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1.
采用交叉色关联的加性色噪声和乘性色噪声驱动的单模激光立方模型,通过诺维科夫理论和福克斯近似以及斯特拉托诺维奇近似,得到反映激光统计性质的强度关联函数C的表达式;研究关联时间τ、净增益系数a0和交叉关联强度λ对强度关联函数C的影响.数值模拟发现,在阈值以上(a0>0)时,关联函数C随关联时间τ的增大而增大;在阈值以下(a0<0)时,关联函数C随关联时间τ的增大而减小.无论在阈值以上还是阈值以下,关联函数C均随交叉关联强度λ的增大而减小.在C-a0曲线上存在单峰.
关键词:
单模激光
交叉关联
强度涨落
强度关联函数 相似文献
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在弱波导近似下,用标量Helmholtz方程的解作为零级近似解,考虑了折射率梯度的影响,把∇ε项看作微扰项,用微扰法给出了具有色散位移特性的三角形折射率剖面单模光纤一级修正解的积分表达式,并给出了数值计算结果.原则上,该方法亦可用于多模光纤. 相似文献
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在对周期性结构进行谐波分析的基础上,导出了非截面二维光子晶体排列矩形波导的本征值方程. 基于此方程,可以对该类光子晶体波导的所有可能模式进行分析. 分析认为,非截面二维光子晶体排列矩形波导内能存在的模式包括E(y),TEy,H(y)和TMy模式;改变波导高度,可以实现E(y)模式和H(y)模式与其他模式通带的完全分离. 然而改变任一结构参数,都不能使E(y)和H(y)的各个模式通带,以及E(y)1模式和H(y)1模式的通带完全隔离. 波导单模工作的带宽由E(y)1和E(y)2模式的低端截止频率决定.
关键词:
波导
光子晶体
本征值方程
模式 相似文献
8.
采用密度泛函理论(density functional theory,DFT)中的广义梯度近似(generalized gradient approximation,GGA)对MPb10(M=Ti,V,Cr,Cu,Pd)四种同分异构体的几何结构和磁性进行了计算研究.发现在四种同分异构体中,D4d结构的MPb10(M=Ti,V,Cr,Cu,Pd)具有最大的结合
关键词:
几何结构
磁性
密度泛函 相似文献
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Recently, Nanoparticle Surface Area Monitor (NSAM, TSI model 3550) and EAD (EAD, TSI Model 3070A) have been commercially available
to measure the integral parameters (i.e., total particle surface area and total particle length) of nanoparticles. By comparison,
the configuration of the EAD or NSAM is similar to that of electrical mobility analyzer of the early generation for particle
size distribution measurement. It is therefore possible to use the EAD or NSAM as a particle sizer. To realize the objective
of using the EAD as a sizer, we characterized the average electrical charges of monodisperse particles passing through the
EAD particle charger and ion trap set at voltages ranging from 20 to 2500 V. The average charge data collected at different
ion-trap voltages were then summarized by the empirical correlation using the parameter of Z
p
*V, where Z
p is the particle electrical mobility and V is the ion-trap voltage. A data-reduction scheme was further proposed to retrieve the size distribution of sampled particles
from the EAD readout at different ion-trap voltages. In the scheme, the functional format of each mode in a number size distribution
of particles was assumed as log-normal, but the number of modes in an entire size distribution is not limited. A criterion
was used to best fit the simulated EAD readouts with experimental ones by varying the count median diameter (CMD), geometric
standard deviation (σ
g), and total particle number (N
t
) of each mode in a particle size distribution. Experiments were performed to verify the proposed scheme. 相似文献
12.
In the paper calculation of the moments of inertia for nuclei from the region 87 ≤ Z ≤ 100 and 130 ≤ N ≤ 156 was made in dependence on the angular momentum of their rotational states. The experimental values of the moments of
inertia were calculated for rotational energy of the classic rotor in its quantum form, with the use of a simple formula.
The moment of inertia term appearing in the formula was treated as a variable. The calculations were carried out on the basis
of experimental data for the energies of the rotational levels for 51 bands built on ground states for even-even nuclei and
for nuclei with odd mass number A. In addition, 30 rotational bands built on excited states were also analysed in the investigated region in case of even-even
nuclei. For many bands and nuclei the considered dependence of the moment of inertia on angular momentum has been found in
the analytical form by fitting polynomials to the experimental data. It turned out that obtained results for the moments of
inertia made it possible to describe the energies of rotational levels with a relative deviation not greater or only slightly
greater than 1%. In general, in the case of 12 bands of ground level the maximum relative deviation of obtained level energies
is smaller than 1%.
相似文献
13.
We investigate here the origin of nuclear levelwidth as an effect of the coupling of particle mode and the surface vibration
mode of the nucleus. This interaction is taken to be stochastic in nature, characterized by a single correlation timet
0, the random nature of the interaction originating from the partition of the total hamiltonian into those of the two modes.
The Redfield equation of motion for the density matrix for the particle mode is solved. The solution of the Redfield equation
shows that the occupation number in any particle state decays with a time constant depending on the correlation timet
0 and the quantum-mechanical matrix elements of the interaction hamiltonian. The inverse of this decay time will give the width
of this level. Numerical calculations have been done for
82
207
Pb125. 相似文献
14.
Jamal T. Manassah 《Laser Physics》2012,22(3):559-565
Using eigenmode analysis I calculate in the linear regime the emission characteristics from a slab of two-level resonant atoms
excited by a delta-pulse propagating normal to the surface of the slab. I show that the qualitative features of the emitted
spectra in the forward and backward directions to be different from each other; I also find the effects of the total linewidth
of the resonance line and of the deviation in the spatial periodicity of the initial atomic polarization from k
0, where k
0 = ω0/c and ω0 is the two level resonant frequency, on the spectra. The dominant spatial mode of the system is identified as the key parameter
for determining the forward emission spectral width. 相似文献
15.
提出了一种基于耦合介质纳米线的深亚波长局域波导,通过两根紧邻的高折射率介质纳米线的耦合,该波导可以将光场有效束缚在纳米线之间的低折射率纳米缝隙中. 计算模拟的结果表明,该波导的有效模场面积达到Λ20/200,比单根纳米线波导小一个数量级,这种深亚波长的模场束缚能力可以与表面等离激元混合波导相比拟. 计算模拟的结果还表明,纳米线可能带有的低折射率氧化膜、低折射率衬底的存在、以及纳米线间尺寸存在的一定差异对于该波导结构的实际应用都不会产生很大
关键词:
介质波导
亚波长局域
表面等离激元波导
纳米线 相似文献
16.
P. PALMIERI C. PUZZARINI V. AQUILANTI G. CAPECCHI S. CAVALLI D. DE FAZIO 《Molecular physics》2013,111(21):1835-1849
The reaction He + H+ 2(v,j = 0) → HeH+(v′ = 0, j′) for v = 0, 1,2 and 3 and for scattering energies near the threshold (0.95–1.15 eV) has been studied by calculating ab initio points at MRCI level and ‘exact’ integral quantum reactive cross-sections. More than 1400 nuclear geometries have been chosen to cover the most important regions for the dynamics, an extended set of points being taken directly on a hyperspherical coordinate grid. A many-body expansion with a large number of terms permits an accurate analytical representation of the potential energy surface with a root-mean-square deviation <12meV. The hyperquantization algorithm has been extended to obtain quantum mechanical integral cross-sections which are compared with previous calculations and with experimental results. 相似文献
17.
Non-stoichiometric metals with strongly varying electron concentration: Gd-monochalcogenides and LaS
W. Beckenbaugh J. Evers G. Güntherodt E. Kaldis P. Wachter 《Journal of Physics and Chemistry of Solids》1975,36(4):239-248
The reflectivity of single crystals of Gd monochalcogenides and of LaS has been measured at 300 K in the spectral region between 0.03 and 12eV. Special attention has been given to the chemical analysis of the materials and the determination of the deviation from stoichiometry. The optical constants have been determined by means of a Kramers-Kronig relation. A coupled mode of plasmons with interband transitions has been observed. The separation into interband transitions and free electron behaviour permitted the determination of the number of free carriers and their effective mass. It can be shown that the carrier concentration changes much more drastically than the stoichiometry. By comparison with LaS the position of the 4f7 levels of GdS was found to be 9 eV below the Fermi level. 相似文献
18.
E. Lotfi K. Jamshidi-Ghaleh F. Moslem H. Masalehdan 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2010,60(2):369-372
The photonic band-gap of the two kinds of 1D photonic crystal structure
which is composed of the form of (AB)
N1
C
m
(BA)
N2
, one with a
metamaterial defect layer (MDL) and the other one with a dielectric defect
layer (DDL) are studied. Our results show that in both cases, where there is
only one defect layer, m=1, no defect mode exists, but for two defect
layers (m=2) there is a single defect mode which is centered in the middle
of the band-gap. The width of the defect mode in DDL is narrower than that
in MDL. For a number of defects of more than two (m>2) and even, in both of
the MDL and DDL structures, there is only one defect mode. For m>2 and
odd, the defect mode in the MDL vanishes, but for DDL there is two defect-mode symmetrically centered in the middle of the
band-gap. The effects of the
defect layers refractive index value, the periodicity number of the
structures and the incident angle on the properties of the defect modes and
the transmittance spectrum are discussed. 相似文献
19.
Quantum fluctuations of the number of photons of the fundamental mode and of the second harmonic in the process of intracavity
generation of the second harmonic in the unstable region of the system are studied. The distribution functions of the number
of photons of interacting modes are calculated in the positive P-representation. The functions of the joint distribution of the number of photons of the fundamental mode and the number of
photons in the second harmonic are also studied. 相似文献
20.
The spectrum of capillary oscillations of a charged oblate spheroidal drop is calculated in neglect of the interaction between
modes by means of a perturbation expansion in the small deviation of the equilibrium shape of the drop from spherical. The
critical conditions for instability of its nth mode with respect to the self-charge are calculated in the form of an analytical function describing how the dimensionless
Rayleigh parameter characterizing the stability of the drop depends on the value of the spheroidal deformation.
Zh. Tekh. Fiz. 69, 10–14 (July 1999) 相似文献