shifts are derived using the stationary-phase method, in the case that total
reflection does and does not occur at the first interface. The sign of the
lateral shift in two situations is discussed, and the necessary conditions
for the lateral shift to be positive or negative are given. It is shown that
the thickness and physical parameters of the anisotropic metamaterial slab,
as well as the incident angle of the light beam, strongly affect the
properties of the lateral shift, and numerical results validate these
conclusions. The effect of a lossy metamaterial on the lateral shift is also
investigated. A restriction on the thickness of the slab is obtained, which
is necessary for the stationary-phase method to remain valid. 相似文献
15.
Xiangbo Yang Youyan Liu 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,15(4):625-631
After establishing the method of constructing a class of one-dimensional (1D) Fibonacci-class quasiperiodic (FC(n)) ferroelectric domains system, we have studied the properties of the electric field of the second harmonic generation (SHG)
by means of the small-signal approximation in the case of the vertically transmission. It was found that only the second harmonic
light (SHL) peaks which were indexed by two special integers q and p would be the brightest and the spectra whose positions were decided by successive FC(n) integers and were perfect self-similar without considering the dispersive effect of the refractive index on SHL. The effect of the vacancies
for some special spectral lines was also studied generally. The analytic results were confirmed by the numerical simulations.
Received 26 October 1999 and Received in final form 6 January 2000 相似文献
16.
E.G. Mishchenko M. Patra C.W.J. Beenakker 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,13(2):289-297
A theory is presented for the frequency dependence of the power spectrum of photon current fluctuations originating from a
disordered medium. Both the cases of an absorbing medium (“grey body”) and of an amplifying medium (“random laser”) are considered
in a waveguide geometry. The semiclassical approach (based on a Boltzmann-Langevin equation) is shown to be in complete agreement
with a fully quantum mechanical theory, provided that the effects of wave localization can be neglected. The width of the
peak in the power spectrum around zero frequency is much smaller than the inverse coherence time, characteristic for black-body
radiation. Simple expressions for the shape of this peak are obtained, in the absorbing case, for waveguide lengths large
compared to the absorption length, and, in the amplifying case, close to the laser threshold.
Received 8 August 2000 相似文献
17.
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
18.
M. Lontano D. Ryutov 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,18(3):347-351
We demonstrate the in situ detection of cold 87Rb atoms near a dielectric surface using the absorption of a weak, resonant evanescent wave. We have used this technique in
time of flight experiments determining the density of atoms falling on the surface. A quantitative understanding of the measured
curve was obtained using a detailed calculation of the evanescent intensity distribution. We have also used it to detect atoms
trapped near the surface in a standing-wave optical dipole potential. This trap was loaded by inelastic bouncing on a strong,
repulsive evanescent potential. We estimate that we trap 1.5×104 atoms at a density 100 times higher than the falling atoms.
Received 14 May 2002 Published online 8 October 2002
RID="a"
ID="a"e-mail: spreeuw@science.uva.nl 相似文献
19.
S.-y. Xie Y.-p. Yang X. Wu 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,13(1):129-143
We study the spontaneous emission properties of a V-type three-level atom embedded in a photonic crystal with the anisotropic
dispersion relation. We show that the localized field can disappear and the diffusion field can become intense in some regions.
This originates from no singularity of the density of states. The quantum interference leads to oscillatory, quasi-oscillatory
or complete decay behavior of population. The complete decay can also be realized in certain condition without depending on
the initial state.
Received 9 April 2000 and Received in final form 1st August 2000 相似文献
20.
S. M. Vuković N. B. Aleksić D. V. Timotijević 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,39(2):295-301
We studied electromagnetic beam reflection from layered
structures that include materials with negative refraction. Excitation of
leaky surface waves leads to the formation of anomalous lateral shifts in the reflected beams
with single or double peak structures. The presence of reasonable losses
within material with negative refraction, besides significant influence on
manifestation of the giant lateral shifts, can lead to their total
suppression and anomalously high absorption of the incident radiation. If,
in addition to the resonant excitation of leaky surface waves, radiation
inflow exactly compensates their irreversible damping, total absorption of the incoming
radiation can be achieved for moderately wide beams. 相似文献